import { onBeforeUnmount, ref, type Ref } from 'vue';
import type { LngLat } from 'vue-tianditu2';
import { toStamp } from '../hooks/use-map';

export type TrackPoint = { longitude: number; latitude: number; time?: any; speed?: number };

export function useTrackPlayback(points: Ref<TrackPoint[]>) {
	const playing = ref(false);
	const speed = ref(5);
	const progress = ref(0);
	const playPos = ref<LngLat | null>(null);
	let raf = 0;
	let startedAt = 0;
	let elapsed = 0;

	function path(): LngLat[] {
		return points.value
			.filter(p => Number(p.longitude) && Number(p.latitude))
			.map(p => [Number(p.longitude), Number(p.latitude)] as LngLat);
	}

	function duration() {
		const list = points.value;
		if (list.length < 2) return 8000;
		const t0 = toStamp(list[0].time);
		const t1 = toStamp(list[list.length - 1].time);
		const real = t1 > t0 ? t1 - t0 : list.length * 2000;
		return Math.max(real, 4000);
	}

	function at(ratio: number): LngLat | null {
		const list = path();
		if (!list.length) return null;
		if (list.length === 1) return list[0];
		const times = points.value.map((p, i) => toStamp(p.time) || i * 1000);
		const t0 = times[0];
		const t1 = times[times.length - 1];
		const span = Math.max(t1 - t0, 1);
		const target = t0 + span * ratio;
		let i = 0;
		while (i < times.length - 1 && times[i + 1] < target) i += 1;
		const a = list[i];
		const b = list[Math.min(i + 1, list.length - 1)];
		const seg = Math.max(times[Math.min(i + 1, times.length - 1)] - times[i], 1);
		const k = Math.min(Math.max((target - times[i]) / seg, 0), 1);
		return [a[0] + (b[0] - a[0]) * k, a[1] + (b[1] - a[1]) * k];
	}

	function tick(now: number) {
		if (!playing.value) return;
		const total = duration() / Math.max(speed.value, 1);
		elapsed += now - startedAt;
		startedAt = now;
		const ratio = Math.min(elapsed / total, 1);
		progress.value = Math.round(ratio * 100);
		playPos.value = at(ratio);
		if (ratio >= 1) {
			playing.value = false;
			return;
		}
		raf = requestAnimationFrame(tick);
	}

	function play() {
		if (!points.value.length) return;
		if (progress.value >= 100) {
			progress.value = 0;
			elapsed = 0;
		}
		playing.value = true;
		startedAt = performance.now();
		raf = requestAnimationFrame(tick);
	}

	function pause() {
		playing.value = false;
		cancelAnimationFrame(raf);
	}

	function stop() {
		pause();
		elapsed = 0;
		progress.value = 0;
		playPos.value = points.value.length
			? [Number(points.value[0].longitude), Number(points.value[0].latitude)]
			: null;
	}

	function reset() {
		stop();
		playPos.value = null;
	}

	onBeforeUnmount(pause);

	return { playing, speed, progress, playPos, path, play, pause, stop, reset };
}