/**
 * MIT License
 *
 * Copyright (c) 2025 Chris M. Perez
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

import { signal } from '../../reactivity/signal.js';
import { watchEffect } from '../../effects/effect.js';
import type { Signal } from '../../types/index.js';
import type {
	EmitContextData,
	EmitOptions,
	EventSignal,
	EventMap,
} from '../types/index.js';

export function useEventSignal<T extends EventMap, P>(
	ctx: EmitContextData<T>,
	event: string,
	options: EmitOptions = {}
): EventSignal<P> {
	let sourceSig = ctx.signals.get(event) as Signal<P | undefined> | undefined;
	if (!sourceSig) {
		sourceSig = signal<P | undefined>(undefined);
		ctx.signals.set(event, sourceSig as Signal<unknown>);
	}

	if (
		!options.debounce &&
		!options.throttle &&
		!options.once &&
		!options.filter
	) {
		const sig = sourceSig;
		return {
			get value() {
				return sig.value;
			},
		};
	}

	const resultSig = signal<P | undefined>(undefined);
	let lastUpdateTime = 0;
	let debounceTimer: ReturnType<typeof setTimeout> | null = null;
	let hasFired = false;
	const source = sourceSig;

	watchEffect(() => {
		const value = source.value;
		if (value === undefined) return;

		if (options.once && hasFired) return;

		if (options.filter && !options.filter(value)) return;

		const now = Date.now();

		if (typeof options.throttle === 'number') {
			if (now - lastUpdateTime < options.throttle) return;
			lastUpdateTime = now;
		}

		if (typeof options.debounce === 'number') {
			if (debounceTimer) clearTimeout(debounceTimer);
			debounceTimer = setTimeout(() => {
				resultSig.value = value;
				if (options.once) hasFired = true;
			}, options.debounce);
			return;
		}

		resultSig.value = value;
		if (options.once) hasFired = true;
	});

	return {
		get value() {
			return resultSig.value;
		},
	};
}

export function createEventSignal<P>(initialValue?: P): Signal<P | undefined> {
	return signal<P | undefined>(initialValue);
}