import { Injectable } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import * as nodemailer from 'nodemailer';
import { SendMailerDto } from './mailer.interface';
import Mail from 'nodemailer/lib/mailer';

@Injectable()
export class MailerService {
  constructor(
    private readonly configService: ConfigService
  ) {}
  mailTransport() {
    const transporter = nodemailer.createTransport({
      service: 'gmail',
      host: this.configService.get<string>('MAIL_HOST'),
      auth: {
        user: this.configService.get<string>('MAIL_USER'),
        pass: this.configService.get<string>('MAIL_PASS'),
      },
      secure: true,
      port: this.configService.get<number>('MAIL_PORT'),
    });
    return transporter;
  }

  template(html: string, replacements: Record<string, string>) {
    return html.replace(/%(\w*)%/g, function (m, key) {
      return replacements.hasOwnProperty(key) ? replacements[key] : '';
    });
  }

  async sendMail(dto: SendMailerDto) {
    const { from, reciepients, subject } = dto;
    const html = dto.placeholderReplacements
      ? this.template(dto.html, dto.placeholderReplacements)
      : dto.html;
    const transporter = this.mailTransport();
    const fromName = from?.name ?? this.configService.get<string>('APP_NAME');
    const fromAddress =
      from?.address ?? this.configService.get<string>('MAIL_USER');
    const options: Mail.Options = {
      from: {
        name: fromName,
        address: fromAddress,
      },
      to: reciepients,
      subject,
      html: this.template(html, dto.placeholderReplacements || {}),
    };
    try {
      const result = await transporter.sendMail(options);
      return result;
    } catch (er) {
      console.log(er);
    }
  }
}