import { useState, useEffect, useCallback } from 'react';
import { supabase } from '@/lib/supabaseClient';
import { usernameSchema } from '@/lib/validation';
import { useDebounce } from './useDebounce';

export type UsernameValidationState = {
  isValid: boolean;
  isAvailable: boolean | null;
  isChecking: boolean;
  error: string | null;
};

export function useUsernameValidation(username: string, currentUsername?: string) {
  const [state, setState] = useState<UsernameValidationState>({
    isValid: false,
    isAvailable: null,
    isChecking: false,
    error: null,
  });

  const debouncedUsername = useDebounce(username, 500);

  const checkUsernameAvailability = useCallback(async (normalizedUsername: string) => {
    try {
      const { data, error } = await supabase
        .from('profiles')
        .select('username')
        .eq('username', normalizedUsername)
        .maybeSingle();

      if (error) throw error;

      const isAvailable = !data;
      setState({
        isValid: isAvailable,
        isAvailable,
        isChecking: false,
        error: isAvailable ? null : 'Username is already taken',
      });
    } catch (error: unknown) {
      setState({
        isValid: false,
        isAvailable: null,
        isChecking: false,
        error: 'Error checking username availability',
      });
    }
  }, []);

  useEffect(() => {
    if (!debouncedUsername || debouncedUsername === currentUsername) {
      setState({
        isValid: debouncedUsername === currentUsername,
        isAvailable: null,
        isChecking: false,
        error: null,
      });
      return;
    }

    // Validate format first
    const validation = usernameSchema.safeParse(debouncedUsername);
    if (!validation.success) {
      setState({
        isValid: false,
        isAvailable: null,
        isChecking: false,
        error: validation.error.issues[0].message,
      });
      return;
    }

    // Check availability
    setState(prev => ({ ...prev, isChecking: true, error: null }));
    
    checkUsernameAvailability(validation.data);
  }, [debouncedUsername, currentUsername, checkUsernameAvailability]);

  return state;
}