/**
 * 编译模板
 * 2012-6-6 @TooBug: define 方法名改为 compile，与 Node Express 保持一致
 * @name    template.compile
 * @param   {String}    模板字符串
 * @param   {Object}    编译选项
 *
 *      - openTag       {String}
 *      - closeTag      {String}
 *      - filename      {String}
 *      - escape        {Boolean}
 *      - compress      {Boolean}
 *      - debug         {Boolean}
 *      - cache         {Boolean}
 *      - parser        {Function}
 *
 * @return  {Function}  渲染方法
 */
var compile = template.compile = function (source, options) {
    
    // 合并默认配置
    options = options || {};
    for (var name in defaults) {
        if (options[name] === undefined) {
            options[name] = defaults[name];
        }
    }


    var filename = options.filename;


    try {
        
        var Render = compiler(source, options);
        
    } catch (e) {
    
        e.filename = filename || 'anonymous';
        e.name = 'Syntax Error';

        return showDebugInfo(e);
        
    }
    
    
    // 对编译结果进行一次包装

    function render (data) {
        
        try {
            
            return new Render(data, filename) + '';
            
        } catch (e) {
            
            // 运行时出错后自动开启调试模式重新编译
            if (!options.debug) {
                options.debug = true;
                return compile(source, options)(data);
            }
            
            return showDebugInfo(e)();
            
        }
        
    }
    

    render.prototype = Render.prototype;
    render.toString = function () {
        return Render.toString();
    };


    if (filename && options.cache) {
        cacheStore[filename] = render;
    }

    
    return render;

};




// 数组迭代
var forEach = utils.$each;


// 静态分析模板变量
var KEYWORDS =
    // 关键字
    'break,case,catch,continue,debugger,default,delete,do,else,false'
    + ',finally,for,function,if,in,instanceof,new,null,return,switch,this'
    + ',throw,true,try,typeof,var,void,while,with'

    // 保留字
    + ',abstract,boolean,byte,char,class,const,double,enum,export,extends'
    + ',final,float,goto,implements,import,int,interface,long,native'
    + ',package,private,protected,public,short,static,super,synchronized'
    + ',throws,transient,volatile'

    // ECMA 5 - use strict
    + ',arguments,let,yield'

    + ',undefined';

var REMOVE_RE = /\/\*[\w\W]*?\*\/|\/\/[^\n]*\n|\/\/[^\n]*$|"(?:[^"\\]|\\[\w\W])*"|'(?:[^'\\]|\\[\w\W])*'|\s*\.\s*[$\w\.]+/g;
var SPLIT_RE = /[^\w$]+/g;
var KEYWORDS_RE = new RegExp(["\\b" + KEYWORDS.replace(/,/g, '\\b|\\b') + "\\b"].join('|'), 'g');
var NUMBER_RE = /^\d[^,]*|,\d[^,]*/g;
var BOUNDARY_RE = /^,+|,+$/g;
var SPLIT2_RE = /^$|,+/;


// 获取变量
function getVariable (code) {
    return code
    .replace(REMOVE_RE, '')
    .replace(SPLIT_RE, ',')
    .replace(KEYWORDS_RE, '')
    .replace(NUMBER_RE, '')
    .replace(BOUNDARY_RE, '')
    .split(SPLIT2_RE);
};


// 字符串转义
function stringify (code) {
    return "'" + code
    // 单引号与反斜杠转义
    .replace(/('|\\)/g, '\\$1')
    // 换行符转义(windows + linux)
    .replace(/\r/g, '\\r')
    .replace(/\n/g, '\\n') + "'";
}


function compiler (source, options) {
    
    var debug = options.debug;
    var openTag = options.openTag;
    var closeTag = options.closeTag;
    var parser = options.parser;
    var compress = options.compress;
    var escape = options.escape;
    

    
    var line = 1;
    var uniq = {$data:1,$filename:1,$utils:1,$helpers:1,$out:1,$line:1};
    


    var isNewEngine = ''.trim;// '__proto__' in {}
    var replaces = isNewEngine
    ? ["$out='';", "$out+=", ";", "$out"]
    : ["$out=[];", "$out.push(", ");", "$out.join('')"];

