import React, { useState, useEffect, useContext, createContext } from 'react';
import { Home, Upload, List, ShoppingCart, TrendingUp, Calendar, Trash2, Edit2, Save, X } from 'lucide-react';
import { LineChart, Line, XAxis, YAxis, CartesianGrid, Tooltip, BarChart, Bar, PieChart, Pie, Cell, ResponsiveContainer } from 'recharts';

const StoreContext = createContext();
const StoreProvider = ({ children }) => {
  const [products, setProducts] = useState(() => {
    const stored = localStorage.getItem('grocery-tracker-storage');
    return stored ? JSON.parse(stored) : [];
  });

  useEffect(() => {
    localStorage.setItem('grocery-tracker-storage', JSON.stringify(products));
  }, [products]);

  const addProduct = (product) => {
    setProducts(prev => [...prev, { ...product, id: Date.now() }]);
  };

  const updateProduct = (id, product) => {
    setProducts(prev => prev.map(p => p.id === id ? { ...p, ...product } : p));
  };

  const deleteProduct = (id) => {
    setProducts(prev => prev.filter(p => p.id !== id));
  };

  const clearProducts = () => {
    setProducts([]);
  };

  return (
    <StoreContext.Provider value={{ products, addProduct, updateProduct, deleteProduct, clearProducts }}>
      {children}
    </StoreContext.Provider>
  );
};

const useStore = () => {
  const context = useContext(StoreContext);
  if (!context) {
    throw new Error('useStore must be used within a StoreProvider');
  }
  return context;
};

const MISTRAL_API_KEY = process.env.REACT_APP_MISTRAL_API_KEY;
const MISTRAL_API_URL = 'https://api.mistral.ai/v1/chat/completions';

const convertImageToBase64 = (file) => {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.onload = () => resolve(reader.result);
    reader.onerror = reject;
    reader.readAsDataURL(file);
  });
};

const extractTextFromImage = async (file, userApiKey) => {
  const apiKeyToUse = userApiKey || MISTRAL_API_KEY;
  
  try {
    const base64Image = await convertImageToBase64(file);
    
    const response = await fetch(MISTRAL_API_URL, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Authorization': `Bearer ${apiKeyToUse}`
      },
      body: JSON.stringify({
        model: 'pixtral-12b-2409',
        messages: [
          {
            role: 'user',
            content: [
              {
                type: 'text',
                text: 'Extract all text from this receipt image. Please provide the raw text exactly as it appears, maintaining the original structure and formatting.'
              },
              {
                type: 'image_url',
                image_url: {
                  url: base64Image
                }
              }
            ]
          }
        ],
        max_tokens: 1000,
        temperature: 0.1
      })
    });

    if (!response.ok) {
      throw new Error(`Mistral API error: ${response.status} ${response.statusText}`);
    }

    const data = await response.json();
    return data.choices[0].message.content;
  } catch (error) {
    console.error('Error extracting text from image:', error);
    throw new Error('Failed to extract text from image');
  }
};

const processReceiptText = async (text, userApiKey) => {
  const apiKeyToUse = userApiKey || MISTRAL_API_KEY;
  
  try {
    const response = await fetch(MISTRAL_API_URL, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Authorization': `Bearer ${apiKeyToUse}`
      },
      body: JSON.stringify({
        model: 'mistral-large-latest',
        messages: [
          {
            role: 'user',
            content: `Analyze this receipt text and extract product information. Return a JSON array with objects containing: name, price, store (with name and address), and date.
Receipt text:
${text}
Please return ONLY a valid JSON array in this format:
[
  {
    "name": "Product Name",
    "price": 2.50,
    "store": {
      "name": "Store Name",
      "address": "Store Address"
    },
    "date": "MM/DD/YYYY"
  }
]`
          }
        ],
        max_tokens: 2000,
        temperature: 0.1
      })
    });

    if (!response.ok) {
      throw new Error(`Mistral API error: ${response.status} ${response.statusText}`);
    }

    const data = await response.json();
    const jsonResponse = data.choices[0].message.content;
    
    const jsonMatch = jsonResponse.match(/\[[\s\S]*\]/);
    if (!jsonMatch) {
      throw new Error('Invalid JSON response from Mistral');
    }

