import fs from "node:fs";
import type { Message } from "@grammyjs/types";
import { formatLocationText } from "openclaw/plugin-sdk/channel-inbound";
import type { MsgContext } from "openclaw/plugin-sdk/reply-runtime";
import { logVerbose } from "openclaw/plugin-sdk/runtime-env";
import { replaceFileAtomicSync } from "openclaw/plugin-sdk/security-runtime";
import { resolveTelegramPrimaryMedia } from "./bot/body-helpers.js";
import {
  buildSenderName,
  extractTelegramLocation,
  getTelegramTextParts,
  normalizeForwardedContext,
} from "./bot/helpers.js";

export type TelegramReplyChainEntry = NonNullable<MsgContext["ReplyChain"]>[number];

export type TelegramCachedMessageNode = TelegramReplyChainEntry & {
  sourceMessage: Message;
};

export type TelegramMessageCache = {
  record: (params: {
    accountId: string;
    chatId: string | number;
    msg: Message;
    threadId?: number;
  }) => TelegramCachedMessageNode | null;
  get: (params: {
    accountId: string;
    chatId: string | number;
    messageId?: string;
  }) => TelegramCachedMessageNode | null;
};

type MessageWithExternalReply = Message & { external_reply?: Message };

type TelegramMessageCacheBucket = {
  messages: Map<string, TelegramCachedMessageNode>;
};

const DEFAULT_MAX_MESSAGES = 5000;
const persistedMessageCacheBuckets = new Map<string, TelegramMessageCacheBucket>();

function telegramMessageCacheKey(params: {
  accountId: string;
  chatId: string | number;
  messageId: string;
}) {
  return `${params.accountId}:${params.chatId}:${params.messageId}`;
}

export function resolveTelegramMessageCachePath(storePath: string): string {
  return `${storePath}.telegram-messages.json`;
}

function resolveReplyMessage(msg: Message): Message | undefined {
  const externalReply = (msg as MessageWithExternalReply).external_reply;
  return msg.reply_to_message ?? externalReply;
}

function resolveMessageBody(msg: Message): string | undefined {
  const text = getTelegramTextParts(msg).text.trim();
  if (text) {
    return text;
  }
  const location = extractTelegramLocation(msg);
  if (location) {
    return formatLocationText(location);
  }
  return resolveTelegramPrimaryMedia(msg)?.placeholder;
}

function resolveMediaType(placeholder?: string): string | undefined {
  return placeholder?.match(/^<media:([^>]+)>$/)?.[1];
}

function normalizeMessageNode(
  msg: Message,
  params: { threadId?: number },
): TelegramCachedMessageNode | null {
  if (typeof msg.message_id !== "number") {
    return null;
  }
  const media = resolveTelegramPrimaryMedia(msg);
  const fileId = media?.fileRef.file_id;
  const forwardedFrom = normalizeForwardedContext(msg);
  const replyMessage = resolveReplyMessage(msg);
  const body = resolveMessageBody(msg);
  return {
    sourceMessage: msg,
    messageId: String(msg.message_id),
    sender: buildSenderName(msg) ?? "unknown sender",
    ...(msg.from?.id != null ? { senderId: String(msg.from.id) } : {}),
    ...(msg.from?.username ? { senderUsername: msg.from.username } : {}),
    ...(msg.date ? { timestamp: msg.date * 1000 } : {}),
    ...(body ? { body } : {}),
    ...(media ? { mediaType: resolveMediaType(media.placeholder) ?? media.placeholder } : {}),
    ...(fileId ? { mediaRef: `telegram:file/${fileId}` } : {}),
    ...(replyMessage?.message_id != null ? { replyToId: String(replyMessage.message_id) } : {}),
    ...(forwardedFrom?.from ? { forwardedFrom: forwardedFrom.from } : {}),
    ...(forwardedFrom?.fromId ? { forwardedFromId: forwardedFrom.fromId } : {}),
    ...(forwardedFrom?.fromUsername ? { forwardedFromUsername: forwardedFrom.fromUsername } : {}),
    ...(forwardedFrom?.date ? { forwardedDate: forwardedFrom.date * 1000 } : {}),
    ...(params.threadId != null ? { threadId: String(params.threadId) } : {}),
  };
}

