// Global variables
let categories = [];
let documents = [];
let authToken = null;
let currentUser = null;

// Initialize app
document.addEventListener('DOMContentLoaded', function() {
    checkAuth();
});

// Authentication functions
function checkAuth() {
    authToken = localStorage.getItem('authToken');
    currentUser = localStorage.getItem('currentUser');
    
    if (authToken && currentUser) {
        showMainApp();
        document.getElementById('welcomeUser').textContent = `Welcome, ${currentUser}`;
        loadStats();
        loadCategories();
        setupFileUploads();
    } else {
        showLoginModal();
    }
}

function showLoginModal() {
    document.getElementById('loginModal').style.display = 'flex';
    document.getElementById('mainApp').style.display = 'none';
}

function showMainApp() {
    document.getElementById('loginModal').style.display = 'none';
    document.getElementById('mainApp').style.display = 'block';
}

function logout() {
    localStorage.removeItem('authToken');
    localStorage.removeItem('currentUser');
    authToken = null;
    currentUser = null;
    showLoginModal();
}

// Login form handler
document.getElementById('loginForm').addEventListener('submit', async (e) => {
    e.preventDefault();
    
    const username = document.getElementById('username').value;
    const password = document.getElementById('password').value;
    const resultDiv = document.getElementById('loginResult');
    
    const formData = new FormData();
    formData.append('username', username);
    formData.append('password', password);
    
    try {
        const response = await fetch('/api/login', {
            method: 'POST',
            body: formData
        });
        
        const result = await response.json();
        
        if (response.ok) {
            authToken = result.access_token;
            currentUser = result.username;
            localStorage.setItem('authToken', authToken);
            localStorage.setItem('currentUser', currentUser);
            
            showMainApp();
            document.getElementById('welcomeUser').textContent = `Welcome, ${currentUser}`;
            loadStats();
            loadCategories();
            setupFileUploads();
        } else {
            showResult(resultDiv, result.detail, 'error');
        }
    } catch (error) {
        showResult(resultDiv, 'Login failed: ' + error.message, 'error');
    }
});

// API request with authentication
async function authenticatedFetch(url, options = {}) {
    if (!authToken) {
        throw new Error('No authentication token');
    }
    
    const defaultOptions = {
        headers: {
            'Authorization': `Bearer ${authToken}`,
            ...options.headers
        }
    };
    
    const response = await fetch(url, { ...options, ...defaultOptions });
    
    if (response.status === 401) {
        logout();
        throw new Error('Authentication failed');
    }
    
    return response;
}

// Tab management
function showTab(tabName) {
    // Hide all tabs
    document.querySelectorAll('.tab-content').forEach(tab => {
        tab.classList.remove('active');
    });
    document.querySelectorAll('.tab-button').forEach(btn => {
        btn.classList.remove('active');
    });

    // Show selected tab
    document.getElementById(tabName).classList.add('active');
    event.target.classList.add('active');

    // Load data for specific tabs
    if (tabName === 'browse') {
        loadCategories();
        loadAllDocuments();
    }
}

// Setup file upload drag & drop
function setupFileUploads() {
    const uploads = [
        { div: 'categoryUpload', input: 'categoryFile' },
        { div: 'classifyUpload', input: 'classifyFile' },
        { div: 'ocrUpload', input: 'ocrFile' }
    ];

    uploads.forEach(upload => {
        const uploadDiv = document.getElementById(upload.div);
        const fileInput = document.getElementById(upload.input);

        uploadDiv.addEventListener('click', () => fileInput.click());

        uploadDiv.addEventListener('dragover', (e) => {
            e.preventDefault();
            uploadDiv.classList.add('dragover');
        });

        uploadDiv.addEventListener('dragleave', () => {
            uploadDiv.classList.remove('dragover');
        });

        uploadDiv.addEventListener('drop', (e) => {
            e.preventDefault();
            uploadDiv.classList.remove('dragover');
            const files = e.dataTransfer.files;
            if (files.length > 0) {
                fileInput.files = files;
                uploadDiv.querySelector('p').textContent = files[0].name;
            }
        });

        fileInput.addEventListener('change', () => {
            if (fileInput.files.length > 0) {
                uploadDiv.querySelector('p').textContent = fileInput.files[0].name;
            }
        });
    });
}