    const products = JSON.parse(jsonMatch[0]);
    return products.map(product => ({
      ...product,
      price: parseFloat(product.price) || 0
    }));
  } catch (error) {
    console.error('Error processing receipt text:', error);
    throw new Error('Failed to process receipt text');
  }
};

const UploadTab = () => {
  const { addProduct } = useStore();
  const [file, setFile] = useState(null);
  const [loading, setLoading] = useState(false);
  const [step, setStep] = useState('upload');
  const [extractedText, setExtractedText] = useState('');
  const [processedProducts, setProcessedProducts] = useState([]);
  const [error, setError] = useState(null);
  const [apiKey, setApiKey] = useState('');

  const handleFileSelect = (e) => {
    const selectedFile = e.target.files[0];
    if (selectedFile && selectedFile.type.startsWith('image/')) {
      setFile(selectedFile);
      setStep('upload');
      setError(null);
    }
  };

  const handleUpload = async () => {
    if (!file) return;
    
    if (!apiKey && !MISTRAL_API_KEY) {
      setError('Please enter your Mistral API key or configure REACT_APP_MISTRAL_API_KEY environment variable.');
      return;
    }
    
    setLoading(true);
    setError(null);
    setStep('extracting');
    
    try {
      const text = await extractTextFromImage(file, apiKey);
      setExtractedText(text);
      setStep('processing');
      
      const products = await processReceiptText(text, apiKey);
      setProcessedProducts(products);
      setStep('review');
    } catch (error) {
      console.error('Error processing receipt:', error);
      setError(error.message);
      setStep('upload');
    } finally {
      setLoading(false);
    }
  };

  const handleSaveProducts = () => {
    processedProducts.forEach(product => addProduct(product));
    setFile(null);
    setExtractedText('');
    setProcessedProducts([]);
    setStep('upload');
    setError(null);
    alert('Products saved successfully');
  };

  return (
    <div className="p-6">
      <h2 className="text-3xl font-bold text-gray-800 mb-6">Upload Receipt</h2>
      
      <div className="bg-white rounded-lg shadow p-6">
        {error && (
          <div className="mb-4 p-4 bg-red-50 border border-red-200 rounded-lg">
            <p className="text-red-700">{error}</p>
          </div>
        )}
        
        {step === 'upload' && (
          <div className="space-y-4">
            <div className="mb-4">
              <label htmlFor="apiKey" className="block text-sm font-medium text-gray-700 mb-2">
                Mistral API Key
              </label>
              <input
                id="apiKey"
                type="password"
                value={apiKey}
                onChange={(e) => setApiKey(e.target.value)}
                placeholder="Enter your Mistral API key"
                className="w-full px-3 py-2 border border-gray-300 rounded-lg focus:outline-none focus:ring-2 focus:ring-blue-500 focus:border-transparent"
              />
              <p className="text-xs text-gray-500 mt-1">
                Required to process receipt images
              </p>
            </div>
            
            <div className="border-2 border-dashed border-gray-300 rounded-lg p-8 text-center">
              <Upload className="mx-auto h-12 w-12 text-gray-400 mb-4" />
              <label className="cursor-pointer">
                <span className="text-lg font-medium text-gray-700">
                  Select a receipt image
                </span>
                <input
                  type="file"
                  accept="image/*"
                  onChange={handleFileSelect}
                  className="hidden"
                />
              </label>
              {file && (
                <p className="mt-2 text-sm text-gray-500">
                  Selected file: {file.name}
                </p>
              )}
            </div>
            
            {file && (
              <button
                onClick={handleUpload}
                disabled={loading}
                className="w-full bg-blue-600 text-white py-3 px-4 rounded-lg hover:bg-blue-700 disabled:opacity-50"
              >
                {loading ? 'Processing...' : 'Process Receipt'}
              </button>
            )}
          </div>
        )}
        
        {step === 'extracting' && (
          <div className="text-center py-8">
            <div className="animate-spin rounded-full h-12 w-12 border-b-2 border-blue-600 mx-auto mb-4"></div>
            <p className="text-lg font-medium text-gray-700">Extracting text from image...</p>
          </div>
        )}
        
