/**
 * External dependencies
 */
import { toDate } from 'date-fns';

/**
 * Internal dependencies
 */
import type { InputState } from '../input-control/reducer/state';
import type { InputAction } from '../input-control/reducer/actions';
import { COMMIT, PRESS_DOWN, PRESS_UP } from '../input-control/reducer/actions';

/**
 * Like date-fn's toDate, but tries to guess the format when a string is
 * given.
 *
 * @param input Value to turn into a date.
 */
export function inputToDate( input: Date | string | number ): Date {
	if ( typeof input === 'string' ) {
		return new Date( input );
	}
	return toDate( input );
}

/**
 * Converts a 12-hour time to a 24-hour time.
 * @param hours
 * @param isPm
 */
export function from12hTo24h( hours: number, isPm: boolean ) {
	return isPm ? ( ( hours % 12 ) + 12 ) % 24 : hours % 12;
}

/**
 * Converts a 24-hour time to a 12-hour time.
 * @param hours
 */
export function from24hTo12h( hours: number ) {
	return hours % 12 || 12;
}

/**
 * Creates an InputControl reducer used to pad an input so that it is always a
 * given width. For example, the hours and minutes inputs are padded to 2 so
 * that '4' appears as '04'.
 *
 * @param pad How many digits the value should be.
 */
export function buildPadInputStateReducer( pad: number ) {
	return ( state: InputState, action: InputAction ) => {
		const nextState = { ...state };
		if (
			action.type === COMMIT ||
			action.type === PRESS_UP ||
			action.type === PRESS_DOWN
		) {
			if ( nextState.value !== undefined ) {
				nextState.value = nextState.value
					.toString()
					.padStart( pad, '0' );
			}
		}
		return nextState;
	};
}

/**
 * Validates the target of a React event to ensure it is an input element and
 * that the input is valid.
 * @param event
 */
export function validateInputElementTarget( event: React.SyntheticEvent ) {
	// `instanceof` checks need to get the instance definition from the
	// corresponding window object — therefore, the following logic makes
	// the component work correctly even when rendered inside an iframe.
	const HTMLInputElementInstance =
		( event.target as HTMLInputElement )?.ownerDocument.defaultView
			?.HTMLInputElement ?? HTMLInputElement;

	if ( ! ( event.target instanceof HTMLInputElementInstance ) ) {
		return false;
	}

	return event.target.validity.valid;
}