'use client';

import React, { useState, useRef, useCallback, useEffect } from 'react';
import { Send } from 'lucide-react';
import { cn } from '@/lib/utils';
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from '@/components/ui/select';

type AIProvider = 'claude' | 'openai';

interface ChatComposerProps {
  /** Callback when a message is sent */
  onSend: (message: string, provider?: AIProvider) => void;
  /** Whether the input is disabled */
  disabled?: boolean;
  /** Whether a response is currently streaming */
  isStreaming?: boolean;
  /** Show provider selector dropdown */
  showProviderSelector?: boolean;
}

/**
 * ChatComposer - Message input area for the Control Center
 *
 * Features auto-resizing textarea, send button, optional provider selector,
 * and keyboard shortcuts for sending messages.
 */
export const ChatComposer: React.FC<ChatComposerProps> = ({
  onSend,
  disabled = false,
  isStreaming = false,
  showProviderSelector = false,
}) => {
  const [message, setMessage] = useState('');
  const [provider, setProvider] = useState<AIProvider>('claude');
  const textareaRef = useRef<HTMLTextAreaElement>(null);

  const isDisabled = disabled || isStreaming;
  const canSend = message.trim().length > 0 && !isDisabled;

  // Auto-resize textarea based on content
  const adjustTextareaHeight = useCallback(() => {
    const textarea = textareaRef.current;
    if (textarea) {
      // Reset height to auto to get the correct scrollHeight
      textarea.style.height = 'auto';
      // Set height to scrollHeight, with min and max constraints
      const newHeight = Math.min(Math.max(textarea.scrollHeight, 44), 200);
      textarea.style.height = `${newHeight}px`;
    }
  }, []);

  useEffect(() => {
    adjustTextareaHeight();
  }, [message, adjustTextareaHeight]);

  const handleSend = useCallback(() => {
    if (!canSend) return;

    const trimmedMessage = message.trim();
    onSend(trimmedMessage, showProviderSelector ? provider : undefined);
    setMessage('');

    // Reset textarea height after clearing
    if (textareaRef.current) {
      textareaRef.current.style.height = '44px';
    }
  }, [canSend, message, onSend, provider, showProviderSelector]);

  const handleKeyDown = useCallback(
    (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
      // Ctrl/Cmd + Enter to send
      if ((e.ctrlKey || e.metaKey) && e.key === 'Enter') {
        e.preventDefault();
        handleSend();
      }
    },
    [handleSend]
  );

  const handleChange = useCallback(
    (e: React.ChangeEvent<HTMLTextAreaElement>) => {
      setMessage(e.target.value);
    },
    []
  );

  return (
    <div
      className={cn(
        'bg-[#F0F4F8]',
        'rounded-2xl',
        'p-4',
        'shadow-[6px_6px_12px_#bfc3cc,-6px_-6px_12px_#ffffff]',
        'transition-all duration-300'
      )}
    >
      <div className="flex flex-col gap-3">
        {/* Provider selector (optional) */}
        {showProviderSelector && (
          <div className="flex items-center gap-2">
            <span className="text-sm text-gray-600">Provider:</span>
            <Select
              value={provider}
              onValueChange={(value: AIProvider) => setProvider(value)}
              disabled={isDisabled}
            >
              <SelectTrigger
                className={cn(
                  'w-[140px] h-8',
                  'bg-[#F0F4F8]',
                  'border-0',
                  'shadow-[inset_2px_2px_4px_rgba(0,0,0,0.05),inset_-2px_-2px_4px_rgba(255,255,255,0.8)]',
                  'rounded-lg',
                  'text-sm',
                  'focus:ring-indigo-500'
                )}
              >
                <SelectValue placeholder="Select provider" />
              </SelectTrigger>
              <SelectContent>
                <SelectItem value="claude">Claude</SelectItem>
                <SelectItem value="openai">OpenAI</SelectItem>
              </SelectContent>
            </Select>
          </div>
        )}

        {/* Main input area */}
        <div className="flex items-end gap-3">
          <div className="flex-1 relative">
            <textarea
              ref={textareaRef}
              value={message}
              onChange={handleChange}
              onKeyDown={handleKeyDown}
              placeholder="Ask me anything about your GHL account..."
              disabled={isDisabled}
              rows={1}
              className={cn(
                'w-full',
                'min-h-[44px]',
                'max-h-[200px]',
                'px-4 py-3',
                'bg-[#F0F4F8]',
                'border-0',
                'rounded-xl',
                'shadow-[inset_3px_3px_6px_rgba(0,0,0,0.06),inset_-3px_-3px_6px_rgba(255,255,255,0.9)]',
                'text-gray-800',
                'placeholder:text-gray-400',
                'resize-none',
                'focus:outline-none',
                'focus:ring-2',
                'focus:ring-indigo-400',
                'focus:ring-offset-0',
                'transition-all duration-200',
                'disabled:opacity-50',
                'disabled:cursor-not-allowed',
                'text-sm md:text-base'
              )}
            />
          </div>

          {/* Send button */}
          <button
            onClick={handleSend}
            disabled={!canSend}
            aria-label="Send message"
            className={cn(
              'flex items-center justify-center',
              'w-11 h-11',
              'rounded-xl',
              'transition-all duration-200',
              canSend
                ? [
                    'bg-indigo-500',
                    'text-white',
                    'shadow-[4px_4px_8px_#bfc3cc,-4px_-4px_8px_#ffffff]',
                    'hover:bg-indigo-600',
                    'hover:shadow-[2px_2px_4px_#bfc3cc,-2px_-2px_4px_#ffffff]',
                    'active:shadow-[inset_2px_2px_4px_rgba(0,0,0,0.1)]',
                  ]
                : [
                    'bg-[#F0F4F8]',
                    'text-gray-400',
                    'shadow-[inset_2px_2px_4px_rgba(0,0,0,0.05),inset_-2px_-2px_4px_rgba(255,255,255,0.8)]',
                    'cursor-not-allowed',
                  ]
            )}
          >
            <Send className="w-5 h-5" />
          </button>
        </div>

        {/* Keyboard shortcut hint */}
        <div className="flex justify-end">
          <span className="text-xs text-gray-400">
            Press <kbd className="px-1.5 py-0.5 bg-gray-200 rounded text-gray-600 font-mono">Ctrl</kbd>
            {' + '}
            <kbd className="px-1.5 py-0.5 bg-gray-200 rounded text-gray-600 font-mono">Enter</kbd>
            {' to send'}
          </span>
        </div>
      </div>
    </div>
  );
};

export default ChatComposer;