import { Resend } from "resend";
import { render } from "@react-email/render";
import log from "./logger";

/**
 * Email service using Resend
 *
 * Environment variables required:
 * - RESEND_API_KEY: API key from Resend dashboard
 * - EMAIL_FROM: Sender email address (e.g., "FitAI <noreply@fitai.com>")
 * - EMAIL_REPLY_TO: Reply-to email address (optional)
 */

const resend = new Resend(process.env.RESEND_API_KEY);

const DEFAULT_FROM = process.env.EMAIL_FROM || "FitAI <noreply@fitai.com>";
const DEFAULT_REPLY_TO = process.env.EMAIL_REPLY_TO;

export interface SendEmailOptions {
  to: string | string[];
  subject: string;
  react: React.ReactElement;
  from?: string;
  replyTo?: string;
}

/**
 * Send an email using Resend
 *
 * @param options - Email options including recipient, subject, and React component
 * @returns Response from Resend API
 *
 * @example
 * ```tsx
 * import { WelcomeEmail } from '@/emails/welcome-email';
 *
 * await sendEmail({
 *   to: 'user@example.com',
 *   subject: 'Welcome to FitAI',
 *   react: <WelcomeEmail name="John" />
 * });
 * ```
 */
export async function sendEmail({
  to,
  subject,
  react,
  from = DEFAULT_FROM,
  replyTo = DEFAULT_REPLY_TO,
}: SendEmailOptions) {
  try {
    // Check if email is configured
    if (!process.env.RESEND_API_KEY) {
      log.warn("RESEND_API_KEY not configured. Email not sent.", {
        to,
        subject,
      });
      return { success: false, error: "Email not configured" };
    }

    const { data, error } = await resend.emails.send({
      from,
      to,
      subject,
      react,
      ...(replyTo && { replyTo }),
    });

    if (error) {
      log.error("Failed to send email", error, { to, subject });
      return { success: false, error: error.message };
    }

    log.info("Email sent successfully", { to, subject, emailId: data?.id });
    return { success: true, data };
  } catch (error) {
    log.error("Email service error", error, { to, subject });
    return { success: false, error: "Email service error" };
  }
}

/**
 * Send a welcome email to a new user
 */
export async function sendWelcomeEmail(email: string, name: string) {
  const { WelcomeEmail } = await import("@/emails/welcome-email");

  return sendEmail({
    to: email,
    subject: "Welcome to FitAI!",
    react: WelcomeEmail({ name }),
  });
}

/**
 * Send an invitation email to a new user
 */
export async function sendInvitationEmail(
  email: string,
  role: string,
  inviteUrl: string,
) {
  const { UserInvitationEmail } = await import(
    "@/emails/user-invitation-email"
  );

  return sendEmail({
    to: email,
    subject: "You've been invited to join FitAI",
    react: UserInvitationEmail({ email, role, inviteUrl }),
  });
}

/**
 * Send a trainer assignment notification email
 */
export async function sendTrainerAssignmentEmail(
  clientEmail: string,
  clientName: string,
  trainerName: string,
) {
  const { TrainerAssignmentEmail } = await import(
    "@/emails/trainer-assignment-email"
  );

  return sendEmail({
    to: clientEmail,
    subject: "You've been assigned a trainer",
    react: TrainerAssignmentEmail({ clientName, trainerName }),
  });
}

/**
 * Send a recommendation notification email to a client
 */
export async function sendRecommendationEmail(
  clientEmail: string,
  clientName: string,
  recommendationText: string,
) {
  const { RecommendationEmail } = await import("@/emails/recommendation-email");

  return sendEmail({
    to: clientEmail,
    subject: "New fitness recommendation from your trainer",
    react: RecommendationEmail({ clientName, recommendationText }),
  });
}