document.addEventListener('DOMContentLoaded', () => {
    // DOM Elements
    const dropZone = document.getElementById('dropZone');
    const fileInput = document.getElementById('fileInput');
    const translateBtn = document.getElementById('translateBtn');
    const previewSection = document.getElementById('previewSection');
    const downloadBtn = document.getElementById('downloadBtn');
    const previewFrame = document.getElementById('previewFrame');
    const themeToggle = document.querySelector('#themeToggle');

    // File handling
    dropZone.addEventListener('click', () => fileInput.click());
    
    fileInput.addEventListener('change', (e) => {
        if (e.target.files.length) {
            handleFileSelection(e.target.files[0]);
        }
    });

    ['dragenter', 'dragover', 'dragleave', 'drop'].forEach(eventName => {
        dropZone.addEventListener(eventName, preventDefaults, false);
    });

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

    ['dragenter', 'dragover'].forEach(eventName => {
        dropZone.addEventListener(eventName, highlight, false);
    });

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

    function highlight() {
        dropZone.classList.add('highlight');
    }

    function unhighlight() {
        dropZone.classList.remove('highlight');
    }

    dropZone.addEventListener('drop', (e) => {
        const dt = e.dataTransfer;
        const file = dt.files[0];
        if (file && file.type === 'application/pdf') {
            handleFileSelection(file);
        } else {
            alert('Please upload a valid PDF file.');
        }
    });

    function handleFileSelection(file) {
        const fileName = file.name;
        const fileSize = (file.size / (1024 * 1024)).toFixed(2); // in MB
        
        if (fileSize > 50) {
            alert('File size exceeds 50MB limit.');
            return;
        }

        // Update UI to show selected file
        dropZone.innerHTML = `
            <i data-feather="file-text" class="w-12 h-12 text-primary-500 mb-4"></i>
            <p class="text-gray-900 dark:text-white font-medium">${fileName}</p>
            <p class="text-sm text-gray-500 dark:text-gray-400">${fileSize} MB</p>
        `;
        feather.replace();
    }

    // Translation process
    translateBtn.addEventListener('click', async () => {
        if (!fileInput.files.length) {
            alert('Please select a PDF file first.');
            return;
        }

        // Show loading state
        translateBtn.disabled = true;
        translateBtn.innerHTML = `
            <i data-feather="loader" class="animate-spin mr-2"></i>
            Translating...
        `;
        feather.replace();

        // Simulate translation process
        setTimeout(() => {
            // In a real app, this would upload the file to a server for processing
            // and then return the translated PDF
            
            // For demo purposes, we'll just show the preview section
            previewSection.classList.remove('hidden');
            previewFrame.src = URL.createObjectURL(fileInput.files[0]);
            
            // Reset button state
            translateBtn.disabled = false;
            translateBtn.innerHTML = `
                <i data-feather="globe" class="mr-2"></i>
                Translate Document
            `;
            feather.replace();
        }, 3000);
    });

    // Download functionality
    downloadBtn.addEventListener('click', () => {
        if (previewFrame.src) {
            const a = document.createElement('a');
            a.href = previewFrame.src;
            a.download = `translated_${fileInput.files[0].name}`;
            a.click();
        }
    });
});