/* @flow */

import DropdownMenu, {
    DropdownItem,
    DropdownItemGroup
} from '@atlaskit/dropdown-menu';
import React, { Component } from 'react';

import { translate } from '../../base/i18n/functions';

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

    /**
     * MediaDeviceInfos used for display in the select element.
     */
    devices: Array<Object>,

    /**
     * If false, will return a selector with no selection options.
     */
    hasPermission: boolean,

    /**
     * CSS class for the icon to the left of the dropdown trigger.
     */
    icon: string,

    /**
     * If true, will render the selector disabled with a default selection.
     */
    isDisabled: boolean,

    /**
     * The translation key to display as a menu label.
     */
    label: string,

    /**
     * The callback to invoke when a selection is made.
     */
    onSelect: Function,

    /**
     * The default device to display as selected.
     */
    selectedDeviceId: string,

    /**
     * Invoked to obtain translated strings.
     */
    t: Function
};

/**
 * React component for selecting a device from a select element. Wraps
 * AKDropdownMenu with device selection specific logic.
 *
 * @extends Component
 */
class DeviceSelector extends Component<Props> {
    /**
     * Initializes a new DeviceSelector instance.
     *
     * @param {Object} props - The read-only React Component props with which
     * the new instance is to be initialized.
     */
    constructor(props) {
        super(props);

        this._onSelect = this._onSelect.bind(this);
        this._createDropdownItem = this._createDropdownItem.bind(this);
    }

    /**
     * Implements React's {@link Component#render()}.
     *
     * @inheritdoc
     * @returns {ReactElement}
     */
    render() {
        if (!this.props.hasPermission) {
            return this._renderNoPermission();
        }

        if (!this.props.devices || !this.props.devices.length) {
            return this._renderNoDevices();
        }

        const items = this.props.devices.map(this._createDropdownItem);
        const defaultSelected = this.props.devices.find(item =>
            item.deviceId === this.props.selectedDeviceId
        );

        return this._createDropdown({
            defaultSelected,
            isDisabled: this.props.isDisabled,
            items,
            placeholder: this.props.t('deviceSelection.selectADevice')
        });
    }

    /**
     * Creates a React Element for displaying the passed in text surrounded by
     * two icons. The left icon is the icon class passed in through props and
     * the right icon is AtlasKit ExpandIcon.
     *
     * @param {string} triggerText - The text to display within the element.
     * @private
     * @returns {ReactElement}
     */
    _createDropdownTrigger(triggerText) {
        return (
            <div className = 'device-selector-trigger'>
                <span className = 'device-selector-trigger-text'>
                    { triggerText }
                </span>
            </div>
        );
    }

    _createDropdownItem: (Object) => void;

    /**
     * Creates an object in the format expected by AKDropdownMenu for an option.
     *
     * @param {MediaDeviceInfo} device - An object with a label and a deviceId.
     * @private
     * @returns {Object} The passed in media device description converted to a
     * format recognized as a valid AKDropdownMenu item.
     */
    _createDropdownItem(device) {
        return (
            <DropdownItem
                key = { device.deviceId }
                // eslint-disable-next-line react/jsx-no-bind
                onClick = {
                    e => {
                        e.stopPropagation();
                        this._onSelect(device.deviceId);
                    }
                }>
                { device.label || device.deviceId }
            </DropdownItem>
        );
    }

    /**
     * Creates a AKDropdownMenu Component using passed in props and options. If
     * the dropdown needs to be disabled, then only the AKDropdownMenu trigger
     * element is returned to simulate a disabled state.
     *
     * @param {Object} options - Additional configuration for display.
     * @param {Object} options.defaultSelected - The option that should be set
     * as currently chosen.
     * @param {boolean} options.isDisabled - If true, only the AKDropdownMenu
     * trigger component will be returned to simulate a disabled dropdown.
     * @param {Array} options.items - All the selectable options to display.
     * @param {string} options.placeholder - The translation key to display when
     * no selection has been made.
     * @private
     * @returns {ReactElement}
     */
    _createDropdown(options) {
        const triggerText
            = (options.defaultSelected && (options.defaultSelected.label || options.defaultSelected.deviceId))
                || options.placeholder;
        const trigger = this._createDropdownTrigger(triggerText);

        if (options.isDisabled || !options.items.length) {
            return (
                <div className = 'device-selector-trigger-disabled'>
                    { trigger }
                </div>
            );
        }

        return (
            <div className = 'dropdown-menu'>
                <DropdownMenu
                    shouldFitContainer = { true }
                    trigger = { triggerText }
                    triggerButtonProps = {{
                        shouldFitContainer: true
                    }}
                    triggerType = 'button'>
                    <DropdownItemGroup>
                        { options.items }
                    </DropdownItemGroup>
                </DropdownMenu>
            </div>
        );
    }

    _onSelect: (Object) => void;

    /**
     * Invokes the passed in callback to notify of selection changes.
     *
     * @param {Object} newDeviceId - Selected device id from DropdownMenu option.
     * @private
     * @returns {void}
     */
    _onSelect(newDeviceId) {
        if (this.props.selectedDeviceId !== newDeviceId) {
            this.props.onSelect(newDeviceId);
        }
    }

    /**
     * Creates a Select Component that is disabled and has a placeholder
     * indicating there are no devices to select.
     *
     * @private
     * @returns {ReactElement}
     */
    _renderNoDevices() {
        return this._createDropdown({
            isDisabled: true,
            placeholder: this.props.t('settings.noDevice')
        });
    }

    /**
     * Creates a AKDropdownMenu Component that is disabled and has a placeholder
     * stating there is no permission to display the devices.
     *
     * @private
     * @returns {ReactElement}
     */
    _renderNoPermission() {
        return this._createDropdown({
            isDisabled: true,
            placeholder: this.props.t('deviceSelection.noPermission')
        });
    }
}

export default translate(DeviceSelector);