## UI components for content analysis in Biblioshiny ----

#' Content Analysis Tab Item with two main tabs for Biblioshiny UI
#'
#' This creates a tabItem with 2 main tabs:
#' 1. Import PDF File - Contains the PDF upload interface and analysis results (with 3 sub-tabs)
#' 2. Info & References - Contains help documentation
#'
#' @param id Character, the tab item ID (default: "content_analysis")
#' @return A tabItem object for biblioshiny

content_analysis_tab <- function(id = "content_analysis") {
  tabItem(
    tabName = id,

    # Main tabsetPanel with Import and Info & References
    tabsetPanel(
      id = "content_analysis_main_tabs",
      type = "tabs",

      # ===========================================
      # MAIN TAB 1: IMPORT PDF FILE
      # ===========================================
      tabPanel(
        title = "Import and Analyze PDF File",
        value = "tab_import_pdf",
        icon = icon("upload"),

        br(),

        # Tab header
        fluidRow(
          column(
            7,
            div(
              class = "page-header",
              h2(
                "Scientific Article Content Analysis",
                style = "color: #2E86AB; margin-bottom: 10px;"
              ),
              p(
                "Upload a PDF file and analyze citation patterns, context, and co-occurrence networks.",
                style = "color: #666; font-size: 16px; margin-bottom: 20px;"
              )
            )
          ),
          column(
            5,
            div(
              style = "text-align: right; padding-top: 15px;",

              # Document metadata display (shown after text extraction)
              conditionalPanel(
                condition = "output.metadata_available",
                uiOutput("pdf_metadata_display")
              ),

              # Export buttons (shown after analysis completion)
              conditionalPanel(
                condition = "output.analysis_completed",
                div(
                  style = "display: flex; gap: 8px; justify-content: flex-end; flex-wrap: wrap;",
                  downloadButton(
                    "download_all_results",
                    "Export All Results",
                    icon = icon("file-excel"),
                    class = "btn-success",
                    style = "font-weight: bold; margin-top: 10px;"
                  ),
                  actionButton(
                    "export_all_images",
                    "Export All Images",
                    icon = icon("image"),
                    class = "btn-info",
                    style = "font-weight: bold; margin-top: 10px;"
                  )
                )
              )
            )
          )
        ),

        fluidRow(
          # ===========================================
          # RIGHT PANEL: TABBED RESULTS (column 10)
          # ===========================================
          column(
            10,

            # NEW: Button to open modal and DOI field (visible only after extraction)
            conditionalPanel(
              condition = "output.text_extracted && !output.analysis_completed",
              div(
                style = "margin-bottom: 15px; padding: 15px; background-color: #e8f4f8; border-radius: 5px;",

                # First row: preview button and message
                fluidRow(
                  column(
                    6,
                    align = "center",
                    actionButton(
                      "open_preview_btn",
                      "View Extracted Text & PDF Preview",
                      icon = icon("file-alt"),
                      class = "btn-info",
                      onclick = "$('#previewModal').modal('show');",
                      style = "width: 70%;"
                    )
                  ),
                  column(
                    6,
                    align = "center",
                    downloadButton(
                      "save_text_file",
                      "Save Extracted Text",
                      icon = icon("save"),
                      class = "btn-success",
                      style = "width: 70%;"
                    )
                  )
                ),
                fluidRow(
                  column(
                    12,
                    div(
                      style = "margin-top: 10px;",
                      span(
                        icon("check-circle", style = "color: #27ae60;"),
                        " Text extracted successfully!",
                        style = "color: #555; font-weight: 500;"
                      )
                    ),
                    helpText(
                      "💾 The 'Save' button will save the text with DOI and citation format info for easy reloading.",
                      style = "margin-top: 5px; font-size: 11px; color: #666; font-style: italic;"
                    )
                  )
                ),

                # Second row: DOI field
                fluidRow(
                  style = "margin-top: 15px;",
                  column(
                    12,
                    div(
                      style = "background-color: white; padding: 10px; border-radius: 4px; border: 1px solid #d1e7f0;",
                      fluidRow(
                        column(
                          2,
                          tags$label(
                            "Document DOI:",
                            style = "margin-top: 8px; font-weight: bold; color: #2E86AB;"
                          )
                        ),
                        column(
                          4,
                          textInput(
                            "pdf_doi_input",
                            label = NULL,
                            value = "",
                            placeholder = "Enter or edit DOI (e.g., 10.1234/example)",
                            width = "100%"
                          )
                        ),
                        column(
                          6,
                          div(
                            style = "margin-top: 8px;",
                            uiOutput("doi_status_icon")
                          )
                        )
                      ),
                      helpText(
                        "The DOI is used to fetch reference details from Crossref. Edit if needed or add manually if not detected.",
                        style = "margin-bottom: 0px; margin-top: -5px; font-size: 11px; color: #666;"
                      )
                    )
                  )
                )
              )
            ),

            conditionalPanel(
              condition = "output.analysis_completed",

              # NEW: Info after analysis
              div(
                style = "margin-bottom: 10px;",
                fluidRow(
                  column(
                    4,
                    actionButton(
                      "reopen_preview_btn",
                      "View Original Text",
                      icon = icon("file-alt"),
                      class = "btn-default btn-sm",
                      onclick = "$('#previewModal').modal('show');"
                    )
                  ),
                  column(
                    8,
                    div(
                      style = "text-align: right; padding-top: 5px;",
                      tags$strong("DOI: ", style = "color: #2E86AB;"),
                      tags$span(
                        textOutput("doi_display_after_analysis", inline = TRUE),
                        style = "font-family: 'Courier New', monospace; color: #555; background-color: #f8f9fa; padding: 4px 8px; border-radius: 3px; border: 1px solid #dee2e6;"
                      )
                    )
                  )
                )
              ),
              tabsetPanel(
                id = "content_tabs",
                type = "tabs",

                # ===========================================
                # TAB 1: DESCRIPTIVE STATISTICS
                # ===========================================
                tabPanel(
                  title = "Descriptive Statistics",
                  value = "tab_stats",

                  br(),

                  # Summary Statistics Cards
                  fluidRow(
                    column(
                      3,
                      div(
                        class = "info-box bg-aqua",
                        span(class = "info-box-icon", icon("file-text")),
                        div(
                          class = "info-box-content",
                          span("Total Words", class = "info-box-text"),
                          span(
                            textOutput("total_words", inline = TRUE),
                            class = "info-box-number"
                          )
                        )
                      )
                    ),
                    column(
                      3,
                      div(
                        class = "info-box bg-green",
                        span(class = "info-box-icon", icon("quote-right")),
                        div(
                          class = "info-box-content",
                          span("Citations Found", class = "info-box-text"),
                          span(
                            textOutput("total_citations", inline = TRUE),
                            class = "info-box-number"
                          )
                        )
                      )
                    ),
                    column(
                      3,
                      div(
                        class = "info-box bg-yellow",
                        span(class = "info-box-icon", icon("users")),
                        div(
                          class = "info-box-content",
                          span("Narrative Citations", class = "info-box-text"),
                          span(
                            textOutput("narrative_citations", inline = TRUE),
                            class = "info-box-number"
                          )
                        )
                      )
                    ),
                    column(
                      3,
                      div(
                        class = "info-box bg-red",
                        span(class = "info-box-icon", icon("chart-line")),
                        div(
                          class = "info-box-content",
                          span("Citation Density", class = "info-box-text"),
                          span(
                            textOutput("citation_density", inline = TRUE),
                            class = "info-box-number"
                          ),
                          span("/1000 words", class = "info-box-more")
                        )
                      )
                    )
                  ),

