import {
  albumDb,
  purchaseDb,
  telegramApproverDb,
  telegramSessionDb,
  telegramSettingsDb,
} from "./db";
import { Album, Purchase, PurchaseStatus, TelegramUserSession } from "./types";
import { formatPrice } from "./utils";

interface TelegramResponse<T> {
  ok: boolean;
  result?: T;
  description?: string;
}

interface TelegramUser {
  id: number;
  first_name?: string;
  last_name?: string;
  username?: string;
}

interface TelegramMessage {
  message_id: number;
  chat: { id: number };
  from?: TelegramUser;
  text?: string;
  caption?: string;
  photo?: Array<{ file_id: string; width: number; height: number; file_size?: number }>;
}

export interface TelegramUpdate {
  message?: TelegramMessage;
  callback_query?: {
    id: string;
    from: TelegramUser;
    data?: string;
    message?: TelegramMessage;
  };
}

function getTelegramConfig(): { baseUrl: string; token: string } {
  const settings = telegramSettingsDb.get();
  if (!settings.botToken) {
    throw new Error("Telegram bot token is not configured in the admin panel");
  }
  return { baseUrl: settings.baseUrl.replace(/\/$/, ""), token: settings.botToken };
}

export function isTelegramConfigured(): boolean {
  return Boolean(telegramSettingsDb.get().botToken);
}

export async function callTelegram<T = unknown>(
  method: string,
  payload: Record<string, unknown>,
): Promise<T> {
  const { baseUrl, token } = getTelegramConfig();
  const response = await fetch(`${baseUrl}/bot${token}/${method}`, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify(payload),
  });
  const body = (await response.json()) as TelegramResponse<T>;
  if (!response.ok || !body.ok) throw new Error(body.description || `Telegram ${method} failed`);
  return body.result as T;
}

async function callTelegramMultipart<T = unknown>(method: string, form: FormData): Promise<T> {
  const { baseUrl, token } = getTelegramConfig();
  const response = await fetch(`${baseUrl}/bot${token}/${method}`, { method: "POST", body: form });
  const body = (await response.json()) as TelegramResponse<T>;
  if (!response.ok || !body.ok) throw new Error(body.description || `Telegram ${method} failed`);
  return body.result as T;
}

export async function registerTelegramWebhook(appUrl?: string): Promise<void> {
  const publicUrl = (appUrl || process.env.NEXT_PUBLIC_APP_URL || "https://podzahr.com").replace(/\/$/, "");
  const secret = process.env.TELEGRAM_WEBHOOK_SECRET;
  if (!publicUrl.startsWith("https://")) {
    throw new Error("NEXT_PUBLIC_APP_URL must be a public HTTPS URL");
  }
  if (!secret) throw new Error("TELEGRAM_WEBHOOK_SECRET is not configured");

  await callTelegram("setWebhook", {
    url: `${publicUrl}/api/telegram/webhook`,
    secret_token: secret,
    allowed_updates: ["message", "callback_query"],
  });
}

function albumIdsForPurchase(purchase: Purchase): string[] {
  return purchase.albumIds?.length ? purchase.albumIds : [purchase.albumId];
}

function albumsForPurchase(purchase: Purchase): Album[] {
  return albumIdsForPurchase(purchase)
    .map((id) => albumDb.getById(id))
    .filter((album): album is Album => Boolean(album));
}

function totalForAlbums(albums: Album[]): number {
  return albums.reduce((total, album) => total + album.price, 0);
}

function displayName(user: TelegramUser): string {
  const name = [user.first_name, user.last_name].filter(Boolean).join(" ").trim();
  return name || (user.username ? `@${user.username}` : String(user.id));
}

function ensureSession(user: TelegramUser, chatId: number): TelegramUserSession {
  const existing = telegramSessionDb.get(String(user.id));
  return telegramSessionDb.upsert({
    userId: String(user.id),
    chatId: String(chatId),
    state: existing?.state || "browsing",
    cartAlbumIds: existing?.cartAlbumIds || [],
    displayName: displayName(user),
  });
}

function mainMenuKeyboard() {
  return {
    inline_keyboard: [[
      { text: "Browse albums", callback_data: "catalog" },
      { text: "My cart", callback_data: "cart" },
    ]],
  };
}

async function showCatalog(chatId: number | string): Promise<void> {
  const albums = albumDb.getAll();
  if (albums.length === 0) {
    await callTelegram("sendMessage", { chat_id: chatId, text: "There are no albums available." });
    return;
  }
  await callTelegram("sendMessage", {
    chat_id: chatId,
    text: "Choose albums to add to your cart:",
    reply_markup: {
      inline_keyboard: [
        ...albums.map((album) => [{
          text: `Add ${album.title} — ${formatPrice(album.price)}`,
          callback_data: `cart:add:${album.id}`,
        }]),
        [{ text: "View cart", callback_data: "cart" }],
      ],
    },
  });
}

