/**
 * Typewriter style output to screen.
 *
 * Usage:
 * 	var t = new Typewriter(element);
 *	t.type(string,ondone);
 *
 * Parameters:
 * 	string -- HTML string to output
 * 	ondone -- function to execute when typing is done
 *	       or URL to redirect the browser to when done
 *
 * Version 2.1
 * Copyright 2004,2010, Mack Pexton, mackpexton.com
 * License http://www.opensource.org/licenses/mit-license.php
 */

(function(){

var typewriter = function(e) {
	this.e = (typeof e == 'string') ? document.getElementById(e) : e;	// element where typing goes
	this.is_done = false;		// flag set when done typing
}

typewriter.prototype = {
	timing: [	// milli-second pauses before and after characters
			//regexp,   before  after
			[ /[\w,:]/,   50,    50 ],	// regular characters
			[ /&.{2,7};/, 50,    50 ],	// html entities
			[ / /,        50,   300 ],	// space character (pause between words)
			[ /\W/,      750,    50 ],	// punctuation
			[ /./,        50,    50 ]	// everything else
		],
	ondone_pause: 1500,		// pause before invoking function/url when done

	type: function(str,ondone) {
		var sarr = str.split(''),	// make array of individual characters
		    index = 0,			// initialize counter
		    scurr = this.e.innerHTML,	// initialize displayed string
		    beforeChar=1, afterChar=2, state=afterChar,
		    timing = this.timing,
		    pause = this.ondone_pause,
		    t = this,
		    html_tags = function() {
			// return html tags
			var i = index, l = sarr.length,
			    c, s = '',
			    j, lookahead;
			TAG:while (i < l) {
				c = sarr[i];
				if (c != '<') break;

				// Look for tag closing bracket.
				lookahead = c;
				for (j=i+1; j<l; j++) {
					lookahead += sarr[j];
					if (sarr[j] == '>') {
						s += lookahead;
						i = j + 1;
						continue TAG;
					}
				}
				// End bracket of tag not found.
				break;
			}
			index = i;	// readjust global index to sarr array
			return s;
		    },
		    typer = function() {
			var i, l, c, s;

			if (state == beforeChar) {
				state = afterChar;	// next state

				// Search timing array for time to wait before displaying next character.
				c = sarr[index-1];
				for (i=0,l=timing.length; i<l; i++) {
					if (timing[i][0].test(c)) {
						setTimeout(arguments.callee,timing[i][1]);
						return;
					}
				}

				// Should not be here if timing array properly defined. 
				setTimeout(arguments.callee,50);
				return;
			}

			// Add any following html tags to current output.
			scurr += html_tags();

			// Display current output string.
			t.e.innerHTML = scurr + '_';

			if (index < sarr.length) {

				// Process next character.
				c = sarr[index++];
				if (c == '&') {
					// Gather HTML entity
					s = c;
					for (i=index,l=Math.floor(index+7,sarr.length); i<=l; i++) {
						s += sarr[i];
						// Look for entity closing character.
						if (sarr[i] == ';') {
							scurr += s;
							index = i+1;
							c = sarr[index++];
							break;
						}
					}
					// Entity closing semi-colon not found, just output '&'.
					scurr += c;
				}
				else {
					scurr += c;
				}

				state = beforeChar;	// next state

				// Search timing array for time to wait till after displaying next character.
				for (i=0,l=timing.length; i<l; i++) {
					if (timing[i][0].test(c)) {
						setTimeout(arguments.callee,timing[i][2]);
						return;
					}
				}

				// Should not be here if timing array properly defined. 
				setTimeout(arguments.callee,50);
				return;
			}
			else {
				t.is_done = true;
				t.e.innerHTML = scurr+' ';	// remove typing cursor _

				if (ondone) {
					if (typeof ondone == 'function') setTimeout(ondone,pause);
					if (typeof ondone == 'string')   setTimeout('location.href="'+ondone+'"', pause);
				}

				return;
			}
		};
		typer();	// start typing
	},
}

// Expose
this.Typewriter = typewriter;

})();