(function() {
    'use strict';
    // Drag and drop functionality

    let draggedFiles = [];
    let targetGroupingFolder = null;

    // Setup drag and drop
    function setupDragAndDrop() {
        // Prevent default drag behaviors
        ['dragenter', 'dragover', 'dragleave', 'drop'].forEach(eventName => {
            document.addEventListener(eventName, preventDefaults, false);
        });
    
        // Highlight drop zones
        ['dragenter', 'dragover'].forEach(eventName => {
            document.addEventListener(eventName, highlight, false);
        });
    
        ['dragleave', 'drop'].forEach(eventName => {
            document.addEventListener(eventName, unhighlight, false);
        });
    
        // Handle drops on grouping folders (for creating transmittals)
        document.getElementById('groupingFoldersList').addEventListener('drop', handleDrop, false);
    
        // Handle drops on the main app area (for adding directories).
        // Note: the root element is id="appContainer" (id="app" was a
        // stale reference that crashed dragDrop init in local mode).
        document.getElementById('appContainer').addEventListener('drop', handleAppDrop, false);
    }

    // Prevent default behaviors
    function preventDefaults(e) {
        e.preventDefault();
        e.stopPropagation();
    }

    // Highlight drop zone
    function highlight(e) {
        const folderItem = e.target.closest('.folder-item');
        if (folderItem && folderItem.parentElement.id === 'groupingFoldersList') {
            folderItem.classList.add('drag-over');
        }
    }

    // Remove highlight
    function unhighlight(e) {
        document.querySelectorAll('.drag-over').forEach(item => {
            item.classList.remove('drag-over');
        });
    }

    // Handle directory drop on main app area (for adding directories)
    async function handleAppDrop(e) {
        // Check if this is a drop on a grouping folder (handled separately)
        const folderItem = e.target.closest('.folder-item');
        if (folderItem && folderItem.parentElement.id === 'groupingFoldersList') {
            return; // Let handleDrop handle this
        }
    
        // Check if dataTransfer has directory items
        const items = e.dataTransfer.items;
        if (!items || items.length === 0) return;
    
        // Process each dropped item
        for (let i = 0; i < items.length; i++) {
            const item = items[i];
        
            // Check if it's a directory using the File System Access API
            if (item.kind === 'file') {
                const entry = await item.getAsFileSystemHandle();
            
                if (entry && entry.kind === 'directory') {
                    // Check if already added
                    const exists = window.app.directories.some(d => d.name === entry.name);
                    if (exists) {

                        continue;
                    }
                
                    // Add to directories
                    window.app.directories.push({
                        handle: entry,
                        name: entry.name,
                        path: entry.name
                    });
                
                    // Hide empty state if this is the first directory
                    if (window.app.directories.length === 1) {
                        window.app.modules.app.hideEmptyState();
                    }
                
                    // Scan the new directory
                    await window.app.modules.directory.scanDirectory(entry, entry.name);
                }
            }
        }
    
        // Update UI after processing all dropped directories
        if (window.app.directories.length > 0) {
            window.app.modules.app.updateUI();
        }
    }

    // Handle file drop on grouping folder (for creating transmittals)
    async function handleDrop(e) {
        const folderItem = e.target.closest('.folder-item');
        if (!folderItem) return;
    
        const files = Array.from(e.dataTransfer.files);
        if (files.length === 0) return;
    
        // Find the grouping folder
        const folderPath = folderItem.getAttribute('data-path');
        const groupingFolder = window.app.groupingFolders.find(f => f.path === folderPath);
        if (!groupingFolder) return;
    
        targetGroupingFolder = groupingFolder;
        draggedFiles = files;
    
        // Show transmittal creation dialog
        showTransmittalDialog();
    }

    // Show transmittal creation dialog
    function showTransmittalDialog() {
        const modal = document.getElementById('dropModal');
    
        // Generate default transmittal name
        const today = new Date();
        const dateStr = today.toISOString().split('T')[0]; // YYYY-MM-DD
    
        // Try to extract tracking number from first file
        let trackingNumber = 'TRACKING';
        let title = 'Transmittal';
    
        if (draggedFiles.length > 0) {
            const firstFile = draggedFiles[0];
            const parsed = zddc.parseFilename(firstFile.name) || {};
            if (parsed.trackingNumber) {
                trackingNumber = parsed.trackingNumber;
            }
            if (parsed.title) {
                title = parsed.title;
            }
        }
    
        const defaultName = `${dateStr}_${trackingNumber} (IFI) - ${title}`;
        document.getElementById('transmittalName').value = defaultName;
    
