import { getRouterParam, setHeader } from "h3";
import { getAuthContext } from "../../../../utils/auth";
import { requireTelegramBotToken, telegramApiBase, telegramBotApi } from "../../../../utils/telegram";

type TelegramProfilePhotoSize = {
  file_id?: string;
};

type TelegramUserProfilePhotosResult = {
  photos?: TelegramProfilePhotoSize[][];
};

type TelegramGetFileResult = {
  file_path?: string;
};

function parseUserId(input: string) {
  if (!/^\d+$/.test(input)) return null;
  const value = Number(input);
  if (!Number.isSafeInteger(value) || value <= 0) return null;
  return value;
}

export default defineEventHandler(async (event) => {
  await getAuthContext(event);

  const rawUserId = String(getRouterParam(event, "userId") ?? "").trim();
  const userId = parseUserId(rawUserId);
  if (!userId) {
    throw createError({ statusCode: 400, statusMessage: "invalid telegram user id" });
  }

  const profile = await telegramBotApi<TelegramUserProfilePhotosResult>("getUserProfilePhotos", {
    user_id: userId,
    limit: 1,
  });

  const sizes = profile.photos?.[0] ?? [];
  const best = sizes[sizes.length - 1];
  const fileId = String(best?.file_id ?? "").trim();
  if (!fileId) {
    throw createError({ statusCode: 404, statusMessage: "avatar not found" });
  }

  const fileMeta = await telegramBotApi<TelegramGetFileResult>("getFile", { file_id: fileId });
  const filePath = String(fileMeta.file_path ?? "").trim();
  if (!filePath) {
    throw createError({ statusCode: 404, statusMessage: "avatar path not found" });
  }

  const token = requireTelegramBotToken();
  const upstream = await fetch(`${telegramApiBase()}/file/bot${token}/${filePath}`);
  if (!upstream.ok) {
    throw createError({ statusCode: 502, statusMessage: "failed to load telegram avatar" });
  }

  const contentType = upstream.headers.get("content-type") || "image/jpeg";
  const buffer = Buffer.from(await upstream.arrayBuffer());

  setHeader(event, "content-type", contentType);
  setHeader(event, "cache-control", "private, max-age=300");
  return buffer;
});