/**
 * System takes care of updating all the entities (based on their component data)
 * @param graphics
 * @param apiSystem GameLib.API.System
 * @param apiUrl
 * @param token
 * @constructor
 */
GameLib.System.Storage = function(
    graphics,
    apiSystem,
    apiUrl,
    token
) {

    if (GameLib.Utils.UndefinedOrNull(apiUrl)) {
        console.warn('Need an API URL for a storage system');
    }
    this.apiUrl = apiUrl;

    GameLib.System.call(
        this,
        graphics,
        apiSystem
    );

    if (GameLib.Utils.UndefinedOrNull(token)) {
        token = null;
    }
    this.token = token;

    this.subscribe(
        GameLib.Event.LOGGED_IN,
        function(data) {
            this.token = data.token;
        }
    )

};

GameLib.System.Storage.prototype = Object.create(GameLib.System.prototype);
GameLib.System.Storage.prototype.constructor = GameLib.System.Storage;


/**
 * 'Saves' data to baseURL
 */
GameLib.System.Storage.prototype.save = function(data) {

    if (typeof XMLHttpRequest === 'undefined') {
        console.log('Implement server side save here');
        return;
    }

    var xhr = new XMLHttpRequest();

    xhr.open(
        'POST',
        this.apiUrl + '/component/create'
    );

    xhr.setRequestHeader("Accept", "application/json");
    xhr.setRequestHeader("Content-Type", "application/json");

    xhr.onreadystatechange = function () {
        if (this.readyState === 4) {
            try {
                var response = JSON.parse(this.responseText)
            } catch (error) {
                GameLib.Event.Emit(
                    GameLib.Event.SAVE_FAILURE,
                    {
                        message: this.responseText
                    }
                )
            }

            if (response.result === 'success') {
                GameLib.Event.Emit(
                    GameLib.Event.SAVE_SUCCESS,
                    {
                        message: response.message || 'Successfully saved the component'
                    }
                )
            } else {
                GameLib.Event.Emit(
                    GameLib.Event.SAVE_FAILURE,
                    {
                        message: response.message || 'The server responded but failed to save the component'
                    }
                )
            }
        }
    };

    xhr.send(JSON.stringify({
        component : data,
        session : this.token
    }));

};

/**
 * 'Loads' data from baseURL
 */
GameLib.System.Storage.prototype.load = function(data) {

    if (typeof XMLHttpRequest === 'undefined') {
        console.log('Implement server side load here');
        return;
    }

    var xhr = new XMLHttpRequest();

    xhr.open(
        'GET',
        this.apiUrl + '/component/' + data.id
    );

    xhr.onreadystatechange = function (xhr) {
        return function () {
            if (xhr.readyState === 4) {
                this.publish(
                    GameLib.Event.LOADED,
                    {
                        component: JSON.parse(xhr.responseText)
                    }
                )
            }
        }
    }(xhr).bind(this);

    xhr.send();
};