import { dbGlobal } from "drizzle-pkg/lib/db";
import { users as usersTable, captchaCodes } from "drizzle-pkg/lib/schema/auth";
import { eq, and, lt, sql } from "drizzle-orm";
import { compare, hash } from "bcryptjs";
import log4js from "logger";
import { signToken, type JwtPayload } from "#server/utils/jwt";
import { generateCaptchaCode, generateCaptchaToken, generateCaptchaSvg, captchaSvgToDataUri } from "#server/utils/captcha";

const logger = log4js.getLogger("AUTH");
const CAPTCHA_EXPIRY_MS = 5 * 60 * 1000;
const BCRYPT_ROUNDS = 12;

// ========== Captcha ==========

export async function createCaptcha() {
  const code = generateCaptchaCode();
  const token = generateCaptchaToken();
  const expiresAt = new Date(Date.now() + CAPTCHA_EXPIRY_MS);

  await dbGlobal.insert(captchaCodes).values({
    token,
    code,
    expiresAt,
  });

  const svg = generateCaptchaSvg(code);
  const dataUri = captchaSvgToDataUri(svg);

  return { token, image: dataUri };
}

async function verifyAndConsumeCaptcha(token: string, code: string): Promise<boolean> {
  const now = new Date();

  // Atomic: mark as used only if not already used and not expired, returning the code
  const [record] = await dbGlobal
    .update(captchaCodes)
    .set({ used: true })
    .where(
      and(
        eq(captchaCodes.token, token),
        eq(captchaCodes.used, false),
        sql`${captchaCodes.expiresAt} > ${now.getTime()}`,
      ),
    )
    .returning({ code: captchaCodes.code });

  if (!record) return false;

  return record.code.toUpperCase() === code.toUpperCase();
}

// ========== Register ==========

export async function registerUser(username: string, password: string, captchaToken: string, captchaCode: string) {
  const validCaptcha = await verifyAndConsumeCaptcha(captchaToken, captchaCode);
  if (!validCaptcha) {
    return { success: false, message: "验证码错误或已过期" };
  }

  if (!/^[a-zA-Z0-9_]{3,20}$/.test(username)) {
    return { success: false, message: "用户名需为3-20位字母、数字或下划线" };
  }

  if (password.length < 8) {
    return { success: false, message: "密码长度不能少于8位" };
  }

  const [existing] = await dbGlobal
    .select({ id: usersTable.id })
    .from(usersTable)
    .where(eq(usersTable.username, username));

  if (existing) {
    return { success: false, message: "用户名已被注册" };
  }

  const hashedPassword = await hash(password, BCRYPT_ROUNDS);

  const [newUser] = await dbGlobal
    .insert(usersTable)
    .values({
      username,
      password: hashedPassword,
    })
    .returning({ id: usersTable.id, username: usersTable.username, role: usersTable.role });

  const token = signToken({ userId: newUser.id, username: newUser.username });

  return { success: true, token, user: newUser };
}

// ========== Login ==========

export async function loginUser(username: string, password: string, captchaToken: string, captchaCode: string) {
  const validCaptcha = await verifyAndConsumeCaptcha(captchaToken, captchaCode);
  if (!validCaptcha) {
    return { success: false, message: "验证码错误或已过期" };
  }

  const [user] = await dbGlobal
    .select()
    .from(usersTable)
    .where(eq(usersTable.username, username));

  // Constant-time check: always run bcrypt compare even if user doesn't exist
  const dummyHash = "$2a$12$" + "0".repeat(53);
  const hashToCheck = user ? user.password : dummyHash;
  const validPassword = await compare(password, hashToCheck);

  if (!user || !validPassword) {
    return { success: false, message: "用户名或密码错误" };
  }

  const token = signToken({ userId: user.id, username: user.username });

  return {
    success: true,
    token,
    user: {
      id: user.id,
      username: user.username,
      email: user.email,
      nickname: user.nickname,
      avatar: user.avatar,
      role: user.role,
    },
  };
}

// ========== Get current user ==========

export async function getCurrentUser(payload: JwtPayload) {
  const [user] = await dbGlobal
    .select()
    .from(usersTable)
    .where(eq(usersTable.id, payload.userId));

  if (!user) return null;

  return {
    id: user.id,
    username: user.username,
    email: user.email,
    nickname: user.nickname,
    avatar: user.avatar,
    role: user.role,
    createdAt: user.createdAt,
  };
}

// ========== Cleanup expired captchas ==========

export async function cleanupExpiredCaptchas() {
  await dbGlobal
    .delete(captchaCodes)
    .where(lt(captchaCodes.expiresAt, new Date()));
}

export { getUsers } from "./legacy";