        // Show file preview
        updateFilePreview();
    
        modal.classList.remove('hidden');
    }

    // Update file preview in dialog
    function updateFilePreview() {
        const tbody = document.getElementById('filesPreviewBody');
    
        const rows = draggedFiles.map(file => {
            const parsed = zddc.parseFilename(file.name) || {};
        
            // Generate ZDDC-compliant name
            let newName = file.name;
            if (parsed.trackingNumber) {
                newName = `${parsed.trackingNumber}_${parsed.revision || 'A'} (${parsed.status || 'IFI'}) - ${parsed.title}.${parsed.extension}`;
            }
        
            const isValid = !!parsed.trackingNumber;
        
            return `
                <tr>
                    <td>${window.app.modules.app.escapeHtml(file.name)}</td>
                    <td>
                        <input type="text" 
                               class="form-input" 
                               value="${window.app.modules.app.escapeHtml(newName)}"
                               data-original="${window.app.modules.app.escapeHtml(file.name)}"
                               style="width: 100%;">
                    </td>
                    <td style="color: ${isValid ? 'green' : 'red'};">
                        ${isValid ? '✓ Valid' : '✗ Invalid'}
                    </td>
                </tr>
            `;
        }).join('');
    
        tbody.innerHTML = rows;
    }

    // Confirm transmittal creation
    async function confirmTransmittal() {
        const transmittalName = document.getElementById('transmittalName').value.trim();
    
        // Validate transmittal folder name
        if (!window.app.modules.parser.isTransmittalFolder(transmittalName)) {
            alert('Invalid transmittal folder name. Must follow format: YYYY-MM-DD_TRACKINGNUMBER (STATUS) - TITLE');
            return;
        }
    
        try {
            // Create transmittal folder
            const transmittalHandle = await targetGroupingFolder.handle.getDirectoryHandle(transmittalName, { create: true });
        
            // Get file mappings from preview
            const fileMappings = [];
            const inputs = document.querySelectorAll('#filesPreviewBody input');
            inputs.forEach((input, index) => {
                fileMappings.push({
                    originalFile: draggedFiles[index],
                    newName: input.value.trim()
                });
            });
        
            // Save files with new names
            for (const mapping of fileMappings) {
                const fileHandle = await transmittalHandle.getFileHandle(mapping.newName, { create: true });
                const writable = await fileHandle.createWritable();
                await writable.write(mapping.originalFile);
                await writable.close();
            }
        
            // Close modal
            document.getElementById('dropModal').classList.add('hidden');
        
            // Refresh to show new files
            await window.app.modules.directory.refreshDirectories();
        
            alert(`Transmittal created successfully with ${fileMappings.length} files.`);
        
        } catch (err) {
            console.error('Error creating transmittal:', err);
            alert('Error creating transmittal: ' + err.message);
        }
    }

    // Handle drag and drop on table rows (for metadata copy)
    function setupTableRowDragDrop() {
        document.getElementById('filesTableBody').addEventListener('dragover', (e) => {
            const tr = e.target.closest('tr');
            if (tr) {
                e.preventDefault();
                tr.classList.add('drag-over');
            }
        });
    
        document.getElementById('filesTableBody').addEventListener('dragleave', (e) => {
            const tr = e.target.closest('tr');
            if (tr) {
                tr.classList.remove('drag-over');
            }
        });
    
        document.getElementById('filesTableBody').addEventListener('drop', async (e) => {
            const tr = e.target.closest('tr');
            if (!tr) return;
        
            tr.classList.remove('drag-over');
        
            // Get tracking number and title from the row
            const trackingNumber = tr.querySelector('td[data-field="trackingNumber"]').textContent;
            const title = tr.querySelector('td[data-field="title"]').textContent;
        
            const files = Array.from(e.dataTransfer.files);
            if (files.length === 0) return;
        
            // For table row drops, just copy metadata
            alert(`Would copy metadata:\nTracking Number: ${trackingNumber}\nTitle: ${title}\n\nTo ${files.length} file(s)`);
        });
    }

    window.app.modules.dragDrop = {
        setupDragAndDrop,
        showTransmittalDialog,
        updateFilePreview,
        confirmTransmittal,
        setupTableRowDragDrop
    };

})();