/*==================================================*
 $Id: slideshow.js,v 1.16 2003/10/14 12:39:00 pat Exp $
 Copyright 2000-2003 Patrick Fitzgerald
 http://slideshow.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:
// "slide" - contains all the information for a single slide
// "slideshow" - consists of multiple slide objects and runs the slideshow

//==================================================
// slide object
//==================================================
function slide(src, link, text, target, attr){
    // This is the constructor function for the slide object.
    // It is called automatically when you create a new slide object.
    // For example:
    // s = new slide();
    
    // 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 slide, 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 slide
    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 slide
        
        if (!document.images) {
            return;
        }
        
        if (!this.loaded) {
            this.image.src = this.src;
            this.loaded = true;
        }
    }
    
    //--------------------------------------------------
    this.hotlink = function(){
        // This method jumps to the slide's link.
        // If a window was specified for the slide, then it opens a new window.
        
        var mywindow;
        
        // If this slide 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;
        }
    }
}

//==================================================
// slideshow object
//==================================================
function slideshow(slideshowname){
    // This is the constructor function for the slideshow object.
    // It is called automatically when you create a new object.
    // For example:
    // ss = new slideshow("ss");
    
    // Name of this object
    // (required if you want your slideshow to auto-play)
    // For example, "SLIDES1"
    this.name = slideshowname;
    
    // When we reach the last slide, should we loop around to start the
    // slideshow 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.SLIDES1IMG
    this.image;
    
    // ID of a DIV element on your HTML page that will contain the text.
    // For example, "slides2text"
    // Note: after you set this variable, you should call
    // the update() method to update the slideshow display.
    this.textid;
    
    // TEXTAREA element on your HTML page.
    // For example, document.SLIDES1FORM.SLIDES1TEXT
    // 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 slides.
    // Individual slides can override this.
    this.timeout = 3000;
    
    // Hook functions to be called before and after updating the slide
    // this.pre_update_hook = function() { }
    // this.post_update_hook = function() { }
    
    // These are private variables
    this.slides = new Array();
    this.current = 0;
    this.timeoutid = 0;
    
    //--------------------------------------------------
    // Public methods
    //--------------------------------------------------
    this.add_slide = function(slide){
        // Add a slide to the slideshow.
        // For example:
        // SLIDES1.add_slide(new slide("s1.jpg", "link.html"))
        
        var i = this.slides.length;
        
        // Prefetch the slide image if necessary
        if (this.prefetch == -1) {
            slide.load();
        }
        
        this.slides[i] = slide;
    }
    
    //--------------------------------------------------
    this.play = function(timeout){
        // This method implements the automatically running slideshow.
        // If you specify the "timeout" argument, then a new default
        // timeout will be set for the slideshow.
        
        // 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 slide has a custom timeout, use it;
        // otherwise use the default timeout
        if (typeof this.slides[this.current].timeout != 'undefined') {
            timeout = this.slides[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 slideshow if it is automatically running.
        
        if (this.timeoutid != 0) {
        
            clearTimeout(this.timeoutid);
            this.timeoutid = 0;
            
        }
    }
    
    //--------------------------------------------------
    this.update = function(){
        // This method updates the slideshow image on the page
        
        // Make sure the slideshow 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 slide
        var slide = this.slides[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 slide image if necessary
        slide.load();
        
        // Apply the filters for the image transition
        if (dofilter) {
        
            // If the user has specified a custom filter for this slide,
            // then set it now
            if (slide.filter &&
            this.image.style &&
            this.image.style.filter) {
            
                this.image.style.filter = slide.filter;
                
            }
            this.image.filters[0].Apply();
        }
        
        // Update the image.
        this.image.src = slide.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 slide image(s)
            next = this.current;
            prev = this.current;
            count = 0;
            do {
            
                // Get the next and previous slide number
                // Loop past the ends of the slideshow if necessary
                if (++next >= this.slides.length) 
                    next = 0;
                if (--prev < 0) 
                    prev = this.slides.length - 1;
                
                // Preload the slide image
                this.slides[next].load();
                this.slides[prev].load();
                
                // Keep going until we have fetched
                // the designated number of slides
            
            }
            while (++count < this.prefetch);
        }
    }
    
    //--------------------------------------------------
    this.goto_slide = function(n){
        // This method jumpts to the slide number you specify.
        // If you use slide number -1, then it jumps to the last slide.
        // You can use this to make links that go to a specific slide,
        // or to go to the beginning or end of the slideshow.
        // Examples:
        // onClick="myslides.goto_slide(0)"
        // onClick="myslides.goto_slide(-1)"
        // onClick="myslides.goto_slide(5)"
        
        if (n == -1) {
            n = this.slides.length - 1;
        }
        
        if (n < this.slides.length && n >= 0) {
            this.current = n;
        }
        
        this.update();
    }
    
    
    //--------------------------------------------------
    this.goto_random_slide = function(include_current){
        // Picks a random slide (other than the current slide) and
        // displays it.
        // If the include_current parameter is true,
        // then 
        // See also: shuffle()
        
        var i;
        
        // Make sure there is more than one slide
        if (this.slides.length > 1) {
        
            // Generate a random slide number,
            // but make sure it is not the current slide
            do {
                i = Math.floor(Math.random() * this.slides.length);
            }
            while (i == this.current);
            
            // Display the slide
            this.goto_slide(i);
        }
    }
    
    
    //--------------------------------------------------
    this.next = function(){
        // This method advances to the next slide.
        
