isDom = typeof window != 'undefined';

(function (root) {
    var self = {};

    self.addSlashes = function (str) {
        return str.replace(/\\/g, '\\\\')
            .replace(/"/g, '\\"')
            .replace(/\r/g, '\\r')
            .replace(/\n/g, '\\n');
    };

    self.escape = function (data) {
        if (typeof data != 'string') {
            data += '';
        }

        return data.replace(/&|<|>|'|"/g, function (unit) {
            return {
                '&': '&amp;',
                '<': '&lt;',
                '>': '&gt;',
                '"': '&quot;',
                "'": '&#39;'
            } [unit];
        });
    };

    self.compile = function (str) {
        var re = /\{\*(?:[\s\S]*?)\*\}|\{literal\}([\s\S]*?)\{\/literal\}|<\?([\s\S]*?)\?>|^@(.*)|(#|\$)\{(.*?)\}|\{>(.*?)\}/img;
        var matches;
        var start = 0;
        var end;
        var body = 'var out="",escape=' + self.escape + ';with(context){';

        for (;;) {
            matches = re.exec(str);
            end = matches ? re.lastIndex - matches[0].length : str.length;

            if (end > start) {
                body += 'out+="' + self.addSlashes(str.slice(start, end)) + '";';
            }

            if (!matches) {
                break;
            }

            if (matches[1]) {
                body += 'out+="' + self.addSlashes(matches[1]) + '";'
            }
            else if (matches[2]) {
                body += matches[2];
            }
            else if (matches[3]) {
                body += matches[3];
            }
            else if (matches[4]) {
                body += 'out+='
                    + (matches[4] == '$'
                        ? 'escape(' + matches[5] + ')'
                        : matches[5])
                    + ';'
            }
            else if (matches[6]) {
                body += 'out+=' + matches[6] + '(context);';
            }

            start = re.lastIndex;
        }

        body += '}return out';

        try {
            var fn = new Function('context', body);
            // console.log(fn + '');

            return function (context) {
                context = context || {};

                try {
                    return fn(context);
                }
                catch (err) {
                    console.log(err);
                    return '';
                }
            };
        }
        catch (err) {
            console.log(err);
            return '';
        }
    };

    self.render = isDom
        ? function (id) {
            var elem = root.document.getElementById(id);
            return self.compile(elem.innerHTML);
        }

        : function (filename) {
            var fs = require('fs');
            var data = fs.readFileSync(filename, 'utf8');
            var fn = self.compile(data);

            fs.watchFile(filename, function (curr, prev) {
                fs.readFile(filename, 'utf8', function (err, data) {
                    if (err) {
                        throw err;
                    }

                    fn = self.compile(data);
                });
            });

            return function (data) {
                return fn(data);
            };
        };

    root[isDom ? 'Template' : 'exports'] = self;
})(isDom ? window : module);