/**

* 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$',
        DEFAULT_NOTES_SEPARATOR = 'note:',
        DEFAULT_ELEMENT_ATTRIBUTES_SEPARATOR = '\\\.element\\\s*?(.+?)$',
        DEFAULT_SLIDE_ATTRIBUTES_SEPARATOR = '\\\.slide:\\\s*?(\\\S.+?)$';

/**
 * 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 + '}'), '\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] instanceof Array ) {
                        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 ) {
                                        // file protocol yields status code 0 (useful for local debug, mobile applications etc.)
                                        if ( ( xhr.status >= 200 && xhr.status < 300 ) || xhr.status === 0 ) {

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

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

                }
                else {
                        section.innerHTML = createMarkdownSlide( getMarkdownFromSlide( section ) );
                }
        }

}

/**
 * Check if a node value has the attributes pattern.
 * If yes, extract it and add that value as one or several attributes
 * the the terget element.
 *
 * You need Cache Killer on Chrome to see the effect on any FOM transformation
 * directly on refresh (F5)
 * http://stackoverflow.com/questions/5690269/disabling-chrome-cache-for-website-development/7000899#answer-11786277
 */
function addAttributeInElement( node, elementTarget, separator ) {

        var mardownClassesInElementsRegex = new RegExp( separator, 'mg' );
        var mardownClassRegex = new RegExp( "([^\"= ]+?)=\"([^\"=]+?)\"", 'mg' );
        var nodeValue = node.nodeValue;
        if( matches = mardownClassesInElementsRegex.exec( nodeValue ) ) {

                var classes = matches[1];
                nodeValue = nodeValue.substring( 0, matches.index ) + nodeValue.substring( mardownClassesInElementsRegex.lastIndex );
                node.nodeValue = nodeValue;
                while( matchesClass = mardownClassRegex.exec( classes ) ) {
                        elementTarget.setAttribute( matchesClass[1], matchesClass[2] );
                }
                return true;
        }
        return false;
}

/**
 * Add attributes to the parent element of a text node,
 * or the element of an attribute node.
 */
function addAttributes( section, element, previousElement, separatorElementAttributes, separatorSectionAttributes ) {

        if ( element != null && element.childNodes != undefined && element.childNodes.length > 0 ) {
                previousParentElement = element;
                for( var i = 0; i < element.childNodes.length; i++ ) {
                        childElement = element.childNodes[i];
                        if ( i > 0 ) {
                                j = i - 1;
                                while ( j >= 0 ) {
                                        aPreviousChildElement = element.childNodes[j];
                                        if ( typeof aPreviousChildElement.setAttribute == 'function' && aPreviousChildElement.tagName != "BR" ) {
                                                previousParentElement = aPreviousChildElement;
                                                break;
                                        }
                                        j = j - 1;
                                }
                        }
                        parentSection = section;
                        if( childElement.nodeName ==  "section" ) {
                                parentSection = childElement ;
                                previousParentElement = childElement ;
                        }
                        if ( typeof childElement.setAttribute == 'function' || childElement.nodeType == Node.COMMENT_NODE ) {
                                addAttributes( parentSection, childElement, previousParentElement, separatorElementAttributes, separatorSectionAttributes );
                        }
                }
        }

        if ( element.nodeType == Node.COMMENT_NODE ) {
                if ( addAttributeInElement( element, previousElement, separatorElementAttributes ) == false ) {
                        addAttributeInElement( element, section, separatorSectionAttributes );
                }
        }
}

/**
 * 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 );
                        addAttributes(  section, section, null, section.getAttribute( 'data-element-attributes' ) ||
                                                        section.parentNode.getAttribute( 'data-element-attributes' ) ||
                                                        DEFAULT_ELEMENT_ATTRIBUTES_SEPARATOR,
                                                        section.getAttribute( 'data-attributes' ) ||
                                                        section.parentNode.getAttribute( 'data-attributes' ) ||
                                                        DEFAULT_SLIDE_ATTRIBUTES_SEPARATOR);

                        // 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

};

}));