    var concat = isNewEngine
        ? "$out+=text;return $out;"
        : "$out.push(text);";
          
    var print = "function(){"
    +      "var text=''.concat.apply('',arguments);"
    +       concat
    +  "}";

    var include = "function(filename,data){"
    +      "data=data||$data;"
    +      "var text=$utils.$include(filename,data,$filename);"
    +       concat
    +   "}";

    var headerCode = "'use strict';"
    + "var $utils=this,$helpers=$utils.$helpers,"
    + (debug ? "$line=0," : "");
    
    var mainCode = replaces[0];

    var footerCode = "return new String(" + replaces[3] + ");"
    
    // html与逻辑语法分离
    forEach(source.split(openTag), function (code) {
        code = code.split(closeTag);
        
        var $0 = code[0];
        var $1 = code[1];
        
        // code: [html]
        if (code.length === 1) {
            
            mainCode += html($0);
         
        // code: [logic, html]
        } else {
            
            mainCode += logic($0);
            
            if ($1) {
                mainCode += html($1);
            }
        }
        

    });
    
    var code = headerCode + mainCode + footerCode;
    
    // 调试语句
    if (debug) {
        code = "try{" + code + "}catch(e){"
        +       "throw {"
        +           "filename:$filename,"
        +           "name:'Render Error',"
        +           "message:e.message,"
        +           "line:$line,"
        +           "source:" + stringify(source)
        +           ".split(/\\n/)[$line-1].replace(/^\\s+/,'')"
        +       "};"
        + "}";
    }
    
    
    
    try {
        
        
        var Render = new Function("$data", "$filename", code);
        Render.prototype = utils;

        return Render;
        
    } catch (e) {
        e.temp = "function anonymous($data,$filename) {" + code + "}";
        throw e;
    }



    
    // 处理 HTML 语句
    function html (code) {
        
        // 记录行号
        line += code.split(/\n/).length - 1;

        // 压缩多余空白与注释
        if (compress) {
            code = code
            .replace(/\s+/g, ' ')
            .replace(/<!--[\w\W]*?-->/g, '');
        }
        
        if (code) {
            code = replaces[1] + stringify(code) + replaces[2] + "\n";
        }

        return code;
    }
    
    
    // 处理逻辑语句
    function logic (code) {

        var thisLine = line;
       
        if (parser) {
        
             // 语法转换插件钩子
            code = parser(code, options);
            
        } else if (debug) {
        
            // 记录行号
            code = code.replace(/\n/g, function () {
                line ++;
                return "$line=" + line +  ";";
            });
            
        }
        
        
        // 输出语句. 编码: <%=value%> 不编码:<%=#value%>
        // <%=#value%> 等同 v2.0.3 之前的 <%==value%>
        if (code.indexOf('=') === 0) {

            var escapeSyntax = escape && !/^=[=#]/.test(code);

            code = code.replace(/^=[=#]?|[\s;]*$/g, '');

            // 对内容编码
            if (escapeSyntax) {

                var name = code.replace(/\s*\([^\)]+\)/, '');

                // 排除 utils.* | include | print
                
                if (!utils[name] && !/^(include|print)$/.test(name)) {
                    code = "$escape(" + code + ")";
                }

            // 不编码
            } else {
                code = "$string(" + code + ")";
            }
            

            code = replaces[1] + code + replaces[2];

        }
        
        if (debug) {
            code = "$line=" + thisLine + ";" + code;
        }
        
        // 提取模板中的变量名
        forEach(getVariable(code), function (name) {
            
            // name 值可能为空，在安卓低版本浏览器下
            if (!name || uniq[name]) {
                return;
            }

            var value;

            // 声明模板变量
            // 赋值优先级:
            // [include, print] > utils > helpers > data
            if (name === 'print') {

                value = print;

            } else if (name === 'include') {
                
                value = include;
                
            } else if (utils[name]) {

                value = "$utils." + name;

            } else if (helpers[name]) {

                value = "$helpers." + name;

            } else {

                value = "$data." + name;
            }
            
            headerCode += name + "=" + value + ",";
            uniq[name] = true;
            
            
        });
        
        return code + "\n";
    }
    
    
};