                  fluidRow(
                    column(
                      3,
                      div(
                        class = "info-box bg-purple",
                        span(class = "info-box-icon", icon("graduation-cap")),
                        div(
                          class = "info-box-content",
                          span("Flesch-Kincaid Grade", class = "info-box-text"),
                          span(
                            textOutput("flesch_kincaid_grade", inline = TRUE),
                            class = "info-box-number"
                          )
                        )
                      )
                    ),
                    column(
                      3,
                      div(
                        class = "info-box bg-blue",
                        span(class = "info-box-icon", icon("book-reader")),
                        div(
                          class = "info-box-content",
                          span("Reading Ease", class = "info-box-text"),
                          span(
                            textOutput("flesch_reading_ease", inline = TRUE),
                            class = "info-box-number"
                          )
                        )
                      )
                    ),
                    column(
                      3,
                      div(
                        class = "info-box bg-teal",
                        span(class = "info-box-icon", icon("robot")),
                        div(
                          class = "info-box-content",
                          span("ARI Index", class = "info-box-text"),
                          span(
                            textOutput("ari_index", inline = TRUE),
                            class = "info-box-number"
                          )
                        )
                      )
                    ),
                    column(
                      3,
                      div(
                        class = "info-box bg-maroon",
                        span(class = "info-box-icon", icon("cloud")),
                        div(
                          class = "info-box-content",
                          span("Gunning Fog Index", class = "info-box-text"),
                          span(
                            textOutput("gunning_fog_index", inline = TRUE),
                            class = "info-box-number"
                          )
                        )
                      )
                    )
                  ),
                  # Readability Indices Details
                  fluidRow(
                    column(
                      6,
                      div(
                        class = "box box-info",
                        div(
                          class = "box-header with-border",
                          h5("Readability Indices", style = "color: #3498db;")
                        ),
                        div(
                          class = "box-body",
                          conditionalPanel(
                            condition = "output.analysis_completed",
                            uiOutput("readability_details_html")
                          ),
                          conditionalPanel(
                            condition = "!output.analysis_completed",
                            div(
                              style = "text-align: center; padding: 20px; color: #999;",
                              p(
                                "Readability indices will appear here after analysis."
                              )
                            )
                          )
                        )
                      )
                    ),
                    column(
                      6,
                      div(
                        class = "box box-primary",
                        div(
                          class = "box-header with-border",
                          h5("Text Statistics", style = "color: #2E86AB;")
                        ),
                        div(
                          class = "box-body",
                          conditionalPanel(
                            condition = "output.analysis_completed",
                            uiOutput("text_stats")
                          ),
                          conditionalPanel(
                            condition = "!output.analysis_completed",
                            div(
                              style = "text-align: center; padding: 20px; color: #999;",
                              p(
                                "Text statistics will appear here after analysis."
                              )
                            )
                          )
                        )
                      )
                    )
                  ),
                  # Detailed Analysis Tables
                  fluidRow(
                    div(
                      class = "box box-primary",
                      div(
                        class = "box-header with-border",
                        h4(
                          "N-grams Analysis",
                          class = "box-title",
                          style = "color: #2E86AB;"
                        )
                      ),
                      column(
                        4,
                        h5(
                          "Top Unigrams",
                          class = "box-title",
                          style = "color: #2E86AB;"
                        ),
                        uiOutput("frequent_words_table")
                      ),
                      column(
                        4,
                        h5("Top Bigrams", style = "color: #2E86AB;"),
                        uiOutput("bigrams_table")
                      ),
                      column(
                        4,
                        h5("Top Trigrams", style = "color: #2E86AB;"),
                        uiOutput("trigrams_table")
                      )
                    )
                  ),
                  hr(),
                  # N-grams Analysis
                  fluidRow(
                    column(
                      12,
                      div(
                        class = "box-body",
                        fluidRow(
                          column(
                            6,
                            div(
                              class = "box box-primary",
                              h5(
                                "Citation Types Distribution",
                                class = "box-title",
                                style = "color: #2E86AB;"
                              ),
                              div(
                                class = "box-header with-border",
                                div(
                                  class = "box-body",
                                  uiOutput("citation_types_table")
                                )
                              )
                            )
                          ),
                          column(
                            6,
                            div(
                              class = "box box-success",
                              h5(
                                "Citations by Section",
                                class = "box-title",
                                style = "color: #27ae60;"
                              ),
                              div(
                                class = "box-header with-border",
                                div(
                                  class = "box-body",
                                  uiOutput("citation_sections_table")
                                )
                              )
                            )
                          )
                        )
                      )
                    )
                  )
                ),

                # Add this new tabPanel AFTER the "Network Analysis" tab in the content_analysis_tab function

                tabPanel(
                  title = "Word Trends",
                  value = "tab_trends",

                  br(),

                  # Word Selection and Configuration
                  fluidRow(
                    column(
                      12,
                      div(
                        class = "box box-primary",
                        div(
                          class = "box-header with-border",
                          h4(
                            "Word Distribution Analysis",
                            class = "box-title",
                            style = "color: #2E86AB;"
                          ),
                          div(
                            class = "box-tools pull-right",
                            downloadButton(
                              "download_word_trends",
                              "Export Data",
                              class = "btn btn-primary btn-sm",
                              icon = icon("download")
                            )
                          )
                        ),
                        div(
                          class = "box-body",
                          fluidRow(
                            column(
                              4,
                              selectizeInput(
                                "trend_words",
                                "Select words to track:",
                                choices = NULL,
                                selected = NULL,
                                multiple = TRUE,
                                options = list(
                                  placeholder = 'Type or select words...',
                                  maxItems = 10,
                                  plugins = list('remove_button')
                                )
                              ),
                              helpText(
                                "Select up to 10 words from the most frequent terms in your document."
                              )
                            ),
                            column(
                              3,
                              radioButtons(
                                "segmentation_type",
                                "Segmentation:",
                                choices = list(
                                  "Auto (use sections if available)" = "auto",
                                  "Document sections" = "sections",
                                  "Equal-length segments" = "segments"
                                ),
                                selected = "auto"
                              )
                            ),
                            column(
                              2,
                              conditionalPanel(
                                condition = "input.segmentation_type == 'segments'",
                                numericInput(
                                  "n_segments",
                                  "Number of segments:",
                                  value = 10,
                                  min = 5,
                                  max = 20,
                                  step = 1
                                )
                              )
                            ),
                            column(
                              3,
                              radioButtons(
                                "trend_plot_type",
                                "Visualization type:",
                                choices = list(
                                  "Line chart" = "line",
                                  "Area chart" = "area"
                                ),
                                selected = "line"
                              ),
                              checkboxInput(
                                "trend_show_points",
                                "Show data points",
                                value = TRUE
                              )
                              # ,checkboxInput("trend_smooth",
                              #               "Smooth lines",
                              #               value = TRUE
                              # )
                            )
                          ),
                          hr(),
                          fluidRow(
                            column(
                              12,
                              actionButton(
                                "update_trends",
                                "Update Visualization",
                                icon = icon("refresh"),
                                class = "btn-info",
                                style = "margin-bottom: 10px;"
                              ),
                              conditionalPanel(
                                condition = "input.segmentation_type == 'sections' && !output.sections_available",
                                div(
                                  style = "background-color: #fff3cd; padding: 10px; border-radius: 5px; margin-top: 10px; border-left: 4px solid #ffc107;",
                                  icon(
                                    "exclamation-triangle",
                                    style = "color: #856404;"
                                  ),
                                  span(
                                    " Document sections are not available. The analysis will use equal-length segments instead.",
                                    style = "color: #856404; margin-left: 8px;"
                                  )
                                )
                              )
                            )
                          )
                        )
                      )
                    )
                  ),

