/**

* The reveal.js markdown plugin. Handles parsing of
* markdown inside of presentations as well as loading
* of external markdown documents.
*/

(function( root, factory ) {

if( typeof exports === 'object' ) {
    module.exports = factory( require( './marked' ) );
}
else {
    // Browser globals (root is window)
    root.RevealMarkdown = factory( root.marked );
    root.RevealMarkdown.initialize();
}

}( this, function( marked ) {

if( typeof marked === 'undefined' ) {
    throw 'The reveal.js Markdown plugin requires marked to be loaded';
}

if( typeof hljs !== 'undefined' ) {
    marked.setOptions({
        highlight: function( lang, code ) {
            return hljs.highlightAuto( lang, code ).value;
        }
    });
}

var DEFAULT_SLIDE_SEPARATOR = '^\n---\n$',
    DEFAULT_NOTES_SEPARATOR = 'note:';

/**
 * Retrieves the markdown contents of a slide section
 * element. Normalizes leading tabs/whitespace.
 */
function getMarkdownFromSlide( section ) {

    var template = section.querySelector( 'script' );

    // strip leading whitespace so it isn't evaluated as code
    var text = ( template || section ).textContent;

    var leadingWs = text.match( /^\n?(\s*)/ )[1].length,
        leadingTabs = text.match( /^\n?(\t*)/ )[1].length;

    if( leadingTabs > 0 ) {
        text = text.replace( new RegExp('\\n?\\t{' + leadingTabs + '}','g'), '\n' );
    }
    else if( leadingWs > 1 ) {
        text = text.replace( new RegExp('\\n? {' + leadingWs + '}','g'), '\n' );
    }

    return text;

}

/**
 * Given a markdown slide section element, this will
 * return all arguments that aren't related to markdown
 * parsing. Used to forward any other user-defined arguments
 * to the output markdown slide.
 */
function getForwardedAttributes( section ) {

    var attributes = section.attributes;
    var result = [];

    for( var i = 0, len = attributes.length; i < len; i++ ) {
        var name = attributes[i].name,
            value = attributes[i].value;

        // disregard attributes that are used for markdown loading/parsing
        if( /data\-(markdown|separator|vertical|notes)/gi.test( name ) ) continue;

        if( value ) {
            result.push( name + '=' + value );
        }
        else {
            result.push( name );
        }
    }

    return result.join( ' ' );

}

/**
 * Inspects the given options and fills out default
 * values for what's not defined.
 */
function getSlidifyOptions( options ) {

    options = options || {};
    options.separator = options.separator || DEFAULT_SLIDE_SEPARATOR;
    options.notesSeparator = options.notesSeparator || DEFAULT_NOTES_SEPARATOR;
    options.attributes = options.attributes || '';

    return options;

}

/**
 * Helper function for constructing a markdown slide.
 */
function createMarkdownSlide( content, options ) {

    options = getSlidifyOptions( options );

    var notesMatch = content.split( new RegExp( options.notesSeparator, 'mgi' ) );

    if( notesMatch.length === 2 ) {
        content = notesMatch[0] + '<aside class="notes" data-markdown>' + notesMatch[1].trim() + '</aside>';
    }

    return '<script type="text/template">' + content + '</script>';

}

/**
 * Parses a data string into multiple slides based
 * on the passed in separator arguments.
 */
function slidify( markdown, options ) {

    options = getSlidifyOptions( options );

    var separatorRegex = new RegExp( options.separator + ( options.verticalSeparator ? '|' + options.verticalSeparator : '' ), 'mg' ),
        horizontalSeparatorRegex = new RegExp( options.separator );

    var matches,
        lastIndex = 0,
        isHorizontal,
        wasHorizontal = true,
        content,
        sectionStack = [];

    // iterate until all blocks between separators are stacked up
    while( matches = separatorRegex.exec( markdown ) ) {
        notes = null;

        // determine direction (horizontal by default)
        isHorizontal = horizontalSeparatorRegex.test( matches[0] );

        if( !isHorizontal && wasHorizontal ) {
            // create vertical stack
            sectionStack.push( [] );
        }

        // pluck slide content from markdown input
        content = markdown.substring( lastIndex, matches.index );

        if( isHorizontal && wasHorizontal ) {
            // add to horizontal stack
            sectionStack.push( content );
        }
        else {
            // add to vertical stack
            sectionStack[sectionStack.length-1].push( content );
        }

        lastIndex = separatorRegex.lastIndex;
        wasHorizontal = isHorizontal;
    }

