import { useState, useRef } from 'react';
import { searchUsers, ensureUserExists, type UserSummary } from '@/services/userApi';

/**
 * Custom Hook: useUserSearch
 * 
 * Purpose: Manages user search functionality with debouncing
 * 
 * Responsibilities:
 * - Handles user search with @ prefix
 * - Debounces search requests
 * - Manages search results and loading states
 * - Validates and ensures users exist in database
 */
export function useUserSearch() {
  const [searchResults, setSearchResults] = useState<UserSummary[]>([]);
  const [searchLoading, setSearchLoading] = useState(false);
  const searchTimer = useRef<any>(null);

  const searchUsersDebounced = async (searchTerm: string, limit: number = 10) => {
    if (searchTimer.current) {
      clearTimeout(searchTimer.current);
    }

    if (!searchTerm || !searchTerm.startsWith('@') || searchTerm.length < 2) {
      setSearchResults([]);
      setSearchLoading(false);
      return;
    }

    setSearchLoading(true);
    searchTimer.current = setTimeout(async () => {
      try {
        const term = searchTerm.slice(1); // remove leading '@'
        const response = await searchUsers(term, limit);
        const results = response.data?.data || [];
        setSearchResults(results);
      } catch (err) {
        console.error('User search failed:', err);
        setSearchResults([]);
      } finally {
        setSearchLoading(false);
      }
    }, 300);
  };

  const clearSearch = () => {
    if (searchTimer.current) {
      clearTimeout(searchTimer.current);
    }
    setSearchResults([]);
    setSearchLoading(false);
  };

  const ensureUser = async (user: UserSummary) => {
    try {
      const dbUser = await ensureUserExists({
        userId: user.userId,
        email: user.email,
        displayName: user.displayName,
        firstName: user.firstName,
        lastName: user.lastName,
        department: user.department,
        phone: user.phone,
        mobilePhone: user.mobilePhone,
        designation: user.designation,
        jobTitle: user.jobTitle,
        manager: user.manager,
        employeeId: user.employeeId,
        employeeNumber: user.employeeNumber,
        secondEmail: user.secondEmail,
        location: user.location
      });
      return dbUser;
    } catch (err) {
      console.error('Failed to ensure user exists:', err);
      throw err;
    }
  };

  return {
    searchResults,
    searchLoading,
    searchUsersDebounced,
    clearSearch,
    ensureUser
  };
}

/**
 * Custom Hook: useMultiUserSearch
 * 
 * Purpose: Manages multiple independent user searches (e.g., for multiple approver fields)
 */
export function useMultiUserSearch() {
  const [userSearchResults, setUserSearchResults] = useState<Record<number, UserSummary[]>>({});
  const [userSearchLoading, setUserSearchLoading] = useState<Record<number, boolean>>({});
  const searchTimers = useRef<Record<number, any>>({});

  const searchUsersForIndex = async (index: number, searchTerm: string, limit: number = 10) => {
    if (searchTimers.current[index]) {
      clearTimeout(searchTimers.current[index]);
    }

    if (!searchTerm || !searchTerm.startsWith('@') || searchTerm.length < 2) {
      setUserSearchResults(prev => ({ ...prev, [index]: [] }));
      setUserSearchLoading(prev => ({ ...prev, [index]: false }));
      return;
    }

    setUserSearchLoading(prev => ({ ...prev, [index]: true }));
    searchTimers.current[index] = setTimeout(async () => {
      try {
        const term = searchTerm.slice(1);
        const response = await searchUsers(term, limit);
        const results = response.data?.data || [];
        setUserSearchResults(prev => ({ ...prev, [index]: results }));
      } catch (err) {
        console.error(`User search failed for index ${index}:`, err);
        setUserSearchResults(prev => ({ ...prev, [index]: [] }));
      } finally {
        setUserSearchLoading(prev => ({ ...prev, [index]: false }));
      }
    }, 300);
  };

  const clearSearchForIndex = (index: number) => {
    if (searchTimers.current[index]) {
      clearTimeout(searchTimers.current[index]);
    }
    setUserSearchResults(prev => ({ ...prev, [index]: [] }));
    setUserSearchLoading(prev => ({ ...prev, [index]: false }));
  };

  return {
    userSearchResults,
    userSearchLoading,
    searchUsersForIndex,
    clearSearchForIndex
  };
}