// mailer.service.ts
import { Inject, Injectable } from '@nestjs/common';
import { Transporter } from 'nodemailer';
import * as fs from 'fs';
import * as path from 'path';
import * as Handlebars from 'handlebars';
import { MailTemplateDTO } from 'src/auth/auth.dto';

@Injectable()
export class MailService {
    private templatesCache = new Map<string, Handlebars.TemplateDelegate>();

    constructor(@Inject('MAIL_TRANSPORTER') private readonly transporter: Transporter) {
        console.log(path.join(process.cwd(), 'public', 'mail-templates', 'a.hbs'));

    }

    private loadTemplate(templateName: string): Handlebars.TemplateDelegate {
        if (this.templatesCache.has(templateName)) {
            return this.templatesCache.get(templateName)!;
        }

        const templatePath = path.join(process.cwd(), 'public', 'mail-templates', `${templateName}.hbs`);
        const source = fs.readFileSync(templatePath, 'utf8');
        const compiled = Handlebars.compile(source);
        this.templatesCache.set(templateName, compiled);
        return compiled;
    }

    async sendMail(data: MailTemplateDTO) {
        const template = this.loadTemplate(data.templateName);
        const html = template(data.variables);

        const mailOptions = {
            to: data.to,
            subject: data.subject,
            html,
        };

        return this.transporter.sendMail(mailOptions);
    }
}