// @flow

import React, { PureComponent } from 'react';
import type { Dispatch } from 'redux';

import { openDialog } from '../../../base/dialog';
import { IconUserGroups } from '../../../base/icons';
import { Label } from '../../../base/label';
import { getParticipantCount } from '../../../base/participants';
import { connect } from '../../../base/redux';
import { SpeakerStats } from '../../../speaker-stats';
import { isSpeakerStatsDisabled } from '../../../speaker-stats/functions';


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

    /**
     * Number of the conference participants.
     */
    count: number,

    /**
     * Conference data.
     */
    conference: Object,

    /**
     * Invoked to open Speaker stats.
     */
    dispatch: Dispatch<any>,

    /**
     * Weather or not the speaker stats is disabled.
     */
     _isSpeakerStatsDisabled: Boolean,
};

/**
 * ParticipantsCount react component.
 * Displays the number of participants and opens Speaker stats on click.
 *
 * @class ParticipantsCount
 */
class ParticipantsCount extends PureComponent<Props> {
    /**
     * Initializes a new ParticipantsCount instance.
     *
     * @param {Object} props - The read-only properties with which the new
     * instance is to be initialized.
     */
    constructor(props: Props) {
        super(props);

        this._onClick = this._onClick.bind(this);
    }

    _onClick: () => void;

    /**
     * Callback invoked to display {@code SpeakerStats}.
     *
     * @private
     * @returns {void}
     */
    _onClick() {
        const { dispatch, conference } = this.props;

        dispatch(openDialog(SpeakerStats, { conference }));
    }

    /**
     * Implements React's {@link PureComponent#render()}.
     *
     * @inheritdoc
     * @returns {ReactElement}
     */
    render() {
        const { count } = this.props;

        if (count <= 2) {
            return null;
        }

        return (
            <Label
                icon = { IconUserGroups }
                onClick = { !this.props._isSpeakerStatsDisabled && this._onClick }
                text = { count } />
        );
    }
}


/**
 * Maps (parts of) the Redux state to the associated props for the
 * {@code ParticipantsCount} component.
 *
 * @param {Object} state - The Redux state.
 * @private
 * @returns {Props}
 */
function mapStateToProps(state) {
    return {
        conference: state['features/base/conference'].conference,
        count: getParticipantCount(state),
        _isSpeakerStatsDisabled: isSpeakerStatsDisabled(state)
    };
}

export default connect(mapStateToProps)(ParticipantsCount);