/*

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']});