import { Module } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { MailerModule } from '@nestjs-modules/mailer';
import { SettingsModule } from '../settings/settings.module';
import { SettingsService } from '../settings/settings.service';
import { MailService } from './mail.service';

/**
 * MailModule — system email delivery (password reset, welcome emails).
 *
 * D-06: SMTP transport is now sourced from the DB SmtpConfig row (priority 1)
 * with an env-var fallback (priority 2) when no DB row exists.
 *
 * Transport priority:
 *   1. DB SmtpConfig (first row — single-tenant default; set via /settings/smtp)
 *   2. Env vars: MAIL_HOST / MAIL_PORT / MAIL_USER / MAIL_PASS
 *   3. Legacy env vars: TESSERA_SMTP_HOST / TESSERA_SMTP_PORT / TESSERA_SMTP_USER / TESSERA_SMTP_PASSWORD
 *   4. Final hardcoded fallback: localhost:1025 (Mailhog / dev default)
 *
 * The factory is async because getStartupSmtpConfig() reads from the DB.
 * No circular import risk: MailModule → SettingsModule → CalendarModule (no reverse edges).
 */
@Module({
  imports: [
    SettingsModule,
    MailerModule.forRootAsync({
      imports: [SettingsModule],
      useFactory: async (settingsService: SettingsService, configService: ConfigService) => {
        // Priority 1: DB SmtpConfig (getStartupSmtpConfig uses findFirst — single-tenant default)
        const db = await settingsService.getStartupSmtpConfig();

        if (db) {
          // T-07-11: DB password used only to build transport; never logged
          return {
            transport: {
              host: db.host,
              port: db.port,
              secure: db.secure,
              requireTLS: db.requireTLS,
              auth: db.username
                ? { user: db.username, pass: db.password ?? '' }
                : undefined,
            },
            defaults: {
              from: db.fromAddress,
            },
          };
        }

        // Priority 2: Env vars (new names first, legacy TESSERA_SMTP_* as secondary fallback)
        const host =
          configService.get<string>('MAIL_HOST') ??
          configService.get<string>('TESSERA_SMTP_HOST') ??
          'localhost';

        const port =
          configService.get<number>('MAIL_PORT') ??
          configService.get<number>('TESSERA_SMTP_PORT') ??
          1025;

        const user =
          configService.get<string>('MAIL_USER') ??
          configService.get<string>('TESSERA_SMTP_USER') ??
          '';

        const pass =
          configService.get<string>('MAIL_PASS') ??
          configService.get<string>('TESSERA_SMTP_PASSWORD') ??
          '';

        const from =
          configService.get<string>('TESSERA_SMTP_FROM') ??
          'Tessera <tessera@tessera.local>';

        const secure =
          configService.get<string>('TESSERA_SMTP_SECURE', 'false') === 'true';

        return {
          transport: {
            host,
            port,
            secure,
            auth: { user, pass },
          },
          defaults: { from },
        };
      },
      inject: [SettingsService, ConfigService],
    }),
  ],
  providers: [MailService],
  exports: [MailService],
})
export class MailModule {}