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === "object" && value !== null && !Array.isArray(value);
}

function isString(value: unknown): value is string {
  return typeof value === "string" && value.length > 0;
}

function readOptionalString(record: Record<string, unknown>, key: string): string | undefined {
  const value = record[key];
  return isString(value) ? value : undefined;
}

function isTelegramSourceMessage(value: unknown): value is Message {
  return (
    isRecord(value) &&
    typeof value.message_id === "number" &&
    Number.isFinite(value.message_id) &&
    typeof value.date === "number" &&
    Number.isFinite(value.date)
  );
}

function parsePersistedNode(value: unknown): TelegramCachedMessageNode | null {
  if (!isRecord(value) || !isTelegramSourceMessage(value.sourceMessage)) {
    return null;
  }
  const threadId = Number(readOptionalString(value, "threadId"));
  return normalizeMessageNode(value.sourceMessage, Number.isFinite(threadId) ? { threadId } : {});
}

function readPersistedMessages(filePath: string, maxMessages: number) {
  const messages = new Map<string, TelegramCachedMessageNode>();
  if (!fs.existsSync(filePath)) {
    return messages;
  }
  try {
    const parsed = JSON.parse(fs.readFileSync(filePath, "utf-8"));
    if (!Array.isArray(parsed)) {
      return messages;
    }
    for (const entry of parsed.slice(-maxMessages)) {
      if (!isRecord(entry) || !isString(entry.key)) {
        continue;
      }
      const node = parsePersistedNode(entry.node);
      if (node) {
        messages.set(entry.key, node);
      }
    }
  } catch (error) {
    logVerbose(`telegram: failed to read message cache: ${String(error)}`);
  }
  return messages;
}

function persistMessages(params: {
  messages: Map<string, TelegramCachedMessageNode>;
  persistedPath?: string;
}) {
  const { persistedPath, messages } = params;
  if (!persistedPath) {
    return;
  }
  if (messages.size === 0) {
    fs.rmSync(persistedPath, { force: true });
    return;
  }
  const serialized = Array.from(messages, ([key, node]) => ({
    key,
    node: {
      sourceMessage: node.sourceMessage,
      ...(node.threadId ? { threadId: node.threadId } : {}),
    },
  }));
  replaceFileAtomicSync({
    filePath: persistedPath,
    content: JSON.stringify(serialized),
    tempPrefix: ".telegram-message-cache",
  });
}

function resolveMessageCacheBucket(params: {
  persistedPath?: string;
  maxMessages: number;
}): TelegramMessageCacheBucket {
  const { persistedPath, maxMessages } = params;
  if (!persistedPath) {
    return { messages: new Map<string, TelegramCachedMessageNode>() };
  }
  const existing = persistedMessageCacheBuckets.get(persistedPath);
  if (existing) {
    if (!fs.existsSync(persistedPath)) {
      existing.messages.clear();
    }
    return existing;
  }
  const bucket = {
    messages: readPersistedMessages(persistedPath, maxMessages),
  };
  persistedMessageCacheBuckets.set(persistedPath, bucket);
  return bucket;
}

export function createTelegramMessageCache(params?: {
  maxMessages?: number;
  persistedPath?: string;
}): TelegramMessageCache {
  const maxMessages = params?.maxMessages ?? DEFAULT_MAX_MESSAGES;
  const { messages } = resolveMessageCacheBucket({
    persistedPath: params?.persistedPath,
    maxMessages,
  });

  const get: TelegramMessageCache["get"] = ({ accountId, chatId, messageId }) => {
    if (!messageId) {
      return null;
    }
    const key = telegramMessageCacheKey({ accountId, chatId, messageId });
    const entry = messages.get(key);
    if (!entry) {
      return null;
    }
    messages.delete(key);
    messages.set(key, entry);
    return entry;
  };

  return {
    record: ({ accountId, chatId, msg, threadId }) => {
      const entry = normalizeMessageNode(msg, { threadId });
      if (!entry?.messageId) {
        return null;
      }
      const key = telegramMessageCacheKey({ accountId, chatId, messageId: entry.messageId });
      messages.delete(key);
      messages.set(key, entry);
      while (messages.size > maxMessages) {
        const oldest = messages.keys().next().value;
        if (oldest === undefined) {
          break;
        }
        messages.delete(oldest);
      }
      try {
        persistMessages({ messages, persistedPath: params?.persistedPath });
      } catch (error) {
        logVerbose(`telegram: failed to persist message cache: ${String(error)}`);
      }
      return entry;
    },
    get,
  };
}

export function buildTelegramReplyChain(params: {
  cache: TelegramMessageCache;
  accountId: string;
  chatId: string | number;
  msg: Message;
  maxDepth?: number;
}): TelegramCachedMessageNode[] {
  const replyMessage = resolveReplyMessage(params.msg);
  if (!replyMessage?.message_id) {
    return [];
  }
  const maxDepth = params.maxDepth ?? 4;
  const visited = new Set<string>();
  const chain: TelegramCachedMessageNode[] = [];
  let current =
    params.cache.get({
      accountId: params.accountId,
      chatId: params.chatId,
      messageId: String(replyMessage.message_id),
    }) ?? normalizeMessageNode(replyMessage, {});

  while (current?.messageId && chain.length < maxDepth && !visited.has(current.messageId)) {
    visited.add(current.messageId);
    chain.push(current);
    current = params.cache.get({
      accountId: params.accountId,
      chatId: params.chatId,
      messageId: current.replyToId,
    });
  }

  return chain;
}