import { Injectable, UnauthorizedException, BadRequestException, NotFoundException } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository, Not, MoreThan } from 'typeorm';
import { JwtService } from '@nestjs/jwt';
import { ConfigService } from '@nestjs/config';
import * as bcrypt from 'bcryptjs';
import { User } from '../entities/user.entity';
import { LoginDto, RegisterDto } from './dto/auth.dto';

// 内存中的登录失败计数器（按IP+用户名）
const loginAttempts = new Map<string, { count: number; lockedUntil?: Date }>();
const MAX_ATTEMPTS = 5;
const LOCK_MINUTES = 15;

@Injectable()
export class AuthService {
  constructor(
    @InjectRepository(User) private userRepo: Repository<User>,
    private jwtService: JwtService,
    private configService: ConfigService,
  ) {}

  async register(dto: RegisterDto) {
    const exists = await this.userRepo.findOne({ where: { username: dto.username } });
    if (exists) throw new UnauthorizedException('用户名已存在');
    const hash = await bcrypt.hash(dto.password, 10);
    const user = this.userRepo.create({
      username: dto.username,
      passwordHash: hash,
      name: dto.name,
      role: 'operator',
      allowedMenus: (dto as any).allowedMenus ? JSON.stringify((dto as any).allowedMenus) : null as any,
    });
    await this.userRepo.save(user);
    return { message: '注册成功' };
  }

  async login(dto: LoginDto, ip?: string) {
    const attemptKey = `${ip || 'unknown'}:${dto.username}`;
    const attempt = loginAttempts.get(attemptKey);

    // 检查是否在锁定期
    if (attempt?.lockedUntil && attempt.lockedUntil > new Date()) {
      const remaining = Math.ceil((attempt.lockedUntil.getTime() - Date.now()) / 60000);
      throw new UnauthorizedException(`账号已被临时锁定，请 ${remaining} 分钟后重试`);
    }

    const user = await this.userRepo.findOne({ where: { username: dto.username } });
    if (!user) {
      this.recordFailedAttempt(attemptKey);
      throw new UnauthorizedException('用户名或密码错误');
    }
    if (!user.isActive) throw new UnauthorizedException('账号已被禁用，请联系管理员');
    const valid = await bcrypt.compare(dto.password, user.passwordHash);
    if (!valid) {
      this.recordFailedAttempt(attemptKey);
      const att = loginAttempts.get(attemptKey);
      const remaining = MAX_ATTEMPTS - (att?.count || 0);
      if (remaining > 0) {
        throw new UnauthorizedException(`用户名或密码错误，还剩 ${remaining} 次尝试机会`);
      }
      throw new UnauthorizedException(`登录失败次数过多，账号已被锁定 ${LOCK_MINUTES} 分钟`);
    }

    // 登录成功，清除失败计数
    loginAttempts.delete(attemptKey);

    // 记录登录时间
    user.lastLoginAt = new Date();
    await this.userRepo.save(user);
    const payload = { sub: user.id, username: user.username, role: user.role };
    const allowedMenus = user.allowedMenus ? JSON.parse(user.allowedMenus) : null;
    return { access_token: this.jwtService.sign(payload), user: { id: user.id, username: user.username, name: user.name, role: user.role, allowedMenus } };
  }

  private recordFailedAttempt(key: string) {
    const attempt = loginAttempts.get(key) || { count: 0 };
    attempt.count++;
    if (attempt.count >= MAX_ATTEMPTS) {
      attempt.lockedUntil = new Date(Date.now() + LOCK_MINUTES * 60 * 1000);
    }
    loginAttempts.set(key, attempt);
  }

  async validateUser(payload: any) {
    return this.userRepo.findOne({ where: { id: payload.sub } });
  }

  async initAdmin() {
    const count = await this.userRepo.count();
    if (count === 0) {
      const adminPassword = this.configService.get('ADMIN_PASSWORD', 'admin123');
      const hash = await bcrypt.hash(adminPassword, 10);
      await this.userRepo.save(this.userRepo.create({ username: 'admin', passwordHash: hash, name: '管理员', role: 'admin' }));
      console.log(`已创建默认管理员: admin / ${adminPassword === 'admin123' ? 'admin123 (请尽快修改!)' : '******'}`);
    }
  }

  // ---- 用户管理 CRUD ----

  async findAllUsers() {
    const users = await this.userRepo.find({
      select: ['id', 'username', 'name', 'role', 'isActive', 'allowedMenus', 'lastLoginAt', 'createdAt', 'updatedAt'],
      order: { createdAt: 'DESC' },
    });
    return users.map(u => ({
      ...u,
      allowedMenus: u.allowedMenus ? JSON.parse(u.allowedMenus) : null,
    }));
  }

  async updateUser(id: number, data: { name?: string; role?: string; isActive?: boolean; username?: string; allowedMenus?: string[] }) {
    const user = await this.userRepo.findOne({ where: { id } });
    if (!user) throw new NotFoundException('用户不存在');
    if (user.username === 'admin' && data.role && data.role !== 'admin') {
      throw new BadRequestException('不能修改默认管理员的角色');
    }
    if (user.username === 'admin' && data.isActive === false) {
      throw new BadRequestException('不能禁用默认管理员');
    }
    if (data.username !== undefined && data.username !== user.username) {
      const exists = await this.userRepo.findOne({ where: { username: data.username } });
      if (exists) throw new BadRequestException('用户名已存在');
      user.username = data.username;
    }
    if (data.name !== undefined) user.name = data.name;
    if (data.role !== undefined) user.role = data.role;
    if (data.isActive !== undefined) user.isActive = data.isActive;
    if (data.allowedMenus !== undefined) user.allowedMenus = data.allowedMenus ? JSON.stringify(data.allowedMenus) : null as any;
    await this.userRepo.save(user);
    return { message: '更新成功' };
  }

  async resetPassword(id: number, newPassword: string) {
    const user = await this.userRepo.findOne({ where: { id } });
    if (!user) throw new NotFoundException('用户不存在');
    user.passwordHash = await bcrypt.hash(newPassword, 10);
    await this.userRepo.save(user);
    return { message: '密码已重置' };
  }

  async removeUser(id: number) {
    const user = await this.userRepo.findOne({ where: { id } });
    if (!user) throw new NotFoundException('用户不存在');
    if (user.username === 'admin') throw new BadRequestException('不能删除默认管理员');
    await this.userRepo.delete(id);
    return { message: '用户已删除' };
  }
}