frontend/src/App.tsx

import React, { useState } from 'react';

function App() {
  const [file, setFile] = useState<File | null>(null);
  const [question, setQuestion] = useState('');
  const [answer, setAnswer] = useState('');
  const [context, setContext] = useState<string[]>([]);
  const [isLoading, setIsLoading] = useState(false);
  const [uploadStatus, setUploadStatus] = useState('');

  const handleFileUpload = async (e: React.ChangeEvent<HTMLInputElement>) => {
    if (!e.target.files?.length) return;
    
    const uploadedFile = e.target.files[0];
    setFile(uploadedFile);
    setIsLoading(true);
    setUploadStatus('Processing...');

    const formData = new FormData();
    formData.append('file', uploadedFile);

    try {
      const response = await fetch('/api/upload', {
        method: 'POST',
        body: formData,
      });
      const data = await response.json();
      console.log('File uploaded:', data);
      setUploadStatus(`Processing ${uploadedFile.name} done. You can now ask questions!`);
    } catch (error) {
      console.error('Error uploading file:', error);
      setUploadStatus('Error processing file. Please try again.');
    } finally {
      setIsLoading(false);
    }
  };

  const handleAskQuestion = async (e: React.FormEvent) => {
    e.preventDefault();
    if (!question.trim()) return;

    setIsLoading(true);
    setAnswer('');
    setContext([]);
    
    try {
      const response = await fetch('/api/ask', {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
        },
        body: JSON.stringify({ query: question }),
      });
      const data = await response.json();
      setAnswer(data.answer);
      setContext(data.context || []);
    } catch (error) {
      console.error('Error asking question:', error);
      setAnswer('Error getting answer. Please try again.');
    } finally {
      setIsLoading(false);
    }
  };

  return (
    <div className="container mx-auto p-4 max-w-4xl">
      <h1 className="text-3xl font-bold mb-8">Document Q&A</h1>
      
      <div className="mb-8">
        <div className="text-center mb-4">
          {!file && (
            <p className="text-lg">Please upload a Text or PDF file to begin!</p>
          )}
        </div>
        <label className="block text-sm font-medium mb-2">
          Upload Document (PDF/TXT)
        </label>
        <input
          type="file"
          accept=".pdf,.txt"
          onChange={handleFileUpload}
          className="block w-full text-sm border rounded-lg cursor-pointer"
        />
        {uploadStatus && (
          <p className="mt-2 text-sm text-gray-600">{uploadStatus}</p>
        )}
      </div>

      <form onSubmit={handleAskQuestion} className="mb-8">
        <div className="mb-4">
          <label className="block text-sm font-medium mb-2">
            Ask a Question
          </label>
          <input
            type="text"
            value={question}
            onChange={(e) => setQuestion(e.target.value)}
            className="w-full p-2 border rounded-lg"
            placeholder="Type your question here..."
            disabled={!file || isLoading}
          />
        </div>
        <button
          type="submit"
          disabled={!file || !question || isLoading}
          className="bg-blue-500 text-white px-4 py-2 rounded-lg disabled:opacity-50"
        >
          {isLoading ? 'Loading...' : 'Ask'}
        </button>
      </form>

      {answer && (
        <div className="mb-8">
          <h2 className="text-xl font-semibold mb-4">Answer:</h2>
          <p className="p-4 bg-gray-100 rounded-lg whitespace-pre-wrap">{answer}</p>
        </div>
      )}

      {context.length > 0 && (
        <div>
          <h2 className="text-xl font-semibold mb-2">Source Excerpts:</h2>
          <p className="text-sm text-gray-600 mb-4">Below are the relevant excerpts from your document that were used to generate the answer:</p>
          <div className="space-y-2">
            {context.map((text, index) => (
              <div key={index} className="p-4 bg-gray-50 rounded-lg border border-gray-200">
                <p className="text-sm text-gray-500 mb-1">Excerpt {index + 1}:</p>
                <p className="text-sm">{text}</p>
              </div>
            ))}
          </div>
        </div>
      )}
    </div>
  );
}

export default App;