import path from "node:path";
import { GrammyError } from "grammy";
import { root as fsRoot } from "openclaw/plugin-sdk/file-access-runtime";
import type { TelegramTransport } from "../fetch.js";
import { cacheSticker, getCachedSticker } from "../sticker-cache.js";
import {
  formatErrorMessage,
  logVerbose,
  MediaFetchError,
  resolveTelegramApiBase,
  retryAsync,
  saveMediaBuffer,
  saveRemoteMedia,
  shouldRetryTelegramTransportFallback,
  warn,
} from "./delivery.resolve-media.runtime.js";
import { resolveTelegramMediaPlaceholder } from "./helpers.js";
import type { StickerMetadata, TelegramContext } from "./types.js";

const FILE_TOO_BIG_RE = /file is too big/i;
const GrammyErrorCtor: typeof GrammyError | undefined =
  typeof GrammyError === "function" ? GrammyError : undefined;

function buildTelegramMediaSsrfPolicy(apiRoot?: string, dangerouslyAllowPrivateNetwork?: boolean) {
  const hostnames = ["api.telegram.org"];
  let allowedHostnames: string[] | undefined;
  if (apiRoot) {
    try {
      const customHost = new URL(apiRoot).hostname;
      if (customHost && !hostnames.includes(customHost)) {
        hostnames.push(customHost);
        // A configured custom Bot API host is an explicit operator override and
        // may legitimately live on a private network (for example, self-hosted
        // Bot API or an internal reverse proxy). Keep that host reachable while
        // still enforcing resolved-IP checks for the default public host.
        allowedHostnames = [customHost];
      }
    } catch (err) {
      logVerbose(`telegram: invalid apiRoot URL "${apiRoot}": ${String(err)}`);
    }
  }
  return {
    // Restrict media downloads to the configured Telegram API hosts while still
    // enforcing SSRF checks on the resolved and redirected targets.
    hostnameAllowlist: hostnames,
    ...(allowedHostnames ? { allowedHostnames } : {}),
    ...(dangerouslyAllowPrivateNetwork ? { allowPrivateNetwork: true } : {}),
    allowRfc2544BenchmarkRange: true,
  };
}

/**
 * Returns true if the error is Telegram's "file is too big" error.
 * This happens when trying to download files >20MB via the Bot API.
 * Unlike network errors, this is a permanent error and should not be retried.
 */
function isFileTooBigError(err: unknown): boolean {
  if (GrammyErrorCtor && err instanceof GrammyErrorCtor) {
    return FILE_TOO_BIG_RE.test(err.description);
  }
  return FILE_TOO_BIG_RE.test(formatErrorMessage(err));
}

/**
 * Returns true if the error is a transient network error that should be retried.
 * Returns false for permanent errors like "file is too big" (400 Bad Request).
 */
function isRetryableGetFileError(err: unknown): boolean {
  // Don't retry "file is too big" - it's a permanent 400 error
  if (isFileTooBigError(err)) {
    return false;
  }
  // Retry all other errors (network issues, timeouts, etc.)
  return true;
}

interface MediaMetadata {
  fileRef?:
    | NonNullable<TelegramContext["message"]["photo"]>[number]
    | TelegramContext["message"]["video"]
    | TelegramContext["message"]["video_note"]
    | TelegramContext["message"]["document"]
    | TelegramContext["message"]["audio"]
    | TelegramContext["message"]["voice"];
  fileName?: string;
  mimeType?: string;
}

function resolveMediaMetadata(msg: TelegramContext["message"]): MediaMetadata {
  return {
    fileRef:
      msg.photo?.[msg.photo.length - 1] ??
      msg.video ??
      msg.video_note ??
      msg.document ??
      msg.audio ??
      msg.voice,
    fileName:
      msg.document?.file_name ??
      msg.audio?.file_name ??
      msg.video?.file_name ??
      msg.animation?.file_name,
    mimeType:
      msg.audio?.mime_type ??
      msg.voice?.mime_type ??
      msg.video?.mime_type ??
      msg.document?.mime_type ??
      msg.animation?.mime_type,
  };
}

async function resolveTelegramFileWithRetry(
  ctx: TelegramContext,
): Promise<{ file_path?: string } | null> {
  try {
    return await retryAsync(() => ctx.getFile(), {
      attempts: 3,
      minDelayMs: 1000,
      maxDelayMs: 4000,
      jitter: 0.2,
      label: "telegram:getFile",
      shouldRetry: isRetryableGetFileError,
      onRetry: ({ attempt, maxAttempts }) =>
        logVerbose(`telegram: getFile retry ${attempt}/${maxAttempts}`),
    });
  } catch (err) {
    // Handle "file is too big" separately - Telegram Bot API has a 20MB download limit
    if (isFileTooBigError(err)) {
      logVerbose(
        warn(
          "telegram: getFile failed - file exceeds Telegram Bot API 20MB limit; skipping attachment",
        ),
      );
      return null;
    }
    // All retries exhausted — return null so the message still reaches the agent
    // with a type-based placeholder (e.g. <media:audio>) instead of being dropped.
    logVerbose(`telegram: getFile failed after retries: ${String(err)}`);
    return null;
  }
}

