text: 'use strict';
  
  var latex = require('../../utils/latex');
  var extend = require('../../utils/object').extend;
  
  function factory (type, config, load, typed, math) {
    var Node = load(require('./Node'));
    var SymbolNode = load(require('./SymbolNode'));
  
    /**
     * @constructor FunctionNode
     * @extends {./Node}
     * invoke a list with arguments on a node
     * @param {./Node | string} fn Node resolving with a function on which to invoke
     *                             the arguments, typically a SymboNode or AccessorNode
     * @param {./Node[]} args
     */
    function FunctionNode(fn, args) {
      if (!(this instanceof FunctionNode)) {
        throw new SyntaxError('Constructor must be called with the new operator');
      }
  
      if (typeof fn === 'string') {
        fn = new SymbolNode(fn);
      }
  
      // validate input
      if (!fn || !fn.isNode) throw new TypeError('Node expected as parameter "fn"');
      if (!Array.isArray(args)
          || !args.every(function (arg) {return arg && arg.isNode;})) {
        throw new TypeError('Array containing Nodes expected for parameter "args"');
      }
  
      this.fn = fn;
      this.args = args || [];
  
      // readonly property name
      Object.defineProperty(this, 'name', {
        get: function () {
          return this.fn.name || '';
        }.bind(this),
        set: function () {
          throw new Error('Cannot assign a new name, name is read-only');
        }
      });
  
      // TODO: deprecated since v3, remove some day
      var deprecated = function () {
        throw new Error('Property `FunctionNode.object` is deprecated, use `FunctionNode.fn` instead');
      };
      Object.defineProperty(this, 'object', { get: deprecated, set: deprecated });
    }
  
    FunctionNode.prototype = new Node();
  
    FunctionNode.prototype.type = 'FunctionNode';
  
    FunctionNode.prototype.isFunctionNode = true;
  
    /**
     * Compile the node to javascript code
     * @param {Object} defs     Object which can be used to define functions
     *                          or constants globally available for the compiled
     *                          expression
     * @param {Object} args     Object with local function arguments, the key is
     *                          the name of the argument, and the value is `true`.
     *                          The object may not be mutated, but must be
     *                          extended instead.
     * @return {string} js
     * @private
     */
    FunctionNode.prototype._compile = function (defs, args) {
      // compile fn and arguments
      var jsFn = this.fn._compile(defs, args);
      var jsArgs = this.args.map(function (arg) {
        return arg._compile(defs, args);
      });
      var jsScope = this._compileScope(defs, args);
      var argsName;
  
      if (this.fn.isSymbolNode) {
        // we can statically determine whether the function has an rawArgs property
        var name = this.fn.name;
        var fn = defs.math[name];
        var isRaw = (typeof fn === 'function') && (fn.rawArgs == true);
  
        if (isRaw) {
          // pass unevaluated parameters (nodes) to the function
          argsName = this._getUniqueArgumentsName(defs);
          defs[argsName] = this.args;
  
          return jsFn + '(' + argsName + ', math, ' + jsScope + ')';
        }
        else {
          // "regular" evaluation
          return jsFn + '(' + jsArgs.join(', ') + ')';
        }
      }
      else if (this.fn.isAccessorNode && this.fn.index.isObjectProperty()) {
        // execute the function with the right context: the object of the AccessorNode
        argsName = this._getUniqueArgumentsName(defs);
        defs[argsName] = this.args;
  
        var jsObject = this.fn.object._compile(defs, args);
        var prop = this.fn.index.getObjectProperty();
  
        return '(function () {' +
            'var object = ' + jsObject + ';' +
            'return (object["' + prop + '"] && object["' + prop + '"].rawArgs) ' +
            ' ? object["' + prop + '"](' + argsName + ', math, ' + jsScope + ')' +
            ' : object["' + prop + '"](' + jsArgs.join(', ') + ')' +
            '})()';
      }
      else { // this.fn.isAccessorNode && !this.fn.index.isObjectProperty()
        // we have to dynamically determine whether the function has a rawArgs property
        argsName = this._getUniqueArgumentsName(defs);
        defs[argsName] = this.args;
  
        return '(function () {' +
            'var fn = ' + jsFn + ';' +
            'return (fn && fn.rawArgs) ' +
            ' ? fn(' + argsName + ', math, ' + jsScope + ')' +
            ' : fn(' + jsArgs.join(', ') + ')' +
            '})()';
      }
    };
  