async function showCart(userId: string, chatId: number | string): Promise<void> {
  const session = telegramSessionDb.get(userId);
  const albums = (session?.cartAlbumIds || [])
    .map((id) => albumDb.getById(id))
    .filter((album): album is Album => Boolean(album));
  if (albums.length === 0) {
    await callTelegram("sendMessage", {
      chat_id: chatId,
      text: "Your cart is empty.",
      reply_markup: { inline_keyboard: [[{ text: "Browse albums", callback_data: "catalog" }]] },
    });
    return;
  }

  await callTelegram("sendMessage", {
    chat_id: chatId,
    text: [
      "Your cart:",
      ...albums.map((album, index) => `${index + 1}. ${album.title} — ${formatPrice(album.price)}`),
      "",
      `Total: ${formatPrice(totalForAlbums(albums))}`,
    ].join("\n"),
    reply_markup: {
      inline_keyboard: [
        ...albums.map((album) => [{ text: `Remove ${album.title}`, callback_data: `cart:remove:${album.id}` }]),
        [{ text: "Checkout", callback_data: "checkout" }],
        [
          { text: "Add more", callback_data: "catalog" },
          { text: "Clear cart", callback_data: "cart:clear" },
        ],
      ],
    },
  });
}

async function beginCheckout(session: TelegramUserSession): Promise<void> {
  const settings = telegramSettingsDb.get();
  const albums = session.cartAlbumIds
    .map((id) => albumDb.getById(id))
    .filter((album): album is Album => Boolean(album));
  if (albums.length === 0) return showCart(session.userId, session.chatId);
  if (!settings.cardNumber || !settings.cardHolderName) {
    await callTelegram("sendMessage", {
      chat_id: session.chatId,
      text: "Card payment is not configured yet. Please try again later.",
    });
    return;
  }

  telegramSessionDb.upsert({ ...session, state: "awaiting_receipt" });
  await callTelegram("sendMessage", {
    chat_id: session.chatId,
    text: [
      `Total: ${formatPrice(totalForAlbums(albums))}`,
      "",
      `Card number: ${settings.cardNumber}`,
      `Cardholder: ${settings.cardHolderName}`,
      "",
      "Transfer the amount, then send either the transaction ID as text or a screenshot of the receipt.",
    ].join("\n"),
  });
}

function purchaseMessage(purchase: Purchase): string {
  const albums = albumsForPurchase(purchase);
  return [
    "New Telegram purchase awaiting review",
    "",
    `Purchase: #${purchase.id}`,
    `Albums: ${albums.map((album) => album.title).join(", ") || purchase.albumId}`,
    `Amount: ${formatPrice(totalForAlbums(albums))}`,
    `Customer: ${purchase.customerName || "N/A"}`,
    `Telegram user: ${purchase.telegramUserId || "N/A"}`,
    `Transaction: ${purchase.transactionId}`,
    `Receipt: ${purchase.txReceipt || purchase.receiptType || "N/A"}`,
  ].join("\n");
}

function reviewKeyboard(purchaseId: number) {
  return {
    inline_keyboard: [[
      { text: "Approve", callback_data: `purchase:approved:${purchaseId}` },
      { text: "Reject", callback_data: `purchase:rejected:${purchaseId}` },
    ]],
  };
}

export async function sendPurchaseForReview(
  chatId: string | number,
  purchase: Purchase,
): Promise<void> {
  if (!purchase.id) return;
  const payload = {
    chat_id: chatId,
    reply_markup: reviewKeyboard(purchase.id),
  };
  if (purchase.receiptType === "photo" && purchase.receiptTelegramFileId) {
    await callTelegram("sendPhoto", {
      ...payload,
      photo: purchase.receiptTelegramFileId,
      caption: purchaseMessage(purchase),
    });
    return;
  }
  await callTelegram("sendMessage", { ...payload, text: purchaseMessage(purchase) });
}

export async function notifyPurchaseApprovers(purchase: Purchase): Promise<void> {
  if (!isTelegramConfigured() || purchase.approvalStatus !== "pending") return;
  const results = await Promise.allSettled(
    telegramApproverDb.getAll().map(({ userId }) => sendPurchaseForReview(userId, purchase)),
  );
  for (const result of results) {
    if (result.status === "rejected") {
      console.error("Telegram purchase notification failed:", result.reason);
    }
  }
}

