/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab filetype=javascript : */
/** 
 * @license 
 * Core UI functions for pdf2htmlEX 
 * Copyright 2012,2013 Lu Wang <coolwanglu@gmail.com> and other contributors 
 * https://github.com/coolwanglu/pdf2htmlEX/blob/master/share/LICENSE 
 */
/*
 * pdf2htmlEX.js : a simple UI for pdf2htmlEX
 *
 * Copyright 2012,2013 Lu Wang <coolwanglu@gmail.com> and other contributors
 */

/*
 * Dependencies:
 * jQuery
 */

/*
 * Attention:
 * This files is to be optimized by closure-compiler, 
 * so pay attention to the forms of property names:
 *
 * string/bracket form is safe, won't be optimized:
 * var obj={ 'a':'b' }; obj['a'] = 'b';
 * name/dot form will be optimized, the name is likely to be modified:
 * var obj={ a:'b' }; obj.a = 'b';
 *
 * Either form can be used for internal objects, 
 * but must be consistent for each one respectively.
 *
 * string/bracket form must be used for external objects
 * e.g. DEFAULT_CONFIG, object stored in page-data
 * property names are part of the `protocol` in these cases.
 *
 */

'use strict';

/* The namespace */
(function(pdf2htmlEX){
  /** 
   * @const 
   * @struct
   */
  var CSS_CLASS_NAMES = {
    page_frame       : '@CSS_PAGE_FRAME_CN@',
    page_content_box : '@CSS_PAGE_CONTENT_BOX_CN@',
    page_data        : '@CSS_PAGE_DATA_CN@',
    background_image : '@CSS_BACKGROUND_IMAGE_CN@',
    link             : '@CSS_LINK_CN@',
    __dummy__        : 'no comma'
  };

  /** 
   * @const 
   * @dict
   */
  var DEFAULT_CONFIG = {
    // id of the element to put the pages in
    'container_id' : 'page-container',
    // id of the element for sidebar (to open and close)
    'sidebar_id' : 'sidebar',
    // id of the element for outline
    'outline_id' : 'outline',
    // class for the loading indicator
    'loading_indicator_cls' : 'loading-indicator',
    // How many page shall we preload that are below the last visible page
    'preload_pages' : 3,
    // how many ms should we wait before actually rendering the pages and after a scroll event
    'render_timeout' : 100,
    // zoom ratio step for each zoom in/out event
    'scale_step' : 0.9,
    // register global key handler
    'register_key_handler' : true,

    '__dummy__'        : 'no comma'
  };

  /** @const */
  var EPS = 1e-6;

  function invert(ctm) {
    var det = ctm[0] * ctm[3] - ctm[1] * ctm[2];
    return [ ctm[3] / det
            ,-ctm[1] / det
            ,-ctm[2] / det
            ,ctm[0] / det
            ,(ctm[2] * ctm[5] - ctm[3] * ctm[4]) / det
            ,(ctm[1] * ctm[4] - ctm[0] * ctm[5]) / det
          ];
  };
  function transform(ctm, pos) {
    return [ctm[0] * pos[0] + ctm[2] * pos[1] + ctm[4]
           ,ctm[1] * pos[0] + ctm[3] * pos[1] + ctm[5]];
  };
  /** 
   * @constructor 
   * @struct
   */
  function Page(page, container) {
    if(!page) return;

    this.loaded = false;
    this.shown = false;
    this.$p = $(page); // page frame element
    this.$container = $(container);

    this.n = parseInt(this.$p.data('page-no'), 16);
    // content box
    this.$b = $('.'+CSS_CLASS_NAMES.page_content_box, this.$p);

    // page size
    // Need to make rescale work when page_content_box is not loaded, yet
    this.h = this.$p.height();     
    this.w = this.$p.width();