    /**
     * Merge function arguments into scope before passing to the actual function.
     * This is needed when the function has `rawArgs=true`. In that case we have
     * to pass the `scope` as third argument, including any variables of
     * enclosing functions.
     * @param {Object} defs     Object which can be used to define functions
     *                          or constants globally available for the compiled
     *                          expression
     * @param {Object} args     Object with local function arguments, the key is
     *                          the name of the argument, and the value is `true`.
     *                          The object may not be mutated, but must be
     *                          extended instead.
     * @return {string} js
     * @private
     */
    FunctionNode.prototype._compileScope = function (defs, args) {
      var names = Object.keys(args);
      if (names.length === 0) {
        return 'scope';
      }
      else {
        // merge arguments into scope
        defs.extend = extend;
  
        var jsArgs = names
            .map(function (arg) {
              return '"' + arg + '": ' + arg;
            })
            .join(', ');
  
        return 'extend(extend({}, scope), {' + jsArgs + '})';
      }
    };
  
    /**
     * Get a unique name for a arguments to store in defs
     * @param {Object} defs
     * @return {string} A string like 'args1', 'args2', ...
     * @private
     */
    FunctionNode.prototype._getUniqueArgumentsName = function (defs) {
      var argsName;
      var i = 0;
  
      do {
        argsName = 'args' + i;
        i++;
      }
      while (argsName in defs);
  
      return argsName;
    };
  
    /**
     * Execute a callback for each of the child nodes of this node
     * @param {function(child: Node, path: string, parent: Node)} callback
     */
    FunctionNode.prototype.forEach = function (callback) {
      for (var i = 0; i < this.args.length; i++) {
        callback(this.args[i], 'args[' + i + ']', this);
      }
    };
  
    /**
     * Create a new FunctionNode having it's childs be the results of calling
     * the provided callback function for each of the childs of the original node.
     * @param {function(child: Node, path: string, parent: Node): Node} callback
     * @returns {FunctionNode} Returns a transformed copy of the node
     */
    FunctionNode.prototype.map = function (callback) {
      var fn = this.fn.map(callback);
      var args = [];
      for (var i = 0; i < this.args.length; i++) {
        args[i] = this._ifNode(callback(this.args[i], 'args[' + i + ']', this));
      }
      return new FunctionNode(fn, args);
    };
  
    /**
     * Create a clone of this node, a shallow copy
     * @return {FunctionNode}
     */
    FunctionNode.prototype.clone = function () {
      return new FunctionNode(this.fn, this.args.slice(0));
    };
  
    //backup Node's toString function
    //@private
    var nodeToString = FunctionNode.prototype.toString;
  
    /**
     * Get string representation. (wrapper function)
     * This overrides parts of Node's toString function.
     * If callback is an object containing callbacks, it
     * calls the correct callback for the current node,
     * otherwise it falls back to calling Node's toString
     * function.
     *
     * @param {Object} options
     * @return {string} str
     * @override
     */
    FunctionNode.prototype.toString = function (options) {
      var customString;
      var name = this.fn.toString(options);
      if (options && (typeof options.handler === 'object') && options.handler.hasOwnProperty(name)) {
        //callback is a map of callback functions
        customString = options.handler[name](this, options);
      }
  
      if (typeof customString !== 'undefined') {
        return customString;
      }
  
      //fall back to Node's toString
      return nodeToString.call(this, options);
    };
  
    /**
     * Get string representation
     * @param {Object} options
     * @return {string} str
     */
    FunctionNode.prototype._toString = function (options) {
      var args = this.args.map(function (arg) {
        return arg.toString(options);
      });
  
      // format the arguments like "add(2, 4.2)"
      return this.fn.toString(options) + '(' + args.join(', ') + ')';
    };
  
    /*
     * Expand a LaTeX template
     *
     * @param {string} template
     * @param {Node} node
     * @param {Object} options
     * @private
     **/
    function expandTemplate(template, node, options) {
      var latex = '';
  
