import { useState, useEffect, useCallback } from 'react';
import { eq } from 'drizzle-orm';
import { useDatabase } from './useDatabase';
import { currentUser, appState } from '../db/schema';

// ─── Types ─────────────────────────────────────────────────────────────────────

interface UseThemeModeReturn {
  isDark: boolean;
  toggleTheme: () => Promise<void>;
  setDark: (isDark: boolean) => Promise<void>;
  loading: boolean;
}

// ─── Hook ──────────────────────────────────────────────────────────────────────
// Reads the dark_mode preference. It first checks the app_state table (key:
// "dark_mode") and falls back to system default (false = light).

const DARK_MODE_KEY = 'dark_mode';

export function useThemeMode(): UseThemeModeReturn {
  const { db } = useDatabase();
  const [isDark, setIsDark] = useState(false);
  const [loading, setLoading] = useState(true);

  // ── Load theme preference ────────────────────────────────────────────────────

  const loadTheme = useCallback(async () => {
    try {
      const rows = await db
        .select()
        .from(appState)
        .where(eq(appState.key, DARK_MODE_KEY))
        .all();

      if (rows.length > 0) {
        setIsDark(rows[0].value === 'true');
      } else {
        // Check current_user table for darkMode field
        const userRows = await db.select().from(currentUser).limit(1).all();
        if (userRows.length > 0) {
          const userData = userRows[0] as Record<string, unknown>;
          if (typeof userData.darkMode === 'number') {
            setIsDark(userData.darkMode === 1);
          } else if (typeof userData.darkMode === 'boolean') {
            setIsDark(userData.darkMode);
          }
        }
      }
    } catch (error) {
      console.error('[useThemeMode] Failed to load theme preference:', error);
      setIsDark(false);
    } finally {
      setLoading(false);
    }
  }, [db]);

  useEffect(() => {
    loadTheme();
  }, [loadTheme]);

  // ── Toggle theme ─────────────────────────────────────────────────────────────

  const toggleTheme = useCallback(async () => {
    const newValue = !isDark;
    await setDark(newValue);
  }, [isDark]);

  // ── Set dark mode explicitly ─────────────────────────────────────────────────

  const setDark = useCallback(
    async (dark: boolean) => {
      try {
        setIsDark(dark);

        // Upsert into app_state table
        await db
          .insert(appState)
          .values({ key: DARK_MODE_KEY, value: String(dark) })
          .onConflictDoUpdate({
            target: appState.key,
            set: { value: String(dark), updatedAt: new Date().toISOString() },
          })
          .run();
      } catch (error) {
        console.error('[useThemeMode] Failed to save theme preference:', error);
      }
    },
    [db],
  );

  return {
    isDark,
    toggleTheme,
    setDark,
    loading,
  };
}