                  # Visualization
                  fluidRow(
                    column(
                      12,
                      div(
                        class = "box box-success",
                        div(
                          class = "box-header with-border",
                          h4(
                            "Word Distribution Over Document",
                            class = "box-title",
                            style = "color: #27ae60;"
                          )
                        ),
                        div(
                          class = "box-body",
                          conditionalPanel(
                            condition = "output.trends_available",
                            plotlyOutput("word_trends_plot", height = "600px")
                          ),
                          conditionalPanel(
                            condition = "!output.trends_available",
                            div(
                              style = "text-align: center; padding: 60px; color: #999;",
                              icon(
                                "chart-line",
                                style = "font-size: 48px; margin-bottom: 20px;"
                              ),
                              h4(
                                "No visualization available",
                                style = "color: #666;"
                              ),
                              p(
                                "Select words from the list above and click 'Update Visualization' to see their distribution across the document.",
                                style = "font-size: 14px;"
                              )
                            )
                          )
                        )
                      )
                    )
                  ),

                  # Statistics Table
                  fluidRow(
                    column(
                      12,
                      div(
                        class = "box box-info",
                        div(
                          class = "box-header with-border",
                          h4(
                            "Distribution Statistics",
                            class = "box-title",
                            style = "color: #3498db;"
                          )
                        ),
                        div(
                          class = "box-body",
                          conditionalPanel(
                            condition = "output.trends_available",
                            uiOutput("word_trends_table")
                          ),
                          conditionalPanel(
                            condition = "!output.trends_available",
                            div(
                              style = "text-align: center; padding: 20px; color: #999;",
                              p(
                                "Statistics will appear here after visualization is generated."
                              )
                            )
                          )
                        )
                      )
                    )
                  )
                ),

                # ===========================================
                # TAB 2: IN-CONTEXT CITATION ANALYSIS
                # ===========================================
                tabPanel(
                  title = "In-Context Citations",
                  value = "tab_contexts",

                  br(),

                  # Search and Filter Controls - SINGLE ROW
                  fluidRow(
                    column(
                      12,
                      div(
                        class = "box box-primary",
                        div(
                          class = "box-header with-border",
                          h4(
                            "In-Context Citation Analysis",
                            class = "box-title",
                            style = "color: #2E86AB;"
                          ),
                          div(
                            class = "box-tools pull-right",
                            downloadButton(
                              "download_contexts",
                              "Export Contexts",
                              class = "btn btn-primary btn-sm",
                              icon = icon("download")
                            )
                          )
                        ),
                        div(
                          class = "box-body",
                          # SINGLE ROW with all controls
                          fluidRow(
                            column(
                              4,
                              textInput(
                                "context_search",
                                "Search in contexts:",
                                placeholder = "Type to search citations or context...",
                                width = "100%"
                              )
                            ),
                            column(
                              2,
                              numericInput(
                                "context_min_words",
                                "Min context words:",
                                value = 10,
                                min = 5,
                                max = 100,
                                width = "100%"
                              )
                            ),
                            column(
                              2,
                              radioButtons(
                                "citation_segmentation",
                                "Group citations by:",
                                choices = list(
                                  "Auto (use sections if available)" = "auto",
                                  "Document sections" = "sections",
                                  "Equal-length segments" = "segments"
                                ),
                                selected = "auto",
                                inline = FALSE
                              )
                            ),
                            column(
                              2,
                              conditionalPanel(
                                condition = "input.citation_segmentation == 'segments'",
                                numericInput(
                                  "n_segments_citations",
                                  "Number of segments:",
                                  value = 10,
                                  min = 5,
                                  max = 20,
                                  step = 1
                                )
                              )
                            ),
                            column(
                              2,
                              br(),
                              actionButton(
                                "update_citation_grouping",
                                "Update Grouping",
                                icon = icon("refresh"),
                                class = "btn-info btn-block",
                                style = "margin-top: 5px;"
                              ),
                              conditionalPanel(
                                condition = "input.citation_segmentation == 'sections' && !output.sections_available",
                                div(
                                  style = "background-color: #fff3cd; padding: 5px; border-radius: 3px; margin-top: 8px; border-left: 3px solid #ffc107; font-size: 11px;",
                                  icon(
                                    "exclamation-triangle",
                                    style = "color: #856404; font-size: 10px;"
                                  ),
                                  span(
                                    " Sections not available",
                                    style = "color: #856404; margin-left: 5px;"
                                  )
                                )
                              ),
                              conditionalPanel(
                                condition = "$('html').hasClass('shiny-busy')",
                                div(
                                  style = "margin-top: 8px; text-align: center;",
                                  icon(
                                    "spinner",
                                    class = "fa-spin",
                                    style = "color: #3498db; font-size: 12px;"
                                  ),
                                  span(
                                    "Updating...",
                                    style = "color: #3498db; font-style: italic; margin-left: 3px; font-size: 11px;"
                                  )
                                )
                              )
                            )
                          )
                        )
                      )
                    )
                  ),

                  # Citation Contexts Display
                  fluidRow(
                    column(
                      12,
                      div(
                        class = "box box-success",
                        div(
                          class = "box-header with-border",
                          h4(
                            "Citation Contexts Visualization",
                            class = "box-title",
                            style = "color: #27ae60;"
                          )
                        ),
                        div(
                          class = "box-body",
                          uiOutput("citation_contexts_html")
                        )
                      )
                    )
                  )
                ),

