// Telegram delivery for the daily digest.
//
// Setup:
//   1. Message @BotFather on Telegram → /newbot → copy the token
//   2. Put TELEGRAM_BOT=<token> in .env (TELEGRAM_TOKEN also accepted)
//   3. Send your bot any message ("hi"), then run: bun run telegram.ts --setup
//      That prints your chat ID; put it in .env as TELEGRAM_CHAT_ID=<id>
const env = Object.fromEntries(
  (await Bun.file(".env").text())
    .split("\n")
    .filter((l) => l.includes("=") && !l.trimStart().startsWith("#"))
    .map((l) => {
      const i = l.indexOf("=");
      return [l.slice(0, i).trim(), l.slice(i + 1).trim()];
    })
);

export const TOKEN = env.TELEGRAM_BOT ?? env.TELEGRAM_TOKEN ?? "";
export const CHAT_ID = env.TELEGRAM_CHAT_ID ?? env.TELEGRAM_CHAT ?? "";

const API = (m: string) => `https://api.telegram.org/bot${TOKEN}/${m}`;

/** Telegram hard-caps a message at 4096 chars; split on line boundaries. */
function chunk(text: string, limit = 3900): string[] {
  const out: string[] = [];
  let buf = "";
  for (const line of text.split("\n")) {
    if (buf.length + line.length + 1 > limit) {
      out.push(buf);
      buf = "";
    }
    buf += (buf ? "\n" : "") + line;
  }
  if (buf) out.push(buf);
  return out;
}

export function escapeHtml(s: string): string {
  return s.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;");
}

export async function send(text: string): Promise<void> {
  if (!TOKEN || !CHAT_ID) {
    throw new Error("TELEGRAM_BOT / TELEGRAM_CHAT_ID missing from .env — see telegram.ts header");
  }
  for (const part of chunk(text)) {
    const res = await fetch(API("sendMessage"), {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({
        chat_id: CHAT_ID,
        text: part,
        parse_mode: "HTML",
        link_preview_options: { is_disabled: true },
      }),
    });
    if (!res.ok) throw new Error(`Telegram ${res.status}: ${await res.text()}`);
    await Bun.sleep(400); // stay under the ~1 msg/sec limit
  }
}

// --setup: discover the chat ID from recent messages to the bot
if (import.meta.main && process.argv.includes("--setup")) {
  if (!TOKEN) {
    console.error("Add TELEGRAM_BOT=<token> to .env first (get one from @BotFather).");
    process.exit(1);
  }
  const res = await fetch(API("getUpdates"));
  const data = (await res.json()) as any;
  const chats = new Map<string, string>();
  for (const u of data.result ?? []) {
    const c = u.message?.chat ?? u.channel_post?.chat;
    if (c) chats.set(String(c.id), c.username ?? c.title ?? c.first_name ?? "");
  }
  if (!chats.size) {
    console.log("No messages found. Send your bot a message in Telegram, then re-run this.");
    process.exit(1);
  }
  console.log("Add this to .env:\n");
  for (const [id, name] of chats) console.log(`TELEGRAM_CHAT_ID=${id}   # ${name}`);
}