document.addEventListener('DOMContentLoaded', function() {
    // File upload handling
    const dropArea = document.getElementById('drop-area');
    const fileInput = document.getElementById('file-input');
    const filePreview = document.getElementById('file-preview');
    const uploadForm = document.getElementById('upload-form');

    // Only initialize if elements exist
    if (!dropArea || !fileInput || !filePreview || !uploadForm) {
        console.warn('Some upload elements not found, skipping initialization');
        return;
    }

    // Prevent default drag behaviors
    ['dragenter', 'dragover', 'dragleave', 'drop'].forEach(eventName => {
        dropArea.addEventListener(eventName, preventDefaults, false);
        document.body.addEventListener(eventName, preventDefaults, false);
    });

    // Highlight drop area when item is dragged over it
    ['dragenter', 'dragover'].forEach(eventName => {
        dropArea.addEventListener(eventName, highlight, false);
    });

    ['dragleave', 'drop'].forEach(eventName => {
        dropArea.addEventListener(eventName, unhighlight, false);
    });

    // Handle dropped files
    dropArea.addEventListener('drop', handleDrop, false);

    // Click to upload functionality
    dropArea.addEventListener('click', function(e) {
        // Prevent triggering if clicking the button itself
        if (e.target.tagName !== 'BUTTON' && e.target.tagName !== 'I') {
            fileInput.click();
        }
    });

    // Handle file input change
    fileInput.addEventListener('change', function(e) {
        handleFiles(e.target.files);
    });

    function preventDefaults(e) {
        e.preventDefault();
        e.stopPropagation();
    }

    function highlight() {
        dropArea.style.borderColor = 'var(--primary-color)';
        dropArea.style.backgroundColor = 'rgba(139, 92, 246, 0.05)';
        dropArea.classList.add('dragover');
    }

    function unhighlight() {
        dropArea.style.borderColor = 'var(--border-color)';
        dropArea.style.backgroundColor = 'var(--background-light)';
        dropArea.classList.remove('dragover');
    }

    function handleDrop(e) {
        const dt = e.dataTransfer;
        const files = dt.files;
        handleFiles(files);
    }

    function handleFiles(files) {
        if (files.length > 0) {
            const file = files[0];
            
            // Validate file type
            const allowedTypes = ['application/pdf', 'application/msword', 
                'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
                'application/vnd.ms-powerpoint',
                'application/vnd.openxmlformats-officedocument.presentationml.presentation',
                'text/plain'];
            
            const allowedExtensions = ['.pdf', '.doc', '.docx', '.ppt', '.pptx', '.txt'];
            const fileExtension = '.' + file.name.split('.').pop().toLowerCase();
            
            if (!allowedTypes.includes(file.type) && !allowedExtensions.includes(fileExtension)) {
                alert('Please select a valid file type (PDF, Word, PowerPoint, or Text)');
                return;
            }
            
            // Check file size (50MB limit)
            if (file.size > 50 * 1024 * 1024) {
                alert('File size must be less than 50MB');
                return;
            }
            
            showFilePreview(file);
            
            // Auto-fill title if empty
            const titleInput = document.getElementById('title');
            if (titleInput && !titleInput.value) {
                titleInput.value = file.name.replace(/\.[^/.]+$/, "");
            }
        }
    }

    function showFilePreview(file) {
        const fileIcon = document.getElementById('file-icon');
        const fileName = document.getElementById('file-name');
        const fileSize = document.getElementById('file-size');
        
        if (!fileIcon || !fileName || !fileSize) {
            console.warn('File preview elements not found');
            return;
        }
        
        // Get file extension
        const extension = file.name.split('.').pop().toLowerCase();
        
