import React from 'react'

class Timer extends React.Component {
	constructor(props) {
		super(props)
		this.stopTime = Date.now() + (props.startTime * 1000)
	}

	state = {
		time: this.props.startTime * 10,
	}

	componentDidMount() {
		this.startCount()
	}

	componentWillReceiveProps(nextProps) {
		if (this.props.startTime !== nextProps.startTime) {
			this.stopTime = Date.now() + (nextProps.startTime * 1000)
			this.startCount()
		}
	}

	componentWillUnmount() {
		clearInterval(this.timer)
	}

	startCount = () => {
		this.timer = setInterval(this.stick, 1000)
	}

	stick = () => {
		const now = Date.now()
		if (this.stopTime - now <= 0) {
			this.setState(() => ({ time: 0 }))
			clearInterval(this.timer)
		} else {
			const time = Math.floor((this.stopTime - now) / 100)
			this.setState(() => ({ time }))
		}
	}

	render() {
		const { time } = this.state
		const seconds = Math.floor(time / 10)
		return <span>{seconds}</span>
	}
}

export default Timer