/*==================================================*
 $Id: covershow.js,v 1.16 2003/10/14 12:39:00 pat Exp $
 Copyright 2000-2003 Patrick Fitzgerald
 http://covershow.barelyfitz.com/

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *==================================================*/

// There are two objects defined in this file:
// "cover" - contains all the information for a single cover
// "covershow" - consists of multiple cover objects and runs the covershow

//==================================================
// cover object
//==================================================
function cover(src,link,text,target,attr) {
  // This is the constructor function for the cover object.
  // It is called automatically when you create a new cover object.
  // For example:
  // s = new cover();

  // Image URL
  this.src = src;

  // Link URL
  this.link = link;

  // Text to display
  this.text = text;

  // Name of the target window ("_blank")
  this.target = target;

  // Custom duration for the cover, in milliseconds.
  // This is an optional parameter.
  // this.timeout = 3000

  // Attributes for the target window:
  // width=n,height=n,resizable=yes or no,scrollbars=yes or no,
  // toolbar=yes or no,location=yes or no,directories=yes or no,
  // status=yes or no,menubar=yes or no,copyhistory=yes or no
  // Example: "width=200,height=300"
  this.attr = attr;

  // Create an image object for the cover
  if (document.images) {
    this.image = new Image();
  }

  // Flag to tell when load() has already been called
  this.loaded = false;

  //--------------------------------------------------
  this.load = function() {
    // This method loads the image for the cover

    if (!document.images) { return; }

    if (!this.loaded) {
      this.image.src = this.src;
      this.loaded = true;
    }
  }

  //--------------------------------------------------
  this.hotlink = function() {
    // This method jumps to the cover's link.
    // If a window was specified for the cover, then it opens a new window.

    var mywindow;

    // If this cover does not have a link, do nothing
    if (!this.link) return;

    // Open the link in a separate window?
    if (this.target) {

      // If window attributes are specified,
      // use them to open the new window
      if (this.attr) {
        mywindow = window.open(this.link, this.target, this.attr);
  
      } else {
        // If window attributes are not specified, do not use them
        // (this will copy the attributes from the originating window)
        mywindow = window.open(this.link, this.target);
      }

      // Pop the window to the front
      if (mywindow && mywindow.focus) mywindow.focus();

    } else {
      // Open the link in the current window
      location.href = this.link;
    }
  }
}

//==================================================
// covershow object
//==================================================
function covershow( covershowname ) {
  // This is the constructor function for the covershow object.
  // It is called automatically when you create a new object.
  // For example:
  // ss = new covershow("ss");

  // Name of this object
  // (required if you want your covershow to auto-play)
  // For example, "coverS1"
  this.name = covershowname;

  // When we reach the last cover, should we loop around to start the
  // covershow again?
  this.repeat = true;

  // Number of images to pre-fetch.
  // -1 = preload all images.
  //  0 = load each image is it is used.
  //  n = pre-fetch n images ahead of the current image.
  // I recommend preloading all images unless you have large
  // images, or a large amount of images.
  this.prefetch = -1;

  // IMAGE element on your HTML page.
  // For example, document.images.coverS1IMG
  this.image;

  // ID of a DIV element on your HTML page that will contain the text.
  // For example, "covers2text"
  // Note: after you set this variable, you should call
  // the update() method to update the covershow display.
  this.textid;

  // TEXTAREA element on your HTML page.
  // For example, document.coverS1form.coverS1TEXT
  // This is a depracated method for displaying the text,
  // but you might want to supply it for older browsers.
  this.textarea;

  // Milliseconds to pause between covers.
  // Individual covers can override this.
  this.timeout = 8000;

  // Hook functions to be called before and after updating the cover
  // this.pre_update_hook = function() { }
  // this.post_update_hook = function() { }

  // These are private variables
  this.covers = new Array();
  this.current = 0;
  this.timeoutid = 0;

  //--------------------------------------------------
  // Public methods
  //--------------------------------------------------
  this.add_cover = function(cover) {
    // Add a cover to the covershow.
    // For example:
    // coverS1.add_cover(new cover("s1.jpg", "link.html"))
  
    var i = this.covers.length;
  
    // Prefetch the cover image if necessary
    if (this.prefetch == -1) {
      cover.load();
    }

    this.covers[i] = cover;
  }

  //--------------------------------------------------
  this.play = function(timeout) {
    // This method implements the automatically running covershow.
    // If you specify the "timeout" argument, then a new default
    // timeout will be set for the covershow.
  