    // if page is loaded
    if (this.$b.length > 0) {
      /*
       * scale ratios
       *
       * default_r : the first one
       * set_r : last set
       * cur_r : currently using
       */
      this.default_r = this.set_r = this.cur_r = this.h / this.$b.height();
      this.page_data = $($('.'+CSS_CLASS_NAMES.page_data, this.$p)[0]).data('data');

      this.ctm = this.page_data['ctm'];
      this.ictm = invert(this.ctm);

      this.loaded = true;
    }
  };
  $.extend(Page.prototype, /** @lends {Page.prototype} */ {
    /* hide & show are for contents, the page frame is still there */
    hide : function(){
      this.$b.removeClass('opened');
      this.shown = false;
    },
    show : function(){
      if (this.loaded) {
        if (! this.shown) {
          this.$b.addClass('opened');
          this.shown = true;
        }
      }
    },
    rescale : function(ratio) {
      if(ratio == 0) {
        this.set_r = this.default_r;
      } else {
        this.set_r = ratio;
      }

      if(Math.abs(this.set_r - this.cur_r) > EPS) {
        this.cur_r = this.set_r;
        this.$b.css('transform', 'scale('+this.cur_r.toFixed(3)+')');
      }

      this.$p.height(this.h * this.set_r);
      this.$p.width(this.w * this.set_r);
    },
    /* return if any part of this page is shown in the container */
    is_visible : function() {
      var off = this.position();
      return !((off[1] > this.h) || (off[1] + this.$container.height() < 0));
    },
    /* return if this page or any neighbor of it is visible */
    is_nearly_visible : function() {
      var off = this.position();
      /* 
       * I should use the height of the previous page or the next page here
       * but since they are not easily available, just use '*2', which should be a good estimate in most cases
       */
      return !((off[1] > this.h * 2) || (off[1] + this.$container.height() * 2 < 0));
    },
    /*
     * return the coordinate of the top-left corner of container
     * in our coordinate system
     */
    position : function () {
      var rect = this.$p[0].getBoundingClientRect();
      // getBoundingClientRect will be called on $container 
      // for a lot of times(= #pages), just hope JIT works
      var rect_c = this.$container[0].getBoundingClientRect();
      return [rect_c.left-rect.left, rect_c.top-rect.top];
      /*
      var off = this.$p.offset();
      var off_c = this.$container.offset();
      return [off_c.left-off.left, off_c.top-off.top];
      */
    }
  });

  /** 
   * export pdf2htmlEX.Viewer 
   * @constructor
   */
  function Viewer(config) {
    /* do nothing if jQuery is not ready */
    if(!jQuery) return;

    this.config = $.extend({}, DEFAULT_CONFIG, config);
    this.pages_loading = [];
    this.init_before_loading_content();

    var _ = this;
    $(function(){_.init_after_loading_content();});
  };

  $.extend(Viewer.prototype, /** @lends {Viewer.prototype} */ {
    scale : 1,

    init_before_loading_content : function() {
      /*hide all pages before loading, will reveal only visible ones later */
      this.pre_hide_pages();
    },

    init_after_loading_content : function() {
      this.$sidebar = $('#'+this.config['sidebar_id']);
      this.$outline = $('#'+this.config['outline_id']);
      this.$container = $('#'+this.config['container_id']);
      this.$loading_indicator = $('.'+this.config['loading_indicator_cls']);

      // Open the outline if nonempty
      if(this.$outline.children().length > 0) {
        this.$sidebar.addClass('opened');
      }

      this.find_pages();

      // register schedule rendering
      var _ = this;
      this.$container.scroll(function(){ _.schedule_render(); });

      if(this.config['register_key_handler'])
        this.register_key_handler();

