import { Injectable } from '@nestjs/common';
import { User } from '../entities/user.entity';
import { PasswordResetToken } from '../entities/password-reset-token.entity';
import * as nodemailer from 'nodemailer';
import * as handlebars from 'handlebars';

export class Email {
  from: string;
  to: string[];
  subject: string;
  text: string;
  html?: string;
}

const WELCOME_MAIL_TEMPLATE: HandlebarsTemplateDelegate<{
  username: string;
  link: string;
}> = handlebars.compile(
  `
Hello {{username}},

You've been added to QiVisor.
To complete your registration click the link below:
{{link}}

Best,
QiVisor
`.trim(),
);

const PASSWORD_RESET_MAIL_TEMPLATE: HandlebarsTemplateDelegate<{
  username: string;
  link: string;
}> = handlebars.compile(
  `
Hello {{username}},

To reset your password click the link below:
{{link}}

Best,
QiVisor
`.trim(),
);

@Injectable()
export class MailerService {
  async sendWelcomeEmail(user: User, token: PasswordResetToken) {
    const fromEmail =
      process.env.SMTP_FROM_EMAIL || 'registrationdev - qivisor@viravix.com';
    const email: Email = {
      from: `"QiVisor Dev version" <${fromEmail}>`,
      to: [`"${user.username}" <${user.email}>`],
      subject: 'Welcome to QiVisor',
      text: WELCOME_MAIL_TEMPLATE({
        username: user.username,
        link: token.token,
      }),
    };
    await this.sendEmail(email);
  }

  async sendResetPasswordEmail(user: User, token: PasswordResetToken) {
    const fromEmail =
      process.env.SMTP_FROM_EMAIL || 'password-reset-dev-qivisor@viravix.com';
    const email: Email = {
      from: `"QiVisor Dev version Password Reset" <${fromEmail}>`,
      to: [`"${user.username}" <${user.email}>`],
      subject: 'Password Reset',
      text: PASSWORD_RESET_MAIL_TEMPLATE({
        username: user.username,
        link: token.token,
      }),
    };
    await this.sendEmail(email);
  }

  async sendEmail(email: Email) {
    const testAccount = process.env.SMTP_HOST
      ? {}
      : await nodemailer.createTestAccount();

    const transporter = nodemailer.createTransport({
      host: process.env.SMTP_HOST || 'smtp.ethereal.email',
      port: process.env.SMTP_PORT || 587,
      secure: false,
      auth: {
        user: process.env.SMTP_USER || testAccount.user,
        pass: process.env.SMTP_PASSWORD || testAccount.pass,
      },
    });

    const info = await transporter.sendMail(email);
    console.log('Message sent: ', info);
    if (!process.env.SMTP_HOST) {
      console.log('Preview URL: %s', nodemailer.getTestMessageUrl(info));
    }
  }
}