"use client";

import {
	ArrowRightDoubleIcon,
	MagicWand05Icon,
} from "@hugeicons/core-free-icons";
import { HugeiconsIcon } from "@hugeicons/react";
import { PanelView } from "./base-panel";
import { Button } from "@/components/ui/button";
import { useEditor } from "@/editor/use-editor";
import { useElementSelection } from "@/timeline/hooks/element/use-element-selection";
import { isVisualElement } from "@/timeline/element-utils";
import type { TimelineElement, TimelineTrack } from "@/timeline";
import {
	type TransitionKind,
	withVisualTransitionParams,
} from "@/rendering/transition";

const transitions: Array<{
	kind: TransitionKind;
	name: string;
	description: string;
	inDuration: number;
	outDuration: number;
}> = [
	{
		kind: "fade",
		name: "Soft fade",
		description: "Clean dissolve for slides and stills.",
		inDuration: 0.35,
		outDuration: 0,
	},
	{
		kind: "push-left",
		name: "Slide left",
		description: "Deck-like horizontal slide motion.",
		inDuration: 0.45,
		outDuration: 0,
	},
	{
		kind: "push-right",
		name: "Slide right",
		description: "Reverse horizontal slide motion.",
		inDuration: 0.45,
		outDuration: 0,
	},
	{
		kind: "zoom",
		name: "Zoom in",
		description: "Subtle punch-in with a fade edge.",
		inDuration: 0.4,
		outDuration: 0,
	},
	{
		kind: "zoom-out",
		name: "Zoom out",
		description: "Settle inward from a wider opening.",
		inDuration: 0.4,
		outDuration: 0,
	},
	{
		kind: "spin",
		name: "Spin dissolve",
		description: "A restrained turn with a soft fade.",
		inDuration: 0.45,
		outDuration: 0,
	},
];

export function TransitionsView() {
	const editor = useEditor();
	const { selectedElements } = useElementSelection();
	const scene = useEditor((currentEditor) =>
		currentEditor.scenes.getActiveSceneOrNull(),
	);
	const currentTime = useEditor((currentEditor) =>
		currentEditor.playback.getCurrentTime(),
	);
	const selectedVisualElements = editor.timeline
		.getElementsWithTracks({ elements: selectedElements })
		.filter(({ element }) => isVisualElement(element));
	const nearestTarget = scene
		? findNearestTransitionTarget({
				tracks: [scene.tracks.main, ...scene.tracks.overlay],
				currentTime,
			})
		: null;
	const targets =
		selectedVisualElements.length > 0
			? selectedVisualElements
			: nearestTarget
				? [nearestTarget]
				: [];
	const selectedCount = selectedVisualElements.length;

	const applyTransition = ({
		kind,
		inDuration,
		outDuration,
	}: {
		kind: TransitionKind;
		inDuration: number;
		outDuration: number;
	}) => {
		if (targets.length === 0) {
			return;
		}

		editor.timeline.updateElements({
			updates: targets.map(({ track, element }) => ({
				trackId: track.id,
				elementId: element.id,
				patch: {
					params: withVisualTransitionParams({
						params: element.params,
						transitionKind: kind,
						inDuration,
						outDuration,
					}),
				},
			})),
		});
	};

	return (
		<PanelView title="Transitions" contentClassName="flex flex-col gap-3 pb-3">
			<div className="rounded-md border bg-accent/20 p-3">
				<div className="flex items-center gap-2 text-sm font-medium">
					<HugeiconsIcon icon={MagicWand05Icon} className="size-4" />
					Apply at the cut
				</div>
				<p className="text-muted-foreground mt-1 text-xs leading-relaxed">
					{selectedCount > 0
						? `${selectedCount} selected clip${selectedCount === 1 ? "" : "s"}.`
						: nearestTarget
							? `Ready for the cut into ${nearestTarget.element.name}.`
							: "Add at least two image or video clips to one track."}
				</p>
			</div>