      // handle links
      this.$container.add(this.$outline).on('click', '.'+CSS_CLASS_NAMES.link, this, this.link_handler);

      this.render();
    },

    /*
     * set up this.pages and this.page_map
     * pages is an array holding all the Page objects
     * page-Map maps an original page number (in PDF) to the corresponding index in page
     */
    find_pages : function() {
      var new_pages = [];
      var new_page_map = {};
      var $pl= this.$container.find('.'+CSS_CLASS_NAMES.page_frame);
      /* don't use for(..in..) since $pl is more than an Array */
      for(var i = 0, l = $pl.length; i < l; ++i) {
        var p = new Page($pl[i], this.$container);
        new_page_map[p.n] = i;
        new_pages.push(p);
      }
      this.pages = new_pages;
      this.page_map = new_page_map;
    },

    load_page : function(idx, pages_to_preload, successCallback, errorCallback) {
      var pages = this.pages;
      if (idx >= pages.length)
        return;  // Page does not exist

      var cur_page = pages[idx];
      if (cur_page.loaded)
        return;  // Page is loaded

      if (this.pages_loading[idx])
        return;  // Page is already loading

      var page_no_hex = cur_page.n.toString(16);
      var $pf = cur_page.$p;

      this.$loading_indicator.clone().show().appendTo($pf);

      var url = $pf.data('page-url');
      if (url) {
        this.pages_loading[idx] = true;       // Set semaphore

        /* closure variables */
        var _ = this;
        var _idx = idx;

        $.ajax({
          url: url,
          dataType: 'text'
        }).done(function(data){
          // replace the old page with loaded data
          // the loading indicator on this page should also be destroyed
          var p = _.pages[idx];
          p.$p.replaceWith(data);

          var $new_pf = _.$container.find('#' + CSS_CLASS_NAMES.page_frame + p.n.toString(16));
          p = new Page($new_pf, _.$container);
          p.hide();
          p.rescale(_.scale);

          // disable background image dragging
          $new_pf.find('.'+CSS_CLASS_NAMES.background_image).on('dragstart', function(e){return false;});

          _.pages[idx] = p;
          _.schedule_render();

          // Reset loading token
          delete _.pages_loading[idx];

          if (successCallback) successCallback(_.pages[idx]);
        }).fail(function(jqXHR, textStatus, errorThrown){
          // Reset loading token
          delete _.pages_loading[idx];

          if (errorCallback) errorCallback();
        });
      }
      // Concurrent prefetch of the next pages
      if (pages_to_preload === undefined)
        pages_to_preload = this.config['preload_pages'];

      if (--pages_to_preload > 0)
        this.load_page(idx+1, pages_to_preload);
    },

    pre_hide_pages : function() {
      /* pages might have not been loaded yet, so add a CSS rule */
      var s = '@media screen{.'+CSS_CLASS_NAMES.page_content_box+'{display:none;}}';
      var n = document.createElement('style');
      n.type = 'text/css';
      if (n.styleSheet) {
        n.styleSheet.cssText = s;
      } else {
        n.appendChild(document.createTextNode(s));
      }
      document.getElementsByTagName('head')[0].appendChild(n);
    },

    render : function () {
      /* hide (positional) invisible pages */
      var pl = this.pages;
      var pm = this.page_map;
      for(var i = 0, l = pl.length; i < l; ++i) {
        var p = pl[i];
        if(p.is_nearly_visible()){
          if (p.loaded) {
            p.show();
          } else
            this.load_page(pm[p.n]);
        } else {
          p.hide();
        }
      }
    },

    schedule_render : function() {
      if(this.render_timer)
        clearTimeout(this.render_timer);

      var _ = this;
      this.render_timer = setTimeout(function () {
        _.render();
      }, this.config['render_timeout']);
    },

    /*
     * Handling key events, zooming, scrolling etc.
     */
    register_key_handler: function () {
      /* 
       * When user try to zoom in/out using ctrl + +/- or mouse wheel
       * handle this and prevent the default behaviours
       *
       * Code credit to PDF.js
       */
      var _ = this;
      // Firefox specific event, so that we can prevent browser from zooming
      $(window).on('DOMMouseScroll', function(e) {
        if (e.ctrlKey) {
          e.preventDefault();
          _.rescale(Math.pow(_.config['scale_step'], e.detail), true);
        }
      });

