import "dotenv/config";
import express from "express";
import cors from "cors";
import helmet from "helmet";
import rateLimit from "express-rate-limit";
import { chatRouter } from "./routes/chat";
import { projectsRouter } from "./routes/projects";
import { projectChatRouter } from "./routes/projectChat";
import { documentsRouter } from "./routes/documents";
import { tabularRouter } from "./routes/tabular";
import { workflowsRouter } from "./routes/workflows";
import { userRouter } from "./routes/user";
import { downloadsRouter } from "./routes/downloads";

const app = express();
const PORT = process.env.PORT ?? 3001;
const isProduction = process.env.NODE_ENV === "production";

function envInt(name: string, fallback: number): number {
  const raw = process.env[name];
  if (!raw) return fallback;
  const parsed = Number.parseInt(raw, 10);
  return Number.isFinite(parsed) && parsed > 0 ? parsed : fallback;
}

function minutes(value: number): number {
  return value * 60 * 1000;
}

function hours(value: number): number {
  return minutes(value * 60);
}

function makeLimiter(options: {
  windowMs: number;
  max: number;
  message?: string;
}) {
  return rateLimit({
    windowMs: options.windowMs,
    max: options.max,
    standardHeaders: true,
    legacyHeaders: false,
    skip: (req) => req.method === "OPTIONS",
    message: {
      detail:
        options.message ?? "Too many requests. Please try again later.",
    },
  });
}

const generalLimiter = makeLimiter({
  windowMs: minutes(envInt("RATE_LIMIT_GENERAL_WINDOW_MINUTES", 15)),
  max: envInt("RATE_LIMIT_GENERAL_MAX", 300),
});

const chatLimiter = makeLimiter({
  windowMs: minutes(envInt("RATE_LIMIT_CHAT_WINDOW_MINUTES", 15)),
  max: envInt("RATE_LIMIT_CHAT_MAX", 30),
  message: "Too many chat requests. Please try again later.",
});

const chatCreateLimiter = makeLimiter({
  windowMs: minutes(envInt("RATE_LIMIT_CHAT_CREATE_WINDOW_MINUTES", 15)),
  max: envInt("RATE_LIMIT_CHAT_CREATE_MAX", 60),
});

const uploadLimiter = makeLimiter({
  windowMs: hours(envInt("RATE_LIMIT_UPLOAD_WINDOW_HOURS", 1)),
  max: envInt("RATE_LIMIT_UPLOAD_MAX", 50),
  message: "Too many upload requests. Please try again later.",
});

app.disable("x-powered-by");
app.set("trust proxy", envInt("TRUST_PROXY_HOPS", 1));

app.use(
  helmet({
    contentSecurityPolicy: false,
    crossOriginEmbedderPolicy: false,
    hsts: isProduction
      ? {
          maxAge: 15552000,
          includeSubDomains: true,
        }
      : false,
    referrerPolicy: { policy: "no-referrer" },
  }),
);

app.use(
  cors({
    origin: process.env.FRONTEND_URL ?? "http://localhost:3000",
    credentials: true,
  }),
);

app.use(generalLimiter);

app.use(express.json({ limit: "50mb" }));

app.post("/chat", chatLimiter);
app.post("/projects/:projectId/chat", chatLimiter);
app.post("/tabular-review/:reviewId/chat", chatLimiter);
app.post("/tabular-review/:reviewId/generate", chatLimiter);
app.post("/chat/create", chatCreateLimiter);
app.post("/chat/:chatId/generate-title", chatCreateLimiter);
app.post("/single-documents", uploadLimiter);
app.post("/single-documents/:documentId/versions", uploadLimiter);
app.post("/projects/:projectId/documents", uploadLimiter);

app.use("/chat", chatRouter);
app.use("/projects", projectsRouter);
app.use("/projects/:projectId/chat", projectChatRouter);
app.use("/single-documents", documentsRouter);
app.use("/tabular-review", tabularRouter);
app.use("/workflows", workflowsRouter);
app.use("/user", userRouter);
app.use("/users", userRouter);
app.use("/download", downloadsRouter);

app.get("/health", (_req, res) => res.json({ ok: true }));

app.listen(PORT, () => {
  console.log(`Mike backend running on port ${PORT}`);
});