var page_stack = new Array();
var oebps_dir = '';
var opf_file = '';
var ncx_file = '';
var abs_container_bottom = null;

function process_content() {
    $('#content p').css('color','white');
    
    // This won't be accurate until the content is first loaded
    abs_container_bottom = $('#book').height() + $('#book').offset().top;
    
    var target_height = null;
    var para_offset = null;
    var obscured_para = null;
    var last_unobscured_para = null;
    
    // Find the paragraph that's below the bounding box
    $('#content p:visible').each(function() {
       var top = parseInt($(this).offset().top);
       para_offset = parseInt(top + $(this).height());
       var line_height = parseInt($(this).css('line-height').replace('px', ''));
       
       if (para_offset > abs_container_bottom) {
           var top_with_padding = top + (line_height);
           if ( top_with_padding > abs_container_bottom) {
               // We went too far; this paragraph starts below the fold.
               // This means the previous paragraph broke acceptably, so just return
               return false;
           }
           obscured_para = $(this);
           var letter_width = obscured_para.css('font-size').replace('px', '');
           var para_width   = obscured_para.css('width').replace('px', '');
           target_height    = abs_container_bottom - line_height;
           return false;
       }
       last_unobscured_para = $(this);
       
  });

    /* Given a paragraph that needs to be broken, find the minimum displayable
       text and push the remaining text to a new paragraph.
       This could be improved by accelerating quickly when the disparity between
       the current height and target height are great. 
       Also investigate methods to preserve the DOM integrity of the original
       by wrapping the overflow into a hidden span rather than by segmenting
       it into a new paragraph.
    */
         
    if (obscured_para != null && obscured_para.text() != '') {
        text_overflow = new Array();
        
        while (para_offset > target_height) {
            t = obscured_para.text();
            index = t.length - 1;
            // Jump by word
            while (index > 0 && t.charAt(index) != ' ') {
                index--;
            }
            text_overflow.push(t.substr(index + 1, t.length - 1));
            obscured_para.text(t.substr(0, index));
            if (index == 0) {
                break;
            }
            
            para_offset = parseInt(obscured_para.position().top + obscured_para.height());
        }
        
        // Put the overflow text into a new paragraph after the last one
        obscured_para.after($('<p/>').text(text_overflow.reverse().join(' ')));
        
        // Hide all the remaining paragraphs
        obscured_para.nextAll('p').hide();
        
    }
    var status = new Object();
    status.top = $($('#content p:visible')[0]);
    if (obscured_para != null) {
        status.bottom = obscured_para;
    }
    else {
        status.bottom = last_unobscured_para;
        // Are there any more paragraphs?  If so, hide them
        if (last_unobscured_para) {
            last_unobscured_para.nextAll('p').hide();
        }
    }
    page_stack.push(status);
    $('#content p').css('color','black');
    
    // Now look at what is visible and figure out what page this is
    var num_chars = 0;
    $('#content p:visible').each(function() {
            num_chars += $(this).text().length;
    });

    var num_chars_invisible = 0;
    $('#content p:hidden').each(function() {
            num_chars_invisible += $(this).text().length;
    });

    var num_chars_before = 0;
    status.top.prevAll('p').each(function() {
            num_chars_before += $(this).text().length;
    });
    
    var invisible = 500 / num_chars_invisible;
    var all = num_chars_invisible + num_chars;
    var percent = num_chars_before / all;
    if (num_chars_invisible == num_chars_before) {
        percent = 1;
    }
    var width = 500 * percent;
    $('#remaining').css('width', width + 'px');
}

function fade_content(content) {
    content.attr('class', 'faded');
}

function load_content() {
    page = $(this).attr('href');
    // Unselect other sections
    $('.selected').attr('class', 'unselected');
    $(this).attr('class', 'selected');
    $('#content').load(page, null, process_content);
    return false;
}

function next() {
    var top = page_stack[page_stack.length-1].bottom;
    if (top) {
        top.prevAll('p').hide();
        top.hide();
        if (top.nextAll('p').length == 0) {
            return next_chapter();
        }
        top.nextAll('p').show();
    }
    else {
        return next_chapter();
    }
    process_content();
}
function previous() {
    /* If we have no pages to go back to, call the previous chapter function instead.
       This isn't really what the reader probably means -- they want to turn
       back to the previous _page_ before the beginning of that chapter,
       but we could only potentially do that if we had visited the page already
       and had it in the stack.
    */
    var status = page_stack.pop();
    if (status.top.prev('p').length == 0) {
        return previous_chapter();
    }
    status.top.hide();
    status = page_stack.pop();
    status.bottom.hide();
    status.top.show();
    status.top.nextAll('p:hidden').show();
    process_content();
}

function next_chapter() {
    // Simulate a click event on the next chapter after the selected one
    $('a.selected').parent().next('li').find('a').click();
    
