"use strict";
var Document = module.exports = (function(){
	// CONSTRUCTOR
	/**
	 * Represents a `Document` (i.e., an `Object`) in `mongo` but in `munge` this is only a set of static helpers since we treat all `Object`s like `Document`s.
	 *
	 * @class Document
	 * @namespace mungedb.aggregate.pipeline
	 * @module mungedb-aggregate
	 * @constructor
	 **/
	var klass = function Document(){
		if(this.constructor == Document) throw new Error("Never create instances! Use static helpers only.");
	}, base = Object, proto = klass.prototype = Object.create(base.prototype, {constructor:{value:klass}});

	// DEPENDENCIES
	var Value = require("./Value");

	// STATIC MEMBERS
	/**
	 * Shared "_id"
	 * @static
	 * @property ID_PROPERTY_NAME
	 **/
	klass.ID_PROPERTY_NAME = "_id";

	/**
	 * Compare two documents.
	 *
	 * BSON document field order is significant, so this just goes through the fields in order.
	 * The comparison is done in roughly the same way as strings are compared, but comparing one field at a time instead of one character at a time.
	 *
	 * @static
	 * @method compare
	 * @param rL left document
	 * @param rR right document
	 * @returns an integer less than zero, zero, or an integer greater than zero, depending on whether rL < rR, rL == rR, or rL > rR
	 **/
	klass.compare = function compare(l, r){	//TODO: might be able to replace this with a straight compare of docs using JSON.stringify()
		var lPropNames = Object.getOwnPropertyNames(l),
			lPropNamesLength = lPropNames.length,
			rPropNames = Object.getOwnPropertyNames(r),
			rPropNamesLength = rPropNames.length;

		for(var i = 0; true; ++i) {
			if (i >= lPropNamesLength) {
				if (i >= rPropNamesLength) return 0; // documents are the same length
				return -1; // left document is shorter
			}

			if (i >= rPropNamesLength) return 1; // right document is shorter

			var nameCmp = Value.compare(lPropNames[i], rPropNames[i]);
			if (nameCmp !== 0) return nameCmp; // field names are unequal


			var valueCmp = Value.compare(l[lPropNames[i]], r[rPropNames[i]]);
			if (valueCmp) return valueCmp; // fields are unequal
		}

		/* NOTREACHED */
		throw new Error("This should never happen");	//verify(false)
//		return 0;
	};

	/**
	 * Clone a document
	 * @static
	 * @method clone
	 * @param document
	 **/
	klass.clone = function(document){
		var obj = {};
		for(var key in document){
			if(document.hasOwnProperty(key)){
				var withObjVal = document[key];
				if(withObjVal.constructor === Object){
					obj[key] = Document.clone(withObjVal);
				}else{
					obj[key] = withObjVal;
				}
			}
		}
		return obj;
	};
//	proto.addField = function addField(){ throw new Error("Instead of `Document#addField(key,val)` you should just use `obj[key] = val`"); }
//	proto.setField = function addField(){ throw new Error("Instead of `Document#setField(key,val)` you should just use `obj[key] = val`"); }
//  proto.getField = function getField(){ throw new Error("Instead of `Document#getField(key)` you should just use `var val = obj[key];`"); }

	return klass;
})();