      $(window).on('keydown', function keydown(e) {
        var handled = false;
        /*
        var cmd = (e.ctrlKey ? 1 : 0)
                  | (e.altKey ? 2 : 0)
                  | (e.shiftKey ? 4 : 0)
                  | (e.metaKey ? 8 : 0)
                  ;
                  */
        var with_ctrl = e.ctrlKey || e.metaKey;
        var with_alt = e.altKey;
        switch (e.keyCode) {
          case 61: // FF/Mac '='
          case 107: // FF '+' and '='
          case 187: // Chrome '+'
            if(with_ctrl){
              _.rescale(1.0 / _.config['scale_step'], true);
              handled = true;
            }
            break;
          case 173: // FF/Mac '-'
          case 109: // FF '-'
          case 189: // Chrome '-'
            if(with_ctrl){
              _.rescale(_.config['scale_step'], true);
              handled = true;
            }
            break;
          case 48: // '0'
            if(with_ctrl){
              _.rescale(0, false);
              handled = true;
            }
            break;
          case 33: // Page UP:
            if (with_alt) { // alt-pageup    -> scroll one page up
              _.scroll_to(_.get_prev_page());
            } else { // pageup        -> scroll one screen up
              _.$container.scrollTop(_.$container.scrollTop()-_.$container.height());
            }
            handled = true;
            break;
          case 34: // Page DOWN
            if (with_alt) { // alt-pagedown  -> scroll one page down
              _.scroll_to(_.get_next_page());
            } else { // pagedown      -> scroll one screen down
              _.$container.scrollTop(_.$container.scrollTop()+_.$container.height());
            }
            handled = true;
            break;
          case 35: // End
            if (with_ctrl) {
              _.$container.scrollTop(_.$container[0].scrollHeight);
              handled = true;
            }
            break;
          case 36: // Home
            if (e.with_ctrl) {
              _.$container.scrollTop(0);
              handled = true;
            }
            break;
        }
        if(handled) {
          e.preventDefault();
          return;
        }
      });
    },

    // TODO
    get_next_page : function() { return undefined; },
    get_prev_page : function() { return undefined; },

    // TODO: offsetX/Y is by default the center of container
    rescale : function (ratio, is_relative, offsetX, offsetY) {
      if (! offsetX)
        offsetX = 0;
      if (! offsetY)
        offsetY = 0;

      // Save offset of the active page
      var active_page = this.get_active_page();
      if(!active_page) return;

      var prev_offset = active_page.$p[0].getBoundingClientRect();
      var old_scale = this.scale;
      var pl = this.pages;

      // Set new scale
      if (ratio == 0) {
        this.scale = 1;
        is_relative = false;
      }
      else if (is_relative)
        this.scale *= ratio;
      else
        this.scale = ratio;

      // Rescale pages
      for(var i = 0, l = pl.length; i < l; ++i) 
          pl[i].rescale(this.scale);  

      // Correct container scroll to keep view aligned while zooming
      var correction_top = active_page.$p[0].getBoundingClientRect().top - prev_offset.top;
      this.$container.scrollTop( this.$container.scrollTop() + correction_top + offsetY );

      // Take the center of the view as a reference
      var prev_center_x = this.$container.width() / 2 - prev_offset.left;
      // Calculate the difference respect the center of the view after the zooming
      var correction_left = prev_center_x * (this.scale/old_scale - 1) + active_page.$p.offset().left - prev_offset.left;
      // Scroll the container accordingly to keep alignment to the initial reference
      this.$container.scrollLeft( this.$container.scrollLeft() + correction_left + offsetX );

      // some pages' visibility may be toggled, wait for next render()
      this.schedule_render();
    },

    fit_width : function () {
      var active_page = this.get_active_page();
      if(!active_page) return;

      this.rescale(this.$container.width() / active_page.w, false);
      this.scroll_to(this.page_map[active_page.n], [0,0]);
    },

    fit_height : function () {
      var active_page = this.get_active_page();
      if(!active_page) return;

      this.rescale(this.$container.height() / active_page.h, false);
      this.scroll_to(this.page_map[active_page.n], [0,0]);
    },