        {step === 'processing' && (
          <div className="text-center py-8">
            <div className="animate-spin rounded-full h-12 w-12 border-b-2 border-green-600 mx-auto mb-4"></div>
            <p className="text-lg font-medium text-gray-700">Processing products...</p>
          </div>
        )}
        
        {step === 'review' && (
          <div className="space-y-4">
            <h3 className="text-xl font-semibold text-gray-800">Detected Products</h3>
            
            <div className="bg-gray-50 rounded-lg p-4 mb-4">
              <h4 className="font-medium text-gray-700 mb-2">Extracted Text:</h4>
              <pre className="text-sm text-gray-600 whitespace-pre-wrap max-h-32 overflow-y-auto">
                {extractedText}
              </pre>
            </div>
            
            <div className="bg-gray-50 rounded-lg p-4 max-h-96 overflow-y-auto">
              {processedProducts.length > 0 ? (
                processedProducts.map((product, index) => (
                  <div key={index} className="flex justify-between items-center py-2 border-b border-gray-200 last:border-b-0">
                    <div>
                      <span className="font-medium">{product.name}</span>
                      <span className="text-sm text-gray-500 ml-2">
                        ({product.store?.name || 'Unknown Store'})
                      </span>
                    </div>
                    <span className="font-bold text-green-600">${product.price.toFixed(2)}</span>
                  </div>
                ))
              ) : (
                <p className="text-gray-500 text-center py-4">No products detected</p>
              )}
            </div>
            
            <div className="flex space-x-3">
              <button
                onClick={handleSaveProducts}
                disabled={processedProducts.length === 0}
                className="flex-1 bg-green-600 text-white py-3 px-4 rounded-lg hover:bg-green-700 disabled:opacity-50"
              >
                Save Products
              </button>
              <button
                onClick={() => setStep('upload')}
                className="flex-1 bg-gray-600 text-white py-3 px-4 rounded-lg hover:bg-gray-700"
              >
                Cancel
              </button>
            </div>
          </div>
        )}
      </div>
    </div>
  );
};

const Sidebar = ({ activeTab, setActiveTab }) => {
  const tabs = [
    { id: 'home', label: 'Home', icon: Home },
    { id: 'upload', label: 'Upload', icon: Upload },
    { id: 'list', label: 'List', icon: List }
  ];

  return (
    <div className="w-64 bg-white border-r border-gray-200 h-screen">
      <div className="p-6">
        <h1 className="text-2xl font-bold text-gray-800 flex items-center">
          <ShoppingCart className="mr-2" />
          Grocery Tracker
        </h1>
      </div>
      <nav className="mt-6">
        {tabs.map(tab => {
          const Icon = tab.icon;
          return (
            <button
              key={tab.id}
              onClick={() => setActiveTab(tab.id)}
              className={`w-full flex items-center px-6 py-3 text-left transition-colors ${
                activeTab === tab.id 
                  ? 'bg-blue-50 text-blue-600 border-r-2 border-blue-600' 
                  : 'text-gray-600 hover:bg-gray-50'
              }`}
            >
              <Icon className="mr-3 h-5 w-5" />
              {tab.label}
            </button>
          );
        })}
      </nav>
    </div>
  );
};

const HomeTab = () => {
  const { products } = useStore();
  
  const totalSpent = products.reduce((sum, p) => sum + p.price, 0);
  
  const productsByStore = products.reduce((acc, p) => {
    const key = p.store.name;
    if (!acc[key]) acc[key] = [];
    acc[key].push(p);
    return acc;
  }, {});

  const priceVariations = products.reduce((acc, p) => {
    if (!acc[p.name]) acc[p.name] = [];
    acc[p.name].push(p);
    return acc;
  }, {});

  const productsWithVariation = Object.entries(priceVariations)
    .filter(([_, prods]) => prods.length > 1)
    .map(([name, prods]) => ({
      name,
      minPrice: Math.min(...prods.map(p => p.price)),
      maxPrice: Math.max(...prods.map(p => p.price)),
      difference: Math.max(...prods.map(p => p.price)) - Math.min(...prods.map(p => p.price))
    }))
    .sort((a, b) => b.difference - a.difference)
    .slice(0, 5);

  const spendingByStore = Object.entries(productsByStore).map(([name, prods]) => ({
    name,
    spending: prods.reduce((sum, p) => sum + p.price, 0),
    products: prods.length
  }));

  const COLORS = ['#3b82f6', '#10b981', '#f59e0b', '#ef4444', '#8b5cf6'];

  return (
    <div className="p-6 space-y-6">
      <h2 className="text-3xl font-bold text-gray-800">Dashboard</h2>
      
