/**
 * Outbound messages. Email goes through the app's Resend account (reply-to = merchant);
 * SMS and WhatsApp use the merchant's own Twilio / Meta Cloud API credentials so
 * messaging costs stay on their account.
 *
 * WhatsApp business-initiated messages must use a pre-approved template. Datewise sends
 * the merchant's chosen template with the rendered reminder text as body parameter {{1}}.
 */
import { decrypt } from "./crypto.server";
import type { AppSettings } from "./settings";

export type Channel = "email" | "sms" | "whatsapp";

export interface OutboundMessage {
  channel: Channel;
  to: string;
  subject?: string;
  body: string;
}

export class NotConfigured extends Error {}

async function post(url: string, init: RequestInit) {
  const ctrl = new AbortController();
  const t = setTimeout(() => ctrl.abort(), 8000);
  try {
    const r = await fetch(url, { ...init, signal: ctrl.signal });
    if (!r.ok) throw new Error(`${new URL(url).host} ${r.status}: ${(await r.text()).slice(0, 300)}`);
    return r;
  } finally {
    clearTimeout(t);
  }
}

export async function send(settings: AppSettings, shopName: string, msg: OutboundMessage): Promise<void> {
  if (msg.channel === "email") {
    const key = process.env.RESEND_API_KEY;
    const domain = process.env.EMAIL_FROM_DOMAIN;
    if (!key || !domain) throw new NotConfigured("Email sending is not configured on the server");
    const from = `${settings.messaging.emailFromName || shopName} <reminders@${domain}>`;
    await post("https://api.resend.com/emails", {
      method: "POST",
      headers: { Authorization: `Bearer ${key}`, "Content-Type": "application/json" },
      body: JSON.stringify({
        from,
        to: [msg.to],
        reply_to: settings.messaging.replyTo || undefined,
        subject: msg.subject ?? `Your order with ${shopName}`,
        text: msg.body,
      }),
    });
    return;
  }
  if (msg.channel === "sms") {
    const t = settings.messaging.twilio;
    if (!t) throw new NotConfigured("Connect Twilio in Settings to send SMS");
    const auth = Buffer.from(`${t.accountSid}:${decrypt(t.authTokenEnc)}`).toString("base64");
    await post(`https://api.twilio.com/2010-04-01/Accounts/${t.accountSid}/Messages.json`, {
      method: "POST",
      headers: { Authorization: `Basic ${auth}`, "Content-Type": "application/x-www-form-urlencoded" },
      body: new URLSearchParams({ To: msg.to, From: t.from, Body: msg.body }),
    });
    return;
  }
  const w = settings.messaging.whatsapp;
  if (!w) throw new NotConfigured("Connect WhatsApp in Settings to send WhatsApp messages");
  await post(`https://graph.facebook.com/v21.0/${w.phoneNumberId}/messages`, {
    method: "POST",
    headers: { Authorization: `Bearer ${decrypt(w.tokenEnc)}`, "Content-Type": "application/json" },
    body: JSON.stringify({
      messaging_product: "whatsapp",
      to: msg.to.replace(/[^\d]/g, ""),
      type: "template",
      template: {
        name: w.templateName,
        language: { code: w.templateLang },
        components: [{ type: "body", parameters: [{ type: "text", text: msg.body.slice(0, 1000) }] }],
      },
    }),
  });
}