                # ===========================================
                # TAB 3: NETWORK ANALYSIS
                # ===========================================
                tabPanel(
                  title = "Network Analysis",
                  value = "tab_network",

                  br(),

                  # Network Visualization
                  fluidRow(
                    div(
                      class = "box box-primary",
                      div(
                        class = "box-header with-border",
                        h4(
                          "Citation Co-occurrence Network",
                          class = "box-title",
                          style = "color: #2E86AB;"
                        ),
                        div(
                          class = "box-tools pull-right",
                          downloadButton(
                            "download_network",
                            "Export Network",
                            class = "btn btn-primary btn-sm",
                            icon = icon("download")
                          )
                        )
                      ),
                      div(
                        class = "box-body",
                        div(
                          style = "margin-bottom: 15px; padding: 10px; background-color: #f0f8ff; border-radius: 5px; display: flex; align-items: center; flex-wrap: wrap; gap: 15px;",
                          div(
                            style = "flex: 1; min-width: 300px;",
                            icon("info-circle", style = "color: #3498db;"),
                            span(
                              " Nodes are colored by paper section. Use the slider to adjust node spacing.",
                              style = "color: #555; font-size: 13px; margin-left: 8px;"
                            )
                          ),
                          div(
                            style = "display: flex; align-items: center; gap: 12px; flex-wrap: wrap;",
                            tags$label(
                              "Max nodes/section:",
                              style = "margin: 0; font-size: 12px; color: #555; white-space: nowrap;"
                            ),
                            numericInput(
                              "network_max_nodes",
                              label = NULL,
                              value = 10,
                              min = 3,
                              max = 50,
                              step = 1,
                              width = "70px"
                            ),
                            tags$label(
                              "Node size:",
                              style = "margin: 0; font-size: 12px; color: #555; white-space: nowrap;"
                            ),
                            sliderInput(
                              "network_node_size",
                              label = NULL,
                              min = 1,
                              max = 10,
                              value = 5,
                              step = 1,
                              width = "100px",
                              ticks = FALSE
                            ),
                            tags$label(
                              "Label size:",
                              style = "margin: 0; font-size: 12px; color: #555; white-space: nowrap;"
                            ),
                            sliderInput(
                              "network_label_size",
                              label = NULL,
                              min = 1,
                              max = 10,
                              value = 5,
                              step = 1,
                              width = "100px",
                              ticks = FALSE
                            ),
                            tags$label(
                              "Spacing:",
                              style = "margin: 0; font-size: 12px; color: #555; white-space: nowrap;"
                            ),
                            sliderInput(
                              "network_spacing",
                              label = NULL,
                              min = 1,
                              max = 10,
                              value = 5,
                              step = 1,
                              width = "100px",
                              ticks = FALSE
                            ),
                            tags$label(
                              "Repulsion:",
                              style = "margin: 0; font-size: 12px; color: #555; white-space: nowrap;"
                            ),
                            sliderInput(
                              "network_repulsion",
                              label = NULL,
                              min = 1,
                              max = 10,
                              value = 5,
                              step = 1,
                              width = "100px",
                              ticks = FALSE
                            ),
                            tags$label(
                              "Max edge dist.:",
                              style = "margin: 0; font-size: 12px; color: #555; white-space: nowrap;"
                            ),
                            numericInput(
                              "network_edge_distance",
                              label = NULL,
                              value = 1000,
                              min = 100,
                              max = 2000,
                              step = 100,
                              width = "80px"
                            ),
                            actionButton(
                              "update_network_layout",
                              "Update",
                              icon = icon("refresh"),
                              class = "btn-primary btn-sm",
                              style = "padding: 3px 12px;"
                            )
                          )
                        ),
                        div(
                          style = "height: 75vh; min-height: 700px; border: 1px solid #ddd; border-radius: 5px;",
                          visNetworkOutput(
                            "citation_network",
                            width = "100%",
                            height = "100%"
                          )
                        )
                      )
                    )
                  ),
                  fluidRow(
                    column(
                      6,
                      div(
                        class = "box box-info",
                        div(
                          class = "box-header with-border",
                          h4(
                            "Network Information",
                            class = "box-title",
                            style = "color: #3498db;"
                          )
                        ),
                        div(
                          class = "box-body",
                          verbatimTextOutput("network_info")
                        )
                      )
                    ),
                    column(
                      6,
                      div(
                        class = "box box-success",
                        div(
                          class = "box-header with-border",
                          h4(
                            "Strongest Connections",
                            class = "box-title",
                            style = "color: #27ae60;"
                          )
                        ),
                        div(
                          class = "box-body",
                          uiOutput("strongest_connections")
                        )
                      )
                    )
                  )
                ),

                # ===========================================
                # TAB 4: CITATION CLUSTERS
                # ===========================================
                tabPanel(
                  title = "Citation Clusters",
                  value = "tab_clusters",

                  br(),

                  # Cluster Summary Table
                  fluidRow(
                    column(
                      12,
                      div(
                        class = "box box-primary",
                        div(
                          class = "box-header with-border",
                          h4(
                            "Citation Cluster Analysis",
                            class = "box-title",
                            style = "color: #2E86AB;"
                          ),
                          div(
                            class = "box-tools pull-right",
                            downloadButton(
                              "download_clusters",
                              "Export Data",
                              class = "btn btn-primary btn-sm",
                              icon = icon("download")
                            )
                          )
                        ),
                        div(
                          class = "box-body",
                          conditionalPanel(
                            condition = "output.clusters_available",
                            div(
                              style = "margin-bottom: 15px; padding: 10px; background-color: #f0f8ff; border-radius: 5px;",
                              icon("info-circle", style = "color: #3498db;"),
                              span(
                                " Citation clusters are described using TF-IDF analysis of reference titles grouped by document section.",
                                style = "color: #555; font-size: 13px; margin-left: 8px;"
                              )
                            ),
                            uiOutput("cluster_summary_table")
                          ),
                          conditionalPanel(
                            condition = "!output.clusters_available",
                            div(
                              style = "text-align: center; padding: 60px; color: #999;",
                              icon(
                                "project-diagram",
                                style = "font-size: 48px; margin-bottom: 20px;"
                              ),
                              h4(
                                "No cluster data available",
                                style = "color: #666;"
                              ),
                              p(
                                "Citation cluster analysis will appear here after the content analysis is complete.",
                                style = "font-size: 14px;"
                              ),
                              p(
                                "Clusters are based on TF-IDF analysis of reference titles grouped by document section.",
                                style = "font-size: 12px; color: #999;"
                              )
                            )
                          )
                        )
                      )
                    )
                  ),

                  # TF-IDF Bar Chart
                  conditionalPanel(
                    condition = "output.clusters_available",
                    fluidRow(
                      column(
                        12,
                        div(
                          class = "box box-success",
                          div(
                            class = "box-header with-border",
                            h4(
                              "Top TF-IDF Terms by Section",
                              class = "box-title",
                              style = "color: #27ae60;"
                            )
                          ),
                          div(
                            class = "box-body",
                            uiOutput("cluster_tfidf_bars_ui")
                          )
                        )
                      )
                    ),

                    # Heatmap and References per Section side by side
                    fluidRow(
                      column(
                        7,
                        div(
                          class = "box box-info",
                          div(
                            class = "box-header with-border",
                            h4(
                              "TF-IDF Heatmap: Terms vs Sections",
                              class = "box-title",
                              style = "color: #3498db;"
                            )
                          ),
                          div(
                            class = "box-body",
                            plotlyOutput("cluster_tfidf_heatmap", height = "600px")
                          )
                        )
                      ),
                      column(
                        5,
                        div(
                          class = "box box-warning",
                          div(
                            class = "box-header with-border",
                            h4(
                              "References per Section",
                              class = "box-title",
                              style = "color: #e67e22;"
                            )
                          ),
                          div(
                            class = "box-body",
                            plotlyOutput("cluster_refs_per_section", height = "600px")
                          )
                        )
                      )
                    ),

