import { resolve, join, relative } from "node:path";
import { promises as fsp } from "node:fs";
import { decodePath, withLeadingSlash, withoutTrailingSlash, parseURL } from "ufo";
import mime from "mime";
import { STATIC_DIR, STATIC_PUBLIC_PREFIX } from "../constants/upload";

if (import.meta.dev) {
    console.log("plugin: 00.static");
}

const METHODS = new Set(["HEAD", "GET"]);
const SAFE_BASE_DIR = resolve(STATIC_DIR);

const CACHE_CONTROL = "public, max-age=31536000, immutable";

export default defineNitroPlugin((nitroApp) => {
    nitroApp.hooks.hook("request", async (event) => {
        if (!event.path.startsWith(STATIC_PUBLIC_PREFIX)) return;

        const { req } = event.node;
        const method = req.method;

        if (method && !METHODS.has(method)) return;

        try {
            const url = event.path.replace(STATIC_PUBLIC_PREFIX, "");
            const pathname = decodePath(
                withLeadingSlash(withoutTrailingSlash(parseURL(url).pathname))
            );

            const targetPath = join(SAFE_BASE_DIR, pathname);
            const resolvedPath = resolve(targetPath);

            // 安全校验
            const rel = relative(SAFE_BASE_DIR, resolvedPath);
            if (rel.startsWith("..") || rel === "..") {
                event.respondWith(new Response("Forbidden", { status: 403 }));
                return;
            }

            const stat = await fsp.stat(resolvedPath);
            if (!stat.isFile()) {
                event.respondWith(new Response("Not Found", { status: 404 }));
                return;
            }

            const mtime = stat.mtime.toUTCString();
            const etag = `"${stat.mtime.getTime().toString(16)}-${stat.size.toString(16)}"`;
            const contentType = mime.getType(resolvedPath) || "application/octet-stream";

            const headers: Record<string, string> = {
                "Cache-Control": CACHE_CONTROL,
                ETag: etag,
                "Last-Modified": mtime,
                Connection: "close",
            };

            // 304 协商缓存
            const ifNoneMatch = req.headers["if-none-match"];
            const ifModifiedSince = req.headers["if-modified-since"];
            if (ifNoneMatch === etag || (ifModifiedSince && ifModifiedSince === mtime)) {
                event.respondWith(new Response(null, { status: 304, headers }));
                return;
            }

            headers["Content-Type"] = contentType;
            headers["Content-Length"] = String(stat.size);

            const body = method === "HEAD" ? null : await fsp.readFile(resolvedPath);

            event.respondWith(new Response(body, { status: 200, headers }));
        } catch (err: any) {
            if (err.code === "ENOENT") {
                event.respondWith(new Response("Not Found", { status: 404 }));
                return;
            }
            event.respondWith(new Response("Server Error", { status: 500 }));
        }
    });
});