      <div className="grid grid-cols-1 md:grid-cols-3 gap-6">
        <div className="bg-white rounded-lg shadow p-6">
          <h3 className="text-lg font-semibold text-gray-700 mb-2">Total Spent</h3>
          <p className="text-3xl font-bold text-blue-600">${totalSpent.toFixed(2)}</p>
        </div>
        
        <div className="bg-white rounded-lg shadow p-6">
          <h3 className="text-lg font-semibold text-gray-700 mb-2">Registered Products</h3>
          <p className="text-3xl font-bold text-green-600">{products.length}</p>
        </div>
        
        <div className="bg-white rounded-lg shadow p-6">
          <h3 className="text-lg font-semibold text-gray-700 mb-2">Stores</h3>
          <p className="text-3xl font-bold text-purple-600">{Object.keys(productsByStore).length}</p>
        </div>
      </div>

      {spendingByStore.length > 0 && (
        <div className="grid grid-cols-1 lg:grid-cols-2 gap-6">
          <div className="bg-white rounded-lg shadow p-6">
            <h3 className="text-lg font-semibold text-gray-700 mb-4">Spending by Store</h3>
            <ResponsiveContainer width="100%" height={300}>
              <BarChart data={spendingByStore}>
                <CartesianGrid strokeDasharray="3 3" />
                <XAxis dataKey="name" />
                <YAxis />
                <Tooltip formatter={(value) => [`$${value.toFixed(2)}`, 'Spending']} />
                <Bar dataKey="spending" fill="#3b82f6" />
              </BarChart>
            </ResponsiveContainer>
          </div>

          <div className="bg-white rounded-lg shadow p-6">
            <h3 className="text-lg font-semibold text-gray-700 mb-4">Spending Distribution</h3>
            <ResponsiveContainer width="100%" height={300}>
              <PieChart>
                <Pie
                  data={spendingByStore}
                  cx="50%"
                  cy="50%"
                  labelLine={false}
                  label={({ name, percent }) => `${name} ${(percent * 100).toFixed(0)}%`}
                  outerRadius={80}
                  fill="#8884d8"
                  dataKey="spending"
                >
                  {spendingByStore.map((entry, index) => (
                    <Cell key={`cell-${index}`} fill={COLORS[index % COLORS.length]} />
                  ))}
                </Pie>
                <Tooltip formatter={(value) => [`$${value.toFixed(2)}`, 'Spending']} />
              </PieChart>
            </ResponsiveContainer>
          </div>
        </div>
      )}

      {productsWithVariation.length > 0 && (
        <div className="bg-white rounded-lg shadow p-6">
          <h3 className="text-lg font-semibold text-gray-700 mb-4 flex items-center">
            <TrendingUp className="mr-2" />
            Products with Highest Price Variation
          </h3>
          <div className="space-y-3">
            {productsWithVariation.map((product, index) => (
              <div key={index} className="flex justify-between items-center p-3 bg-gray-50 rounded">
                <span className="font-medium">{product.name}</span>
                <div className="text-right">
                  <span className="text-sm text-gray-500">
                    ${product.minPrice.toFixed(2)} - ${product.maxPrice.toFixed(2)}
                  </span>
                  <span className="ml-2 text-red-600 font-semibold">
                    +${product.difference.toFixed(2)}
                  </span>
                </div>
              </div>
            ))}
          </div>
        </div>
      )}
    </div>
  );
};

const ListTab = () => {
  const { products, updateProduct, deleteProduct } = useStore();
  const [editingId, setEditingId] = useState(null);
  const [editForm, setEditForm] = useState({});

  const startEdit = (product) => {
    setEditingId(product.id);
    setEditForm(product);
  };

  const saveEdit = () => {
    updateProduct(editingId, editForm);
    setEditingId(null);
    setEditForm({});
  };

  const cancelEdit = () => {
    setEditingId(null);
    setEditForm({});
  };

  const handleDelete = (id) => {
    if (window.confirm('Are you sure you want to delete this product?')) {
      deleteProduct(id);
    }
  };

  return (
    <div className="p-6">
      <h2 className="text-3xl font-bold text-gray-800 mb-6">Product List</h2>
      