      // Match everything of the form ${identifier} or ${identifier[2]} or $$
      // while submatching identifier and 2 (in the second case)
      var regex = new RegExp('\\$(?:\\{([a-z_][a-z_0-9]*)(?:\\[([0-9]+)\\])?\\}|\\$)', 'ig');
  
      var inputPos = 0;   //position in the input string
      var match;
      while ((match = regex.exec(template)) !== null) {   //go through all matches
        // add everything in front of the match to the LaTeX string
        latex += template.substring(inputPos, match.index);
        inputPos = match.index;
  
        if (match[0] === '$$') { // escaped dollar sign
          latex += '$';
          inputPos++;
        }
        else { // template parameter
          inputPos += match[0].length;
          var property = node[match[1]];
          if (!property) {
            throw new ReferenceError('Template: Property ' + match[1] + ' does not exist.');
          }
          if (match[2] === undefined) { //no square brackets
            switch (typeof property) {
              case 'string':
                latex += property;
                break;
              case 'object':
                if (property.isNode) {
                  latex += property.toTex(options);
                }
                else if (Array.isArray(property)) {
                  //make array of Nodes into comma separated list
                  latex += property.map(function (arg, index) {
                    if (arg && arg.isNode) {
                      return arg.toTex(options);
                    }
                    throw new TypeError('Template: ' + match[1] + '[' + index + '] is not a Node.');
                  }).join(',');
                }
                else {
                  throw new TypeError('Template: ' + match[1] + ' has to be a Node, String or array of Nodes');
                }
                break;
              default:
                throw new TypeError('Template: ' + match[1] + ' has to be a Node, String or array of Nodes');
            }
          }
          else { //with square brackets
            if (property[match[2]] && property[match[2]].isNode) {
              latex += property[match[2]].toTex(options);
            }
            else {
              throw new TypeError('Template: ' + match[1] + '[' + match[2] + '] is not a Node.');
            }
          }
        }
      }
      latex += template.slice(inputPos);  //append rest of the template
  
      return latex;
    }
  
    //backup Node's toTex function
    //@private
    var nodeToTex = FunctionNode.prototype.toTex;
  
    /**
     * Get LaTeX representation. (wrapper function)
     * This overrides parts of Node's toTex function.
     * If callback is an object containing callbacks, it
     * calls the correct callback for the current node,
     * otherwise it falls back to calling Node's toTex
     * function.
     *
     * @param {Object} options
     * @return {string}
     */
    FunctionNode.prototype.toTex = function (options) {
      var customTex;
      if (options && (typeof options.handler === 'object') && options.handler.hasOwnProperty(this.name)) {
        //callback is a map of callback functions
        customTex = options.handler[this.name](this, options);
      }
  
      if (typeof customTex !== 'undefined') {
        return customTex;
      }
  
      //fall back to Node's toTex
      return nodeToTex.call(this, options);
    };
  
    /**
     * Get LaTeX representation
     * @param {Object} options
     * @return {string} str
     */
    FunctionNode.prototype._toTex = function (options) {
      var args = this.args.map(function (arg) { //get LaTeX of the arguments
        return arg.toTex(options);
      });
  
      var latexConverter;
  
      if (math[this.name] && ((typeof math[this.name].toTex === 'function') || (typeof math[this.name].toTex === 'object') || (typeof math[this.name].toTex === 'string'))) {
        //.toTex is a callback function
        latexConverter = math[this.name].toTex;
      }
  
      var customToTex;
      switch (typeof latexConverter) {
        case 'function': //a callback function
          customToTex = latexConverter(this, options);
          break;
        case 'string': //a template string
          customToTex = expandTemplate(latexConverter, this, options);
          break;
        case 'object': //an object with different "converters" for different numbers of arguments
          switch (typeof latexConverter[args.length]) {
            case 'function':
              customToTex = latexConverter[args.length](this, options);
              break;
            case 'string':
              customToTex = expandTemplate(latexConverter[args.length], this, options);
              break;
          }
      }
  
      if (typeof customToTex !== 'undefined') {
        return customToTex;
      }
  
      return expandTemplate(latex.defaultTemplate, this, options);
    };
  
    /**
     * Get identifier.
     * @return {string}
     */
    FunctionNode.prototype.getIdentifier = function () {
      return this.type + ':' + this.name;
    };
  
    return FunctionNode;
  }
  
  exports.name = 'FunctionNode';
  exports.path = 'expression.node';
  exports.math = true; // request access to the math namespace as 5th argument of the factory function
  exports.factory = factory;
  