/*
Copyright (c) 2009, Yahoo! Inc. All rights reserved.
Code licensed under the BSD License:
http://developer.yahoo.net/yui/license.txt
version: 3.0.0b1
build: 1163
*/
YUI.add('dataschema-json', function(Y) {

/**
 * Provides a DataSchema implementation which can be used to work with JSON data.
 *
 * @module dataschema
 * @submodule dataschema-json
 */

/**
 * JSON subclass for the DataSchema Utility.
 * @class DataSchema.JSON
 * @extends DataSchema.Base
 * @static
 */
var LANG = Y.Lang,

    SchemaJSON = {

        /////////////////////////////////////////////////////////////////////////////
        //
        // DataSchema.JSON static methods
        //
        /////////////////////////////////////////////////////////////////////////////
        /**
         * Utility function converts JSON locator strings into walkable paths
         *
         * @method DataSchema.JSON.getPath
         * @param locator {String} JSON value locator.
         * @return {String[]} Walkable path to data value.
         * @static
         */
        getPath: function(locator) {
            var path = null,
                keys = [],
                i = 0;

            if (locator) {
                // Strip the ["string keys"] and [1] array indexes
                locator = locator.
                    replace(/\[(['"])(.*?)\1\]/g,
                    function (x,$1,$2) {keys[i]=$2;return '.@'+(i++);}).
                    replace(/\[(\d+)\]/g,
                    function (x,$1) {keys[i]=parseInt($1,10)|0;return '.@'+(i++);}).
                    replace(/^\./,''); // remove leading dot

                // Validate against problematic characters.
                if (!/[^\w\.\$@]/.test(locator)) {
                    path = locator.split('.');
                    for (i=path.length-1; i >= 0; --i) {
                        if (path[i].charAt(0) === '@') {
                            path[i] = keys[parseInt(path[i].substr(1),10)];
                        }
                    }
                }
                else {
                    Y.log("Invalid locator: " + locator, "error", "dataschema-json");
                }
            }
            return path;
        },

        /**
         * Utility function to walk a path and return the value located there.
         *
         * @method DataSchema.JSON.getLocationValue
         * @param path {String[]} Locator path.
         * @param data {String} Data to traverse.
         * @return {Object} Data value at location.
         * @static
         */
        getLocationValue: function (path, data) {
            var i = 0,
                len = path.length;
            for (;i<len;i++) {
                if(!LANG.isUndefined(data[path[i]])) {
                    data = data[path[i]];
                }
                else {
                    data = undefined;
                    break;
                }
            }
            return data;
        },

        /**
         * Applies a given schema to given JSON data.
         *
         * @method apply
         * @param schema {Object} Schema to apply.
         * @param data {Object} JSON data.
         * @return {Object} Schema-parsed data.
         * @static
         */
        apply: function(schema, data) {
            var data_in = data,
                data_out = {results:[],meta:{}};

            // Convert incoming JSON strings
            if(!LANG.isObject(data)) {
                try {
                    data_in = Y.JSON.parse(data);
                }
                catch(e) {
                    data_out.error = e;
                    return data_out;
                }
            }

            if(LANG.isObject(data_in) && schema) {
                // Parse results data
                if(!LANG.isUndefined(schema.resultListLocator)) {
                    data_out = SchemaJSON._parseResults(schema, data_in, data_out);
                }

                // Parse meta data
                if(!LANG.isUndefined(schema.metaFields)) {
                    data_out = SchemaJSON._parseMeta(schema.metaFields, data_in, data_out);
                }
            }
            else {
                Y.log("JSON data could not be schema-parsed: " + Y.dump(data) + " " + Y.dump(data), "error", "dataschema-json");
                data_out.error = new Error("JSON schema parse failure");
            }

            return data_out;
        },

        /**
         * Schema-parsed list of results from full data
         *
         * @method _parseResults
         * @param schema {Object} Schema to parse against.
         * @param json_in {Object} JSON to parse.
         * @param data_out {Object} In-progress parsed data to update.
         * @return {Object} Parsed data object.
         * @static
         * @protected
         */
        _parseResults: function(schema, json_in, data_out) {
            var results = [],
                path,
                error;

            if(schema.resultListLocator) {
                path = SchemaJSON.getPath(schema.resultListLocator);
                if(path) {
                    results = SchemaJSON.getLocationValue(path, json_in);
                    if (results === undefined) {
                        data_out.results = [];
                        error = new Error("JSON results retrieval failure");
                    }
                    else {
                        if(LANG.isArray(schema.resultFields) && LANG.isArray(results)) {
                            data_out = SchemaJSON._getFieldValues(schema.resultFields, results, data_out);
                        }
                        else {
                            data_out.results = [];
                            error = new Error("JSON Schema fields retrieval failure");
                        }
                    }
                }
                else {
                    error = new Error("JSON Schema results locator failure");
                }

                if (error) {
                    Y.log("JSON data could not be parsed: " + Y.dump(json_in), "error", "dataschema-json");
                    data_out.error = error;
                }

