import 'server-only';
import { env } from '@/lib/env';

export type EmailMessage = { to: string; subject: string; html: string };
export type EmailResult = { id: string; provider: string };

export interface EmailProvider {
  name: string;
  send(message: EmailMessage): Promise<EmailResult>;
}

/** Default provider: no keys needed — logs the message and returns a synthetic id. */
export class LogProvider implements EmailProvider {
  name = 'log';
  async send(message: EmailMessage): Promise<EmailResult> {
    console.log(`[email:log] to=${message.to} subject="${message.subject}"`);
    return { id: `log_${Date.now().toString(36)}`, provider: this.name };
  }
}

/** Real provider, activated by RESEND_API_KEY. */
export class ResendProvider implements EmailProvider {
  name = 'resend';
  constructor(private apiKey: string, private from: string) {}
  async send(message: EmailMessage): Promise<EmailResult> {
    const res = await fetch('https://api.resend.com/emails', {
      method: 'POST',
      headers: { Authorization: `Bearer ${this.apiKey}`, 'Content-Type': 'application/json' },
      body: JSON.stringify({ from: this.from, to: message.to, subject: message.subject, html: message.html }),
    });
    if (!res.ok) throw new Error(`Resend error ${res.status}: ${await res.text()}`);
    const data = (await res.json()) as { id: string };
    return { id: data.id, provider: this.name };
  }
}

export function getEmail(): EmailProvider {
  if (env.RESEND_API_KEY) return new ResendProvider(env.RESEND_API_KEY, env.EMAIL_FROM);
  return new LogProvider();
}

export function sendEmail(message: EmailMessage): Promise<EmailResult> {
  return getEmail().send(message);
}