                    # Detailed cluster references table
                    fluidRow(
                      column(
                        12,
                        div(
                          class = "box box-default",
                          div(
                            class = "box-header with-border",
                            h4(
                              "References by Section",
                              class = "box-title",
                              style = "color: #555;"
                            )
                          ),
                          div(
                            class = "box-body",
                            uiOutput("cluster_references_detail")
                          )
                        )
                      )
                    )
                  )
                ),

                # ===========================================
                # TAB 5: REFERENCES
                # ===========================================
                tabPanel(
                  title = "References",
                  value = "tab_references",

                  br(),

                  # Header con info e download
                  fluidRow(
                    column(
                      12,
                      div(
                        class = "box box-primary",
                        div(
                          class = "box-header with-border",
                          h4(
                            "Bibliography",
                            class = "box-title",
                            style = "color: #2E86AB;"
                          ),
                          div(
                            class = "box-tools pull-right",
                            downloadButton(
                              "download_references",
                              "Export References",
                              class = "btn btn-primary btn-sm",
                              icon = icon("download")
                            )
                          )
                        ),
                        div(
                          class = "box-body",
                          conditionalPanel(
                            condition = "output.references_available",

                            # Summary info
                            div(
                              style = "background-color: #e8f4f8; padding: 15px; border-radius: 5px; margin-bottom: 20px;",
                              fluidRow(
                                column(
                                  3,
                                  div(
                                    style = "text-align: center;",
                                    icon(
                                      "book",
                                      style = "font-size: 24px; color: #2E86AB;"
                                    ),
                                    h4(
                                      textOutput("total_refs", inline = TRUE),
                                      style = "color: #2E86AB; margin: 10px 0 5px 0;"
                                    ),
                                    p(
                                      "Total References",
                                      style = "color: #666; margin: 0;"
                                    )
                                  )
                                ),
                                column(
                                  3,
                                  div(
                                    style = "text-align: center;",
                                    icon(
                                      "file-pdf",
                                      style = "font-size: 24px; color: #e74c3c;"
                                    ),
                                    h4(
                                      textOutput("pdf_refs", inline = TRUE),
                                      style = "color: #e74c3c; margin: 10px 0 5px 0;"
                                    ),
                                    p(
                                      "From PDF",
                                      style = "color: #666; margin: 0;"
                                    )
                                  )
                                ),
                                column(
                                  3,
                                  div(
                                    style = "text-align: center;",
                                    icon(
                                      "cloud-download-alt",
                                      style = "font-size: 24px; color: #27ae60;"
                                    ),
                                    h4(
                                      textOutput(
                                        "crossref_refs",
                                        inline = TRUE
                                      ),
                                      style = "color: #27ae60; margin: 10px 0 5px 0;"
                                    ),
                                    p(
                                      "From Crossref",
                                      style = "color: #666; margin: 0;"
                                    )
                                  )
                                ),
                                column(
                                  3,
                                  div(
                                    style = "text-align: center;",
                                    icon(
                                      "database",
                                      style = "font-size: 24px; color: #8e44ad;"
                                    ),
                                    h4(
                                      textOutput(
                                        "openalex_refs",
                                        inline = TRUE
                                      ),
                                      style = "color: #8e44ad; margin: 10px 0 5px 0;"
                                    ),
                                    p(
                                      "From OpenAlex",
                                      style = "color: #666; margin: 0;"
                                    )
                                  )
                                )
                              )
                            ),

                            # Search box
                            fluidRow(
                              column(
                                12,
                                textInput(
                                  "reference_search",
                                  label = NULL,
                                  placeholder = "Search in references (author, title, year, DOI)...",
                                  width = "100%"
                                )
                              )
                            ),

                            hr(),

                            # References list
                            uiOutput("references_html")
                          ),

                          conditionalPanel(
                            condition = "!output.references_available",
                            div(
                              style = "text-align: center; padding: 60px; color: #999;",
                              icon(
                                "book-open",
                                style = "font-size: 48px; margin-bottom: 20px;"
                              ),
                              h4(
                                "No references available",
                                style = "color: #666;"
                              ),
                              p(
                                "References will appear here after the analysis is complete.",
                                style = "font-size: 14px;"
                              ),
                              p(
                                "References can be extracted from the PDF or fetched from Crossref using the document's DOI.",
                                style = "font-size: 12px; color: #999;"
                              )
                            )
                          )
                        )
                      )
                    )
                  )
                ),

                # ===========================================
                # TAB: BIBLIOAI SUMMARY - UI
                # ===========================================

                tabPanel(
                  title = "BiblioAI Summary",
                  value = "tab_biblioai",

                  br(),

                  # Header with API status, Summary Type Selection and Generate Button
                  fluidRow(
                    column(
                      12,
                      div(
                        class = "box box-primary",
                        div(
                          class = "box-header with-border",
                          h4(
                            "AI-Powered Document Summarization",
                            class = "box-title",
                            style = "color: #2E86AB;"
                          ),
                          div(
                            class = "box-tools pull-right",
                            uiOutput("gemini_api_status")
                          )
                        ),
                        div(
                          class = "box-body",
                          fluidRow(
                            column(
                              6,
                              # Summary type selection with grouped options
                              selectInput(
                                "summary_type",
                                label = div(
                                  icon(
                                    "list-alt",
                                    style = "margin-right: 5px;"
                                  ),
                                  tags$strong("Summary Type:")
                                ),
                                choices = list(
                                  "Article Summarization" = list(
                                    "Short Abstract (250 words)" = "short_abstract",
                                    "Narrative Abstract (500-600 words)" = "narrative_abstract",
                                    "IMRaD Structure Summary" = "imrad_summary",
                                    "Thematic Bibliography" = "thematic_bibliography"
                                  ),
                                  "Focus on Article Parts" = list(
                                    "Research Questions & Context" = "research_questions",
                                    "Background & Literature" = "background_literature",
                                    "Methods Summary" = "methods_summary",
                                    "Implications & Conclusions" = "implications",
                                    "Tables & Figures List" = "list_tables_figures"
                                  )
                                ),
                                selected = "short_abstract",
                                width = "100%"
                              )
                            ),
                            column(4), # empty space for future options
                            column(
                              2,
                              # Generate button aligned with select input
                              div(
                                style = "margin-top: 25px;",
                                actionButton(
                                  "generate_summary",
                                  "Generate Summary",
                                  icon = icon("magic"),
                                  class = "btn-success btn-block",
                                  style = "font-weight: bold; padding: 10px;"
                                )
                              )
                            )
                          ),
                          # Progress indicator
                          conditionalPanel(
                            condition = "$('html').hasClass('shiny-busy')",
                            div(
                              style = "text-align: center; margin-top: 10px; padding: 10px; background-color: #f0f8f0; border-radius: 4px;",
                              icon(
                                "spinner",
                                class = "fa-spin",
                                style = "color: #27ae60; font-size: 20px; margin-right: 10px;"
                              ),
                              span(
                                "Generating summary with AI...",
                                style = "color: #27ae60; font-weight: 500;"
                              )
                            )
                          ),
                          # Summary type description
                          div(
                            style = "margin-top: 10px;",
                            uiOutput("summary_type_description")
                          )
                        )
                      )
                    )
                  ),