            }
            return data_out;
        },

        /**
         * Get field data values out of list of full results
         *
         * @method _getFieldValues
         * @param fields {Array} Fields to find.
         * @param array_in {Array} Results to parse.
         * @param data_out {Object} In-progress parsed data to update.
         * @return {Object} Parsed data object.
         * @static
         * @protected
         */
        _getFieldValues: function(fields, array_in, data_out) {
            var results = [],
                len = fields.length,
                i, j,
                field, key, path, parser,
                simplePaths = [], complexPaths = [], fieldParsers = [],
                result, record;

            // First collect hashes of simple paths, complex paths, and parsers
            for (i=0; i<len; i++) {
                field = fields[i]; // A field can be a simple string or a hash
                key = field.key || field; // Find the key

                // Validate and store locators for later
                path = SchemaJSON.getPath(key);
                if (path) {
                    if (path.length === 1) {
                        simplePaths[simplePaths.length] = {key:key, path:path[0]};
                    } else {
                        complexPaths[complexPaths.length] = {key:key, path:path};
                    }
                } else {
                    Y.log("Invalid key syntax: " + key, "warn", "dataschema-json");
                }

                // Validate and store parsers for later
                //TODO: use Y.DataSchema.parse?
                parser = (LANG.isFunction(field.parser)) ? field.parser : Y.Parsers[field.parser+''];
                if (parser) {
                    fieldParsers[fieldParsers.length] = {key:key, parser:parser};
                }
            }

            // Traverse list of array_in, creating records of simple fields,
            // complex fields, and applying parsers as necessary
            for (i=array_in.length-1; i>=0; --i) {
                record = {};
                result = array_in[i];
                if(result) {
                    // Cycle through simpleLocators
                    for (j=simplePaths.length-1; j>=0; --j) {
                        // Bug 1777850: The result might be an array instead of object
                        record[simplePaths[j].key] = Y.DataSchema.Base.parse(
                                (LANG.isUndefined(result[simplePaths[j].path]) ?
                                result[j] : result[simplePaths[j].path]), simplePaths[j]);
                    }

                    // Cycle through complexLocators
                    for (j=complexPaths.length - 1; j>=0; --j) {
                        record[complexPaths[j].key] = Y.DataSchema.Base.parse(
                            (SchemaJSON.getLocationValue(complexPaths[j].path, result)), complexPaths[j] );
                    }

                    // Cycle through fieldParsers
                    for (j=fieldParsers.length-1; j>=0; --j) {
                        key = fieldParsers[j].key;
                        record[key] = fieldParsers[j].parser(record[key]);
                        // Safety net
                        if (LANG.isUndefined(record[key])) {
                            record[key] = null;
                        }
                    }
                    results[i] = record;
                }
            }
            data_out.results = results;
            return data_out;
        },

        /**
         * Parses results data according to schema
         *
         * @method _parseMeta
         * @param metaFields {Object} Metafields definitions.
         * @param json_in {Object} JSON to parse.
         * @param data_out {Object} In-progress parsed data to update.
         * @return {Object} Schema-parsed meta data.
         * @static
         * @protected
         */
        _parseMeta: function(metaFields, json_in, data_out) {
            if(LANG.isObject(metaFields)) {
                var key, path;
                for(key in metaFields) {
                    if (metaFields.hasOwnProperty(key)) {
                        path = SchemaJSON.getPath(metaFields[key]);
                        if (path && json_in) {
                            data_out.meta[key] = SchemaJSON.getLocationValue(path, json_in);
                        }
                    }
                }
            }
            else {
                data_out.error = new Error("JSON meta data retrieval failure");
            }
            return data_out;
        }
    };

Y.DataSchema.JSON = Y.mix(SchemaJSON, Y.DataSchema.Base);



}, '3.0.0b1' ,{requires:['json', 'dataschema-base']});