      <div className="bg-white rounded-lg shadow overflow-hidden">
        <div className="overflow-x-auto">
          <table className="min-w-full divide-y divide-gray-200">
            <thead className="bg-gray-50">
              <tr>
                <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                  Product
                </th>
                <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                  Price
                </th>
                <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                  Store
                </th>
                <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                  Date
                </th>
                <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                  Actions
                </th>
              </tr>
            </thead>
            <tbody className="bg-white divide-y divide-gray-200">
              {products.map((product) => (
                <tr key={product.id}>
                  <td className="px-6 py-4 whitespace-nowrap">
                    {editingId === product.id ? (
                      <input
                        type="text"
                        value={editForm.name}
                        onChange={(e) => setEditForm({...editForm, name: e.target.value})}
                        className="w-full px-3 py-1 border border-gray-300 rounded"
                      />
                    ) : (
                      <div className="text-sm font-medium text-gray-900">{product.name}</div>
                    )}
                  </td>
                  <td className="px-6 py-4 whitespace-nowrap">
                    {editingId === product.id ? (
                      <input
                        type="number"
                        step="0.01"
                        value={editForm.price}
                        onChange={(e) => setEditForm({...editForm, price: parseFloat(e.target.value)})}
                        className="w-full px-3 py-1 border border-gray-300 rounded"
                      />
                    ) : (
                      <div className="text-sm text-gray-900">${product.price.toFixed(2)}</div>
                    )}
                  </td>
                  <td className="px-6 py-4 whitespace-nowrap">
                    <div className="text-sm text-gray-900">{product.store.name}</div>
                    <div className="text-sm text-gray-500">{product.store.address}</div>
                  </td>
                  <td className="px-6 py-4 whitespace-nowrap text-sm text-gray-900">
                    {editingId === product.id ? (
                      <input
                        type="date"
                        value={editForm.date}
                        onChange={(e) => setEditForm({...editForm, date: e.target.value})}
                        className="w-full px-3 py-1 border border-gray-300 rounded"
                      />
                    ) : (
                      product.date
                    )}
                  </td>
                  <td className="px-6 py-4 whitespace-nowrap text-sm font-medium space-x-2">
                    {editingId === product.id ? (
                      <>
                        <button
                          onClick={saveEdit}
                          className="text-green-600 hover:text-green-900"
                        >
                          <Save className="h-4 w-4" />
                        </button>
                        <button
                          onClick={cancelEdit}
                          className="text-gray-600 hover:text-gray-900"
                        >
                          <X className="h-4 w-4" />
                        </button>
                      </>
                    ) : (
                      <>
                        <button
                          onClick={() => startEdit(product)}
                          className="text-blue-600 hover:text-blue-900"
                        >
                          <Edit2 className="h-4 w-4" />
                        </button>
                        <button
                          onClick={() => handleDelete(product.id)}
                          className="text-red-600 hover:text-red-900"
                        >
                          <Trash2 className="h-4 w-4" />
                        </button>
                      </>
                    )}
                  </td>
                </tr>
              ))}
            </tbody>
          </table>
          
          {products.length === 0 && (
            <div className="text-center py-8">
              <p className="text-gray-500">No products registered</p>
            </div>
          )}
        </div>
      </div>
    </div>
  );
};

const App = () => {
  const [activeTab, setActiveTab] = useState('home');

  const renderContent = () => {
    switch (activeTab) {
      case 'home':
        return <HomeTab />;
      case 'upload':
        return <UploadTab />;
      case 'list':
        return <ListTab />;
      default:
        return <HomeTab />;
    }
  };

  return (
    <StoreProvider>
      <div className="flex h-screen bg-gray-100">
        <Sidebar activeTab={activeTab} setActiveTab={setActiveTab} />
        <main className="flex-1 overflow-y-auto">
          {renderContent()}
        </main>
      </div>
    </StoreProvider>
  );
};

export default App;