    // add the remaining slide
    ( wasHorizontal ? sectionStack : sectionStack[sectionStack.length-1] ).push( markdown.substring( lastIndex ) );

    var markdownSections = '';

    // flatten the hierarchical stack, and insert <section data-markdown> tags
    for( var i = 0, len = sectionStack.length; i < len; i++ ) {
        // vertical
        if( sectionStack[i].propertyIsEnumerable( length ) && typeof sectionStack[i].splice === 'function' ) {
            markdownSections += '<section '+ options.attributes +'>';

            sectionStack[i].forEach( function( child ) {
                markdownSections += '<section data-markdown>' +  createMarkdownSlide( child, options ) + '</section>';
            } );

            markdownSections += '</section>';
        }
        else {
            markdownSections += '<section '+ options.attributes +' data-markdown>' + createMarkdownSlide( sectionStack[i], options ) + '</section>';
        }
    }

    return markdownSections;

}

/**
 * Parses any current data-markdown slides, splits
 * multi-slide markdown into separate sections and
 * handles loading of external markdown.
 */
function processSlides() {

    var sections = document.querySelectorAll( '[data-markdown]'),
        section;

    for( var i = 0, len = sections.length; i < len; i++ ) {

        section = sections[i];

        if( section.getAttribute( 'data-markdown' ).length ) {

            var xhr = new XMLHttpRequest(),
                url = section.getAttribute( 'data-markdown' );

            datacharset = section.getAttribute( 'data-charset' );

            // see https://developer.mozilla.org/en-US/docs/Web/API/element.getAttribute#Notes
            if( datacharset != null && datacharset != '' ) {
                xhr.overrideMimeType( 'text/html; charset=' + datacharset );
            }

            xhr.onreadystatechange = function() {
                if( xhr.readyState === 4 ) {
                    if ( xhr.status >= 200 && xhr.status < 300 ) {

                        section.outerHTML = slidify( xhr.responseText, {
                            separator: section.getAttribute( 'data-separator' ),
                            verticalSeparator: section.getAttribute( 'data-vertical' ),
                            notesSeparator: section.getAttribute( 'data-notes' ),
                            attributes: getForwardedAttributes( section )
                        });

                    }
                    else {

                        section.outerHTML = '<section data-state="alert">' +
                            'ERROR: The attempt to fetch ' + url + ' failed with HTTP status ' + xhr.status + '.' +
                            'Check your browser\'s JavaScript console for more details.' +
                            '<p>Remember that you need to serve the presentation HTML from a HTTP server.</p>' +
                            '</section>';

                    }
                }
            };

            xhr.open( 'GET', url, false );

            try {
                xhr.send();
            }
            catch ( e ) {
                alert( 'Failed to get the Markdown file ' + url + '. Make sure that the presentation and the file are served by a HTTP server and the file can be found there. ' + e );
            }

        }
        else if( section.getAttribute( 'data-separator' ) || section.getAttribute( 'data-vertical' ) || section.getAttribute( 'data-notes' ) ) {

            section.outerHTML = slidify( getMarkdownFromSlide( section ), {
                separator: section.getAttribute( 'data-separator' ),
                verticalSeparator: section.getAttribute( 'data-vertical' ),
                notesSeparator: section.getAttribute( 'data-notes' ),
                attributes: getForwardedAttributes( section )
            });

        }
        else {

            section.innerHTML = createMarkdownSlide( getMarkdownFromSlide( section ) );

        }
    }

}

/**
 * Converts any current data-markdown slides in the
 * DOM to HTML.
 */
function convertSlides() {

    var sections = document.querySelectorAll( '[data-markdown]');

    for( var i = 0, len = sections.length; i < len; i++ ) {

        var section = sections[i];

        // Only parse the same slide once
        if( !section.getAttribute( 'data-markdown-parsed' ) ) {

            section.setAttribute( 'data-markdown-parsed', true )

            var notes = section.querySelector( 'aside.notes' );
            var markdown = getMarkdownFromSlide( section );

            section.innerHTML = marked( markdown );

            // If there were notes, we need to re-add them after
            // having overwritten the section's HTML
            if( notes ) {
                section.appendChild( notes );
            }

        }

    }

}

// API
return {

    initialize: function() {
        processSlides();
        convertSlides();
    },

    // TODO: Do these belong in the API?
    processSlides: processSlides,
    convertSlides: convertSlides,
    slidify: slidify

};

}));