    // Make sure we're not already playing
    this.pause();
  
    // If the timeout argument was specified (optional)
    // then make it the new default
    if (timeout) {
      this.timeout = timeout;
    }
  
    // If the current cover has a custom timeout, use it;
    // otherwise use the default timeout
    if (typeof this.covers[ this.current ].timeout != 'undefined') {
      timeout = this.covers[ this.current ].timeout;
    } else {
      timeout = this.timeout;
    }

    // After the timeout, call this.loop()
    this.timeoutid = setTimeout( this.name + ".loop()", timeout);
  }

  //--------------------------------------------------
  this.pause = function() {
    // This method stops the covershow if it is automatically running.
  
    if (this.timeoutid != 0) {

      clearTimeout(this.timeoutid);
      this.timeoutid = 0;

    }
  }

  //--------------------------------------------------
  this.update = function() {
    // This method updates the covershow image on the page

    // Make sure the covershow has been initialized correctly
    if (! this.valid_image()) { return; }
  
    // Call the pre-update hook function if one was specified
    if (typeof this.pre_update_hook == 'function') {
      this.pre_update_hook();
    }

    // Convenience variable for the current cover
    var cover = this.covers[ this.current ];

    // Determine if the browser supports filters
    var dofilter = false;
    if (this.image &&
        typeof this.image.filters != 'undefined' &&
        typeof this.image.filters[0] != 'undefined') {

      dofilter = true;

    }

    // Load the cover image if necessary
    cover.load();
  
    // Apply the filters for the image transition
    if (dofilter) {

      // If the user has specified a custom filter for this cover,
      // then set it now
      if (cover.filter &&
          this.image.style &&
          this.image.style.filter) {

        this.image.style.filter = cover.filter;

      }
      this.image.filters[0].Apply();
    }

    // Update the image.
    this.image.src = cover.image.src;

    // Play the image transition filters
    if (dofilter) {
      this.image.filters[0].Play();
    }

    // Update the text
    this.display_text();

    // Call the post-update hook function if one was specified
    if (typeof this.post_update_hook == 'function') {
      this.post_update_hook();
    }

    // Do we need to pre-fetch images?
    if (this.prefetch > 0) {

      var next, prev, count;

      // Pre-fetch the next cover image(s)
      next = this.current;
      prev = this.current;
      count = 0;
      do {

        // Get the next and previous cover number
        // Loop past the ends of the covershow if necessary
        if (++next >= this.covers.length) next = 0;
        if (--prev < 0) prev = this.covers.length - 1;

        // Preload the cover image
        this.covers[next].load();
        this.covers[prev].load();

        // Keep going until we have fetched
        // the designated number of covers

      } while (++count < this.prefetch);
    }
  }

  //--------------------------------------------------
  this.goto_cover = function(n) {
    // This method jumpts to the cover number you specify.
    // If you use cover number -1, then it jumps to the last cover.
    // You can use this to make links that go to a specific cover,
    // or to go to the beginning or end of the covershow.
    // Examples:
    // onclick="mycovers.goto_cover(0)"
    // onclick="mycovers.goto_cover(-1)"
    // onclick="mycovers.goto_cover(5)"
  
    if (n == -1) {
      n = this.covers.length - 1;
    }
  
    if (n < this.covers.length && n >= 0) {
      this.current = n;
    }
  
    this.update();
  }


  //--------------------------------------------------
  this.goto_random_cover = function(include_current) {
    // Picks a random cover (other than the current cover) and
    // displays it.
    // If the include_current parameter is true,
    // then 
    // See also: shuffle()

    var i;

    // Make sure there is more than one cover
    if (this.covers.length > 1) {

      // Generate a random cover number,
      // but make sure it is not the current cover
      do {
        i = Math.floor(Math.random()*this.covers.length);
      } while (i == this.current);
 
      // Display the cover
      this.goto_cover(i);
    }
  }


  //--------------------------------------------------
  this.next = function() {
    // This method advances to the next cover.

