import { Injectable, Logger, BadRequestException } from '@nestjs/common';
import * as nodemailer from 'nodemailer';
import { PrismaService } from '../prisma/prisma.service';

const OTP_TTL_MS = 10 * 60 * 1000; // 10 minutos

@Injectable()
export class EmailOtpService {
  private readonly logger = new Logger(EmailOtpService.name);
  private readonly otps = new Map<string, { code: string; expiresAt: number }>();

  constructor(private readonly prisma: PrismaService) {}

  private async createTransport() {
    // Prioridad: DB > env vars
    const dbConfig = await this.prisma.settings.findUnique({ where: { key: 'smtp_config' } })
      .then(r => r?.value as any).catch(() => null);

    const host = dbConfig?.host || process.env.SMTP_HOST;
    const port = parseInt(dbConfig?.port || process.env.SMTP_PORT || '587');
    const user = dbConfig?.user || process.env.SMTP_USER;
    const pass = dbConfig?.pass || process.env.SMTP_PASS;

    if (!host || !user || !pass) {
      throw new BadRequestException(
        'Correo no configurado. Configure el SMTP en Ajustes > Email.',
      );
    }

    return nodemailer.createTransport({
      host,
      port,
      secure: port === 465,
      auth: { user, pass },
    });
  }

  async getSmtpConfig() {
    return this.prisma.settings.findUnique({ where: { key: 'smtp_config' } })
      .then(r => (r?.value as any) ?? null);
  }

  async saveSmtpConfig(config: { host: string; port: string; user: string; pass: string; from?: string }) {
    await this.prisma.settings.upsert({
      where: { key: 'smtp_config' },
      create: { key: 'smtp_config', value: config as any },
      update: { value: config as any },
    });
    return { message: 'Configuración SMTP guardada' };
  }

  async sendOtp(email: string): Promise<void> {
    const code = Math.floor(100000 + Math.random() * 900000).toString();
    this.otps.set(email.toLowerCase(), { code, expiresAt: Date.now() + OTP_TTL_MS });

    const dbConfig = await this.prisma.settings.findUnique({ where: { key: 'smtp_config' } })
      .then(r => r?.value as any).catch(() => null);
    const from = dbConfig?.from || process.env.EMAIL_FROM || process.env.SMTP_USER;
    const transporter = await this.createTransport();

    try {
      await transporter.sendMail({
        from: `ProsApp <${from}>`,
        to: email,
        subject: 'Código de verificación ProsApp',
        html: `
          <div style="font-family:sans-serif;max-width:480px;margin:auto;padding:32px">
            <img src="https://prosapp.co/img/logo_prosapp.png" height="40" style="margin-bottom:24px">
            <h2 style="color:#1e293b;margin:0 0 8px">Verifica tu correo</h2>
            <p style="color:#64748b;margin:0 0 24px">Usa este código para vincular tu correo a ProsApp. Válido por 10 minutos.</p>
            <div style="background:#f0f8ff;border:1px solid #bae3ff;border-radius:12px;padding:24px;text-align:center">
              <span style="font-size:36px;font-weight:700;letter-spacing:10px;color:#42A4EF">${code}</span>
            </div>
            <p style="color:#94a3b8;font-size:12px;margin-top:24px">Si no solicitaste esto, ignora este correo.</p>
          </div>
        `,
      });
      this.logger.log(`Email OTP enviado a ${email}`);
      await this.prisma.message_logs.create({
        data: { channel: 'email', recipient: email, body: `OTP: ${code}`, status: 'sent' },
      }).catch(() => {});
    } catch (err) {
      await this.prisma.message_logs.create({
        data: { channel: 'email', recipient: email, body: 'OTP', status: 'error', error: String(err) },
      }).catch(() => {});
      throw err;
    }
  }

  verifyOtp(email: string, code: string): boolean {
    const key = email.toLowerCase();
    const entry = this.otps.get(key);
    if (!entry) return false;
    if (Date.now() > entry.expiresAt) {
      this.otps.delete(key);
      return false;
    }
    if (entry.code !== code) return false;
    this.otps.delete(key);
    return true;
  }
}