/**
 * Telegram Notification Service
 *
 * Sends alerts to admin via Telegram Bot when:
 * - New TRC20 purchase is confirmed
 * - Purchase is marked as distributed
 *
 * Configuration (via environment variables or admin settings table):
 *   TELEGRAM_BOT_TOKEN  — Bot token from @BotFather (e.g. 123456:ABC-DEF...)
 *   TELEGRAM_CHAT_ID    — Chat ID to send messages to (personal or group)
 *
 * How to set up:
 * 1. Open Telegram, search @BotFather, send /newbot
 * 2. Follow prompts to get your Bot Token
 * 3. Start a chat with your bot (or add it to a group)
 * 4. Get Chat ID: https://api.telegram.org/bot<TOKEN>/getUpdates
 * 5. Set TELEGRAM_BOT_TOKEN and TELEGRAM_CHAT_ID in environment variables
 */

const TELEGRAM_API = "https://api.telegram.org";

export interface TelegramConfig {
  botToken: string;
  chatId: string;
}

/**
 * Get Telegram config from environment variables or DB settings.
 * Returns null if not configured.
 */
export async function getTelegramConfig(): Promise<TelegramConfig | null> {
  const botToken = process.env.TELEGRAM_BOT_TOKEN;
  const chatId = process.env.TELEGRAM_CHAT_ID;

  if (!botToken || !chatId) {
    return null;
  }

  return { botToken, chatId };
}

/**
 * Send a message via Telegram Bot API.
 * Uses HTML parse mode for formatting.
 */
export async function sendTelegramMessage(
  config: TelegramConfig,
  message: string
): Promise<boolean> {
  try {
    const url = `${TELEGRAM_API}/bot${config.botToken}/sendMessage`;
    const resp = await fetch(url, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({
        chat_id: config.chatId,
        text: message,
        parse_mode: "HTML",
        disable_web_page_preview: true,
      }),
      signal: AbortSignal.timeout(10_000),
    });

    if (!resp.ok) {
      const err = await resp.text();
      console.warn(`[Telegram] Send failed (${resp.status}): ${err}`);
      return false;
    }

    console.log("[Telegram] Message sent successfully");
    return true;
  } catch (e) {
    console.warn("[Telegram] Send error:", e);
    return false;
  }
}

/**
 * Notify admin about a new TRC20 purchase.
 */
export async function notifyNewTRC20Purchase(purchase: {
  txHash: string;
  fromAddress: string;
  usdtAmount: number;
  xicAmount: number;
  evmAddress: string | null;
}): Promise<void> {
  const config = await getTelegramConfig();
  if (!config) {
    console.log("[Telegram] Not configured — skipping notification (set TELEGRAM_BOT_TOKEN and TELEGRAM_CHAT_ID)");
    return;
  }

  const evmLine = purchase.evmAddress
    ? `\n🔑 <b>EVM Address:</b> <code>${purchase.evmAddress}</code>`
    : "\n⚠️ <b>EVM Address:</b> Not provided (manual distribution required)";

  const txUrl = `https://tronscan.org/#/transaction/${purchase.txHash}`;

  const message = [
    "🟢 <b>New XIC Presale Purchase!</b>",
    "",
    `💰 <b>Amount:</b> $${purchase.usdtAmount.toFixed(2)} USDT`,
    `🪙 <b>XIC Tokens:</b> ${purchase.xicAmount.toLocaleString()} XIC`,
    `📍 <b>From (TRON):</b> <code>${purchase.fromAddress}</code>`,
    evmLine,
    `🔗 <b>TX:</b> <a href="${txUrl}">${purchase.txHash.slice(0, 16)}...</a>`,
    "",
    `⏰ ${new Date().toLocaleString("zh-CN", { timeZone: "Asia/Shanghai" })} (CST)`,
  ].join("\n");

  await sendTelegramMessage(config, message);
}

/**
 * Notify admin when a purchase is marked as distributed.
 */
export async function notifyDistributed(purchase: {
  txHash: string;
  evmAddress: string;
  xicAmount: number;
  distributeTxHash?: string | null;
}): Promise<void> {
  const config = await getTelegramConfig();
  if (!config) return;

  const distTxLine = purchase.distributeTxHash
    ? `\n🔗 <b>Dist TX:</b> <code>${purchase.distributeTxHash}</code>`
    : "";

  const message = [
    "✅ <b>XIC Tokens Distributed!</b>",
    "",
    `🪙 <b>XIC Tokens:</b> ${purchase.xicAmount.toLocaleString()} XIC`,
    `📬 <b>To EVM:</b> <code>${purchase.evmAddress}</code>`,
    distTxLine,
    `🔗 <b>Original TX:</b> <code>${purchase.txHash.slice(0, 16)}...</code>`,
    "",
    `⏰ ${new Date().toLocaleString("zh-CN", { timeZone: "Asia/Shanghai" })} (CST)`,
  ].join("\n");

  await sendTelegramMessage(config, message);
}

/**
 * Test the Telegram connection with a test message.
 * Returns { success, error } for admin UI feedback.
 */
export async function testTelegramConnection(
  botToken: string,
  chatId: string
): Promise<{ success: boolean; error?: string }> {
  try {
    const config: TelegramConfig = { botToken, chatId };
    const message = [
      "🔔 <b>NAC Presale — Telegram Notification Test</b>",
      "",
      "✅ Connection successful! You will receive purchase alerts here.",
      "",
      `⏰ ${new Date().toLocaleString("zh-CN", { timeZone: "Asia/Shanghai" })} (CST)`,
    ].join("\n");

    const ok = await sendTelegramMessage(config, message);
    if (!ok) return { success: false, error: "Failed to send message. Check Bot Token and Chat ID." };
    return { success: true };
  } catch (e) {
    return { success: false, error: e instanceof Error ? e.message : String(e) };
  }
}