import express, { type Express } from "express";
import { existsSync } from "node:fs";
import { resolve } from "node:path";
import pinoHttp from "pino-http";
import session from "express-session";
import ConnectPgSimple from "connect-pg-simple";
import router from "./routes";
import { logger } from "./lib/logger";
import "./types/session.d.ts";

const PgStore = ConnectPgSimple(session);

const isProd = process.env.NODE_ENV === "production";

if (isProd && !process.env.SESSION_SECRET) {
  throw new Error("SESSION_SECRET must be set in production");
}
if (isProd && !process.env.VOTER_SECRET) {
  throw new Error("VOTER_SECRET must be set in production");
}

const app: Express = express();

app.set("trust proxy", 1);

app.use(
  pinoHttp({
    logger,
    serializers: {
      req(req) {
        return {
          id: req.id,
          method: req.method,
          url: req.url?.split("?")[0],
        };
      },
      res(res) {
        return {
          statusCode: res.statusCode,
        };
      },
    },
  }),
);

const allowedOrigins = (process.env.CORS_ORIGIN ?? "")
  .split(",")
  .map((s) => s.trim())
  .filter(Boolean);

app.use((req, res, next) => {
  const origin = req.headers.origin;
  const host = req.headers.host;
  let sameOrigin = false;
  if (origin && host) {
    try {
      sameOrigin = new URL(origin).host === host;
    } catch {
      sameOrigin = false;
    }
  }
  const allow = !origin || sameOrigin || allowedOrigins.includes(origin);
  if (allow) {
    if (origin) res.setHeader("Access-Control-Allow-Origin", origin);
    res.setHeader("Vary", "Origin");
    res.setHeader("Access-Control-Allow-Credentials", "true");
    res.setHeader("Access-Control-Allow-Methods", "GET,HEAD,PUT,PATCH,POST,DELETE");
    res.setHeader("Access-Control-Allow-Headers", "Content-Type, Authorization");
    if (req.method === "OPTIONS") {
      res.sendStatus(204);
      return;
    }
  }
  next();
});
app.use(express.json());
app.use(express.urlencoded({ extended: true }));

app.use(
  session({
    store: new PgStore({
      conString: process.env.DATABASE_URL,
      tableName: "sessions",
      createTableIfMissing: true,
    }),
    secret: process.env.SESSION_SECRET || "dev-secret-change-in-production",
    resave: false,
    saveUninitialized: false,
    cookie: {
      secure: isProd,
      httpOnly: true,
      maxAge: 1000 * 60 * 60 * 24 * 7, // 7 days
      sameSite: "lax",
    },
  }),
);

app.use("/api", router);

// Any unmatched /api route should return a JSON 404 instead of falling
// through to the SPA catch-all below.
app.use("/api", (_req, res) => {
  res.status(404).json({ error: "Not found" });
});

// Central JSON error handler (Express 5 forwards rejected async handlers here).
app.use((err: unknown, _req: express.Request, res: express.Response, _next: express.NextFunction) => {
  const statusCode = (err as { status?: unknown })?.status ?? (err as { statusCode?: unknown })?.statusCode;
  const status = typeof statusCode === "number" && statusCode >= 400 && statusCode < 600 ? statusCode : 500;
  if (isProd) {
    logger.error({ err: (err as Error)?.message }, "Unhandled error");
  } else {
    logger.error({ err }, "Unhandled error");
  }
  res.status(status).json({ error: isProd ? "Internal server error" : (err as Error)?.message ?? "Internal server error" });
});

const staticDir = process.env.STATIC_DIR;
if (staticDir && existsSync(staticDir)) {
  app.use(express.static(staticDir));
  app.get("/*any", (_req, res) => {
    res.sendFile(resolve(staticDir, "index.html"));
  });
  logger.info({ staticDir }, "Serving static files");
}

export default app;