async function saveReceipt(message: TelegramMessage, session: TelegramUserSession): Promise<void> {
  const albums = session.cartAlbumIds
    .map((id) => albumDb.getById(id))
    .filter((album): album is Album => Boolean(album));
  if (albums.length === 0) {
    telegramSessionDb.upsert({ ...session, state: "browsing", cartAlbumIds: [] });
    await showCart(session.userId, session.chatId);
    return;
  }

  const textReceipt = message.text?.trim();
  const photo = message.photo?.at(-1);
  if (!textReceipt && !photo) {
    await callTelegram("sendMessage", {
      chat_id: session.chatId,
      text: "Please send the transaction ID as text or upload a receipt screenshot.",
    });
    return;
  }

  const purchase = purchaseDb.create({
    albumId: albums[0].id,
    albumIds: albums.map((album) => album.id),
    transactionId: `TG-${session.userId}-${Date.now()}-${crypto.randomUUID().slice(0, 8)}`,
    customerName: session.displayName,
    txReceipt: textReceipt || message.caption?.trim() || "Telegram receipt screenshot",
    purchaseDate: Date.now(),
    approvalStatus: "pending",
    paymentMethod: "card-to-card",
    telegramUserId: session.userId,
    telegramChatId: session.chatId,
    receiptType: photo ? "photo" : "text",
    receiptTelegramFileId: photo?.file_id,
  });

  telegramSessionDb.upsert({ ...session, state: "browsing", cartAlbumIds: [] });
  await callTelegram("sendMessage", {
    chat_id: session.chatId,
    text: `Receipt received for purchase #${purchase.id}. You will be notified after review.`,
    reply_markup: mainMenuKeyboard(),
  });
  await notifyPurchaseApprovers(purchase);
}

function resolveFileUrl(url: string): string {
  if (/^https?:\/\//i.test(url)) return url;
  const appUrl = process.env.NEXT_PUBLIC_APP_URL || "https://podzahr.com";
  return new URL(url, appUrl).toString();
}

function safeFileName(value: string): string {
  return value.replace(/[^a-zA-Z0-9._-]+/g, "-").replace(/^-+|-+$/g, "") || "track";
}

async function uploadSong(chatId: string, album: Album, song: Album["songs"][number]): Promise<void> {
  const response = await fetch(resolveFileUrl(song.fullUrl));
  if (!response.ok) throw new Error(`Could not download ${album.title} / ${song.title}`);
  const blob = await response.blob();
  const extension = album.format || "mp3";
  const form = new FormData();
  form.set("chat_id", chatId);
  form.set("caption", `${album.title} — ${song.title}`);
  form.set("document", blob, `${safeFileName(album.title)}-${safeFileName(song.title)}.${extension}`);
  await callTelegramMultipart("sendDocument", form);
}

export async function notifyCustomerOfDecision(purchase: Purchase): Promise<void> {
  if (!purchase.telegramChatId) return;
  if (purchase.approvalStatus === "rejected") {
    await callTelegram("sendMessage", {
      chat_id: purchase.telegramChatId,
      text: `Your purchase #${purchase.id} was rejected. Please contact support if you believe this is a mistake.`,
      reply_markup: mainMenuKeyboard(),
    });
    return;
  }
  if (purchase.approvalStatus !== "approved") return;

  await callTelegram("sendMessage", {
    chat_id: purchase.telegramChatId,
    text: `Congratulations! Purchase #${purchase.id} was approved. Your album files are being uploaded now.`,
  });

  for (const album of albumsForPurchase(purchase)) {
    for (const song of album.songs) {
      try {
        await uploadSong(purchase.telegramChatId, album, song);
      } catch (error) {
        console.error("Telegram album delivery failed:", error);
        await callTelegram("sendMessage", {
          chat_id: purchase.telegramChatId,
          text: `Could not upload ${album.title} — ${song.title}. Please contact support.`,
        });
      }
    }
  }

  await callTelegram("sendMessage", {
    chat_id: purchase.telegramChatId,
    text: "All available album files have been delivered. Thank you!",
    reply_markup: mainMenuKeyboard(),
  });
}

export async function handleTelegramUpdate(update: TelegramUpdate): Promise<void> {
  if (update.callback_query) {
    await handleCallback(update.callback_query);
    return;
  }

  const message = update.message;
  if (!message?.from) return;
  const session = ensureSession(message.from, message.chat.id);
  const command = message.text?.startsWith("/")
    ? message.text.split(/\s+/)[0].split("@")[0]
    : undefined;

