import { Gridicon, SegmentedControl } from '@automattic/components';
import { localize } from 'i18n-calypso';
import { debounce } from 'lodash';
import PropTypes from 'prop-types';
import { Component } from 'react';
import { connect } from 'react-redux';
import FormRange from 'calypso/components/forms/range';
import { SCALE_CHOICES, SCALE_TOUCH_GRID } from 'calypso/lib/media/constants';
import { setPreference, savePreference } from 'calypso/state/preferences/actions';

/**
 * Constants
 */

/**
 * Number of steps on the rendered input range
 * @type {number}
 */
const SLIDER_STEPS = 100;

/**
 * Scale size for small viewports grid option (3 items per row).
 * @type {number}
 */

class MediaLibraryScale extends Component {
	static propTypes = {
		mediaScale: PropTypes.number,
		onChange: PropTypes.func,
		setMediaScalePreference: PropTypes.func,
		saveMediaScalePreference: PropTypes.func,
	};

	static defaultProps = {
		onChange: () => {},
	};

	constructor() {
		super( ...arguments );

		this.onScaleChange = this.onScaleChange.bind( this );
		this.savePreference = this.savePreference.bind( this );
		this.debouncedSavePreference = debounce( this.savePreference, 1000 );
		this.setScaleToMobileGrid = this.setScale.bind( this, SCALE_TOUCH_GRID );
		this.setScaleToMobileFull = this.setScale.bind( this, 1 );

		this.state = {};
	}

	componentWillUnmount() {
		this.debouncedSavePreference.cancel();
	}

	savePreference( value ) {
		this.props.saveMediaScalePreference( value );
	}

	setScale( value ) {
		if ( value === this.props.mediaScale ) {
			return;
		}

		this.props.onChange( value );
		this.props.setMediaScalePreference( value );
		this.debouncedSavePreference( value );
	}

	onScaleChange( event ) {
		const sliderPosition = parseInt( event.target.value, 10 );
		const scaleIndex = ( sliderPosition * SCALE_CHOICES.length ) / SLIDER_STEPS;
		const scale = SCALE_CHOICES[ Math.floor( scaleIndex ) ];

		this.setState( { sliderPosition } );
		this.setScale( scale );
	}

	getSliderPosition() {
		// As part of the smooth motion of the slider, the user can move it
		// between two snap points, and we want to remember this.
		if ( this.state.hasOwnProperty( 'sliderPosition' ) ) {
			return this.state.sliderPosition;
		}

		const scale = this.props.mediaScale;

		// Map the media scale index back to a slider position as follows:
		// index 0 -> position 0
		// index SCALE_CHOICES.length - 1 -> position SLIDER_STEPS - 1
		const scaleIndex = SCALE_CHOICES.indexOf( scale );
		if ( -1 === scaleIndex ) {
			return 0;
		}

		return Math.floor( ( scaleIndex * ( SLIDER_STEPS - 1 ) ) / ( SCALE_CHOICES.length - 1 ) );
	}

	render() {
		const { translate } = this.props;
		const scale = this.props.mediaScale;

		return (
			<div className="media-library__scale">
				<SegmentedControl className="media-library__scale-toggle" compact>
					<SegmentedControl.Item
						selected={ 1 !== scale }
						onClick={ this.setScaleToMobileGrid }
						title={ translate( 'Grid' ) }
					>
						<Gridicon icon="grid" size={ 18 } />
					</SegmentedControl.Item>
					<SegmentedControl.Item
						selected={ 1 === scale }
						onClick={ this.setScaleToMobileFull }
						title={ translate( 'List' ) }
					>
						<Gridicon icon="menu" size={ 18 } />
					</SegmentedControl.Item>
				</SegmentedControl>
				<FormRange
					step="1"
					min="0"
					max={ SLIDER_STEPS - 1 }
					minContent={ <Gridicon icon="image" size={ 12 } /> }
					maxContent={ <Gridicon icon="image" size={ 24 } /> }
					value={ this.getSliderPosition() }
					onChange={ this.onScaleChange }
					className="media-library__scale-range"
				/>
			</div>
		);
	}
}

export default connect( null, {
	setMediaScalePreference: ( value ) => setPreference( 'mediaScale', value ),
	saveMediaScalePreference: ( value ) => savePreference( 'mediaScale', value ),
} )( localize( MediaLibraryScale ) );