        // Increment the image number
        if (this.current < this.slides.length - 1) {
            this.current++;
        }
        else 
            if (this.repeat) {
                this.current = 0;
            }
        
        this.update();
    }
    
    
    //--------------------------------------------------
    this.previous = function(){
        // This method goes to the previous slide.
        
        // Decrement the image number
        if (this.current > 0) {
            this.current--;
        }
        else 
            if (this.repeat) {
                this.current = this.slides.length - 1;
            }
        
        this.update();
    }
    
    
    //--------------------------------------------------
    this.shuffle = function(){
        // This method randomly shuffles the order of the slides.
        
        var i, i2, slides_copy, slides_randomized;
        
        // Create a copy of the array containing the slides
        // in sequential order
        slides_copy = new Array();
        for (i = 0; i < this.slides.length; i++) {
            slides_copy[i] = this.slides[i];
        }
        
        // Create a new array to contain the slides in random order
        slides_randomized = new Array();
        
        // To populate the new array of slides in random order,
        // loop through the existing slides, picking a random
        // slide, removing it from the ordered list and adding it to
        // the random list.
        
        do {
        
            // Pick a random slide from those that remain
            i = Math.floor(Math.random() * slides_copy.length);
            
            // Add the slide to the end of the randomized array
            slides_randomized[slides_randomized.length] = slides_copy[i];
            
            // Remove the slide from the sequential array,
            // so it cannot be chosen again
            for (i2 = i + 1; i2 < slides_copy.length; i2++) {
                slides_copy[i2 - 1] = slides_copy[i2];
            }
            slides_copy.length--;
            
            // Keep going until we have removed all the slides
        
        }
        while (slides_copy.length);
        
        // Now set the slides to the randomized array
        this.slides = slides_randomized;
    }
    
    
    //--------------------------------------------------
    this.get_text = function(){
        // This method returns the text of the current slide
        
        return (this.slides[this.current].text);
    }
    
    
    //--------------------------------------------------
    this.get_all_text = function(before_slide, after_slide){
        // Return the text for all of the slides.
        // For the text of each slide, add "before_slide" in front of the
        // text, and "after_slide" 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 slides in the slideshow
        for (i = 0; i < this.slides.length; i++) {
        
            slide = this.slides[i];
            
            if (slide.text) {
                all_text += before_slide + slide.text + after_slide;
            }
            
        }
        
        return (all_text);
    }
    
    
    //--------------------------------------------------
    this.display_text = function(text){
        // Display the text for the current slide
        
        // If the "text" arg was not supplied (usually it isn't),
        // get the text from the slideshow
        if (!text) {
            text = this.slides[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 slide.
        
        this.slides[this.current].hotlink();
    }
    
    
    //--------------------------------------------------
    this.save_position = function(cookiename){
        // Saves the position of the slideshow in a cookie,
        // so when you return to this page, the position in the slideshow
        // won't be lost.
        
        if (!cookiename) {
            cookiename = this.name + '_slideshow';
        }
        
        document.cookie = cookiename + '=' + this.current;
    }
    
    
    //--------------------------------------------------
    this.restore_position = function(cookiename){
        // If you previously called slideshow_save_position(),
        // returns the slideshow to the previous state.
        
        //Get cookie code by Shelley Powers
        
        if (!cookiename) {
            cookiename = this.name + '_slideshow';
        }
        
        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 slideshow,
        // but you can call it to get a plain HTML version of the slideshow
        // images and text.
        // You should copy the HTML and put it within a NOSCRIPT element, to
        // give non-javascript browsers access to your slideshow information.
        // This also ensures that your slideshow text and images are indexed
        // by search engines.
        
        $html = "\n";
        
        // Loop through all the slides in the slideshow
        for (i = 0; i < this.slides.length; i++) {
        
            slide = this.slides[i];
            
            $html += '<P>';
            
            if (slide.link) {
                $html += '<a href="' + slide.link + '">';
            }
            
            $html += '<img src="' + slide.src + '" ALT="slideshow image">';
            
            if (slide.link) {
                $html += "<\/a>";
            }
            
            if (slide.text) {
                $html += "<BR>\n" + slide.text;
            }
            
            $html += "<\/P>" + "\n\n";
        }
        
        // Make the HTML browser-safe
        $html = $html.replace(/\&/g, "&amp;");
        $html = $html.replace(/</g, "&lt;");
        $html = $html.replace(/>/g, "&gt;");
        
        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 slide, then sets the next timeout.
        // If the next slide image has not completed loading yet,
        // then do not advance to the next slide yet.
        
        // Make sure the next slide image has finished loading
        if (this.current < this.slides.length - 1) {
            next_slide = this.slides[this.current + 1];
            if (next_slide.image.complete == null || next_slide.image.complete) {
                this.next();
            }
        }
        else { // we're at the last slide
            this.next();
        }
        
        // Keep playing the slideshow
        this.play();
    }
    
    
    //--------------------------------------------------
    this.valid_image = function(){
        // Returns 1 if a valid image has been set for the slideshow
        
        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();
    }
}