// Load dashboard stats
async function loadStats() {
    try {
        const response = await authenticatedFetch('/api/stats');
        const stats = await response.json();
        
        const statsHtml = `
            <div class="stat-card">
                <h3>${stats.total_categories}</h3>
                <p><i class="fas fa-tags"></i> Total Categories</p>
            </div>
            <div class="stat-card">
                <h3>${stats.total_documents}</h3>
                <p><i class="fas fa-file"></i> Documents Archived</p>
            </div>
            <div class="stat-card">
                <h3>35%</h3>
                <p><i class="fas fa-percentage"></i> Min Confidence</p>
            </div>
        `;
        
        document.getElementById('stats').innerHTML = statsHtml;
    } catch (error) {
        console.error('Error loading stats:', error);
    }
}

// Load categories
async function loadCategories() {
    try {
        const response = await authenticatedFetch('/api/categories');
        const data = await response.json();
        categories = data.categories;
        
        const buttonsHtml = `
            <button class="category-btn active" onclick="filterDocuments('all')">
                All Documents
            </button>
            ${categories.map(cat => `
                <button class="category-btn" onclick="filterDocuments('${cat}')">
                    ${cat} (${data.counts[cat] || 0})
                </button>
            `).join('')}
        `;
        
        document.getElementById('categoryButtons').innerHTML = buttonsHtml;
    } catch (error) {
        console.error('Error loading categories:', error);
    }
}

// Load all documents
async function loadAllDocuments() {
    try {
        const response = await authenticatedFetch('/api/documents');
        const data = await response.json();
        documents = data.documents;
        displayDocuments(documents);
    } catch (error) {
        console.error('Error loading documents:', error);
    }
}

// Filter documents by category
async function filterDocuments(category) {
    // Update active button
    document.querySelectorAll('.category-btn').forEach(btn => {
        btn.classList.remove('active');
    });
    event.target.classList.add('active');

    try {
        let filteredDocs;
        if (category === 'all') {
            const response = await authenticatedFetch('/api/documents');
            const data = await response.json();
            filteredDocs = data.documents;
        } else {
            const response = await authenticatedFetch(`/api/documents/${category}`);
            const data = await response.json();
            filteredDocs = data.documents;
        }
        
        displayDocuments(filteredDocs);
    } catch (error) {
        console.error('Error filtering documents:', error);
    }
}

// Delete document
async function deleteDocument(documentId, filename) {
    if (!confirm(`Are you sure you want to delete "${filename}"? This action cannot be undone.`)) {
        return;
    }

    try {
        const response = await authenticatedFetch(`/api/documents/${documentId}`, {
            method: 'DELETE'
        });

        const result = await response.json();
        
        if (response.ok) {
            // Refresh the current view
            loadAllDocuments();
            loadStats();
            loadCategories();
            alert('Document deleted successfully');
        } else {
            alert('Failed to delete document: ' + result.detail);
        }
    } catch (error) {
        alert('Error deleting document: ' + error.message);
    }
}

// Display documents
function displayDocuments(docs) {
    const container = document.getElementById('documentsContainer');
    
    if (docs.length === 0) {
        container.innerHTML = '<p>No documents found for this category.</p>';
        return;
    }

    const docsHtml = docs.map(doc => {
        const similarityClass = doc.similarity >= 0.7 ? 'similarity-high' : 
                              doc.similarity >= 0.5 ? 'similarity-medium' : 'similarity-low';
        
        return `
            <div class="document-card">
                <h4><i class="fas fa-file"></i> ${doc.original_filename}</h4>
                <p><strong>Category:</strong> ${doc.category}</p>
                <p><strong>Confidence:</strong> 
                    <span class="similarity-badge ${similarityClass}">
                        ${(doc.similarity * 100).toFixed(1)}%
                    </span>
                </p>
                <p><strong>Upload Date:</strong> ${new Date(doc.upload_date).toLocaleDateString()}</p>
                <p><strong>OCR Preview:</strong></p>
                <div style="max-height: 100px; overflow-y: auto; background: #f8f9fa; padding: 0.5rem; border-radius: 4px; font-size: 0.8rem;">
                    ${doc.ocr_text.substring(0, 200)}${doc.ocr_text.length > 200 ? '...' : ''}
                </div>
                <div class="document-actions">
                    <button class="btn btn-danger" onclick="deleteDocument('${doc.id}', '${doc.original_filename}')">
                        <i class="fas fa-trash"></i> Delete
                    </button>
                </div>
            </div>
        `;
    }).join('');