    // Increment the image number
    if (this.current < this.covers.length - 1) {
      this.current++;
    } else if (this.repeat) {
      this.current = 0;
    }

    this.update();
  }


  //--------------------------------------------------
  this.previous = function() {
    // This method goes to the previous cover.
  
    // Decrement the image number
    if (this.current > 0) {
      this.current--;
    } else if (this.repeat) {
      this.current = this.covers.length - 1;
    }
  
    this.update();
  }


  //--------------------------------------------------
  this.shuffle = function() {
    // This method randomly shuffles the order of the covers.

    var i, i2, covers_copy, covers_randomized;

    // Create a copy of the array containing the covers
    // in sequential order
    covers_copy = new Array();
    for (i = 0; i < this.covers.length; i++) {
      covers_copy[i] = this.covers[i];
    }

    // Create a new array to contain the covers in random order
    covers_randomized = new Array();

    // To populate the new array of covers in random order,
    // loop through the existing covers, picking a random
    // cover, removing it from the ordered list and adding it to
    // the random list.

    do {

      // Pick a random cover from those that remain
      i = Math.floor(Math.random()*covers_copy.length);

      // Add the cover to the end of the randomized array
      covers_randomized[ covers_randomized.length ] =
        covers_copy[i];

      // Remove the cover from the sequential array,
      // so it cannot be chosen again
      for (i2 = i + 1; i2 < covers_copy.length; i2++) {
        covers_copy[i2 - 1] = covers_copy[i2];
      }
      covers_copy.length--;

      // Keep going until we have removed all the covers

    } while (covers_copy.length);

    // Now set the covers to the randomized array
    this.covers = covers_randomized;
  }


  //--------------------------------------------------
  this.get_text = function() {
    // This method returns the text of the current cover
  
    return(this.covers[ this.current ].text);
  }


  //--------------------------------------------------
  this.get_all_text = function(before_cover, after_cover) {
    // Return the text for all of the covers.
    // For the text of each cover, add "before_cover" in front of the
    // text, and "after_cover" after the text.
    // For example:
    // document.write("<ul>");
    // document.write(s.get_all_text("<li>","\n"));
    // document.write("<\/ul>");
  
    all_text = "";
  
    // Loop through all the covers in the covershow
    for (i=0; i < this.covers.length; i++) {
  
      cover = this.covers[i];
    
      if (cover.text) {
        all_text += before_cover + cover.text + after_cover;
      }
  
    }
  
    return(all_text);
  }


  //--------------------------------------------------
  this.display_text = function(text) {
    // Display the text for the current cover
  
    // If the "text" arg was not supplied (usually it isn't),
    // get the text from the covershow
    if (!text) {
      text = this.covers[ this.current ].text;
    }
  
    // If a textarea has been specified,
    // then change the text displayed in it
    if (this.textarea && typeof this.textarea.value != 'undefined') {
      this.textarea.value = text;
    }

    // If a text id has been specified,
    // then change the contents of the HTML element
    if (this.textid) {

      r = this.getElementById(this.textid);
      if (!r) { return false; }
      if (typeof r.innerHTML == 'undefined') { return false; }

      // Update the text
      r.innerHTML = text;
    }
  }


  //--------------------------------------------------
  this.hotlink = function() {
    // This method calls the hotlink() method for the current cover.
  
    this.covers[ this.current ].hotlink();
  }


  //--------------------------------------------------
  this.save_position = function(cookiename) {
    // Saves the position of the covershow in a cookie,
    // so when you return to this page, the position in the covershow
    // won't be lost.
  
    if (!cookiename) {
      cookiename = this.name + '_covershow';
    }
  
    document.cookie = cookiename + '=' + this.current;
  }


  //--------------------------------------------------
  this.restore_position = function(cookiename) {
  // If you previously called covershow_save_position(),
  // returns the covershow to the previous state.
  
