/*==================================================*
 $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,exif,image_name) {
	// 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;

	//EXIF information table
	this.exif = exif;

	// image name
	this.image_name = image_name;

	// 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 = false;

	// 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;

	// ID of a DIV containing HTML for your EXIF info table
	this.exifid;

	// ID of a DIV containing HTML for your image name
	this.imagenameid;

	// TEXTAREA element on your HTML page.
	// For example, document.SLIDES1FORM.SLIDES1TEXT
	// This is a deprecated 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;

	// Redirect URL called at the end of the slideshow
	this.redirect = false;

	// 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;
		} else if (this.redirect) {
			window.location = this.redirect;
		}

		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 ].image_name + ": " + 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();
	}
}
