import React, { useState, useRef, useEffect } from 'react';
import './App.css';
import axios from 'axios';
import ReactMarkdown from 'react-markdown';
import remarkGfm from 'remark-gfm';

// Use relative URL for production (Hugging Face Spaces), absolute for local dev
const API_URL = process.env.REACT_APP_API_URL || 
  (process.env.NODE_ENV === 'production' ? '/api' : 'http://localhost:8000');
const DOCS_URL = process.env.REACT_APP_DOCS_URL || `${API_URL}/documents`;

function App() {
  const [messages, setMessages] = useState([]);
  const [input, setInput] = useState('');
  const [loading, setLoading] = useState(false);
  const [previewUrl, setPreviewUrl] = useState(null);
  const [previewFilename, setPreviewFilename] = useState('');
  const [previewError, setPreviewError] = useState(null);
  const [previewLoading, setPreviewLoading] = useState(false);
  const messagesEndRef = useRef(null);
  const previewUrlRef = useRef(null);

  const scrollToBottom = () => {
    messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' });
  };

  useEffect(() => {
    scrollToBottom();
  }, [messages]);

  useEffect(() => {
    return () => {
      if (previewUrlRef.current) {
        URL.revokeObjectURL(previewUrlRef.current);
      }
    };
  }, []);

  const handleSend = async (e) => {
    e.preventDefault();
    if (!input.trim() || loading) return;

    // Use unique IDs to prevent collision
    const baseTime = Date.now();
    const userMessageId = baseTime;
    const assistantMessageId = baseTime + 1; // Ensure different ID
    
    const userMessage = { id: userMessageId, role: 'user', content: input };
    setMessages(prev => [...prev, userMessage]);
    setInput('');
    setLoading(true);

    try {
      const response = await axios.post(`${API_URL}/ask`, {
        question: input
      });

      const assistantMessage = {
        id: assistantMessageId,
        role: 'assistant',
        content: response.data.answer,
        sources: response.data.sources || []
      };
      setMessages(prev => [...prev, assistantMessage]);
    } catch (error) {
      const errorMessage = {
        id: assistantMessageId,
        role: 'assistant',
        content: error.response?.data?.detail || error.message || 'عذراً، حدث خطأ. يرجى المحاولة مرة أخرى.',
        error: true
      };
      setMessages(prev => [...prev, errorMessage]);
    } finally {
      setLoading(false);
    }
  };

  const handleClearHistory = async () => {
    if (window.confirm('هل أنت متأكد من أنك تريد مسح سجل المحادثة؟')) {
      try {
        await axios.post(`${API_URL}/clear-history`);
        setMessages([]); // Clear local messages state
      } catch (error) {
        console.error('Error clearing history:', error);
        alert('فشل مسح السجل. يرجى المحاولة مرة أخرى.');
      }
    }
  };

  const handleDownload = (source) => {
    if (!source) return;
    const filename = source.split('/').pop() || source;
    const url = `${DOCS_URL}/${encodeURIComponent(filename)}?mode=download`;
    window.open(url, '_blank');
  };

  const handleClosePreview = () => {
    if (previewUrlRef.current) {
      URL.revokeObjectURL(previewUrlRef.current);
      previewUrlRef.current = null;
    }
    setPreviewUrl(null);
    setPreviewError(null);
    setPreviewFilename('');
    setPreviewLoading(false);
  };

  const getDisplaySourceName = (source) => {
    if (!source) return '';
    const fullName = source.split('/').pop() || source;
    const lastDot = fullName.lastIndexOf('.');
    if (lastDot > 0) {
      return fullName.substring(0, lastDot);
    }
    return fullName;
  };

  const handleSourceClick = async (source) => {
    if (!source) return;
    const filename = source.split('/').pop() || source;
    const extension = filename.split('.').pop()?.toLowerCase();
    console.log('[Preview] Requesting preview for:', filename);
    setPreviewFilename(filename);
    setPreviewError(null);
    setPreviewLoading(true);
    if (previewUrlRef.current) {
      URL.revokeObjectURL(previewUrlRef.current);
      previewUrlRef.current = null;
    }
    setPreviewUrl(null);
    if (extension !== 'pdf') {
      const errorMsg = 'المعاينة متاحة فقط لملفات PDF.';
      console.error('[Preview] Error:', errorMsg);
      setPreviewError(errorMsg);
      setPreviewLoading(false);
      return;
    }
    try {
      const url = `${DOCS_URL}/${encodeURIComponent(filename)}?mode=preview`;
      console.log('[Preview] Requesting URL:', url);
      const response = await axios.get(url, { 
        responseType: 'blob',
        timeout: 30000 // 30 second timeout
      });
      console.log('[Preview] Response received, status:', response.status, 'size:', response.data.size);
      
      if (!response.data || response.data.size === 0) {
        throw new Error('Received empty file');
      }
      
      const blob = new Blob([response.data], { type: 'application/pdf' });
      const objectUrl = URL.createObjectURL(blob);
      previewUrlRef.current = objectUrl;
      setPreviewUrl(objectUrl);
      console.log('[Preview] Successfully created object URL');
    } catch (error) {
      console.error('[Preview] Error details:', {
        message: error.message,
        response: error.response?.data,
        status: error.response?.status,
        statusText: error.response?.statusText,
        url: error.config?.url
      });
      
