// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

import { InAppMessage } from '../../../types';
import { InAppMessageConflictHandler, SetConflictHandlerInput } from '../types';

/**
 * The default conflict handler. Can be overridden by `setConflictHandler`.
 */
let conflictHandler: InAppMessageConflictHandler = (
	messages: InAppMessage[],
): InAppMessage => {
	// default behavior is to return the message closest to expiry
	// this function assumes that messages processed by providers already filters out expired messages
	const sorted = messages.sort((a, b) => {
		const endDateA = a.metadata?.endDate;
		const endDateB = b.metadata?.endDate;
		// if both message end dates are falsy or have the same date string, treat them as equal
		if (endDateA === endDateB) {
			return 0;
		}
		// if only message A has an end date, treat it as closer to expiry
		if (endDateA && !endDateB) {
			return -1;
		}
		// if only message B has an end date, treat it as closer to expiry
		if (!endDateA && endDateB) {
			return 1;
		}

		// otherwise, compare them
		return new Date(endDateA) < new Date(endDateB) ? -1 : 1;
	});

	// always return the top sorted
	return sorted[0];
};

/**
 * Sets conflict handler.
 *
 * @internal
 */
export const setConflictHandler = (input: SetConflictHandlerInput): void => {
	conflictHandler = input;
};

/**
 * Returns the current conflict handler.
 *
 * @internal
 */
export const getConflictHandler = (): InAppMessageConflictHandler =>
	conflictHandler;