    //Get cookie code by Shelley Powers
  
    if (!cookiename) {
      cookiename = this.name + '_covershow';
    }
  
    var search = cookiename + "=";
  
    if (document.cookie.length > 0) {
      offset = document.cookie.indexOf(search);
      // if cookie exists
      if (offset != -1) { 
        offset += search.length;
        // set index of beginning of value
        end = document.cookie.indexOf(";", offset);
        // set index of end of cookie value
        if (end == -1) end = document.cookie.length;
        this.current = parseInt(unescape(document.cookie.substring(offset, end)));
        }
     }
  }


  //--------------------------------------------------
  this.noscript = function() {
    // This method is not for use as part of your covershow,
    // but you can call it to get a plain HTML version of the covershow
    // images and text.
    // You should copy the HTML and put it within a NOSCRIPT element, to
    // give non-javascript browsers access to your covershow information.
    // This also ensures that your covershow text and images are indexed
    // by search engines.
  
    $html = "\n";
  
    // Loop through all the covers in the covershow
    for (i=0; i < this.covers.length; i++) {
  
      cover = this.covers[i];
  
      $html += '<P>';
  
      if (cover.link) {
        $html += '<a href="' + cover.link + '">';
      }
  
      $html += '<img src="../test/' + cover.src + '" ALT="covershow image">';
  
      if (cover.link) {
        $html += "<\/a>";
      }
  
      if (cover.text) {
        $html += "<BR>\n" + cover.text;
      }
  
      $html += "<\/P>" + "\n\n";
    }
  
    // Make the HTML browser-safe
    $html = $html.replace(/\&/g, "&" );
    $html = $html.replace(/</g, "&lt;" );
    $html = $html.replace(/>/g, ">" );
  
    return('<pre>' + $html + '</pre>');
  }


  //==================================================
  // Private methods
  //==================================================

  //--------------------------------------------------
  this.loop = function() {
    // This method is for internal use only.
    // This method gets called automatically by a JavaScript timeout.
    // It advances to the next cover, then sets the next timeout.
    // If the next cover image has not completed loading yet,
    // then do not advance to the next cover yet.

    // Make sure the next cover image has finished loading
    if (this.current < this.covers.length - 1) {
      next_cover = this.covers[this.current + 1];
      if (next_cover.image.complete == null || next_cover.image.complete) {
        this.next();
      }
    } else { // we're at the last cover
      this.next();
    }
    
    // Keep playing the covershow
    this.play( );
  }


  //--------------------------------------------------
  this.valid_image = function() {
    // Returns 1 if a valid image has been set for the covershow
  
    if (!this.image)
    {
      return false;
    }
    else {
      return true;
    }
  }

  //--------------------------------------------------
  this.getElementById = function(element_id) {
    // This method returns the element corresponding to the id

    if (document.getElementById) {
      return document.getElementById(element_id);
    }
    else if (document.all) {
      return document.all[element_id];
    }
    else if (document.layers) {
      return document.layers[element_id];
    } else {
      return undefined;
    }
  }
  

  //==================================================
  // Deprecated methods
  // I don't recommend the use of the following methods,
  // but they are included for backward compatibility.
  // You can delete them if you don't need them.
  //==================================================

  //--------------------------------------------------
  this.set_image = function(imageobject) {
    // This method is deprecated; you should use
    // the following code instead:
    // s.image = document.images.myimagename;
    // s.update();

    if (!document.images)
      return;
    this.image = imageobject;
  }

  //--------------------------------------------------
  this.set_textarea = function(textareaobject) {
    // This method is deprecated; you should use
    // the following code instead:
    // s.textarea = document.form.textareaname;
    // s.update();

    this.textarea = textareaobject;
    this.display_text();
  }

  //--------------------------------------------------
  this.set_textid = function(textidstr) {
    // This method is deprecated; you should use
    // the following code instead:
    // s.textid = "mytextid";
    // s.update();

    this.textid = textidstr;
    this.display_text();
  }
}