Update App.js, new modular structure

src/hooks/useAppState.js

@@ -0,0 +1,83 @@
+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
+  };
+};