    // How far is the selected chapter now from the bottom border?
    var selected_position = $('a.selected').position().top;
    var height_of_toc = $('a.selected').height();
    
    if (selected_position - (height_of_toc * 2) > abs_container_bottom / 2) {
        // Hide the first visible chapter item
        $('#toc a:visible:eq(0)').hide();
    }
    $('#remaining').css('width', '0px');
}

function previous_chapter() {
    // Simulate a click event on the next chapter after the selected one
    $('a.selected').parent().prev('li').find('a').click();
    
    // Have we hidden any chapters that we now want to show?
    $('#toc a:visible:eq(0)').parent().prev('li').find('a').show();
    
    $('#remaining').css('width', '0px');
}


/* Open the container file to find the resources */
function container(f) {
    opf_file = $(f).find('rootfile').attr('full-path');               
    // Get the OEPBS dir, if there is one
    if (opf_file.indexOf('/') != -1) {
        oebps_dir = opf_file.substr(0, opf_file.lastIndexOf('/'));
    }
    opf_file = epub_dir + '/' + opf_file;
    jQuery.get(opf_file, {}, opf);
}

/* Open the TOC, get the first item and open it */
function toc(f) {
    
    $(f).find('navPoint').each(function() { 
            var s = $('<span/>').text($(this).find('text:first').text());
            var a = $('<a/>').attr('href', epub_dir + '/' + oebps_dir + '/' + $(this).find('content').attr('src'));
            // If 's' has a parent navPoint, indent it
            if ($(this).parent()[0].tagName.toLowerCase() == 'navpoint') {
              s.addClass('indent');
            }    
            s.appendTo(a);
            a.appendTo($('<li/>').appendTo('#toc'));
        });
    
    // Click on the desired first item link 
    $('#toc a:eq(0)').click();

}
/* Open the OPF file and read some useful metadata from it */
function opf(f) {
    // Get the document title
    // Depending on the browser, namespaces may or may not be handled here
    var title = $(f).find('title').text();  // Safari
    var author = $(f).find('creator').text();  
    $('#content-title').html(title + ' by ' + author);
    // Firefox
    if (title == null || title == '') {
        $('#content-title').html($(f).find('dc\\:title').text() + ' by ' +  $(f).find('dc\\:creator').text());
    }
    // Get the NCX 
    var opf_item_tag = 'opf\\:item';
    if ($(f).find('opf\\:item').length == 0) {
       opf_item_tag = 'item';
    }

    $(f).find(opf_item_tag).each(function() {
            // Cheat and find the first file ending in NCX
            if ( $(this).attr('href').indexOf('.ncx') != -1) {
                ncx_file = epub_dir + '/' + oebps_dir + '/' + $(this).attr('href');
                jQuery.get(ncx_file, {}, toc);
            }
        });
    
}
jQuery(document).ready(function() {
        
         jQuery.get(epub_dir + '/META-INF/container.xml', {}, container);
         $('#toc a').live('click', load_content);

         $('#book').resizable( { alsoResize: '#content',
                                 stop: function() {
            $('#content p').show();
            process_content();

         }});

         $('html').mousewheel(function(event, delta) {
            if (delta > 0) // up
               previous();
            else if (delta < 0) // down
               next();
            return false; // prevent default
         });
        
         $(document).bind('keydown', function(e) {
           var code = (e.keyCode ? e.keyCode : e.which);
           if ( code == 78 ) {  //  'n'
             next();
           }
           if ( code == 80) {  // 'p'
             previous();
           }
           if ( code == 74) { //  'j'
             next_chapter();
           }
           if ( code == 75 ) { //  'k'
             previous_chapter();
           }
             });
    }
    );