interface Props {
    value: number;
    onChange: (value: number) => void;
    widthPx?: number;
    inline?: boolean;
    disabled?: boolean;
}

interface State {
    valueAsString: string;
}

export class InputNumber extends React.Component<Props, State> {
    constructor(props: Props) {
        super(props);
        this.state = { valueAsString: isEmpty(props.value) ? '' : props.value.toString() };
    }

    handleChange = (e: React.ChangeEvent<HTMLInputElement>) => {
        const valueAsString = e.target.value;
        const valueAsNumber = toFloat(valueAsString);
        this.setState({ valueAsString: valueAsString }, () => {
            this.props.onChange(valueAsNumber);
        });

    }
    componentWillReceiveProps(nextProps: Props) {
        if (nextProps.value !== toFloat(this.state.valueAsString)) {
            this.setState({ valueAsString: isEmpty(nextProps.value) ? '' : nextProps.value.toString() });
        }
    }
    render() {
        const { widthPx, inline, disabled } = this.props;
        const style: React.CSSProperties = { width: widthPx || '100%', display: inline ? 'inline-block' : 'block' };
        return (<div style={style}>
            <input type="text" value={this.state.valueAsString} onChange={this.handleChange} style={style} disabled={disabled} />
        </div>);
    }
}

function isEmpty(val: number): boolean {
    const t = typeof val;
    return t === 'undefined' || val === null || (t === 'number' && isNaN(val));
}

function toFloat(s: string) {
    return parseFloat(s.replace(/,/g, ''));
}