    container.innerHTML = `<div class="document-grid">${docsHtml}</div>`;
}

// Form submissions
document.getElementById('uploadForm').addEventListener('submit', async (e) => {
    e.preventDefault();
    
    const fileInput = document.getElementById('categoryFile');
    const labelInput = document.getElementById('categoryLabel');
    const resultDiv = document.getElementById('uploadResult');
    
    if (!fileInput.files[0] || !labelInput.value.trim()) {
        showResult(resultDiv, 'Please select a file and enter a label.', 'error');
        return;
    }

    const formData = new FormData();
    formData.append('file', fileInput.files[0]);
    formData.append('label', labelInput.value.trim());

    showResult(resultDiv, '<div class="loading"></div> Uploading...', 'info');

    try {
        const response = await authenticatedFetch('/api/upload-category', {
            method: 'POST',
            body: formData
        });

        const result = await response.json();
        
        if (response.ok) {
            showResult(resultDiv, result.message, 'success');
            labelInput.value = '';
            fileInput.value = '';
            document.querySelector('#categoryUpload p').textContent = 'Click to select or drag & drop files here';
            loadStats();
            loadCategories();
        } else {
            showResult(resultDiv, result.detail, 'error');
        }
    } catch (error) {
        showResult(resultDiv, 'Upload failed: ' + error.message, 'error');
    }
});

document.getElementById('classifyForm').addEventListener('submit', async (e) => {
    e.preventDefault();
    
    const fileInput = document.getElementById('classifyFile');
    const resultDiv = document.getElementById('classifyResult');
    
    if (!fileInput.files[0]) {
        showResult(resultDiv, 'Please select a file to classify.', 'error');
        return;
    }

    const formData = new FormData();
    formData.append('file', fileInput.files[0]);

    showResult(resultDiv, '<div class="loading"></div> Classifying...', 'info');

    try {
        const response = await authenticatedFetch('/api/classify-document', {
            method: 'POST',
            body: formData
        });

        const result = await response.json();
        
        if (response.ok) {
            const confidenceText = result.confidence === 'high' ? '✅ High Confidence' : '⚠️ Low Confidence';
            const savedText = result.document_saved ? '\n📁 Document saved to archive' : '';
            
            let matchesText = '\n\nTop matches:\n';
            result.matches.forEach(match => {
                matchesText += `• ${match.category}: ${(match.similarity * 100).toFixed(1)}%\n`;
            });

            showResult(resultDiv, 
                `🎯 Classification: ${result.category}\n` +
                `${confidenceText} (${(result.similarity * 100).toFixed(1)}%)${savedText}${matchesText}`,
                result.confidence === 'high' ? 'success' : 'warning'
            );
            
            fileInput.value = '';
            document.querySelector('#classifyUpload p').textContent = 'Click to select or drag & drop files here';
            loadStats();
        } else {
            showResult(resultDiv, result.detail, 'error');
        }
    } catch (error) {
        showResult(resultDiv, 'Classification failed: ' + error.message, 'error');
    }
});

document.getElementById('ocrForm').addEventListener('submit', async (e) => {
    e.preventDefault();
    
    const fileInput = document.getElementById('ocrFile');
    const resultDiv = document.getElementById('ocrResult');
    
    if (!fileInput.files[0]) {
        showResult(resultDiv, 'Please select a file for OCR.', 'error');
        return;
    }

    const formData = new FormData();
    formData.append('file', fileInput.files[0]);

    showResult(resultDiv, '<div class="loading"></div> Extracting text...', 'info');

    try {
        const response = await authenticatedFetch('/api/ocr', {
            method: 'POST',
            body: formData
        });

        const result = await response.json();
        
        if (response.ok) {
            showResult(resultDiv, result.text, 'success');
        } else {
            showResult(resultDiv, result.detail, 'error');
        }
    } catch (error) {
        showResult(resultDiv, 'OCR failed: ' + error.message, 'error');
    }
});

// Utility function to show results
function showResult(element, message, type) {
    const className = type === 'success' ? 'result-success' : 
                    type === 'error' ? 'result-error' : 
                    type === 'warning' ? 'result-warning' : '';
    
    element.innerHTML = `<div class="result-box ${className}">${message}</div>`;
}