import { useEffect, useRef } from "react";
import {
  useChatToolStore,
  type ChatToolAction,
} from "@/store/chatToolStore";

/**
 * Subscribe to chat tool actions and invoke `handler` for each new action.
 *
 * Usage (inside a component with map access):
 * ```ts
 * useChatToolActionHandler((action) => {
 *   switch (action.type) {
 *     case "locate_features": handleLocateFeatures(action.ids, action.layer, action.geometryKind); break;
 *     case "view_history": openHistoryPanel(action.featureInfos, action.dataType); break;
 *     case "view_scada":   openScadaPanel(action.featureInfos); break;
 *   }
 * });
 * ```
 */
export function useChatToolActionHandler(
  handler: (action: ChatToolAction) => void,
) {
  const handlerRef = useRef(handler);
  const lastHandledSeqRef = useRef(0);

  useEffect(() => {
    handlerRef.current = handler;
  }, [handler]);

  useEffect(() => {
    const initialState = useChatToolStore.getState();
    if (
      initialState.lastAction &&
      initialState.actionSeq > lastHandledSeqRef.current &&
      Date.now() - initialState.lastActionAt < 5000
    ) {
      lastHandledSeqRef.current = initialState.actionSeq;
      handlerRef.current(initialState.lastAction);
    } else {
      lastHandledSeqRef.current = initialState.actionSeq;
    }

    const unsubscribe = useChatToolStore.subscribe(
      (state, prevState) => {
        if (
          state.actionSeq !== prevState.actionSeq &&
          state.lastAction &&
          state.actionSeq > lastHandledSeqRef.current
        ) {
          lastHandledSeqRef.current = state.actionSeq;
          handlerRef.current(state.lastAction);
        }
      },
    );
    return unsubscribe;
  }, []);
}