import { cropRgba, decodePng } from "@/lib/services/imager/png-decode";
import { encodePng, parseNitroBundle } from "@/lib/services/swf/nitro-builder";

interface FurniAsset {
	x?: number;
	y?: number;
	source?: string;
}
interface FurniFrame {
	frame: { x: number; y: number; w: number; h: number };
	rotated?: boolean;
}
interface FurniNitroJson {
	name?: string;
	assets?: Record<string, FurniAsset>;
	spritesheet?: { frames?: Record<string, FurniFrame> };
}

/**
 * Extract the furni catalog icon — the `{name}_icon_a` sprite — from a Nitro
 * bundle and return it as a standalone PNG, or null if the bundle has no icon
 * asset / usable frame. Used for sources that embed furni icons inside the
 * `.nitro` instead of serving a separate `{classname}_icon.png`.
 */
export function extractFurniIconPng(nitro: Buffer): Buffer | null {
	let json: FurniNitroJson;
	let png: Buffer;
	try {
		const parsed = parseNitroBundle(nitro);
		json = parsed.json as FurniNitroJson;
		png = parsed.png;
	} catch {
		return null;
	}
	const name = json.name;
	if (!name || !json.assets) return null;

	// The icon asset is conventionally `${name}_icon_a`; fall back to any
	// `${name}_icon*` the bundle exposes.
	const iconKey = json.assets[`${name}_icon_a`]
		? `${name}_icon_a`
		: Object.keys(json.assets).find((k) => k.startsWith(`${name}_icon`));
	if (!iconKey) return null;

	const asset = json.assets[iconKey];
	// An asset may alias another's pixels via `source`; the frame key is the
	// bundle name prefixed onto the asset name. Different converters pack the
	// key with or without a trailing `.png`, so try both.
	const pixelAsset = asset.source ?? iconKey;
	const frames = json.spritesheet?.frames ?? {};
	const frame =
		frames[`${name}_${pixelAsset}`] ?? frames[`${name}_${pixelAsset}.png`];
	if (!frame || frame.rotated) return null;
	const { x, y, w, h } = frame.frame;
	if (w <= 0 || h <= 0) return null;

	try {
		const sheet = decodePng(png);
		const px = cropRgba(sheet.rgba, sheet.width, x, y, w, h);
		return encodePng(w, h, px);
	} catch {
		return null;
	}
}