/* @flow */

import _ from 'lodash';
import React, { Component } from 'react';
import type { Dispatch } from 'redux';

import {
    createShortcutEvent,
    createToolbarEvent,
    sendAnalytics
} from '../../../analytics';
import { connect } from '../../../base/redux';
import { dockToolbox } from '../../../toolbox';

import { setFilmstripHovered, setFilmstripVisible } from '../../actions';
import { shouldRemoteVideosBeVisible } from '../../functions';

import Toolbar from './Toolbar';

declare var APP: Object;
declare var interfaceConfig: Object;

/**
 * The type of the React {@code Component} props of {@link Filmstrip}.
 */
type Props = {

    /**
     * Additional CSS class names top add to the root.
     */
    _className: string,

    /**
     * Whether the UI/UX is filmstrip-only.
     */
    _filmstripOnly: boolean,

    /**
     * Whether or not remote videos are currently being hovered over. Hover
     * handling is currently being handled detected outside of react.
     */
    _hovered: boolean,

    /**
     * Additional CSS class names to add to the container of all the thumbnails.
     */
    _videosClassName: string,

    /**
     * Whether or not the filmstrip videos should currently be displayed.
     */
    _visible: boolean,

    /**
     * The redux {@code dispatch} function.
     */
    dispatch: Dispatch<any>
};

/**
 * Implements a React {@link Component} which represents the filmstrip on
 * Web/React.
 *
 * @extends Component
 */
class Filmstrip extends Component <Props> {
    _isHovered: boolean;

    _notifyOfHoveredStateUpdate: Function;

    _onMouseOut: Function;

    _onMouseOver: Function;

    /**
     * Initializes a new {@code Filmstrip} instance.
     *
     * @param {Object} props - The read-only properties with which the new
     * instance is to be initialized.
     */
    constructor(props: Props) {
        super(props);

        // Debounce the method for dispatching the new filmstrip handled state
        // so that it does not get called with each mouse movement event. This
        // also works around an issue where mouseout and then a mouseover event
        // is fired when hovering over remote thumbnails, which are not yet in
        // react.
        this._notifyOfHoveredStateUpdate
            = _.debounce(this._notifyOfHoveredStateUpdate, 100);

        // Cache the current hovered state for _updateHoveredState to always
        // send the last known hovered state.
        this._isHovered = false;

        // Bind event handlers so they are only bound once for every instance.
        this._onMouseOut = this._onMouseOut.bind(this);
        this._onMouseOver = this._onMouseOver.bind(this);
        this._onShortcutToggleFilmstrip
            = this._onShortcutToggleFilmstrip.bind(this);
        this._onToolbarToggleFilmstrip
            = this._onToolbarToggleFilmstrip.bind(this);
    }

    /**
     * Implements React's {@link Component#componentDidMount}.
     *
     * @inheritdoc
     */
    componentDidMount() {
        if (!this.props._filmstripOnly) {
            APP.keyboardshortcut.registerShortcut(
                'F',
                'filmstripPopover',
                this._onShortcutToggleFilmstrip,
                'keyboardShortcuts.toggleFilmstrip'
            );
        }
    }

    /**
     * Implements React's {@link Component#componentDidUpdate}.
     *
     * @inheritdoc
     */
    componentWillUnmount() {
        APP.keyboardshortcut.unregisterShortcut('F');
    }

    /**
     * Implements React's {@link Component#render()}.
     *
     * @inheritdoc
     * @returns {ReactElement}
     */
    render() {
        // Note: Appending of {@code RemoteVideo} views is handled through
        // VideoLayout. The views do not get blown away on render() because
        // ReactDOMComponent is only aware of the given JSX and not new appended
        // DOM. As such, when updateDOMProperties gets called, only attributes
        // will get updated without replacing the DOM. If the known DOM gets
        // modified, then the views will get blown away.

        return (
            <div className = { `filmstrip ${this.props._className}` }>
                { this.props._filmstripOnly
                    ? <Toolbar /> : this._renderToggleButton() }
                <div
                    className = { this.props._videosClassName }
                    id = 'remoteVideos'>
                    <div
                        className = 'filmstrip__videos'
                        id = 'filmstripLocalVideo'
                        onMouseOut = { this._onMouseOut }
                        onMouseOver = { this._onMouseOver }>
                        <div id = 'filmstripLocalVideoThumbnail' />
                    </div>
                    <div
                        className = 'filmstrip__videos'
                        id = 'filmstripRemoteVideos'>
                        {/*
                          * XXX This extra video container is needed for
                          * scrolling thumbnails in Firefox; otherwise, the flex
                          * thumbnails resize instead of causing overflow.
                          */}
                        <div
                            className = 'remote-videos-container'
                            id = 'filmstripRemoteVideosContainer'
                            onMouseOut = { this._onMouseOut }
                            onMouseOver = { this._onMouseOver }>
                            <div id = 'localVideoTileViewContainer' />
                        </div>
                    </div>
                </div>
            </div>
        );
    }

