/*------------------------------------------------------------------------*\
 * The Element Slider                        Version 2.1 (shinyshell.net) *
 *                                                                        *
 * Author: Electron <xelectronx@gmail.com>                                *
 * Date: 04-04-2008 (Re-architecture of the script from 02-11-2006)       *
 * Copyright: (c) 2006-2008 Electron. All rights reserved and so forth.   *
\*------------------------------------------------------------------------*/

// The number of pixels one step will jump. Smaller is smoother but slower
var slideconfig_steps = 5;

// The speed at which the slider will slide (microseconds between shifts)
var slideconfig_speed = 1;

// -------------------------------------------------------------------------
// No configuration needs to be done below this point
// -------------------------------------------------------------------------

// this could be useful, for example to launch a stream of alert()s
if (navigator.appName.indexOf('Microsoft') != -1) { var is_ie = true; }
else { var is_ie = false; }

/**
 * Register an element (div) to slide when a control element is clicked.
 * 
 * @param string - An element that will trigger the slide when clicked
 * @param string - The ID string of the element that will do the sliding
 * @param string - The ID of a container DIV directly inside the sliding one
 * @param string - Direction of the initial slide ("up" or "down")
 */
function RegisterSlide(anchor_name, sliding_name, container_name, direction) {
	if (typeof direction == "undefined") {
		// the first slide will move upwards unless otherwise specified
		direction = "up";
	}
	
	// save the elements for other functions to use
	anchor_element = document.getElementById(anchor_name);
	anchor_element['slideparams'] = new Array(
		'executing',
		'inty',
		'ie',
		
		// generic element ids
		'anchor_id',
		'sliding_id',
		
		// various stuff
		'original_height',
		'container_height',
		'previous_loop_height',
		'slide_direction',
		'current_direction',
		
		// CharChange(R) variables
		'charcontainer_id',
		'do_charchange',
		'charup',
		'chardown'
	);
	
	anchor_element['slideparams']['executing'] = false;
	anchor_element['slideparams']['anchor_id'] = anchor_name;
	anchor_element['slideparams']['sliding_id'] = sliding_name;
	
	anchor_element['slideparams']['original_height'] = document.getElementById(sliding_name).clientHeight;
	anchor_element['slideparams']['container_height'] = document.getElementById(container_name).clientHeight;
	anchor_element['slideparams']['slide_direction'] = direction.toLowerCase();
	anchor_element.onclick = SlideControl;
}

/**
 * Register an element for a CharChange(R) character change based on
 * the direction of the slide.
 *
 * @param string - ID string of the controller element (button)
 * @param string - ID string of the CharChange containing element
 * @param string - What will be displayed when sliding UP
 * @param string - What is to be shown when sliding DOWN
 */
function RegisterCharChange(anchor_name, charcontainer_name, upstring, downstring) {
	anchor_elm = document.getElementById(anchor_name);
	
	if (typeof anchor_elm["slideparams"] == "undefined") {
		// charchange is not something important enough to send an error
		return false;
	}
	anchor_elm['slideparams']['do_charchange'] = true;
	anchor_elm['slideparams']['charup'] = upstring;
	anchor_elm['slideparams']['chardown'] = downstring;
	
	anchor_elm['slideparams']['charcontainer_id'] = charcontainer_name;
}

/**
 * Register an element for a CharChange(R) character change based on
 * the direction of the slide.
 *
 * @param string - ID string of the controller element (button)
 * @param string - Direction the menu is sliding
 */
function CharChange(anchor_name, direction) {
	anchor_elm = document.getElementById(anchor_name);
	
	if (typeof anchor_elm["slideparams"] == "undefined") {
		// charchange is not something important enough to send an error
		return false;
	}
	sp = anchor_elm['slideparams'];
	
