import nodemailer, { type Transporter } from 'nodemailer';

import { env } from '@/lib/env';
import { logger } from '@/lib/logger';
import { getPortEmailConfig, type PortEmailConfig } from '@/lib/services/port-config';

/**
 * Creates and returns a new Nodemailer SMTP transporter using env defaults.
 * For port-scoped configuration use {@link createPortTransporter} instead.
 *
 * A new instance is created on each call so the factory can be used in
 * contexts where connection pooling is managed externally (e.g. per-request
 * in serverless, or once at worker startup).
 */
export function createTransporter(): Transporter {
  return nodemailer.createTransport({
    host: env.SMTP_HOST,
    port: env.SMTP_PORT,
    // Implicitly secure when port is 465; STARTTLS for all other ports.
    secure: env.SMTP_PORT === 465,
    ...(env.SMTP_USER && env.SMTP_PASS
      ? { auth: { user: env.SMTP_USER, pass: env.SMTP_PASS } }
      : {}),
  });
}

function createTransporterFromConfig(cfg: PortEmailConfig): Transporter {
  return nodemailer.createTransport({
    host: cfg.smtpHost,
    port: cfg.smtpPort,
    secure: cfg.smtpPort === 465,
    ...(cfg.smtpUser && cfg.smtpPass ? { auth: { user: cfg.smtpUser, pass: cfg.smtpPass } } : {}),
  });
}

export interface SendEmailOptions {
  to: string | string[];
  subject: string;
  html: string;
  from?: string;
  /** When provided, port-level email settings override env defaults. */
  portId?: string;
  text?: string;
}

/**
 * Sends a single email via SMTP.
 *
 * Returns the nodemailer info object on success. Propagates errors to the
 * caller — callers in background jobs should wrap in try/catch and handle
 * retries via BullMQ.
 */
export async function sendEmail(
  to: string | string[],
  subject: string,
  html: string,
  from?: string,
  text?: string,
  portId?: string,
): Promise<nodemailer.SentMessageInfo> {
  const cfg = portId ? await getPortEmailConfig(portId) : null;
  const transporter = cfg ? createTransporterFromConfig(cfg) : createTransporter();

  const requestedTo = Array.isArray(to) ? to.join(', ') : to;
  const effectiveTo = env.EMAIL_REDIRECT_TO ?? requestedTo;
  const effectiveSubject = env.EMAIL_REDIRECT_TO
    ? `[redirected from ${requestedTo}] ${subject}`
    : subject;

  const fromHeader =
    from ??
    (cfg ? `${cfg.fromName} <${cfg.fromAddress}>` : undefined) ??
    env.SMTP_FROM ??
    `Port Nimara CRM <noreply@${env.SMTP_HOST}>`;

  const info = await transporter.sendMail({
    from: fromHeader,
    to: effectiveTo,
    subject: effectiveSubject,
    html,
    ...(cfg?.replyTo ? { replyTo: cfg.replyTo } : {}),
    ...(text ? { text } : {}),
  });

  logger.debug(
    { messageId: info.messageId, to: effectiveTo, originalTo: requestedTo, subject, portId },
    env.EMAIL_REDIRECT_TO ? 'Email sent (redirected)' : 'Email sent',
  );

  return info;
}