    /**
     * Dispatches an action to change the visibility of the filmstrip.
     *
     * @private
     * @returns {void}
     */
    _doToggleFilmstrip() {
        this.props.dispatch(setFilmstripVisible(!this.props._visible));
    }

    /**
     * If the current hover state does not match the known hover state in redux,
     * dispatch an action to update the known hover state in redux.
     *
     * @private
     * @returns {void}
     */
    _notifyOfHoveredStateUpdate() {
        if (this.props._hovered !== this._isHovered) {
            this.props.dispatch(dockToolbox(this._isHovered));
            this.props.dispatch(setFilmstripHovered(this._isHovered));
        }
    }

    /**
     * Updates the currently known mouseover state and attempt to dispatch an
     * update of the known hover state in redux.
     *
     * @private
     * @returns {void}
     */
    _onMouseOut() {
        this._isHovered = false;
        this._notifyOfHoveredStateUpdate();
    }

    /**
     * Updates the currently known mouseover state and attempt to dispatch an
     * update of the known hover state in redux.
     *
     * @private
     * @returns {void}
     */
    _onMouseOver() {
        this._isHovered = true;
        this._notifyOfHoveredStateUpdate();
    }

    _onShortcutToggleFilmstrip: () => void;

    /**
     * Creates an analytics keyboard shortcut event and dispatches an action for
     * toggling filmstrip visibility.
     *
     * @private
     * @returns {void}
     */
    _onShortcutToggleFilmstrip() {
        sendAnalytics(createShortcutEvent(
            'toggle.filmstrip',
            {
                enable: this.props._visible
            }));

        this._doToggleFilmstrip();
    }

    _onToolbarToggleFilmstrip: () => void;

    /**
     * Creates an analytics toolbar event and dispatches an action for opening
     * the speaker stats modal.
     *
     * @private
     * @returns {void}
     */
    _onToolbarToggleFilmstrip() {
        sendAnalytics(createToolbarEvent(
            'toggle.filmstrip.button',
            {
                enable: this.props._visible
            }));

        this._doToggleFilmstrip();
    }

    /**
     * Creates a React Element for changing the visibility of the filmstrip when
     * clicked.
     *
     * @private
     * @returns {ReactElement}
     */
    _renderToggleButton() {
        const icon = this.props._visible ? 'icon-menu-down' : 'icon-menu-up';

        return (
            <div className = 'filmstrip__toolbar'>
                <button
                    id = 'toggleFilmstripButton'
                    onClick = { this._onToolbarToggleFilmstrip }>
                    <i className = { icon } />
                </button>
            </div>
        );
    }
}

/**
 * Maps (parts of) the Redux state to the associated {@code Filmstrip}'s props.
 *
 * @param {Object} state - The Redux state.
 * @private
 * @returns {{
 *     _className: string,
 *     _filmstripOnly: boolean,
 *     _hovered: boolean,
 *     _videosClassName: string,
 *     _visible: boolean
 * }}
 */
function _mapStateToProps(state) {
    const { hovered, visible } = state['features/filmstrip'];
    const isFilmstripOnly = Boolean(interfaceConfig.filmStripOnly);
    const reduceHeight = !isFilmstripOnly
        && state['features/toolbox'].visible
        && interfaceConfig.TOOLBAR_BUTTONS.length;
    const remoteVideosVisible = shouldRemoteVideosBeVisible(state);
    const className = `${remoteVideosVisible ? '' : 'hide-videos'} ${
        reduceHeight ? 'reduce-height' : ''}`.trim();
    const videosClassName = `filmstrip__videos${
        isFilmstripOnly ? ' filmstrip__videos-filmstripOnly' : ''}${
        visible ? '' : ' hidden'}`;

    return {
        _className: className,
        _filmstripOnly: isFilmstripOnly,
        _hovered: hovered,
        _videosClassName: videosClassName,
        _visible: visible
    };
}

export default connect(_mapStateToProps)(Filmstrip);