Implement Subscriptions class.

INSERT INTO updates SET `user_id` = 1, `comment_id` = 6,  `action` = 'delete', `created_at` = '2011-10-05 00:00:00';

INSERT INTO updates SET `user_id` = 5, `comment_id` = 9,  `action` = 'delete', `created_at` = '2012-01-08 00:00:00';

INSERT INTO updates SET `user_id` = 6, `comment_id` = 25, `action` = 'delete', `created_at` = '2012-05-20 00:00:00';

-- subscriptions

-- subscribe renku to Ext & Ext.Img

INSERT INTO subscriptions SET `user_id` = 1, `target_id` = 1, `created_at` = '2011-01-01 00:00:00';

INSERT INTO subscriptions SET `user_id` = 1, `target_id` = 8, `created_at` = '2011-01-01 00:00:00';

-- subscribe john to Ext & String#replace

INSERT INTO subscriptions SET `user_id` = 2, `target_id` = 1, `created_at` = '2011-01-01 00:00:00';

INSERT INTO subscriptions SET `user_id` = 2, `target_id` = 6, `created_at` = '2011-01-01 00:00:00';

-- subscribe mary to Ext

INSERT INTO subscriptions SET `user_id` = 3, `target_id` = 1, `created_at` = '2011-01-01 00:00:00';

-- subscribe jack to touch-2 Ext

INSERT INTO subscriptions SET `user_id` = 4, `target_id` = 14, `created_at` = '2011-01-01 00:00:00';

/**

 * Represents a Subscriptions table.

 *

 * @constructor

 * Initializes Subscriptions with a database connection and a target domain.

 *

 * @param {DbFacade} db Instance of DbFacade.

 * @param {String} domain The comments domain within which to work.

 */

function Subscriptions(db, domain) {

    this.db = db;

    this.domain = domain;

}

Subscriptions.prototype = {

    /**

     * Finds all targets a user has subscribed to.

     *

     * @param {Number} user_id ID of the user.

     * @param {Function} callback Called with the result.

     * @param {Error} callback.err The error object.

     * @param {Object[]} callback.targets An array of targets.

     */

    findTargetsByUser: function(user_id, callback) {

        var sql = [

            'SELECT targets.*',

            'FROM subscriptions JOIN targets ON subscriptions.target_id = targets.id',

            'WHERE domain = ? AND user_id = ?'

        ];

        this.db.query(sql, [this.domain, user_id], callback);

    },

    /**

     * Finds all users who have subscribed to a particular target.

     *

     * @param {Number} target_id ID of the target.

     * @param {Function} callback Called with the result.

     * @param {Error} callback.err The error object.

     * @param {Object[]} callback.users An array of users.

     */

    findUsersByTarget: function(target_id, callback) {

        var sql = [

            'SELECT users.*',

            'FROM subscriptions JOIN users ON subscriptions.user_id = users.id',

            'WHERE target_id = ?'

        ];

        this.db.query(sql, [target_id], callback);

    }

};

module.exports = Subscriptions;

describe("Subscriptions", function() {

    var Subscriptions = require("./subscriptions");

    var DbFacade = require('./db_facade');

    var connection;

    var subscriptions;

    beforeEach(function() {

        connection = new DbFacade({

            host: 'localhost',

            user: '',

            password: '',

            database: 'comments_test'

        });

        subscriptions = new Subscriptions(connection, "ext-js-4");

    });

    afterEach(function() {

        connection.end();

    });

    it("#findTargetsByUser returns empty array when user has no subscriptions in current domain", function(done) {

        subscriptions.findTargetsByUser(4, function(err, subs) {

            expect(subs.length).toEqual(0);

            done();

        });

    });

    it("#findTargetsByUser returns all subscription targets of a user", function(done) {

        subscriptions.findTargetsByUser(1, function(err, subs) {

            expect(subs.length).toEqual(2);

            done();

        });

    });

    it("#findTargetsByUser returns subscription target type, cls & member fields", function(done) {

        subscriptions.findTargetsByUser(3, function(err, subs) {

            expect(subs[0].type).toEqual("class");

            expect(subs[0].cls).toEqual("Ext");

            expect(subs[0].member).toEqual("");

            done();

        });

    });

    it("#findUsersByTarget returns empty array when no subscriptions to a target", function(done) {

        subscriptions.findUsersByTarget(2, function(err, subs) {

            expect(subs.length).toEqual(0);

            done();

        });

    });

    it("#findUsersByTarget returns all users who have subscribed to a particular target", function(done) {

        subscriptions.findUsersByTarget(1, function(err, subs) {

            expect(subs.length).toEqual(3);

            done();

        });

    });

    it("#findUsersByTarget returns username and email fields", function(done) {

        subscriptions.findUsersByTarget(8, function(err, subs) {

            expect(subs[0].username).toEqual("renku");

            expect(subs[0].email).toEqual("renku@example.com");

            done();

        });

    });

});