/**
 * useUserPreferences — loads user preferences from API and syncs with uiStore.
 *
 * On load: applies server-side preferences to the Zustand uiStore (theme, locale,
 * sidebar state, AI sidebar tab, etc.).
 * On change: persists uiStore state to the server via upsert mutation.
 */

import { useEffect, useCallback } from 'react';
import { useUIStore, type Theme, type Locale, type AISidebarTab } from '@/store/uiStore';
import {
  useUserPreferences,
  useUpsertUserPreference,
  useDeleteUserPreference,
} from '@/api/userPreferences';

// Known preference keys that map to uiStore fields
const PREF_KEYS = {
  THEME: 'theme',
  LOCALE: 'locale',
  SIDEBAR_OPEN: 'sidebar_open',
  AI_SIDEBAR_COLLAPSED: 'ai_sidebar_collapsed',
  AI_SIDEBAR_TAB: 'ai_sidebar_tab',
  MESSAGE_SIDEBAR_COLLAPSED: 'message_sidebar_collapsed',
  SUGGESTION_SIDEBAR_OPEN: 'suggestion_sidebar_open',
} as const;

export function useUserPreferencesSync() {
  const { data, isLoading } = useUserPreferences();
  const upsertMutation = useUpsertUserPreference();
  const deleteMutation = useDeleteUserPreference();

  const {
    theme,
    locale,
    sidebarOpen,
    aiSidebarCollapsed,
    aiSidebarTab,
    messageSidebarCollapsed,
    suggestionSidebarOpen: _suggestionSidebarOpen,
    setTheme,
    setLocale,
    setSidebarOpen,
    setAISidebarCollapsed,
    setAISidebarTab,
    setMessageSidebarCollapsed,
  } = useUIStore();

  // Apply server preferences to uiStore on initial load
  useEffect(() => {
    if (!data?.preferences) return;

    const prefMap = new Map<string, unknown>();
    for (const pref of data.preferences) {
      prefMap.set(pref.key, pref.value);
    }

    // Only apply if the server has a value — don't override local defaults with null
    if (prefMap.has(PREF_KEYS.THEME)) {
      const serverTheme = prefMap.get(PREF_KEYS.THEME) as Theme;
      if (serverTheme && serverTheme !== theme) {
        setTheme(serverTheme);
      }
    }
    if (prefMap.has(PREF_KEYS.LOCALE)) {
      const serverLocale = prefMap.get(PREF_KEYS.LOCALE) as Locale;
      if (serverLocale && serverLocale !== locale) {
        setLocale(serverLocale);
      }
    }
    if (prefMap.has(PREF_KEYS.SIDEBAR_OPEN)) {
      const serverSidebar = prefMap.get(PREF_KEYS.SIDEBAR_OPEN) as boolean;
      if (serverSidebar !== sidebarOpen) {
        setSidebarOpen(serverSidebar);
      }
    }
    if (prefMap.has(PREF_KEYS.AI_SIDEBAR_COLLAPSED)) {
      const serverCollapsed = prefMap.get(
        PREF_KEYS.AI_SIDEBAR_COLLAPSED
      ) as boolean;
      if (serverCollapsed !== aiSidebarCollapsed) {
        setAISidebarCollapsed(serverCollapsed);
      }
    }
    if (prefMap.has(PREF_KEYS.AI_SIDEBAR_TAB)) {
      const serverTab = prefMap.get(PREF_KEYS.AI_SIDEBAR_TAB) as AISidebarTab;
      if (serverTab && serverTab !== aiSidebarTab) {
        setAISidebarTab(serverTab);
      }
    }
    if (prefMap.has(PREF_KEYS.MESSAGE_SIDEBAR_COLLAPSED)) {
      const serverCollapsed = prefMap.get(
        PREF_KEYS.MESSAGE_SIDEBAR_COLLAPSED
      ) as boolean;
      if (serverCollapsed !== messageSidebarCollapsed) {
        setMessageSidebarCollapsed(serverCollapsed);
      }
    }
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [data]);

  // Persist a single preference to the server
  const savePreference = useCallback(
    (key: string, value: unknown) => {
      upsertMutation.mutate({ key, value });
    },
    [upsertMutation]
  );

  // Delete a preference from the server
  const removePreference = useCallback(
    (key: string) => {
      deleteMutation.mutate(key);
    },
    [deleteMutation]
  );

  return {
    isLoading,
    savePreference,
    removePreference,
    isSaving: upsertMutation.isPending,
    isDeleting: deleteMutation.isPending,
  };
}