    // TODO: preserve active_page idx after rescaling
    get_active_page : function () {
      var pl = this.pages;
      for(var i = 0, l = pl.length; i < l; ++i) {
        if (pl[i].is_visible())
          return pl[i];
      }
      return;
    },

    get_containing_page : function(obj) {
      /* get the page obj containing obj */
      var $p = obj.closest('.'+CSS_CLASS_NAMES.page_frame);
      if($p.length == 0) return;
      /*
       * Get original page number and map it to index of pages
       * TODO: store the index on the dom element
       */
      var pn = (new Page($p[0], null)).n; 
      var pm = this.page_map;
      return (pn in pm) && this.pages[pm[pn]];
    },

    link_handler : function (e) {
      var _ = e.data;
      var t = $(e.currentTarget);

      var cur_pos = [0,0];

      // cur_page might be undefined, e.g. from Outline
      var cur_page = _.get_containing_page(t);
      if(cur_page)
      {
        cur_pos = cur_page.position();
        //get the coordinates in default user system
        cur_pos = transform(cur_page.ictm, [cur_pos[0], cur_page.h-cur_pos[1]]);
      }

      var detail_str = /** @type{string} */ (t.attr('data-dest-detail'));
      if(detail_str === undefined) return;

      var ok = false;
      var detail = JSON.parse(detail_str);

      var target_page_no = detail[0];
      var page_map = this.page_map;
      if(!(target_page_no in page_map)) return;
      var target_page_idx = page_map[target_page_no];
      var target_page = _.pages[target_page_idx];

      var pos = [0,0];
      var upside_down = true;
      // TODO: zoom
      // TODO: BBox
      switch(detail[1]) {
        case 'XYZ':
          pos = [(detail[2] == null) ? cur_pos[0] : detail[2]
            ,(detail[3] == null) ? cur_pos[1] : detail[3]];
          ok = true;
          break;
        case 'Fit':
        case 'FitB':
          pos = [0,0];
          ok = true;
          break;
        case 'FitH':
        case 'FitBH':
          pos = [0, (detail[2] == null) ? cur_pos[1] : detail[2]];
          ok = true;
          break;
        case 'FitV':
        case 'FitBV':
          pos = [(detail[2] == null) ? cur_pos[0] : detail[2], 0];
          ok = true;
          break;
        case 'FitR':
          /* locate the top-left corner of the rectangle */
          pos = [detail[2], detail[5]];
          upside_down = false;
          ok = true;
          break;
        default:
          ok = false;
          break;
      }

      if(ok) {
        /* page should of type Page */
        var transform_and_scroll = function(page) {
          pos = transform(page.ctm, pos);
          if(upside_down) {
            pos[1] = page.h - pos[1];
          }
          _.scroll_to(target_page_idx, pos);
        };

        if (target_page.loaded) {
          transform_and_scroll(target_page);
        } else {
          // Scroll to the exact position once loaded.
          _.load_page(target_page_idx, undefined, transform_and_scroll);

          // In the meantime page gets loaded, scroll approximately position for maximum responsiveness.
          _.scroll_to(target_page_idx, [0,0]);
        }
        e.preventDefault();
      }
    }, 

    /* pos=[x,y], where (0,0) is the top-left corner */
    scroll_to : function(page_idx, pos) {
      var target_page = this.pages[page_idx];
      if(target_page === undefined) return;

      if(pos === undefined)
        pos = [0,0];

      var cur_target_pos = target_page.position();

      this.$container.scrollLeft(this.$container.scrollLeft()-cur_target_pos[0]+pos[0]);
      this.$container.scrollTop(this.$container.scrollTop()-cur_target_pos[1]+pos[1]);
    },

    __last_member__ : 'no comma' /*,*/
  });

  pdf2htmlEX['Viewer'] = Viewer;
})(window['pdf2htmlEX'] = window['pdf2htmlEX'] || {});