import { Injectable, UnauthorizedException, HttpException, HttpStatus } from '@nestjs/common';
import { JwtService } from '@nestjs/jwt';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import * as bcrypt from 'bcrypt';
import { Usuario } from '../usuario/entities/usuario.entity.js';
import { LoginDto } from './dto/login.dto.js';

interface LoginAttempt {
  count: number;
  blockedUntil: Date | null;
}

@Injectable()
export class AuthService {
  private loginAttempts = new Map<string, LoginAttempt>();
  private readonly MAX_ATTEMPTS = 5;
  private readonly BLOCK_DURATION_MS = 60 * 60 * 1000; // 1 hora

  constructor(
    @InjectRepository(Usuario)
    private usuarioRepo: Repository<Usuario>,
    private jwtService: JwtService,
  ) {}

  async login(dto: LoginDto) {
    const attempts = this.loginAttempts.get(dto.usuario);

    if (attempts?.blockedUntil && attempts.blockedUntil > new Date()) {
      const remainingMs = attempts.blockedUntil.getTime() - Date.now();
      const remainingMin = Math.ceil(remainingMs / 60000);
      throw new HttpException(
        `Cuenta bloqueada. Intenta de nuevo en ${remainingMin} minuto(s).`,
        HttpStatus.TOO_MANY_REQUESTS,
      );
    }

    const usuario = await this.usuarioRepo.findOne({
      where: { usuario: dto.usuario },
    });

    if (!usuario) {
      this.trackFailedAttempt(dto.usuario);
      throw new UnauthorizedException('Credenciales inválidas');
    }

    const passwordValid = await bcrypt.compare(dto.password, usuario.password);
    if (!passwordValid) {
      this.trackFailedAttempt(dto.usuario);
      throw new UnauthorizedException('Credenciales inválidas');
    }

    this.loginAttempts.delete(dto.usuario);

    const payload = {
      sub: usuario.idUsuario,
      usuario: usuario.usuario,
      rol: usuario.rol,
    };

    return {
      token: this.jwtService.sign(payload),
      usuario: {
        idUsuario: usuario.idUsuario,
        nombre: usuario.nombre,
        usuario: usuario.usuario,
        rol: usuario.rol,
      },
    };
  }

  private trackFailedAttempt(username: string) {
    const current = this.loginAttempts.get(username);

    if (!current) {
      this.loginAttempts.set(username, {
        count: 1,
        blockedUntil: null,
      });
      return;
    }

    const newCount = current.count + 1;

    if (newCount >= this.MAX_ATTEMPTS) {
      this.loginAttempts.set(username, {
        count: newCount,
        blockedUntil: new Date(Date.now() + this.BLOCK_DURATION_MS),
      });
    } else {
      this.loginAttempts.set(username, {
        count: newCount,
        blockedUntil: null,
      });
    }
  }
}