import { fileURLToPath } from "node:url";
import Fastify from "fastify";
import cors from "@fastify/cors";
import cookie from "@fastify/cookie";
import websocket from "@fastify/websocket";
import { ZodError } from "zod";
import { config } from "./config.js";
import { openDb, ensureAdmin } from "./db.js";
import { hashPassword, registerAuthHook, registerAuthRoutes } from "./auth.js";
import { registerRoutes } from "./routes.js";
import { registerWs } from "./ws.js";

/** A Fastify error carrying a status code and a serializable payload. */
export interface HttpError extends Error {
  statusCode: number;
  payload: object;
}

declare module "fastify" {
  interface FastifyInstance {
    /** Create a throwable HTTP error: `throw app.httpErrors.create(404, { error: "not_found" })`. */
    httpErrors: { create(status: number, payload: object): HttpError };
  }
}

function makeHttpError(status: number, payload: object): HttpError {
  const e = new Error("http_error") as HttpError;
  e.statusCode = status;
  e.payload = payload;
  return e;
}

export async function buildApp() {
  const app = Fastify({ logger: true });
  await app.register(cors, { origin: true, credentials: true });
  await app.register(cookie);
  await app.register(websocket);

  const db = openDb();
  app.decorate("db", db);
  app.decorate("httpErrors", { create: makeHttpError });
  await ensureAdmin(db, hashPassword);

  // Serialize thrown errors into the API's `{ error: "code" }` shape.
  app.setErrorHandler((err, _req, reply) => {
    if (err instanceof ZodError) {
      return reply.code(400).send({ error: "invalid_input", issues: err.issues });
    }
    const status = (err as HttpError).statusCode ?? 500;
    const payload = (err as HttpError).payload ?? { error: "internal_error" };
    return reply.code(status).send(payload);
  });

  app.get("/api/health", async () => {
    let dbUp = false;
    try {
      dbUp = db.prepare("SELECT 1").get() != null;
    } catch {
      dbUp = false;
    }
    return { ok: dbUp, db: dbUp ? "up" : "down", version: config.version, uptime: process.uptime() };
  });

  registerAuthHook(app);
  registerAuthRoutes(app);
  registerRoutes(app);
  registerWs(app);

  return app;
}

export async function start() {
  const app = await buildApp();
  await app.listen({ port: config.port, host: "0.0.0.0" });
  return app;
}

// Auto-boot only when this file is the CLI entry point (pnpm dev / start),
// not when imported by tests (vitest) — otherwise start() would try to bind
// the port and tear the test process down.
const invokedDirectly =
  process.argv[1] !== undefined &&
  fileURLToPath(import.meta.url) === process.argv[1];

if (invokedDirectly) {
  start().catch((err) => {
    console.error("Failed to start server:", err);
    process.exit(1);
  });
}