import { useState, useRef, useCallback, useEffect } from 'react';
import { useInput } from 'ink';
import { GeminiClient } from '../../core/gemini-client.js';
import { type Chat, type PartListUnion } from '@google/genai';
import { HistoryItem } from '../types.js';
import { processGeminiStream } from '../../core/gemini-stream.js';
import { StreamingState } from '../../core/gemini-stream.js';

const addHistoryItem = (
  setHistory: React.Dispatch<React.SetStateAction<HistoryItem[]>>,
  itemData: Omit<HistoryItem, 'id'>,
  id: number,
) => {
  setHistory((prevHistory) => [
    ...prevHistory,
    { ...itemData, id } as HistoryItem,
  ]);
};

export const useGeminiStream = (
  setHistory: React.Dispatch<React.SetStateAction<HistoryItem[]>>,
) => {
  const [streamingState, setStreamingState] = useState<StreamingState>(
    StreamingState.Idle,
  );
  const [initError, setInitError] = useState<string | null>(null);
  const abortControllerRef = useRef<AbortController | null>(null);
  const currentToolGroupIdRef = useRef<number | null>(null);
  const chatSessionRef = useRef<Chat | null>(null);
  const geminiClientRef = useRef<GeminiClient | null>(null);
  const messageIdCounterRef = useRef(0);

  // Initialize Client Effect (remains the same)
  useEffect(() => {
    setInitError(null);
    if (!geminiClientRef.current) {
      try {
        geminiClientRef.current = new GeminiClient();
      } catch (error: any) {
        setInitError(
          `Failed to initialize client: ${error.message || 'Unknown error'}`,
        );
      }
    }
  }, []);

  // Input Handling Effect (remains the same)
  useInput((input, key) => {
    if (streamingState === StreamingState.Responding && key.escape) {
      abortControllerRef.current?.abort();
    }
  });

  // ID Generation Callback (remains the same)
  const getNextMessageId = useCallback((baseTimestamp: number): number => {
    messageIdCounterRef.current += 1;
    return baseTimestamp + messageIdCounterRef.current;
  }, []);

  // Submit Query Callback (updated to call processGeminiStream)
  const submitQuery = useCallback(
    async (query: PartListUnion) => {
      if (streamingState === StreamingState.Responding) {
        // No-op if already going.
        return;
      }

      if (typeof query === 'string' && query.toString().trim().length === 0) {
        return;
      }

      const userMessageTimestamp = Date.now();
      const client = geminiClientRef.current;
      if (!client) {
        setInitError('Gemini client is not available.');
        return;
      }

      if (!chatSessionRef.current) {
        chatSessionRef.current = await client.startChat();
      }

      // Reset state
      setStreamingState(StreamingState.Responding);
      setInitError(null);
      currentToolGroupIdRef.current = null;
      messageIdCounterRef.current = 0;
      const chat = chatSessionRef.current;

      try {
        // Add user message
        if (typeof query === 'string') {
          const trimmedQuery = query.toString();
          addHistoryItem(
            setHistory,
            { type: 'user', text: trimmedQuery },
            userMessageTimestamp,
          );
        } else if (
          // HACK to detect errored function responses.
          typeof query === 'object' &&
          query !== null &&
          !Array.isArray(query) && // Ensure it's a single Part object
          'functionResponse' in query && // Check if it's a function response Part
          query.functionResponse?.response && // Check if response object exists
          'error' in query.functionResponse.response // Check specifically for the 'error' key
        ) {
          const history = chat.getHistory();
          history.push({ role: 'user', parts: [query] });
          return;
        }

        // Prepare for streaming
        abortControllerRef.current = new AbortController();
        const signal = abortControllerRef.current.signal;

        // --- Delegate to Stream Processor ---

        const stream = client.sendMessageStream(chat, query, signal);

        const addHistoryItemFromStream = (
          itemData: Omit<HistoryItem, 'id'>,
          id: number,
        ) => {
          addHistoryItem(setHistory, itemData, id);
        };
        const getStreamMessageId = () => getNextMessageId(userMessageTimestamp);

        // Call the renamed processor function
        await processGeminiStream({
          stream,
          signal,
          setHistory,
          submitQuery,
          getNextMessageId: getStreamMessageId,
          addHistoryItem: addHistoryItemFromStream,
          currentToolGroupIdRef,
        });
      } catch (error: any) {
        // (Error handling for stream initiation remains the same)
        console.error('Error initiating stream:', error);
        if (error.name !== 'AbortError') {
          // Use historyUpdater's function potentially? Or keep addHistoryItem here?
          // Keeping addHistoryItem here for direct errors from this scope.
          addHistoryItem(
            setHistory,
            {
              type: 'error',
              text: `[Error starting stream: ${error.message}]`,
            },
            getNextMessageId(userMessageTimestamp),
          );
        }
      } finally {
        abortControllerRef.current = null;
        setStreamingState(StreamingState.Idle);
      }
    },
    [setStreamingState, setHistory, initError, getNextMessageId],
  );

  return { streamingState, submitQuery, initError };
};