                  # Summary Results - Full Width
                  fluidRow(
                    column(
                      12,
                      div(
                        class = "box box-info",
                        div(
                          class = "box-header with-border",
                          h4(
                            "AI-Generated Summary",
                            class = "box-title",
                            style = "color: #3498db;"
                          ),
                          div(
                            class = "box-tools pull-right",
                            conditionalPanel(
                              condition = "output.summary_available",
                              downloadButton(
                                "download_summary",
                                "Export Summary",
                                class = "btn btn-info btn-sm",
                                icon = icon("download")
                              )
                            )
                          )
                        ),
                        div(
                          class = "box-body",
                          style = "min-height: 500px;",

                          conditionalPanel(
                            condition = "output.summary_available",
                            div(
                              style = "background-color: #f8f9fa; padding: 20px; border-radius: 5px; border: 1px solid #dee2e6;",

                              # Summary metadata
                              div(
                                style = "margin-bottom: 15px; padding-bottom: 10px; border-bottom: 2px solid #3498db;",
                                fluidRow(
                                  column(
                                    6,
                                    tags$strong(
                                      "Summary Type: ",
                                      style = "color: #3498db;"
                                    ),
                                    tags$span(
                                      textOutput(
                                        "summary_type_display",
                                        inline = TRUE
                                      ),
                                      style = "font-weight: bold;"
                                    )
                                  ),
                                  column(
                                    6,
                                    div(
                                      style = "text-align: right;",
                                      tags$strong(
                                        "Generated: ",
                                        style = "color: #3498db;"
                                      ),
                                      textOutput(
                                        "summary_timestamp",
                                        inline = TRUE
                                      )
                                    )
                                  )
                                )
                              ),

                              # Summary content
                              div(
                                style = "line-height: 1.8; color: #333; font-size: 14px; white-space: pre-wrap; word-wrap: break-word;",
                                uiOutput("summary_content_display")
                              )
                            )
                          ),

                          conditionalPanel(
                            condition = "!output.summary_available",
                            div(
                              style = "text-align: center; padding: 80px 20px; color: #999;",
                              icon(
                                "robot",
                                style = "font-size: 64px; margin-bottom: 20px; color: #bbb;"
                              ),
                              h4(
                                "No summary generated yet",
                                style = "color: #666; margin-bottom: 15px;"
                              ),
                              p(
                                "Select your summary type above and click 'Generate Summary' to start.",
                                style = "font-size: 14px; margin-bottom: 10px;"
                              ),
                              p(
                                "Make sure you have uploaded a PDF document first.",
                                style = "font-size: 12px; color: #999;"
                              )
                            )
                          )
                        )
                      )
                    )
                  )
                )
              )
            ),

            # Placeholder when no analysis is done
            conditionalPanel(
              condition = "!output.analysis_completed && !output.text_extracted",
              div(
                style = "text-align: center; margin-top: 100px; color: #999;",
                icon(
                  "file-upload",
                  style = "font-size: 48px; margin-bottom: 20px;"
                ),
                h3(
                  "Upload a PDF file and start the analysis",
                  style = "color: #666;"
                ),
                p(
                  "Select a scientific article in PDF format and configure the analysis parameters to begin.",
                  style = "font-size: 16px;"
                )
              )
            )
          ),

          # ===========================================
          # LEFT PANEL: CONTROLS (column 2)
          # ===========================================
          column(
            2,

            # Import Method Selection
            div(
              class = "box box-info",
              div(
                class = "box-body",
                style = "padding: 15px;",

                div(
                  style = "text-align: center; margin-bottom: 15px;",
                  icon(
                    "file-import",
                    style = "font-size: 28px; color: #2E86AB;"
                  ),
                  h4(
                    "Choose Import Method",
                    style = "color: #2E86AB; margin-top: 10px; margin-bottom: 5px; font-weight: bold;"
                  )
                ),

                radioButtons(
                  "import_method",
                  label = NULL,
                  choices = list(
                    "Import PDF File" = "import_pdf",
                    "Load Saved Text File" = "load_txt"
                  ),
                  selected = "import_pdf",
                  width = "100%"
                ),

                helpText(
                  "Select whether to extract text from a PDF or load a previously saved text file.",
                  style = "font-size: 11px; color: #666; text-align: center; margin-top: -5px;"
                )
              )
            ),

            # PDF Import Card - visible only if import_pdf is selected
            conditionalPanel(
              condition = "input.import_method == 'import_pdf'",
              div(
                class = "box box-primary",
                div(
                  class = "box-body",

                  tags$details(
                    id = "pdf_import_details",
                    open = NA, # Open by default
                    tags$summary(
                      "1. Import PDF File ▼",
                      style = "font-weight: bold; cursor: pointer; color: #2E86AB; font-size: 16px; padding: 8px 0;"
                    ),
                    br(),

                    fileInput(
                      "pdf_file",
                      label = "Choose PDF File",
                      accept = c(".pdf"),
                      buttonLabel = "Browse...",
                      placeholder = "No file selected",
                      width = "100%"
                    ),

                    numericInput(
                      "Columns",
                      label = "Number of Columns in PDF",
                      value = NULL,
                      min = 1,
                      max = 3,
                      step = 1,
                      width = "100%"
                    ),
                    helpText(
                      "Specify if the PDF has multiple columns (e.g., 2 for typical academic articles)."
                    ),

                    # MODIFIED: Citation Type Selection - NO DEFAULT
                    radioButtons(
                      "citation_type_import",
                      label = div(
                        tags$span(
                          "Citation Format in PDF:",
                          style = "color: #d9534f; font-weight: bold;"
                        ),
                        tags$span(
                          " *",
                          style = "color: #d9534f; font-size: 16px;"
                        ),
                        tags$a(
                          icon("info-circle"),
                          href = "#",
                          onclick = "return false;",
                          style = "margin-left: 5px; color: #3498db; cursor: help;",
                          title = "Choose the citation format used in your document. This helps avoid false positives in citation detection."
                        )
                      ),
                      choices = list(
                        "Author-year (Smith, 2020)" = "author_year",
                        "Numeric brackets [1]" = "numeric_bracketed",
                        "Numeric superscript¹" = "numeric_superscript"
                        # ,"All formats (may have false positives)" = "all"
                      ),
                      selected = character(0), # NO DEFAULT SELECTION
                      width = "100%"
                    ),

                    # Warning message when no selection
                    conditionalPanel(
                      condition = "!input.citation_type_import || input.citation_type_import == ''",
                      div(
                        style = "background-color: #fcf8e3; padding: 8px 12px; border-radius: 4px; border-left: 4px solid #f0ad4e; margin-top: -8px; margin-bottom: 10px;",
                        icon("exclamation-triangle", style = "color: #8a6d3b;"),
                        span(
                          " Please select the citation format before extracting text.",
                          style = "color: #8a6d3b; margin-left: 8px; font-size: 12px; font-weight: 500;"
                        )
                      )
                    ),