  if (command === "/start") {
    const settings = telegramSettingsDb.get();
    telegramSessionDb.upsert({ ...session, state: "browsing" });
    await callTelegram("sendMessage", {
      chat_id: message.chat.id,
      text: settings.greetingText,
      reply_markup: mainMenuKeyboard(),
    });
    await showCatalog(message.chat.id);
    return;
  }
  if (command === "/id") {
    const authorized = telegramApproverDb.isAuthorized(session.userId);
    await callTelegram("sendMessage", {
      chat_id: message.chat.id,
      text: `Your Telegram user ID is ${session.userId}.\nApproval access: ${authorized ? "enabled" : "not enabled"}.`,
    });
    return;
  }
  if (command === "/pending") {
    if (!telegramApproverDb.isAuthorized(session.userId)) {
      await callTelegram("sendMessage", { chat_id: message.chat.id, text: "You are not authorized." });
      return;
    }
    const pending = purchaseDb.getAll().filter((purchase) => purchase.approvalStatus === "pending");
    if (pending.length === 0) {
      await callTelegram("sendMessage", { chat_id: message.chat.id, text: "No pending purchases." });
    } else {
      for (const purchase of pending.slice(0, 20)) await sendPurchaseForReview(message.chat.id, purchase);
    }
    return;
  }
  if (command === "/albums") return showCatalog(message.chat.id);
  if (command === "/cart") return showCart(session.userId, message.chat.id);
  if (session.state === "awaiting_receipt") return saveReceipt(message, session);

  await callTelegram("sendMessage", {
    chat_id: message.chat.id,
    text: "Use the buttons below to browse albums or view your cart.",
    reply_markup: mainMenuKeyboard(),
  });
}

async function handleCustomerCallback(
  callback: NonNullable<TelegramUpdate["callback_query"]>,
): Promise<void> {
  const chatId = callback.message?.chat.id;
  if (!chatId) return;
  const session = ensureSession(callback.from, chatId);
  const data = callback.data || "";

  await callTelegram("answerCallbackQuery", { callback_query_id: callback.id });
  if (data === "catalog") return showCatalog(chatId);
  if (data === "cart") return showCart(session.userId, chatId);
  if (data === "checkout") return beginCheckout(session);
  if (data === "cart:clear") {
    telegramSessionDb.upsert({ ...session, state: "browsing", cartAlbumIds: [] });
    return showCart(session.userId, chatId);
  }

  const cartAction = data.match(/^cart:(add|remove):(.+)$/);
  if (!cartAction) return;
  const album = albumDb.getById(cartAction[2]);
  if (!album) {
    await callTelegram("sendMessage", { chat_id: chatId, text: "That album is no longer available." });
    return;
  }

  const cart = new Set(session.cartAlbumIds);
  if (cartAction[1] === "add") cart.add(album.id);
  else cart.delete(album.id);
  telegramSessionDb.upsert({ ...session, state: "browsing", cartAlbumIds: [...cart] });

  await callTelegram("sendMessage", {
    chat_id: chatId,
    text: cartAction[1] === "add" ? `${album.title} added to your cart.` : `${album.title} removed.`,
    reply_markup: mainMenuKeyboard(),
  });
}

async function handleCallback(callback: NonNullable<TelegramUpdate["callback_query"]>) {
  const match = callback.data?.match(/^purchase:(approved|rejected):(\d+)$/);
  if (!match) return handleCustomerCallback(callback);

  const userId = String(callback.from.id);
  if (!telegramApproverDb.isAuthorized(userId)) {
    await callTelegram("answerCallbackQuery", {
      callback_query_id: callback.id,
      text: "You are not authorized to review purchases.",
      show_alert: true,
    });
    return;
  }

  const status = match[1] as PurchaseStatus;
  const purchaseId = Number(match[2]);
  const existing = purchaseDb.getById(purchaseId);
  if (!existing || existing.approvalStatus !== "pending") {
    await callTelegram("answerCallbackQuery", {
      callback_query_id: callback.id,
      text: existing ? `Already ${existing.approvalStatus}.` : "Purchase not found.",
      show_alert: true,
    });
    return;
  }

  const updated = purchaseDb.setStatus(purchaseId, status, userId);
  if (!updated) {
    await callTelegram("answerCallbackQuery", {
      callback_query_id: callback.id,
      text: "This purchase was reviewed by someone else.",
      show_alert: true,
    });
    return;
  }

  await callTelegram("answerCallbackQuery", {
    callback_query_id: callback.id,
    text: `Purchase ${status}.`,
  });
  if (callback.message) {
    await callTelegram("editMessageReplyMarkup", {
      chat_id: callback.message.chat.id,
      message_id: callback.message.message_id,
      reply_markup: { inline_keyboard: [] },
    });
    await callTelegram("sendMessage", {
      chat_id: callback.message.chat.id,
      text: `Purchase #${purchaseId} was ${status} by Telegram user ${userId}.`,
    });
  }

  void notifyCustomerOfDecision(updated).catch((error) => {
    console.error("Telegram customer notification failed:", error);
  });
}