/*
Script: Template.jx
	Basic templating system.

License:
	MIT-style license.

Acknowledgements:
	Original inspired by Charlie Savages' simple templating engine.

*/

(function(){

this.Template = new Class({

	Implements: Options,

	options: {
		pattern: 'raccoon',
		path: '',
		suffix: ''
	},

	regexps: {

		raccoon: {
			pattern: /<#[:|=]?(.*?)#>/g,
			outkey: ':',
			include: '='
		},

		asp: {
			pattern: /<%[=|@]?(.*?)%>/g,
			outkey: '=',
			include: '@'
		},

		php: {
			pattern: /<\?[=|@]?(.*?)\?>/g,
			outkey: '=',
			include: '@'
		}
	},

	forEachExp: /for\s+\((?:var\s*)?(.*?)\s+from\s+(.*?)\s*\)\s*\{\s*([^]*?)\s*\}/g,
	eachExp: /each\s+\((?:var\s*)?(.*?)\s+from\s+(.*?)\s*\)\s*\{\s*([^]*?)\s*\}/g,
	shortTags: /(each|for|if|else|while)+(.*):/g,
	shortEnds: /end(for|if|while|each)?;/g,

	initialize: function(options){
		this.setOptions(options);

		var pattern = this.options.pattern,
			regexps = this.regexps,
			def = regexps.raccoon;
		if (typeOf(pattern) == 'object') {
			this.pattern = pattern.pattern || def.pattern;
			this.outkey = pattern.outkey || def.outkey;
			this.includes = pattern.include || def.include;
		} else {
			this.pattern = regexps[pattern].pattern || def.pattern;
			this.outkey = regexps[pattern].outkey || def.raccoon.outkey;
			this.includes = regexps[pattern].include || def.include;
		}
	},

	parseShortTags: function(str){
		return str.replace(this.shortTags, function(m, tag, exp){
			return [tag == 'else' ? '} ' : '', tag, exp, '{'].join('');
		}).replace(this.shortEnds, '}');
	},

	parseForFrom: function(str){
		return str.replace(this.forEachExp, function(m, key, arr, body){
			return [
				"for (var _ITERATOR_ = 0, _ARRAYLENGTH_ = ",
				arr, ".length; _ITERATOR_ < _ARRAYLENGTH_; _ITERATOR_++){\n",
				"\tvar ", key, " = ", arr, "[_ITERATOR_];\n\t",
				body,
				"\n}"
			].join('');
		});
	},

	parseEachFrom: function(str){
		return str.replace(this.eachExp, function(m, key, arr, body){
			return [
				"var _ITERATOR_ = ", arr, ".reverse().length;\nwhile(_ITERATOR_--){",
				"\tvar ", key, " = ", arr, "[_ITERATOR_];\n\t",
				body,
				"\n}"
			].join('');
		});
	},

	escape: function(str){
		return str.replace(/'/g, '%%LIT_QUOT_SING%%').replace(/"/g, '%%LIT_QUOT_DB%%').replace(/\r|\n/g, '%%LIT_NEW_LINE%%');
	},

	unescape: function(str){
		return str.replace(/%%LIT_QUOT_SING%%/g, "'").replace(/%%LIT_QUOT_DB%%/g, '"').replace(/%%LIT_NEW_LINE%%/g, "\n");
	},

	build: function(str, data){
		var self = this, func, result,
			literal = this.outkey,
			include = this.includes;
		str = this.escape(this.parseEachFrom(this.parseForFrom(this.parseShortTags(str))));
		str = str.replace(this.pattern, function(match, item){
			item = self.unescape(item);
			var chunk, external;
			if (match.charAt(2) == literal) {
				chunk = ['buffer.push(', item, ');\n'];
			} else if (match.charAt(2) == include) {
				external = self.process(item.trim().replace(/"|'/g, ''), data);
				chunk = ['buffer.push("', self.escape(external), '");\n'];
			} else {
				chunk = [item.replace(/^\s+|\s+$/g, ''), '\n'];
			}
			return ['");\n', chunk.join(''), 'buffer.push("'].join('');
		});
		return [
				'var $ = this, buffer = [], print = function(data){ buffer.push(data); },\n',
				'include = function(src){ buffer.push($._include(src, $)); };\n',
				'\nbuffer.push("', str, '");\n',
				'return buffer.join("");\n'
			].join('');
	},

	peek: function(str){
		return this.build(str);
	},

	parse: function(str, data){
		var self = this;
		// return this.peek(str);
		data._include = function(src, data){
			return self.escape(self.process(src, data));
		};
		var func = this.build(str, data),
			result = new Function(func).apply(data);
		delete data._include;
		return this.unescape(result);
	},

	process: function(file, data){
		var name = [this.options.path, file, '.', this.options.suffix].join('');
		file = new File(name);
		if (!file.exists()) throw new Error('Cannot open template ' + name);
		var str = file.open("r").read();
		return this.parse(str, data);
	}

});

})();