                    # AI Support checkbox - visible only when Gemini API is available
                    conditionalPanel(
                      condition = "output.gemini_api_available",
                      div(
                        style = "margin-top: 12px; margin-bottom: 12px; background-color: #e8f8f5; padding: 15px; border-radius: 6px; border-left: 4px solid #17a589;",
                        div(
                          style = "display: flex; align-items: center; gap: 10px;",
                          div(
                            style = "flex-shrink: 0;",
                            checkboxInput(
                              "enable_ai_support",
                              label = NULL,
                              value = FALSE,
                              width = "auto"
                            )
                          ),
                          div(
                            style = "display: flex; align-items: center; flex-grow: 1;",
                            icon(
                              "robot",
                              style = "color: #17a589; margin-right: 10px; font-size: 22px;"
                            ),
                            span(
                              "Enable AI-Enhanced Extraction",
                              style = "font-weight: bold; color: #17a589; font-size: 15px;"
                            )
                          )
                        ),
                        helpText(
                          "Use advanced AI to improve text extraction quality and citation detection accuracy.",
                          style = "margin-top: 8px; margin-bottom: 0px; margin-left: 35px; font-size: 11px; color: #555;"
                        )
                      )
                    ),

                    # Processing spinner - visible ONLY during PDF text extraction (not during analysis)
                    conditionalPanel(
                      condition = "$('html').hasClass('shiny-busy') && (input.extract_text > 0) && !output.text_extracted",
                      div(
                        style = "margin-top: 10px; margin-bottom: 10px; background-color: #fff3cd; padding: 15px; border-radius: 5px; border-left: 4px solid #ffc107; text-align: center;",
                        div(
                          icon(
                            "spinner",
                            class = "fa-spin",
                            style = "font-size: 24px; color: #ff9800; margin-bottom: 10px;"
                          ),
                          br(),
                          tags$strong(
                            "Extracting Text from PDF...",
                            style = "color: #856404; font-size: 14px;"
                          ),
                          br(),
                          tags$span(
                            id = "extraction_status_text",
                            "Please wait while we extract the document content.",
                            style = "color: #856404; font-size: 12px; font-style: italic;"
                          )
                        )
                      )
                    ),

                    # File info display
                    conditionalPanel(
                      condition = "output.pdf_uploaded",
                      div(
                        style = "background-color: #f0f8ff; padding: 10px; border-radius: 5px; margin-top: 10px;",
                        icon("file-pdf", style = "color: #e74c3c;"),
                        span(
                          " PDF uploaded successfully!",
                          style = "color: #27ae60; font-weight: bold;"
                        ),
                        br(),
                        textOutput("pdf_info", inline = TRUE)
                      )
                    ),

                    br(),
                    actionButton(
                      "extract_text",
                      "Extract Text from PDF",
                      icon = icon("file-text"),
                      class = "btn-info btn-block",
                      style = "margin-top: 10px;"
                    )
                  )
                )
              )
            ),
            # End of conditionalPanel for import_pdf

            # Load Text File Card - visible only if load_txt is selected
            conditionalPanel(
              condition = "input.import_method == 'load_txt'",
              div(
                class = "box box-primary",
                div(
                  class = "box-body",
                  tags$details(
                    open = NA, # Open by default
                    tags$summary(
                      "1. Load Saved Text File ▼",
                      style = "font-weight: bold; color: #2E86AB; font-size: 16px; padding: 8px 0; margin-bottom: 15px; display: block;"
                    ),

                    helpText(
                      "Load a .txt file that was previously saved from this tool. The file should have DOI and citation format info in the first lines for automatic configuration.",
                      style = "font-size: 12px; color: #666; margin-bottom: 15px;"
                    ),

                    fileInput(
                      "load_text_file",
                      "Select Text File",
                      accept = c("text/plain", ".txt"),
                      buttonLabel = "Browse...",
                      placeholder = "No file selected",
                      width = "100%"
                    ),

                    # File info display for loaded text
                    conditionalPanel(
                      condition = "output.text_file_loaded",
                      div(
                        style = "background-color: #f0f8ff; padding: 10px; border-radius: 5px; margin-top: 10px;",
                        icon("file-alt", style = "color: #3498db;"),
                        span(
                          " Text file loaded successfully!",
                          style = "color: #27ae60; font-weight: bold;"
                        ),
                        br(),
                        textOutput("text_file_info", inline = TRUE)
                      )
                    )
                  )
                )
              )
            ),
            # End of conditionalPanel for load_txt

            # Analysis Parameters Card
            div(
              class = "box box-success",
              div(
                class = "box-body",

                tags$details(
                  tags$summary(
                    "2. Analysis Parameters ▼",
                    style = "font-weight: bold; cursor: pointer; color: #27ae60; font-size: 16px; padding: 8px 0;"
                  ),
                  br(),

                  # Citation context window
                  numericInput(
                    "window_size",
                    label = "Context Window Size (words)",
                    value = 20,
                    min = 5,
                    max = 50,
                    step = 1,
                    width = "100%"
                  ),
                  helpText(
                    "Number of words before and after each citation to extract."
                  ),

                  # Maximum distance for network
                  numericInput(
                    "max_distance",
                    label = "Max Distance for Network (chars)",
                    value = 800,
                    min = 200,
                    max = 2000,
                    step = 100,
                    width = "100%"
                  ),
                  helpText(
                    "Maximum character distance between citations to consider as connected."
                  ),

                  # Advanced options - OPEN BY DEFAULT
                  tags$details(
                    open = NA,
                    tags$summary(
                      "Advanced Options",
                      style = "font-weight: bold; cursor: pointer;"
                    ),
                    br(),
                    checkboxInput(
                      "parse_multiple",
                      "Parse complex multiple citations",
                      value = TRUE
                    ),
                    checkboxInput(
                      "remove_stopwords",
                      "Remove stopwords from analysis",
                      value = TRUE
                    ),
                    textInput(
                      "custom_stopwords",
                      "Custom stopwords (comma-separated)",
                      value = "",
                      width = "100%"
                    )
                  )
                )
              )
            ),

            # Analysis Button
            div(
              class = "box box-warning",
              div(
                class = "box-header with-border",
                h4(
                  "3. Run Analysis",
                  class = "box-title",
                  style = "color: #f39c12;"
                )
              ),
              div(
                class = "box-body",
                actionButton(
                  "run_analysis",
                  "Start",
                  icon = icon("chart-line"),
                  class = "btn-warning btn-block btn-lg",
                  style = "font-weight: bold; margin-bottom: 10px;"
                ),

                # Progress indicator - ONLY during analysis
                conditionalPanel(
                  condition = "$('html').hasClass('shiny-busy') && (input.run_analysis > 0) && !output.analysis_completed",
                  div(
                    style = "text-align: center; margin-top: 15px;",
                    icon(
                      "spinner",
                      class = "fa-spin",
                      style = "color: #f39c12;"
                    ),
                    br(),
                    span(
                      "Analyzing content...",
                      style = "color: #f39c12; font-style: italic;"
                    )
                  )
                ),