	// whether to do charchange at all...
	if (sp['do_charchange']) {
		if (direction == "up") {
			document.getElementById(sp['charcontainer_id']).innerHTML = sp['charup'];
		} else {
			document.getElementById(sp['charcontainer_id']).innerHTML = sp['chardown'];
		}
	}
}

/**
 * [Internal]
 *
 * Controls the sliding of the element based on the current status.
 */
function SlideControl() {
	var sp = this['slideparams'];
	
	var next_direction = sp['slide_direction'];
	var current_direction = sp['current_direction'];
	
	if (sp['executing'] == true) {
		// the slide is already in progress, so execute a change of direction
		window.clearInterval(this['slideparams']['inty']);
		
		if (current_direction == "up") {
			if (sp['original_height'] == 0) { CharChange(this.id, "up"); }
			else { CharChange(this.id, "down"); }
			
			sp['inty'] = window.setInterval("SlideDown('" + this.id  + "')", slideconfig_speed);
		} else {
			if (sp['original_height'] == 0) { CharChange(this.id, "down"); }
			else { CharChange(this.id, "up"); }
			
			sp['inty'] = window.setInterval("SlideUp('" + this.id + "')", slideconfig_speed);
		}
	} else {
		if (next_direction == "up") {
			if (sp['original_height'] == 0) { CharChange(this.id, "down"); }
			else { CharChange(this.id, "up"); }
			
			sp['executing'] = true;
			sp['inty'] = window.setInterval("SlideUp('" + this.id  + "')", slideconfig_speed);
		} else {
			if (sp['original_height'] == 0) { CharChange(this.id, "up"); }
			else { CharChange(this.id, "down"); }
			
			sp['executing'] = true;
			sp['inty'] = window.setInterval("SlideDown('" + this.id + "')", slideconfig_speed);
		}
	}
}

/**
 * [Internal]
 *
 * Executes the sliding upwards (called by SlideControl)
 *
 * @param string - ID string of the controller element (button)
 */
function SlideUp(anchor_id) {
	var anchor_elm = document.getElementById(anchor_id);
	var sliding_elm = document.getElementById(anchor_elm['slideparams']['sliding_id']);
	anchor_elm['slideparams']['current_direction'] = 'up';
	
	var height = parseInt(sliding_elm.clientHeight, 10);
	
	// hide the overflowing content as the box slides closed
	sliding_elm.style.overflow = 'hidden';
	
	var newheight = height - slideconfig_steps;
	if (newheight > slideconfig_steps) {
		sliding_elm.style.height = newheight + 'px';
		anchor_elm['slideparams']['previous_loop_height'] = newheight;
	} else {
		sliding_elm.style.height = '0px';
		height = 0;
		window.clearInterval(anchor_elm['slideparams']['inty']);
		anchor_elm['slideparams']['executing'] = false;
		anchor_elm['slideparams']['slide_direction'] = "down";
	}
}

/**
 * [Internal]
 *
 * Executes the sliding downwards (called by SlideControl)
 *
 * @param string - ID string of the controller element (button)
 */
function SlideDown(anchor_id) {
	var anchor_elm = document.getElementById(anchor_id);
	var sliding_elm = document.getElementById(anchor_elm['slideparams']['sliding_id']);
	anchor_elm['slideparams']['current_direction'] = 'down';
	
	var height = parseInt(sliding_elm.clientHeight, 10);
	
	var newheight = height + slideconfig_steps;
	sliding_elm.style.height = newheight + 'px';
	anchor_elm['slideparams']['previous_loop_height'] = newheight;
	
	if (newheight >= anchor_elm['slideparams']['container_height']) {
		newheight = anchor_elm['slideparams']['original_height'];
	}
	if (newheight == anchor_elm['slideparams']['original_height']) {
		sliding_elm.style.height = anchor_elm['slideparams']['container_height'] + 'px';
		window.clearInterval(anchor_elm['slideparams']['inty']);
		anchor_elm['slideparams']['executing'] = false;
		anchor_elm['slideparams']['slide_direction'] = "up";
	}
}