import express, { Request, Response, NextFunction } from "express";
import cors from "cors";
import { config } from "./config";
import healthRouter from "./routes/health";
import racesRouter from "./routes/races";

export function createApp(): express.Express {
  const app = express();

  // TEMP: compare Host vs Origin for 200 vs 401 debugging — remove when done
  app.use((req, res, next) => {
    const host = req.headers.host;
    const origin = req.headers.origin;
    res.on("finish", () => {
      console.log(
        JSON.stringify({
          tag: "temp-req-headers",
          host,
          origin: origin ?? null,
          method: req.method,
          path: req.originalUrl ?? req.url,
          status: res.statusCode,
        }),
      );
    });
    next();
  });

  app.use(
    cors({ origin: config.corsOrigin, methods: ["GET", "POST", "PATCH", "DELETE", "OPTIONS"] }),
  );
  app.use(express.json());

  app.use("/api", healthRouter);
  app.use("/api", racesRouter);

  app.use((err: unknown, _req: Request, res: Response, _next: NextFunction) => {
    if (err instanceof SyntaxError && "body" in err) {
      res.status(400).json({ error: "validation_error", details: ["Invalid JSON in request body"] });
      return;
    }
    console.error("[app] Unhandled error:", err);
    res.status(500).json({ error: "unknown_error", details: ["Internal server error"] });
  });

  return app;
}