      let errorMsg = 'تعذر تحميل المعاينة.';
      if (error.response?.data?.detail) {
        errorMsg = `خطأ: ${error.response.data.detail}`;
      } else if (error.response?.status === 404) {
        errorMsg = 'الملف غير موجود.';
      } else if (error.response?.status === 403) {
        errorMsg = 'غير مسموح بالوصول إلى هذا الملف.';
      } else if (error.message) {
        errorMsg = `خطأ: ${error.message}`;
      }
      
      setPreviewError(errorMsg);
    } finally {
      setPreviewLoading(false);
    }
  };

  return (
    <div className="App" dir="rtl">
      <div className="chat-container">
        <div className="chat-header">
          <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center' }}>
            <div>
              <h1>⚖️    المساعد القانوني الذكي لنظام الأحوال الشخصية</h1>
              {/* <p>اطرح أسئلة حول وثائقك القانونية</p> */}
            </div>
            {messages.length > 0 && (
              <button 
                onClick={handleClearHistory}
                className="clear-history-button"
                title="مسح سجل المحادثة"
                style={{
                  background: 'rgba(255, 255, 255, 0.2)',
                  border: '1px solid rgba(255, 255, 255, 0.3)',
                  cursor: 'pointer',
                  fontSize: '14px',
                  padding: '8px 16px',
                  borderRadius: '20px',
                  color: 'white',
                  display: 'flex',
                  alignItems: 'center',
                  gap: '6px',
                  transition: 'background-color 0.2s',
                  fontWeight: '500'
                }}
                onMouseEnter={(e) => e.target.style.backgroundColor = 'rgba(255, 255, 255, 0.3)'}
                onMouseLeave={(e) => e.target.style.backgroundColor = 'rgba(255, 255, 255, 0.2)'}
              >
                <span>🗑️</span>
                <span>مسح المحادثة</span>
              </button>
            )}
          </div>
        </div>

        <div className="messages-container">
          {messages.length === 0 && (
            <div className="welcome-message">
              <h2>مرحباً!</h2>
              <p>ابدأ بطرح سؤالا قانونيا...</p>
            </div>
          )}
          
          {messages.map((msg, idx) => {
            const isAssistant = msg.role === 'assistant';
            const contentIsString = typeof msg.content === 'string';
            const renderContent = () => {
              if (isAssistant && contentIsString) {
                return (
                  <ReactMarkdown remarkPlugins={[remarkGfm]}>
                    {msg.content}
                  </ReactMarkdown>
                );
              }
              if (contentIsString) {
                return msg.content;
              }
              try {
                return JSON.stringify(msg.content, null, 2);
              } catch (err) {
                return 'محتوى غير قابل للعرض';
              }
            };
            return (
              <div key={msg.id || idx} className={`message ${msg.role}`}>
                <div className="message-content">
                  <div className="message-header">
                    {msg.role === 'user' ? '👤 أنت' : '🤖 المساعد القانوني'}
                  </div>
                  <div className={`message-text ${msg.error ? 'error' : ''}`}>
                    {renderContent()}
                  </div>
                  {msg.sources && msg.sources.length > 0 && (
                    <div className="sources">
                      <strong>المصادر:</strong>
                      <ul>
                        {msg.sources.map((source, i) => (
                          <li key={i}>
                            <span className="source-name">{getDisplaySourceName(source)}</span>
                            <div className="source-actions">
                              <button 
                                type="button" 
                                className="source-link"
                                onClick={() => handleSourceClick(source)}
                              >
                                معاينة
                              </button>
                              <button
                                type="button"
                                className="source-link download"
                                onClick={() => handleDownload(source)}
                              >
                                تحميل
                              </button>
                            </div>
                          </li>
                        ))}
                      </ul>
                    </div>
                  )}
                </div>
              </div>
            );
          })}
          
          {loading && (
            <div className="message assistant">
              <div className="message-content">
                <div className="message-header">🤖 المساعد القانوني</div>
                <div className="message-text">
                  <span className="typing-indicator">جاري التفكير...</span>
                </div>
              </div>
            </div>
          )}
          
          <div ref={messagesEndRef} />
        </div>

        <form className="input-container" onSubmit={handleSend}>
          <input
            type="text"
            value={input}
            onChange={(e) => setInput(e.target.value)}
            placeholder="اطرح سؤالاً قانونيا ..."
            disabled={loading}
            className="message-input"
          />
          <button 
            type="submit" 
            disabled={loading || !input.trim()}
            className="send-button"
          >
            إرسال
          </button>
        </form>

        {(previewUrl || previewError || previewLoading) && (
          <div className="preview-panel">
            <div className="preview-header">
              <h3>معاينة المصدر</h3>
              {previewFilename && <span className="preview-filename">{previewFilename}</span>}
              <button className="close-preview" onClick={handleClosePreview}>
                ✕
              </button>
            </div>
            <div className="preview-content">
              {previewLoading ? (
                <p>جاري تحميل المعاينة...</p>
              ) : previewError ? (
                <p className="error">{previewError}</p>
              ) : (
                <iframe
                  src={previewUrl}
                  title={`معاينة ${previewFilename}`}
                  className="pdf-frame"
                />
              )}
            </div>
          </div>
        )}
      </div>
    </div>
  );
}

export default App;