import * as path from 'path';
import * as fs from 'fs';
import * as handlebars from 'handlebars';
import { Injectable } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { MailerOptions, MailerOptionsFactory } from '@nestjs-modules/mailer';
import { HandlebarsAdapter } from '@nestjs-modules/mailer/dist/adapters/handlebars.adapter';

@Injectable()
export class MailConfigService implements MailerOptionsFactory {
  constructor(private configService: ConfigService) {}

  createMailerOptions(): MailerOptions {
    // __dirname resolves to src/mail in dev (ts-node) and dist/mail in the
    // built image, so this stays correct without depending on whether the
    // process was started from a source or compiled checkout.
    const templatesDir = path.join(__dirname, 'mail-templates');

    handlebars.registerPartial(
      'layout',
      fs.readFileSync(
        path.join(templatesDir, 'partials', 'layout.hbs'),
        'utf-8',
      ),
    );

    return {
      transport: {
        host: this.configService.get('mail.host'),
        port: this.configService.get('mail.port'),
        ignoreTLS: this.configService.get('mail.ignoreTLS'),
        secure: this.configService.get('mail.secure'),
        requireTLS: this.configService.get('mail.requireTLS'),
        auth: {
          user: this.configService.get('mail.user'),
          pass: this.configService.get('mail.password'),
        },
      },
      defaults: {
        from: `"${this.configService.get(
          'mail.defaultName',
        )}" <${this.configService.get('mail.defaultEmail')}>`,
      },
      template: {
        dir: templatesDir,
        adapter: new HandlebarsAdapter(),
        options: {
          strict: true,
        },
      },
    } as MailerOptions;
  }
}