import React from 'react';
import { LOCAL_STORAGE_KEY, getDefaultState } from '../constants/defaults.js';

export const useAppState = () => {
  const [appState, setAppState] = React.useState(getDefaultState);
  const [isLoaded, setIsLoaded] = React.useState(false);

  React.useEffect(() => {
    try {
      const savedState = window.localStorage.getItem(LOCAL_STORAGE_KEY);
      if (savedState) {
        const parsedState = JSON.parse(savedState);
        const defaults = getDefaultState();
        setAppState({
          ...defaults,
          ...parsedState,
          pkParams: {...defaults.pkParams, ...parsedState.pkParams},
          uiSettings: {...defaults.uiSettings, ...parsedState.uiSettings},
        });
      }
    } catch (error) {
      console.error("Failed to load state", error);
    }
    setIsLoaded(true);
  }, []);

  React.useEffect(() => {
    if (isLoaded) {
      try {
        const stateToSave = {
          pkParams: appState.pkParams,
          doses: appState.doses,
          steadyStateConfig: appState.steadyStateConfig,
          therapeuticRange: appState.therapeuticRange,
          doseIncrement: appState.doseIncrement,
          uiSettings: appState.uiSettings,
        };
        window.localStorage.setItem(LOCAL_STORAGE_KEY, JSON.stringify(stateToSave));
      } catch (error) {
        console.error("Failed to save state", error);
      }
    }
  }, [appState, isLoaded]);

  const updateState = (key, value) => {
    setAppState(prev => ({ ...prev, [key]: value }));
  };

  const updateNestedState = (parentKey, childKey, value) => {
    setAppState(prev => ({
      ...prev,
      [parentKey]: { ...prev[parentKey], [childKey]: value }
    }));
  };

  const updateUiSetting = (key, value) => {
    const newUiSettings = { ...appState.uiSettings, [key]: value };
    if (key === 'simulationDays') {
      const simDaysNum = parseInt(value, 10) || 1;
      const dispDaysNum = parseInt(newUiSettings.displayedDays, 10) || 1;
      if (dispDaysNum > simDaysNum) {
        newUiSettings.displayedDays = String(simDaysNum);
      }
    }
    setAppState(prev => ({ ...prev, uiSettings: newUiSettings }));
  };

  const handleReset = () => {
    if (window.confirm("Bist du sicher, dass du alle Einstellungen auf die Standardwerte zurücksetzen möchtest? Dies kann nicht rückgängig gemacht werden.")) {
      window.localStorage.removeItem(LOCAL_STORAGE_KEY);
      window.location.reload();
    }
  };

  return {
    appState,
    isLoaded,
    updateState,
    updateNestedState,
    updateUiSetting,
    handleReset
  };
};