import { type NextRequest, NextResponse } from "next/server";
import sharp from "sharp";
import { fetchAvatarImage, parseAvatarQuery } from "@/lib/imager-upstream";

type AvatarFormat = "png" | "webp" | "avif";

function resolveFormat(raw: string | null): AvatarFormat {
	switch (raw?.toLowerCase()) {
		case "webp":
			return "webp";
		case "avif":
			return "avif";
		default:
			return "png";
	}
}

export async function GET(request: NextRequest) {
	const { searchParams } = new URL(request.url);

	const parsed = parseAvatarQuery(searchParams);
	if (!parsed.ok) {
		return NextResponse.json({ error: parsed.message }, { status: 400 });
	}

	const format = resolveFormat(searchParams.get("format"));

	try {
		const { body, contentType, source } = await fetchAvatarImage(
			new URL(request.url).origin,
			parsed.params,
		);

		// Re-encode PNG avatars to WebP/AVIF with sharp to cut bandwidth.
		// Falls back to the original PNG if conversion fails.
		let respBody: Uint8Array = body;
		let respContentType = contentType;
		if (format !== "png") {
			try {
				if (format === "webp") {
					respBody = new Uint8Array(
						await sharp(Buffer.from(body)).webp().toBuffer(),
					);
					respContentType = "image/webp";
				} else {
					respBody = new Uint8Array(
						await sharp(Buffer.from(body)).avif().toBuffer(),
					);
					respContentType = "image/avif";
				}
			} catch {
				respBody = body;
				respContentType = contentType;
			}
		}

		return new NextResponse(respBody as unknown as BodyInit, {
			status: 200,
			headers: {
				"Content-Type": respContentType,
				"Content-Length": String(respBody.length),
				// s-maxage lets Cloudflare/edge cache avatars (currently DYNAMIC),
				// stale-while-revalidate keeps them fresh without blocking requests.
				// The ?format= param is part of the URL, so variants cache separately.
				// Fallback renders use a shorter TTL so the configured imager is
				// retried soon instead of being masked for hours.
				"Cache-Control":
					source === "fallback"
						? "public, max-age=300, s-maxage=3600, stale-while-revalidate=3600"
						: "public, max-age=3600, s-maxage=86400, stale-while-revalidate=86400",
				"X-Imager-Source": source,
				"Access-Control-Allow-Origin": "*",
			},
		});
	} catch {
		return NextResponse.json(
			{ error: "Failed to fetch avatar from upstream" },
			{ status: 502 },
		);
	}
}

export async function OPTIONS() {
	return new NextResponse(null, {
		status: 204,
		headers: {
			"Access-Control-Allow-Origin": "*",
			"Access-Control-Allow-Methods": "GET, OPTIONS",
			"Access-Control-Allow-Headers": "Content-Type, If-None-Match",
		},
	});
}