			<div className="grid grid-cols-1 gap-2">
				{transitions.map((transition) => (
					<TransitionCard
						key={transition.kind}
						transition={transition}
						disabled={targets.length === 0}
						onApply={applyTransition}
					/>
				))}
			</div>
		</PanelView>
	);
}

function findNearestTransitionTarget({
	tracks,
	currentTime,
}: {
	tracks: TimelineTrack[];
	currentTime: number;
}): { track: TimelineTrack; element: TimelineElement } | null {
	let nearest: { track: TimelineTrack; element: TimelineElement } | null = null;
	let nearestDistance = Number.POSITIVE_INFINITY;
	for (const track of tracks) {
		const elements = track.elements
			.filter((element) => element.type === "video" || element.type === "image")
			.slice()
			.sort((left, right) => left.startTime - right.startTime);
		for (let index = 1; index < elements.length; index += 1) {
			const element = elements[index];
			const distance = Math.abs(element.startTime - currentTime);
			if (distance < nearestDistance) {
				nearest = { track, element };
				nearestDistance = distance;
			}
		}
	}
	return nearest;
}

function TransitionCard({
	transition,
	disabled,
	onApply,
}: {
	transition: (typeof transitions)[number];
	disabled: boolean;
	onApply: (transition: (typeof transitions)[number]) => void;
}) {
	const editor = useEditor();
	return (
		<Button
			variant="outline"
			className="group h-auto justify-start overflow-hidden p-0 text-left"
			draggable
			aria-disabled={disabled}
			onClick={() => onApply(transition)}
			onDragStart={(event) =>
				editor.timeline.dragSource.begin({
					dataTransfer: event.dataTransfer,
					dragData: {
						type: "transition",
						id: transition.kind,
						name: transition.name,
						transitionKind: transition.kind,
						inDuration: transition.inDuration,
						outDuration: transition.outDuration,
					},
				})
			}
			onDragEnd={() => editor.timeline.dragSource.end()}
		>
			<div className="flex w-full items-center gap-3 p-2">
				<TransitionPreview kind={transition.kind} />
				<div className="min-w-0 flex-1">
					<div className="text-sm font-medium">{transition.name}</div>
					<div className="text-muted-foreground text-xs leading-snug">
						{transition.description}
					</div>
				</div>
			</div>
		</Button>
	);
}

function TransitionPreview({ kind }: { kind: TransitionKind }) {
	return (
		<div className="relative h-14 w-20 shrink-0 overflow-hidden rounded-sm border bg-background">
			<div className="absolute inset-0 bg-linear-to-br from-accent via-background to-primary/20" />
			<div className="absolute left-2 top-2 h-8 w-8 rounded-sm bg-foreground/80 shadow-sm" />
			<div className="absolute bottom-2 right-2 h-8 w-8 rounded-sm bg-primary/80 shadow-sm" />
			{kind === "fade" && (
				<div className="absolute inset-0 bg-linear-to-r from-transparent via-background/20 to-background/70" />
			)}
			{kind === "push-left" && (
				<HugeiconsIcon
					icon={ArrowRightDoubleIcon}
					className="absolute left-1/2 top-1/2 size-5 -translate-x-1/2 -translate-y-1/2 text-background drop-shadow"
				/>
			)}
			{kind === "push-right" && (
				<HugeiconsIcon
					icon={ArrowRightDoubleIcon}
					className="absolute left-1/2 top-1/2 size-5 -translate-x-1/2 -translate-y-1/2 rotate-180 text-background drop-shadow"
				/>
			)}
			{kind === "zoom" && (
				<div className="absolute left-1/2 top-1/2 size-10 -translate-x-1/2 -translate-y-1/2 rounded-full border border-primary/80 shadow-[0_0_24px_var(--primary)]" />
			)}
			{kind === "zoom-out" && (
				<div className="absolute left-1/2 top-1/2 size-7 -translate-x-1/2 -translate-y-1/2 rounded-full border border-primary/80 shadow-[0_0_18px_var(--primary)]" />
			)}
			{kind === "spin" && (
				<div className="absolute left-1/2 top-1/2 size-9 -translate-x-1/2 -translate-y-1/2 rotate-12 rounded-sm border border-primary/80 shadow-[0_0_18px_var(--primary)]" />
			)}
		</div>
	);
}