                # Reset button
                actionButton(
                  "reset_analysis",
                  "Reset",
                  icon = icon("refresh"),
                  class = "btn-default btn-block",
                  style = "margin-top: 10px;"
                )
              )
            )
          )
        )
        # )
      ), # Close Import PDF File tabPanel

      # ===========================================
      # MAIN TAB 2: INFO & REFERENCES
      # ===========================================
      tabPanel(
        title = "Info & References",
        value = "tab_info_references",
        icon = icon("info-circle"),
        fluidPage(
          fluidRow(
            column(1),
            column(
              10,
              br(),
              HTML(helpContent()$contentAnalysis)
            ),
            column(1)
          )
        )
      )
    ), # Close main tabsetPanel

    # Modal for Preview (Bootstrap native)
    tags$div(
      class = "modal fade",
      id = "previewModal",
      tabindex = "-1",
      role = "dialog",

      tags$div(
        class = "modal-dialog modal-lg",
        role = "document",
        style = "width: 90%; max-width: 1200px;",

        tags$div(
          class = "modal-content",

          # Header
          tags$div(
            class = "modal-header",
            tags$button(
              type = "button",
              class = "close",
              `data-dismiss` = "modal",
              `aria-label` = "Close",
              tags$span(`aria-hidden` = "true", HTML("&times;"))
            ),
            tags$h4(class = "modal-title", "Text & PDF Preview")
          ),

          # Body
          tags$div(
            class = "modal-body",
            style = "max-height: 75vh; overflow-y: auto;",

            tabsetPanel(
              id = "modal_preview_tabs",

              tabPanel(
                "Extracted Text",
                br(),
                div(
                  style = "margin-bottom: 10px;",
                  span(
                    textOutput("text_length_info", inline = TRUE),
                    style = "font-size: 12px; color: #666;"
                  )
                ),
                div(
                  style = paste0(
                    "background-color: #f8f9fa; padding: 15px; ",
                    "border: 1px solid #e9ecef; border-radius: 4px; ",
                    "font-family: 'Consolas', 'Monaco', monospace; ",
                    "font-size: 13px; line-height: 1.4; ",
                    "white-space: pre-wrap; word-wrap: break-word;"
                  ),
                  textOutput("text_preview")
                )
              ),

              tabPanel(
                "PDF Preview",
                br(),
                uiOutput("pdf_viewer")
              )
            )
          ),

          # Footer
          tags$div(
            class = "modal-footer",
            tags$button(
              type = "button",
              class = "btn btn-default",
              `data-dismiss` = "modal",
              "Close"
            )
          )
        )
      )
    ),

    # Modal to manage OpenAlex Reference Cards
    tags$div(
      class = "modal fade",
      id = "oaDetailsModal",
      tabindex = "-1",
      role = "dialog",

      tags$div(
        class = "modal-dialog modal-lg",
        role = "document",
        style = "width: 90%; max-width: 1000px;",

        tags$div(
          class = "modal-content",

          # Header
          tags$div(
            class = "modal-header",
            style = "background: linear-gradient(135deg, #1a5f7a 0%, #2874a6 100%); padding: 20px 25px;",
            tags$button(
              type = "button",
              class = "close",
              `data-dismiss` = "modal",
              `aria-label` = "Close",
              tags$span(
                `aria-hidden` = "true",
                style = "color: white !important; font-size: 32px; opacity: 0.8;",
                HTML("&times;")
              )
            ),
            tags$h4(
              class = "modal-title",
              id = "oaModalTitle",
              style = "margin: 0; padding-right: 30px; color: white !important; font-weight: 600;",
              "Document Details"
            )
          ),

          # Body
          tags$div(
            class = "modal-body",
            id = "oaModalBody",
            style = "max-height: 70vh; overflow-y: auto; padding: 20px;",
            div(
              style = "text-align: center; padding: 40px;",
              icon(
                "spinner",
                class = "fa-spin",
                style = "font-size: 32px; color: #3498db;"
              ),
              p(
                "Loading document details...",
                style = "margin-top: 15px; color: #666;"
              )
            )
          ),

          # Footer
          tags$div(
            class = "modal-footer",
            tags$button(
              type = "button",
              class = "btn btn-default",
              `data-dismiss` = "modal",
              "Close"
            )
          )
        )
      )
    ),

    tags$style(HTML(
      "
  #previewModal .modal-header,
  #oaDetailsModal .modal-header {
    background: linear-gradient(135deg, #1a5f7a 0%, #2874a6 100%) !important;
  }
  
  #previewModal .modal-header .modal-title,
  #oaDetailsModal .modal-header .modal-title,
  #previewModal .modal-header h4,
  #oaDetailsModal .modal-header h4 {
    color: white !important;
    font-weight: 600 !important;
    font-size: 18px !important;
    line-height: 1.4 !important;
  }
  
  #previewModal .modal-header .close,
  #oaDetailsModal .modal-header .close,
  #previewModal .modal-header .close span,
  #oaDetailsModal .modal-header .close span {
    color: white !important;
    opacity: 0.8 !important;
    text-shadow: none !important;
  }
  
  #previewModal .modal-header .close:hover,
  #oaDetailsModal .modal-header .close:hover {
    opacity: 1 !important;
  }
  
  /* Responsive for small screens */
  @media (max-width: 768px) {
    #oaDetailsModal .modal-header .modal-title {
      font-size: 16px !important;
    }
  }
"
    )),

    tags$style(HTML(
      "
  /* Responsive layout for statistics boxes */
  @media (max-width: 992px) {
    .small-box {
      margin-bottom: 15px;
    }
  }
  
  @media (max-width: 768px) {
    .small-box h3 {
      font-size: 28px !important;
    }
    
    .small-box i {
      font-size: 32px !important;
    }
  }
"
    )),

    # JavaScript for OpenAlex  modal
    tags$script(HTML(
      "
  // Function to show OpenAlex details
  function showOADetails(refIndex) {
    // Reset modal content
    $('#oaModalBody').html('<div style=\"text-align: center; padding: 40px;\"><i class=\"fa fa-spinner fa-spin\" style=\"font-size: 32px; color: #3498db;\"></i><p style=\"margin-top: 15px; color: #666;\">Loading document details...</p></div>');
    
    // Send the index to Shiny
    Shiny.setInputValue('selected_oa_ref_index', refIndex, {priority: 'event'});
    
    // Open the modal
    $('#oaDetailsModal').modal('show');
  }
  
  // Custom handler to update modal content
  Shiny.addCustomMessageHandler('updateOAModal', function(data) {
    $('#oaModalTitle').html(data.title);
    $('#oaModalBody').html(data.content);
  });
"
    )),

    tags$script(HTML(
      "
  // Function to open/close the PDF Import box
  Shiny.addCustomMessageHandler('togglePdfImport', function(message) {
    var details = document.getElementById('pdf_import_details');
    if (details) {
      if (message.action === 'close') {
        details.removeAttribute('open');
      } else if (message.action === 'open') {
        details.setAttribute('open', '');
      }
    }
  });
"
    ))
  )
}
