import { Injectable, Logger } from '@nestjs/common';
import { createTransport, Transporter, SentMessageInfo } from 'nodemailer';
import { ConfigService } from '@nestjs/config';
import emailBodies from './comps/emailbuilder';

function MailerFactory(postalBuddy: Transporter<SentMessageInfo>) {
  class Mailer {
    private readonly subject: string;
    private readonly target: string | string[];
    private parsable: string;
    private attachments: { filename: string; content: Buffer | string }[] = [];
    private readonly htmlBody: boolean;
    private readonly logger = new Logger('Mailer');
    public constructor(
      target: string | string[],
      subject: string,
      html?: boolean,
    ) {
      this.subject = subject;
      this.target = target;
      this.parsable = '';
      this.htmlBody = html || true;
    }
    /**
     * Sets the email's body (should be a html string)
     */
    public append(message: string): Mailer {
      this.parsable = message;
      return this;
    }
    public attach(data: Buffer, name = 'file'): Mailer {
      this.attachments.push({ filename: name, content: data });
      return this;
    }
    /**
     * Delivers the email to the address defined in the constructor
     */
    public async deliver(): Promise<boolean> {
      return new Promise<boolean>(async (resolve) => {
        if (typeof this.target == 'string') {
          const r = await postalBuddy.sendMail({
            from: '"Fileglass" noreply@file.glass',
            to: this.target,
            subject: this.subject,
            html: this.htmlBody ? this.parsable : undefined,
            text: !this.htmlBody ? this.parsable : undefined,
            attachments: this.attachments,
          });
          this.logger.log(
            `Email sent to: ${this.target} with subject: ${this.subject}`,
          );
          resolve(true);
        } else {
          this.logger.error('No target was specified');
          resolve(false);
        }
      });
    }
  }

  return Mailer;
}

declare class Mailer {
  constructor(target: string | string[], subject: string, html?: boolean);
  public deliver(): Promise<boolean>;
  public attach(data: Buffer, name?: string): Mailer;
  public append(message: string): Mailer;
}
@Injectable()
export class EmailsService {
  private readonly postalBuddy: Transporter<SentMessageInfo>;
  private readonly logger = new Logger(EmailsService.name);
  public readonly Mailer: typeof Mailer;
  public readonly bodies = emailBodies();

  constructor(private readonly configService: ConfigService) {
    this.postalBuddy = createTransport({
      host: 'smtp.sendgrid.net',
      auth: {
        user: this.configService.get('SG_USER'),
        pass: this.configService.get('SG_KEY'),
      },
      tls: {
        servername: 'smtp.sendgrid.net',
      },
      secure: true,
      requireTLS: true,
    });
    this.logger.log('Email transporter created');
    this.Mailer = MailerFactory(this.postalBuddy);
  }
}