import { jsOMS }  from '../Utils/oLib.js';
import { Logger } from '../Log/Logger.js';

/**
 * Action manager class.
 *
 * @copyright Dennis Eichhorn
 * @license   OMS License 2.2
 * @version   1.0.0
 * @since     1.0.0
 *
 * @todo Karaka/jsOMS#26
 *  Sync/Async events
 *  Events so far can be created sync and async depending on the implementation.
 *  It would be better to make it sync/async depending on a option flag.
 *
 * @todo Karaka/jsOMS#35
 *  Template actions cannot be overwritten
 *  Templates by nature get added and removed from a page (often in order to reuse existing html to minimize the html load).
 *  The problem with templates is that they need to register in the ActionManager.js.
 *  A listener currently is only registered once per id.
 *  Since templates often keep the same id for some elements this results in a problem because the new template will not register a new listener.
 *  Possible solutions:
 *      1. Force unique ids for templates during setup (pro: fast and easy initial solution, con: action event pollution not solved)
 *      2. Whenever a dom element with action elements is removed, also unregister the listeners (pro: clean solution, con: difficult to implement)
 *  Solution 2 will be implemented.
 *  Maybe this can be performed in the dom removing action events or a dom listener would be required to listen for these dom elements.
 */
export class ActionManager
{
    /**
     * @constructor
     *
     * @param {Object} app Application
     *
     * @since 1.0.0
     */
    constructor (app)
    {
        this.logger  = Logger.getInstance();
        this.app     = app;
        this.actions = {};
    };

    /**
     * Bind element.
     *
     * @param {null|string} [id] Element id (optional)
     *
     * @return {void}
     *
     * @since 1.0.0
     */
    bind (id = null)
    {
        const uiElements = id == null ? document.querySelectorAll('[data-action]') : (typeof id.length !== 'undefined' ? id : [id]);
        const length     = uiElements.length;

        for (let i = 0; i < length; ++i) {
            if (uiElements[i] !== null && uiElements[i].hasAttribute('data-action')) {
                this.bindElement(uiElements[i]);
            }
        }
    };

    /**
     * Bind element.
     *
     * @param {Element} e Element to bind
     *
     * @return {void}
     *
     * @since 1.0.0
     */
    bindElement (e)
    {
        if (!jsOMS.isValidJson(e.getAttribute('data-action'))) {
            this.logger.error('Invalid json string: \'' + e.getAttribute('data-action') + '\'');

            return;
        }

        const listeners      = JSON.parse(e.getAttribute('data-action'));
        const listenerLength = listeners.length;
        const self           = this;

        // For every action an event is registered
        for (let i = 0; i < listenerLength; ++i) {
            let c           = [e];
            let hasSelector = false;

            // the selector must be a child of e!!!
            if (Object.prototype.hasOwnProperty.call(listeners[i], 'selector')) {
                c           = document.querySelectorAll(listeners[i].selector);
                hasSelector = true;
            }

            const childLength = c.length;
            for (let j = 0; j < childLength; ++j) {
                this.bindListener(c[j].id, listeners[i]);
            }

            /**
             * @todo Karaka/jsOMS#69
             *  If a element has a selector defined this means the action is defined for all child elements of this selector.
             *  This usually is done in order to avoid defining the same behavior multiple times for similar elements (e.g. elements in a list).
             *  However, in this case it's not unusual that the child elements get changed dynamically (added, changed, removed).
             *  In this case the child element listeners need to be updated on change/addition/removal.
             */
            const observeConfig = { childList: false, attributes: true, subtree: false };

            if (hasSelector) {
                this.app.eventManager.attach(e.id + '-childList', function (data) {
                    const length = data.addedNodes.length;

                    for (let j = 0; j < length; ++j) {
                        self.bindListener(
                            data.addedNodes[j].id,
                            listeners[i],
                            typeof listeners[i].autoremove !== 'undefined' ? listeners[i].autoremove : false
                        );
                    }
                });

                observeConfig.childList = true;
                observeConfig.subtree   = true;
            }

            this.app.eventManager.attach(e.id + '-attributes', function (data) {});
            this.app.uiManager.getDOMObserver().observe(e, observeConfig);
        }
    };

    /**
     * Bind listener for object
     *
     * @param {string} id Element to bind
     * @param {Object} listener Listener object
     *
     * @return {void}
     *
     * @since 1.0.0
     */
    bindListener (id, listener, removable = false)
    {
        const self         = this;
        const actionLength = listener.action.length;

        for (let j = 1; j < actionLength; ++j) {
            if (typeof id === 'undefined' || typeof listener.key === 'undefined') {
                this.logger.error('Invalid element id/key: ' + id + '/' + listener.key);
                return;
            }

            if (this.app.eventManager.isAttached(id + '-' + listener.key + '-' + listener.action[j - 1].key)) {
                return;
            }

            this.app.eventManager.attach(id + '-' + listener.key + '-' + listener.action[j - 1].key, function (data)
            {
                self.runAction(id, listener, listener.action[j], data);
            }, removable, true);
        }

        // Register event for first action
        document.getElementById(id).addEventListener(listener.listener, function (event)
        {
            if (listener.preventDefault) {
                jsOMS.preventAll(event);
            }

            self.runAction(this.id, listener, listener.action[0], event);
        }, false);
    };

    /**
     * Run event action.
     *
     * @param {string} id       Element
     * @param {Object} listener Listener
     * @param {Object} action   Action
     * @param {Object} data     Data for the next action
     *
     * @return {void}
     *
     * @since 1.0.0
     */
    runAction (id, listener, action, data)
    {
        const self = this;

        if (!Object.prototype.hasOwnProperty.call(this.actions, action.type)) {
            this.logger.warning('Undefined action ' + action.type);
            return;
        }

        action.data = data;

        this.actions[action.type](action, function (data)
        {
            self.app.eventManager.trigger(id + '-' + listener.key + '-' + action.key, id, data);
        }, id);
    };

    /**
     * Add action callback.
     *
     * @param {string}   name     Action identifier
     * @param {function} callback Action callback
     *
     * @return {void}
     *
     * @since 1.0.0
     */
    add (name, callback)
    {
        this.actions[name] = callback;
    };
};