import { getQuery, setHeader } from "h3";
import { existsSync } from "node:fs";
import { mkdir, readFile, writeFile } from "node:fs/promises";
import path from "node:path";
import { getAuthContext } from "../../../utils/auth";
import { prisma } from "../../../utils/prisma";
import { requireTelegramBotToken, telegramApiBase, telegramBotApi } from "../../../utils/telegram";

const TELEGRAM_FILE_MARKER = "tg-file:";
const AVATAR_CACHE_DIR = path.join(process.cwd(), ".data", "telegram-avatars");

type TelegramFileMeta = {
  file_id: string;
  file_path?: string;
};

type TelegramChatPhoto = {
  small_file_id?: string;
  big_file_id?: string;
};

type TelegramGetChatResponse = {
  ok?: boolean;
  result?: {
    photo?: TelegramChatPhoto;
  };
};

type TelegramProfilePhotoSize = {
  file_id?: string;
};

type TelegramGetUserProfilePhotosResponse = {
  ok?: boolean;
  result?: {
    photos?: TelegramProfilePhotoSize[][];
  };
};

function parseTelegramFileId(avatarUrl: string | null | undefined) {
  const raw = String(avatarUrl ?? "").trim();
  if (!raw.startsWith(TELEGRAM_FILE_MARKER)) return null;
  const fileId = raw.slice(TELEGRAM_FILE_MARKER.length).trim();
  return fileId || null;
}

function sanitizeCacheKey(input: string) {
  return input.replace(/[^a-zA-Z0-9._-]/g, "_");
}

async function fetchTelegramAvatarFileIdByExternalId(externalId: string) {
  const getChatRes = await telegramBotApi<TelegramGetChatResponse["result"]>("getChat", {
    chat_id: externalId,
  });
  const fromChat = String(getChatRes?.photo?.small_file_id ?? getChatRes?.photo?.big_file_id ?? "").trim();
  if (fromChat) return fromChat;

  const getUserPhotosRes = await telegramBotApi<TelegramGetUserProfilePhotosResponse["result"]>("getUserProfilePhotos", {
    user_id: externalId,
    limit: 1,
  });
  const firstPhotoSizes = Array.isArray(getUserPhotosRes?.photos?.[0]) ? getUserPhotosRes.photos[0] : [];
  const candidate = String(firstPhotoSizes.at(-1)?.file_id ?? firstPhotoSizes[0]?.file_id ?? "").trim();
  return candidate || null;
}

export default defineEventHandler(async (event) => {
  const auth = await getAuthContext(event);
  const query = getQuery(event);
  const contactId = String(query.contactId ?? "").trim();

  if (!contactId) {
    throw createError({ statusCode: 400, statusMessage: "contactId is required" });
  }

  const contact = await prisma.contact.findFirst({
    where: {
      id: contactId,
      teamId: auth.teamId,
    },
    select: {
      avatarUrl: true,
    },
  });

  if (!contact) {
    throw createError({ statusCode: 404, statusMessage: "contact not found" });
  }

  let fileId = parseTelegramFileId(contact.avatarUrl);
  if (!fileId) {
    const identity = await prisma.omniContactIdentity.findFirst({
      where: {
        teamId: auth.teamId,
        contactId,
        channel: "TELEGRAM",
      },
      select: {
        externalId: true,
      },
      orderBy: {
        updatedAt: "desc",
      },
    });

    if (!identity?.externalId) {
      throw createError({ statusCode: 404, statusMessage: "telegram identity is missing" });
    }

    const fetchedFileId = await fetchTelegramAvatarFileIdByExternalId(identity.externalId);
    if (!fetchedFileId) {
      throw createError({ statusCode: 404, statusMessage: "telegram avatar is missing" });
    }

    fileId = fetchedFileId;
    await prisma.contact.update({
      where: { id: contactId },
      data: { avatarUrl: `${TELEGRAM_FILE_MARKER}${fileId}` },
    });
  }

  const cacheKey = sanitizeCacheKey(fileId);
  const cacheBodyPath = path.join(AVATAR_CACHE_DIR, `${cacheKey}.img`);
  const cacheMetaPath = path.join(AVATAR_CACHE_DIR, `${cacheKey}.meta`);

  if (existsSync(cacheBodyPath) && existsSync(cacheMetaPath)) {
    const cachedBody = await readFile(cacheBodyPath);
    const cachedContentType = (await readFile(cacheMetaPath, "utf8")).trim() || "image/jpeg";

    setHeader(event, "content-type", cachedContentType);
    setHeader(event, "cache-control", "private, max-age=300");
    setHeader(event, "content-length", cachedBody.length);
    return cachedBody;
  }

  const meta = await telegramBotApi<TelegramFileMeta>("getFile", { file_id: fileId });
  const filePath = String(meta?.file_path ?? "").trim();
  if (!filePath) {
    throw createError({ statusCode: 502, statusMessage: "telegram file path is unavailable" });
  }

  const apiBase = telegramApiBase().replace(/\/+$/, "");
  const token = requireTelegramBotToken();
  const remote = await fetch(`${apiBase}/file/bot${token}/${filePath}`);
  if (!remote.ok) {
    throw createError({ statusCode: 502, statusMessage: `telegram file fetch failed (${remote.status})` });
  }

  const contentType = remote.headers.get("content-type") || "image/jpeg";
  const contentLength = remote.headers.get("content-length");
  const body = Buffer.from(await remote.arrayBuffer());

  await mkdir(AVATAR_CACHE_DIR, { recursive: true });
  await writeFile(cacheBodyPath, body);
  await writeFile(cacheMetaPath, contentType, "utf8");

  setHeader(event, "content-type", contentType);
  setHeader(event, "cache-control", "private, max-age=300");
  if (contentLength) {
    const parsedLength = Number(contentLength);
    if (Number.isFinite(parsedLength) && parsedLength >= 0) {
      setHeader(event, "content-length", parsedLength);
    }
  }

  return body;
});