function resolveRequiredTelegramTransport(transport?: TelegramTransport): TelegramTransport {
  if (transport) {
    return transport;
  }
  const resolvedFetch = globalThis.fetch;
  if (!resolvedFetch) {
    throw new Error("fetch is not available; set channels.telegram.proxy in config");
  }
  return {
    fetch: resolvedFetch,
    sourceFetch: resolvedFetch,
    // Caller-owned transport constructed from the globalThis fetch — it owns
    // no dispatcher lifecycle of its own, so close() is a no-op.
    close: async () => {},
  };
}

/** Default idle timeout for Telegram media downloads (30 seconds). */
const TELEGRAM_DOWNLOAD_IDLE_TIMEOUT_MS = 30_000;

function usesTrustedTelegramExplicitProxy(transport: TelegramTransport): boolean {
  return (
    transport.dispatcherAttempts?.some(
      (attempt) => attempt.dispatcherPolicy?.mode === "explicit-proxy",
    ) ?? false
  );
}

function resolveTrustedLocalTelegramRoot(
  filePath: string,
  trustedLocalFileRoots?: readonly string[],
): { rootDir: string; relativePath: string } | null {
  if (!path.isAbsolute(filePath)) {
    return null;
  }
  for (const rootDir of trustedLocalFileRoots ?? []) {
    const relativePath = path.relative(rootDir, filePath);
    if (
      relativePath === "" ||
      relativePath === ".." ||
      relativePath.startsWith(`..${path.sep}`) ||
      path.isAbsolute(relativePath)
    ) {
      continue;
    }
    return { rootDir, relativePath };
  }
  return null;
}

async function downloadAndSaveTelegramFile(params: {
  filePath: string;
  token: string;
  transport?: TelegramTransport;
  maxBytes: number;
  telegramFileName?: string;
  mimeType?: string;
  apiRoot?: string;
  trustedLocalFileRoots?: readonly string[];
  dangerouslyAllowPrivateNetwork?: boolean;
}) {
  const trustedLocalFile = resolveTrustedLocalTelegramRoot(
    params.filePath,
    params.trustedLocalFileRoots,
  );
  if (trustedLocalFile) {
    let localFile;
    try {
      const root = await fsRoot(trustedLocalFile.rootDir);
      localFile = await root.read(trustedLocalFile.relativePath, {
        maxBytes: params.maxBytes,
      });
    } catch (err) {
      throw new MediaFetchError(
        "fetch_failed",
        `Failed to read local Telegram Bot API media from ${params.filePath}: ${formatErrorMessage(err)}`,
        { cause: err },
      );
    }
    return await saveMediaBuffer(
      localFile.buffer,
      params.mimeType,
      "inbound",
      params.maxBytes,
      params.telegramFileName ?? path.basename(localFile.realPath),
    );
  }
  if (path.isAbsolute(params.filePath)) {
    throw new MediaFetchError(
      "fetch_failed",
      `Telegram Bot API returned absolute file path ${params.filePath} outside trustedLocalFileRoots`,
    );
  }
  const transport = resolveRequiredTelegramTransport(params.transport);
  const apiBase = resolveTelegramApiBase(params.apiRoot);
  const url = `${apiBase}/file/bot${params.token}/${params.filePath}`;
  return await saveRemoteMedia({
    url,
    fetchImpl: transport.sourceFetch,
    dispatcherAttempts: transport.dispatcherAttempts,
    trustExplicitProxyDns: usesTrustedTelegramExplicitProxy(transport),
    shouldRetryFetchError: shouldRetryTelegramTransportFallback,
    retry: {
      attempts: 3,
      minDelayMs: 1000,
      maxDelayMs: 4000,
      jitter: 0.2,
      label: "telegram:media-download",
      onRetry: ({ attempt, maxAttempts }) =>
        logVerbose(`telegram: media download retry ${attempt}/${maxAttempts}`),
    },
    filePathHint: params.filePath,
    maxBytes: params.maxBytes,
    readIdleTimeoutMs: TELEGRAM_DOWNLOAD_IDLE_TIMEOUT_MS,
    ssrfPolicy: buildTelegramMediaSsrfPolicy(params.apiRoot, params.dangerouslyAllowPrivateNetwork),
    fallbackContentType: params.mimeType,
    originalFilename: params.telegramFileName,
  });
}

