import { Router, type IRouter } from "express";
import { eq, sql } from "drizzle-orm";
import bcrypt from "bcryptjs";
import { db, usersTable } from "@workspace/db";
import { requireAdmin } from "../middleware/auth";
import { writeAuditLog } from "../lib/audit";
import { passwordRateLimit } from "../lib/rate-limit";
import { z } from "zod";

const router: IRouter = Router();

const Tier = z.enum(["free", "premium", "enterprise"]);

const UserCreateSchema = z.object({
  username: z.string().min(2),
  password: z.string().min(6),
  email: z.string().optional(),
  role: z.enum(["admin", "user"]).optional().default("user"),
  tier: Tier.optional().default("free"),
});

const UserUpdateSchema = z.object({
  role: z.enum(["admin", "user"]).optional(),
  tier: Tier.optional(),
});

const SetPasswordSchema = z.object({
  password: z.string().min(6),
});

router.patch("/users/:id/password", requireAdmin, passwordRateLimit, async (req, res): Promise<void> => {
  const id = parseInt(String(req.params.id), 10);
  if (isNaN(id)) {
    res.status(400).json({ error: "Invalid user id" });
    return;
  }

  const parsed = SetPasswordSchema.safeParse(req.body);
  if (!parsed.success) {
    res.status(400).json({ error: parsed.error.message });
    return;
  }

  const [target] = await db
    .select({ id: usersTable.id, authProvider: usersTable.authProvider, username: usersTable.username })
    .from(usersTable)
    .where(eq(usersTable.id, id))
    .limit(1);

  if (!target) {
    res.status(404).json({ error: "User not found" });
    return;
  }

  if (target.authProvider !== "local") {
    res.status(422).json({ error: "oidc" });
    return;
  }

  const passwordHash = await bcrypt.hash(parsed.data.password, 12);
  await db.update(usersTable).set({ passwordHash }).where(eq(usersTable.id, id));

  await writeAuditLog(req, "user", id, "set_password", { username: target.username });
  res.sendStatus(204);
});

router.get("/users", requireAdmin, async (req, res): Promise<void> => {
  const users = await db
    .select({
      id: usersTable.id,
      username: usersTable.username,
      email: usersTable.email,
      role: usersTable.role,
      tier: usersTable.tier,
      authProvider: usersTable.authProvider,
      createdAt: usersTable.createdAt,
    })
    .from(usersTable)
    .orderBy(usersTable.createdAt);
  res.json(users);
});

router.post("/users", requireAdmin, async (req, res): Promise<void> => {
  const parsed = UserCreateSchema.safeParse(req.body);
  if (!parsed.success) {
    res.status(400).json({ error: parsed.error.message });
    return;
  }

  const existing = await db
    .select({ id: usersTable.id })
    .from(usersTable)
    .where(eq(usersTable.username, parsed.data.username))
    .limit(1);

  if (existing.length > 0) {
    res.status(409).json({ error: "Username already exists" });
    return;
  }

  const passwordHash = await bcrypt.hash(parsed.data.password, 12);
  const [user] = await db
    .insert(usersTable)
    .values({
      username: parsed.data.username,
      passwordHash,
      email: parsed.data.email ?? null,
      role: parsed.data.role ?? "user",
      tier: parsed.data.tier ?? "free",
    })
    .returning({
      id: usersTable.id,
      username: usersTable.username,
      email: usersTable.email,
      role: usersTable.role,
      tier: usersTable.tier,
      createdAt: usersTable.createdAt,
    });

  await writeAuditLog(req, "user", user.id, "create", { username: user.username, role: user.role, tier: user.tier });
  res.status(201).json(user);
});

router.patch("/users/:id", requireAdmin, async (req, res): Promise<void> => {
  const id = parseInt(String(req.params.id), 10);
  if (isNaN(id)) {
    res.status(400).json({ error: "Invalid user id" });
    return;
  }

  const parsed = UserUpdateSchema.safeParse(req.body);
  if (!parsed.success) {
    res.status(400).json({ error: parsed.error.message });
    return;
  }

  const [target] = await db
    .select({ id: usersTable.id, role: usersTable.role })
    .from(usersTable)
    .where(eq(usersTable.id, id))
    .limit(1);

  if (!target) {
    res.status(404).json({ error: "User not found" });
    return;
  }

  if (target.role === "admin" && parsed.data.role === "user") {
    if (req.session.user?.sub === String(id)) {
      res.status(400).json({ error: "Cannot demote your own account" });
      return;
    }
    const [{ count }] = await db
      .select({ count: sql<number>`count(*)::int` })
      .from(usersTable)
      .where(eq(usersTable.role, "admin"));
    if (count <= 1) {
      res.status(400).json({ error: "Cannot demote the last admin" });
      return;
    }
  }

  const updateData: Record<string, unknown> = {};
  if (parsed.data.role !== undefined) updateData.role = parsed.data.role;
  if (parsed.data.tier !== undefined) updateData.tier = parsed.data.tier;

  const [user] = await db
    .update(usersTable)
    .set(updateData)
    .where(eq(usersTable.id, id))
    .returning({
      id: usersTable.id,
      username: usersTable.username,
      email: usersTable.email,
      role: usersTable.role,
      tier: usersTable.tier,
      createdAt: usersTable.createdAt,
    });

  await writeAuditLog(req, "user", id, "update", updateData);
  res.json(user);
});

router.delete("/users/:id", requireAdmin, async (req, res): Promise<void> => {
  const id = parseInt(String(req.params.id), 10);
  if (isNaN(id)) {
    res.status(400).json({ error: "Invalid user id" });
    return;
  }

  if (req.session.user?.sub === String(id)) {
    res.status(400).json({ error: "Cannot delete your own account" });
    return;
  }

  const [user] = await db.delete(usersTable).where(eq(usersTable.id, id)).returning();
  if (!user) {
    res.status(404).json({ error: "User not found" });
    return;
  }

  await writeAuditLog(req, "user", id, "delete", { username: user.username });
  res.sendStatus(204);
});

export default router;