        // Set icon and color based on file type
        let iconClass = 'fas fa-file';
        let iconColor = '#6b7280';
        
        switch(extension) {
            case 'pdf':
                iconClass = 'fas fa-file-pdf';
                iconColor = '#ef4444';
                break;
            case 'doc':
            case 'docx':
                iconClass = 'fas fa-file-word';
                iconColor = '#3b82f6';
                break;
            case 'ppt':
            case 'pptx':
                iconClass = 'fas fa-file-powerpoint';
                iconColor = '#f59e0b';
                break;
            case 'txt':
                iconClass = 'fas fa-file-alt';
                iconColor = 'var(--primary-color)';
                break;
        }
        
        fileIcon.innerHTML = `<i class="${iconClass}"></i>`;
        fileIcon.style.background = iconColor;
        fileName.textContent = file.name;
        fileSize.textContent = formatFileSize(file.size);
        
        filePreview.style.display = 'block';
    }

    // Make removeFile global so it can be called from onclick
    window.removeFile = function() {
        fileInput.value = '';
        filePreview.style.display = 'none';
        
        // Clear the title if it was auto-filled
        const titleInput = document.getElementById('title');
        if (titleInput) {
            titleInput.value = '';
        }
    };

    function formatFileSize(bytes) {
        if (bytes === 0) return '0 Bytes';
        const k = 1024;
        const sizes = ['Bytes', 'KB', 'MB', 'GB'];
        const i = Math.floor(Math.log(bytes) / Math.log(k));
        return parseFloat((bytes / Math.pow(k, i)).toFixed(2)) + ' ' + sizes[i];
    }

    // Form submission handling
    uploadForm.addEventListener('submit', function(e) {
        const uploadBtn = document.getElementById('upload-btn');
        const fileInputValue = fileInput.value;
        
        // Check if file is selected
        if (!fileInputValue) {
            e.preventDefault();
            alert('Please select a file to upload');
            return false;
        }
        
        // Show loading state
        const originalText = uploadBtn.innerHTML;
        uploadBtn.innerHTML = '<i class="fas fa-spinner fa-spin me-2"></i>Processing...';
        uploadBtn.disabled = true;
        
        // Re-enable after timeout (failsafe)
        setTimeout(() => {
            uploadBtn.innerHTML = originalText;
            uploadBtn.disabled = false;
        }, 30000);
        
        // Form will submit normally (not via AJAX)
    });

    // Initialize any existing file in the input
    if (fileInput.files && fileInput.files.length > 0) {
        handleFiles(fileInput.files);
    }
});

// Processing mode selection functionality
function selectProcessingMode(mode) {
    // Remove active class from all options
    document.querySelectorAll('.processing-option').forEach(option => {
        option.style.border = '2px solid var(--border-color)';
        option.style.transform = 'none';
        option.style.boxShadow = 'none';
    });
    
    // Select the radio button
    const radioButton = document.getElementById(mode + '_mode');
    if (radioButton) {
        radioButton.checked = true;
        
        // Add active styling to selected option
        const selectedOption = radioButton.closest('.processing-option');
        if (mode === 'fast') {
            selectedOption.style.border = '2px solid #28a745';
            selectedOption.style.boxShadow = '0 4px 15px rgba(40, 167, 69, 0.2)';
        } else {
            selectedOption.style.border = '2px solid #6f42c1';
            selectedOption.style.boxShadow = '0 4px 15px rgba(111, 66, 193, 0.2)';
        }
        selectedOption.style.transform = 'translateY(-2px)';
        
        // Update submit button text
        updateSubmitButtonText(mode);
    }
}

function updateSubmitButtonText(mode) {
    const uploadBtn = document.getElementById('upload-btn');
    if (uploadBtn) {
        if (mode === 'fast') {
            uploadBtn.innerHTML = '<i class="fas fa-bolt me-2"></i>Upload & Process (Fast)';
        } else {
            uploadBtn.innerHTML = '<i class="fas fa-eye me-2"></i>Upload & Process (Advanced OCR)';
        }
    }
}

// Initialize processing mode styling on page load
document.addEventListener('DOMContentLoaded', function() {
    // Set initial styling for fast mode (default)
    selectProcessingMode('fast');
    
    // Add click handlers for processing options
    document.querySelectorAll('.processing-option').forEach(option => {
        option.addEventListener('click', function() {
            const radioButton = this.querySelector('input[type="radio"]');
            if (radioButton) {
                selectProcessingMode(radioButton.value);
            }
        });
    });
});