import React, { useState, useRef, useEffect, useMemo } from 'react';
import { SearchIcon } from './Icons';

interface MultiSelectDropdownProps {
  label: string;
  selected: string[];
  options: string[];
  onChange: (newSelected: string[]) => void;
  className?: string;
}

const MultiSelectDropdown: React.FC<MultiSelectDropdownProps> = ({ label, selected, options, onChange, className }) => {
  const [isOpen, setIsOpen] = useState(false);
  const [searchTerm, setSearchTerm] = useState('');
  const dropdownRef = useRef<HTMLDivElement>(null);
  const inputRef = useRef<HTMLInputElement>(null);

  useEffect(() => {
    const handleClickOutside = (event: MouseEvent) => {
      if (dropdownRef.current && !dropdownRef.current.contains(event.target as Node)) {
        setIsOpen(false);
      }
    };
    document.addEventListener('mousedown', handleClickOutside);
    return () => document.removeEventListener('mousedown', handleClickOutside);
  }, []);

  // Focus input when opening
  useEffect(() => {
    if (isOpen && inputRef.current) {
      inputRef.current.focus();
    }
    if (!isOpen) {
      setSearchTerm(''); // Reset search when closing
    }
  }, [isOpen]);

  const filteredOptions = useMemo(() => {
    if (!searchTerm) return options;
    return options.filter(opt => opt.toLowerCase().includes(searchTerm.toLowerCase()));
  }, [options, searchTerm]);

  const toggleOption = (option: string) => {
    if (selected.includes(option)) {
      onChange(selected.filter((item) => item !== option));
    } else {
      onChange([...selected, option]);
    }
  };

  const handleSelectAll = () => {
    // If searching, only select/deselect visible options
    if (searchTerm) {
      const allFilteredSelected = filteredOptions.every(opt => selected.includes(opt));
      if (allFilteredSelected) {
        // Deselect all filtered options
        onChange(selected.filter(item => !filteredOptions.includes(item)));
      } else {
        // Select all filtered options (add unique ones)
        const newSelected = Array.from(new Set([...selected, ...filteredOptions]));
        onChange(newSelected);
      }
    } else {
      // Standard behavior
      if (selected.length === options.length) {
        onChange([]); // Deselect all
      } else {
        onChange([...options]); // Select all
      }
    }
  };

  const handleClear = () => {
      onChange([]);
  };

  return (
    <div className={`flex flex-col min-w-[150px] relative ${className}`} ref={dropdownRef}>
      <label className="text-xs font-semibold text-slate-400 mb-1 uppercase tracking-wider">{label}</label>
      
      <button
        onClick={() => setIsOpen(!isOpen)}
        className={`w-full text-left bg-surface border border-border hover:border-slate-600 text-sm rounded-lg py-2 px-3 focus:outline-none focus:ring-2 focus:ring-primary/50 transition-colors flex justify-between items-center
        ${selected.length > 0 ? 'text-white font-medium border-primary/50' : 'text-slate-400'}`}
      >
        <span className="truncate">
          {selected.length === 0 
            ? (label === 'Customer' ? 'All Customers' : `All ${label}s`) 
            : `${selected.length} selected`}
        </span>
        <svg className={`fill-current h-4 w-4 transition-transform ${isOpen ? 'rotate-180' : ''}`} xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20">
          <path d="M9.293 12.95l.707.707L15.657 8l-1.414-1.414L10 10.828 5.757 6.586 4.343 8z" />
        </svg>
      </button>

      {isOpen && (
        <div className="absolute top-[calc(100%+4px)] left-0 w-64 max-h-96 overflow-hidden bg-slate-900 border border-slate-700 rounded-xl shadow-2xl z-[100] animate-fade-in flex flex-col">
          
          {/* Search Bar */}
          <div className="p-2 border-b border-slate-800 sticky top-0 bg-slate-900 z-10">
            <div className="relative">
              <span className="absolute left-2.5 top-2.5 text-slate-500">
                <SearchIcon />
              </span>
              <input 
                ref={inputRef}
                type="text" 
                placeholder={`Search ${label}...`}
                className="w-full bg-slate-950 border border-slate-700 text-slate-200 text-sm rounded-md py-1.5 pl-9 pr-2 focus:outline-none focus:border-primary"
                value={searchTerm}
                onChange={(e) => setSearchTerm(e.target.value)}
              />
            </div>
          </div>

          <div className="flex justify-between py-2 px-2 border-b border-slate-800 bg-slate-900/50">
              <button onClick={handleSelectAll} className="text-xs text-primary hover:text-indigo-400 font-medium px-2">
                  {searchTerm 
                    ? (filteredOptions.every(opt => selected.includes(opt)) ? 'Unselect Results' : 'Select Results')
                    : (selected.length === options.length ? 'Unselect All' : 'Select All')
                  }
              </button>
              <button onClick={handleClear} className="text-xs text-slate-400 hover:text-white px-2">
                  Clear
              </button>
          </div>
          
          <div className="space-y-1 overflow-y-auto custom-scrollbar p-2 max-h-60">
            {filteredOptions.map((opt) => (
              <label key={opt} className="flex items-center space-x-3 p-2 rounded hover:bg-slate-800 cursor-pointer group">
                <input
                  type="checkbox"
                  checked={selected.includes(opt)}
                  onChange={() => toggleOption(opt)}
                  className="form-checkbox h-4 w-4 text-primary rounded border-slate-600 bg-slate-800 focus:ring-primary focus:ring-offset-slate-900 transition duration-150 ease-in-out"
                />
                <span className={`text-sm break-all group-hover:text-white ${selected.includes(opt) ? 'text-white' : 'text-slate-400'}`}>
                    {opt}
                </span>
              </label>
            ))}
            {filteredOptions.length === 0 && <div className="p-4 text-center text-xs text-slate-500">No matches found</div>}
          </div>
        </div>
      )}
    </div>
  );
};

export default MultiSelectDropdown;