import bcrypt from 'bcryptjs';
import type { NextFunction, Request, Response } from 'express';
import { Router } from 'express';
import { ok } from '../http/apiResponse.js';
import { ApiError } from '../http/errors.js';
import { query } from '../db/pool.js';

interface UserRow {
  id: string;
  username: string;
  password_hash: string;
  full_name: string;
  email: string | null;
  department: string | null;
  must_change_password: boolean;
  enabled: boolean;
  locked: boolean;
  roles: string[];
}

interface CurrentUser {
  id: number;
  username: string;
  fullName: string;
  department?: string;
  email?: string;
  roles: string[];
  mustChangePassword: boolean;
}

const router = Router();

function asyncRoute(
  handler: (req: Request, res: Response, next: NextFunction) => Promise<void>,
) {
  return (req: Request, res: Response, next: NextFunction) => {
    handler(req, res, next).catch(next);
  };
}

async function findUserByUsername(username: string): Promise<UserRow | undefined> {
  const result = await query<UserRow>(
    `
      SELECT
        u.id,
        u.username,
        u.password_hash,
        u.full_name,
        u.email,
        u.department,
        u.must_change_password,
        u.enabled,
        u.locked,
        COALESCE(array_agg(ur.role) FILTER (WHERE ur.role IS NOT NULL), '{}') AS roles
      FROM users u
      LEFT JOIN user_roles ur ON ur.user_id = u.id
      WHERE u.username = $1
      GROUP BY u.id
    `,
    [username],
  );
  return result.rows[0];
}

async function findUserById(id: number): Promise<UserRow | undefined> {
  const result = await query<UserRow>(
    `
      SELECT
        u.id,
        u.username,
        u.password_hash,
        u.full_name,
        u.email,
        u.department,
        u.must_change_password,
        u.enabled,
        u.locked,
        COALESCE(array_agg(ur.role) FILTER (WHERE ur.role IS NOT NULL), '{}') AS roles
      FROM users u
      LEFT JOIN user_roles ur ON ur.user_id = u.id
      WHERE u.id = $1
      GROUP BY u.id
    `,
    [id],
  );
  return result.rows[0];
}

function toCurrentUser(user: UserRow): CurrentUser {
  return {
    id: Number(user.id),
    username: user.username,
    fullName: user.full_name,
    department: user.department ?? undefined,
    email: user.email ?? undefined,
    roles: user.roles,
    mustChangePassword: user.must_change_password,
  };
}

async function requireCurrentUser(req: Request): Promise<UserRow> {
  const userId = req.session.userId;
  if (!userId) {
    throw new ApiError(401, '로그인이 필요합니다.');
  }

  const user = await findUserById(userId);
  if (!user || !user.enabled || user.locked) {
    req.session.userId = undefined;
    throw new ApiError(401, '로그인이 필요합니다.');
  }

  return user;
}

router.post('/login', asyncRoute(async (req, res) => {
  const username = String(req.body?.username ?? '').trim();
  const password = String(req.body?.password ?? '');

  if (!username || !password) {
    throw new ApiError(400, '아이디와 비밀번호를 입력하세요.');
  }

  const user = await findUserByUsername(username);
  const matches = user ? await bcrypt.compare(password, user.password_hash) : false;
  if (!user || !matches || !user.enabled || user.locked) {
    throw new ApiError(401, '아이디 또는 비밀번호가 올바르지 않습니다.');
  }

  req.session.userId = Number(user.id);
  ok(res, toCurrentUser(user));
}));

router.post('/logout', (req, res, next) => {
  req.session.destroy((error) => {
    if (error) {
      next(error);
      return;
    }
    res.clearCookie('connect.sid');
    ok(res, '로그아웃되었습니다.');
  });
});

router.get('/me', asyncRoute(async (req, res) => {
  const user = await requireCurrentUser(req);
  ok(res, toCurrentUser(user));
}));

router.post('/change-password', asyncRoute(async (req, res) => {
  const user = await requireCurrentUser(req);
  const oldPassword = String(req.body?.oldPassword ?? '');
  const newPassword = String(req.body?.newPassword ?? '');

  if (newPassword.length < 8) {
    throw new ApiError(400, '새 비밀번호는 8자 이상이어야 합니다.');
  }

  if (!(await bcrypt.compare(oldPassword, user.password_hash))) {
    throw new ApiError(400, '현재 비밀번호가 올바르지 않습니다.');
  }

  if (await bcrypt.compare(newPassword, user.password_hash)) {
    throw new ApiError(400, '기존 비밀번호와 다른 비밀번호를 입력하세요.');
  }

  const passwordHash = await bcrypt.hash(newPassword, 12);
  await query(
    `
      UPDATE users
      SET password_hash = $1,
          must_change_password = FALSE,
          updated_at = now()
      WHERE id = $2
    `,
    [passwordHash, Number(user.id)],
  );

  ok(res, '비밀번호가 변경되었습니다.');
}));

router.post('/diagnostics', asyncRoute(async (_req, res) => {
  const tableResult = await query<{
    users_table: string | null;
    user_roles_table: string | null;
    sessions_table: string | null;
  }>(
    `
      SELECT
        to_regclass('public.users')::text AS users_table,
        to_regclass('public.user_roles')::text AS user_roles_table,
        to_regclass('public.user_sessions')::text AS sessions_table
    `,
  );
  const tables = tableResult.rows[0];
  let users: Array<{
    username: string;
    enabled: boolean;
    locked: boolean;
    must_change_password: boolean;
    password_hash_length: number;
    roles: string[];
  }> = [];
  let userQueryError: string | undefined;

  if (tables?.users_table && tables.user_roles_table) {
    try {
      const userResult = await query<{
        username: string;
        enabled: boolean;
        locked: boolean;
        must_change_password: boolean;
        password_hash_length: number;
        roles: string[];
      }>(
        `
          SELECT
            u.username,
            u.enabled,
            u.locked,
            u.must_change_password,
            length(u.password_hash) AS password_hash_length,
            COALESCE(array_agg(ur.role) FILTER (WHERE ur.role IS NOT NULL), '{}') AS roles
          FROM users u
          LEFT JOIN user_roles ur ON ur.user_id = u.id
          WHERE u.username IN ('admin', 'security', 'host', 'a', 's', 'h')
          GROUP BY u.id
          ORDER BY u.username
        `,
      );
      users = userResult.rows;
    } catch (error) {
      userQueryError = error instanceof Error ? error.message : String(error);
    }
  }

  ok(res, {
    authApi: true,
    checkedAt: new Date().toISOString(),
    tables,
    users,
    userQueryError,
  });
}));

export const authRouter = router;