bem-site/gorshochek

'use strict';

const path = require('path');
const Q = require('q');
const baseUtil = require('../../util');

/**
 * Find difference between current and previous models
 * Merges models and saves current model file in cache
 * @param {Model} model - application model instance
 * @param {Object} options - options object
 * @param {Object} options.modelPath - path to model JSON file
 * @returns {Function}
 * @example
 * var Q = require('q');
 * var gorshochek = require('gorshochek');
 * var model = gorshochek.createModel();
 * Q()
 *    .then(tasks.core.mergeModels(model, {modelPath: './examples/model.ru.json'}))
 *    .then(tasks.core.saveModel(model))
 *    .then(tasks.core.rsync(model, {
 *        dest: './data',
 *        exclude: ['*.meta.json', 'model.json', '*.md']
 *    }))
 *    .done();
 */
module.exports = (model, options) => {
    options = options || {};

    // modelPath is required param
    if(!options.modelPath) {
        throw new Error('modelPath should be defined in task options');
    }

    /**
     * Prints changes for all types to log
     * @param {Model} model - application model
     */
    function logModelChanges(model) {
        ['added', 'modified', 'removed'].forEach(type => {
            model.getChanges()[type].forEach(item => {
                console.info(`Page with url: ${item.url} was ${type}`);
            });
        });
    }

    /**
     * Copies new model file into cache folder and replace old model file
     * @returns {Promise}
     */
    function replaceModelFileInCache() {
        return baseUtil.copyFile(options.modelPath, path.join(baseUtil.getCacheFolder(), 'model.json'));
    }

    return () => {
        return Q.all([
            baseUtil.readFileFromCache('model.json', []),
            baseUtil.readJSONFile(options.modelPath)
        ])
        .spread(model.merge.bind(model))
        .then(model.normalize.bind(model))
        .then(logModelChanges)
        .then(replaceModelFileInCache)
        .thenResolve(model);
    };
}