async function resolveStickerMedia(params: {
  msg: TelegramContext["message"];
  ctx: TelegramContext;
  maxBytes: number;
  token: string;
  transport?: TelegramTransport;
  apiRoot?: string;
  trustedLocalFileRoots?: readonly string[];
  dangerouslyAllowPrivateNetwork?: boolean;
}): Promise<
  | {
      path: string;
      contentType?: string;
      placeholder: string;
      stickerMetadata?: StickerMetadata;
    }
  | null
  | undefined
> {
  const { msg, ctx, maxBytes, token, transport } = params;
  if (!msg.sticker) {
    return undefined;
  }
  const sticker = msg.sticker;
  // Skip animated (TGS) and video (WEBM) stickers - only static WEBP supported
  if (sticker.is_animated || sticker.is_video) {
    logVerbose("telegram: skipping animated/video sticker (only static stickers supported)");
    return null;
  }
  if (!sticker.file_id) {
    return null;
  }

  try {
    const file = await resolveTelegramFileWithRetry(ctx);
    if (!file?.file_path) {
      logVerbose("telegram: getFile returned no file_path for sticker");
      return null;
    }
    const saved = await downloadAndSaveTelegramFile({
      filePath: file.file_path,
      token,
      transport,
      maxBytes,
      apiRoot: params.apiRoot,
      trustedLocalFileRoots: params.trustedLocalFileRoots,
      dangerouslyAllowPrivateNetwork: params.dangerouslyAllowPrivateNetwork,
    });

    // Check sticker cache for existing description
    const cached = sticker.file_unique_id ? getCachedSticker(sticker.file_unique_id) : null;
    if (cached) {
      logVerbose(`telegram: sticker cache hit for ${sticker.file_unique_id}`);
      const fileId = sticker.file_id ?? cached.fileId;
      const emoji = sticker.emoji ?? cached.emoji;
      const setName = sticker.set_name ?? cached.setName;
      if (fileId !== cached.fileId || emoji !== cached.emoji || setName !== cached.setName) {
        // Refresh cached sticker metadata on hits so sends/searches use latest file_id.
        cacheSticker({
          ...cached,
          fileId,
          emoji,
          setName,
        });
      }
      return {
        path: saved.path,
        contentType: saved.contentType,
        placeholder: "<media:sticker>",
        stickerMetadata: {
          emoji,
          setName,
          fileId,
          fileUniqueId: sticker.file_unique_id,
          cachedDescription: cached.description,
        },
      };
    }

    // Cache miss - return metadata for vision processing
    return {
      path: saved.path,
      contentType: saved.contentType,
      placeholder: "<media:sticker>",
      stickerMetadata: {
        emoji: sticker.emoji ?? undefined,
        setName: sticker.set_name ?? undefined,
        fileId: sticker.file_id,
        fileUniqueId: sticker.file_unique_id,
      },
    };
  } catch (err) {
    logVerbose(`telegram: failed to process sticker: ${String(err)}`);
    return null;
  }
}

export async function resolveMedia(params: {
  ctx: TelegramContext;
  maxBytes: number;
  token: string;
  transport?: TelegramTransport;
  apiRoot?: string;
  trustedLocalFileRoots?: readonly string[];
  dangerouslyAllowPrivateNetwork?: boolean;
}): Promise<{
  path: string;
  contentType?: string;
  placeholder: string;
  stickerMetadata?: StickerMetadata;
} | null> {
  const {
    ctx,
    maxBytes,
    token,
    transport,
    apiRoot,
    trustedLocalFileRoots,
    dangerouslyAllowPrivateNetwork,
  } = params;
  const msg = ctx.message;
  const stickerResolved = await resolveStickerMedia({
    msg,
    ctx,
    maxBytes,
    token,
    transport,
    apiRoot,
    trustedLocalFileRoots,
    dangerouslyAllowPrivateNetwork,
  });
  if (stickerResolved !== undefined) {
    return stickerResolved;
  }

  const metadata = resolveMediaMetadata(msg);
  const m = metadata.fileRef;
  if (!m?.file_id) {
    return null;
  }

  const file = await resolveTelegramFileWithRetry(ctx);
  if (!file) {
    return null;
  }
  if (!file.file_path) {
    throw new Error("Telegram getFile returned no file_path");
  }
  const saved = await downloadAndSaveTelegramFile({
    filePath: file.file_path,
    token,
    transport,
    maxBytes,
    telegramFileName: metadata.fileName,
    mimeType: metadata.mimeType,
    apiRoot,
    trustedLocalFileRoots,
    dangerouslyAllowPrivateNetwork,
  });
  const placeholder = resolveTelegramMediaPlaceholder(msg) ?? "<media:document>";
  return { path: saved.path, contentType: saved.contentType, placeholder };
}
