milojs/milo-core

'use strict';

var MessengerAPI = require('../messenger/m_api')
    , pathUtils = require('./path_utils')
    , logger = require('../util/logger')
    , _ = require('protojs');


/**
 * Subclass of MessengerAPI that is used to translate messages of Messenger on ModelPath to Messenger on Model.
 */
var ModelPathMsgAPI = _.createSubclass(MessengerAPI, 'ModelPathMsgAPI');

module.exports = ModelPathMsgAPI;


/**
 * ####ModelPathMsgAPI instance methods####
 *
 * - [init](#init) - initializes ModelPathMsgAPI
 * - [translateToSourceMessage](#translateToSourceMessage) - translates relative access paths of ModelPath to full path of Model
 * - [createInternalData](#createInternalData) - changes path in message on model to relative path and adds `fullPath` property to message data
 */
_.extendProto(ModelPathMsgAPI, {
    init: init,
    translateToSourceMessage: translateToSourceMessage,
    createInternalData: createInternalData,
});


/**
 * ModelPathMsgAPI instance method
 * Called by MessengerAPI constructor.
 *
 * @param {String} rootPath root path of model path
 */
function init(rootPath) {
    MessengerAPI.prototype.init.apply(this, arguments);
    this.rootPath = rootPath;
}

/**
 * ModelPathMsgAPI instance method
 * Translates relative access paths of ModelPath to full path of Model.
 *
 * @param {String} accessPath relative access path to be translated
 * @return {String}
 */
function translateToSourceMessage(message) {
    // TODO should prepend RegExes
    // TODO should not prepend changedata too???
    if (message instanceof RegExp)
        return message;
    if (message == 'datachanges')
        return message;
    
    return this.rootPath + message;
}


/**
 * ModelPathMsgAPI instance method
 * Changes path in message on model to relative path and adds `fullPath` property to message data.
 *
 * @param {String} sourceMessage full access path on Model
 * @param {String} message relative access path on ModelPath
 * @param {Object} sourceData data received from Model, will be translated as described to be dispatched to ModelPath
 * @return {Object}
 */
function createInternalData(sourceMessage, message, sourceData) {
    // TODO return on changedata too???
    if (message == 'datachanges') {
        var internalChanges = sourceData.changes
            .map(truncateChangePath, this)
            .filter(function(change) { return change; });
        var internalData = {
            changes: internalChanges,
            transaction: sourceData.transaction
        };

        return internalData
    }

    var internalData = truncateChangePath.call(this, sourceData);
    return internalData;
}


function truncateChangePath(change) {
    var fullPath = change.path
        , path = _.unPrefix(fullPath, this.rootPath);

    if (typeof path == 'string') {
        var change = _.clone(change);
        change.fullPath = fullPath;
        change.path = path;
        return change;
    }
}