document.addEventListener('DOMContentLoaded', () => {
    const dropZone = document.getElementById('drop-zone');
    const fileInput = document.getElementById('file-input');
    const analyzeBtn = document.getElementById('analyze-btn');
    const fileInfo = document.getElementById('file-info');
    const filenameDisplay = document.getElementById('filename-display');
    const removeFileBtn = document.getElementById('remove-file');
    const uploadContent = document.querySelector('.upload-content');
    const loading = document.getElementById('loading');
    const results = document.getElementById('results');
    const resultImg = document.getElementById('result-img');
    const resultVid = document.getElementById('result-vid');
    const totalCount = document.getElementById('total-count');
    const objectList = document.getElementById('object-list');
    const downloadBtn = document.getElementById('download-btn');

    let selectedFile = null;

    // Handle Click to Upload
    dropZone.addEventListener('click', () => fileInput.click());

    fileInput.addEventListener('change', (e) => {
        if (e.target.files.length > 0) {
            handleFile(e.target.files[0]);
        }
    });

    // Handle Drag & Drop
    dropZone.addEventListener('dragover', (e) => {
        e.preventDefault();
        dropZone.classList.add('dragover');
    });

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

    dropZone.addEventListener('drop', (e) => {
        e.preventDefault();
        dropZone.classList.remove('dragover');
        if (e.dataTransfer.files.length > 0) {
            handleFile(e.dataTransfer.files[0]);
        }
    });

    function handleFile(file) {
        selectedFile = file;
        filenameDisplay.textContent = file.name;
        fileInfo.style.display = 'flex';
        uploadContent.style.display = 'none';
        analyzeBtn.disabled = false;

        // Reset results display
        results.style.display = 'none';
        resultImg.style.display = 'none';
        resultVid.style.display = 'none';
    }

    removeFileBtn.addEventListener('click', (e) => {
        e.stopPropagation();
        selectedFile = null;
        fileInput.value = '';
        fileInfo.style.display = 'none';
        uploadContent.style.display = 'block';
        analyzeBtn.disabled = true;
    });

    analyzeBtn.addEventListener('click', async () => {
        if (!selectedFile) return;

        const formData = new FormData();
        formData.append('file', selectedFile);

        // Show loading
        loading.style.display = 'block';
        analyzeBtn.disabled = true;
        results.style.display = 'none';

        try {
            const response = await fetch('/detect', {
                method: 'POST',
                body: formData
            });

            const data = await response.json();

            if (data.success) {
                displayResults(data);
            } else {
                alert('Analysis failed: ' + (data.error || 'Unknown error'));
            }
        } catch (error) {
            console.error('Error:', error);
            alert('An error occurred during analysis.');
        } finally {
            loading.style.display = 'none';
            analyzeBtn.disabled = false;
        }
    });

    function displayResults(data) {
        results.style.display = 'block';

        // Show Image or Video preview
        if (data.type === 'image') {
            resultImg.src = data.result_url + '?t=' + new Date().getTime(); // Prevent caching
            resultImg.style.display = 'block';
            resultVid.style.display = 'none';
            totalCount.textContent = data.total_count;

            // Build object list
            objectList.innerHTML = '';
            for (const [name, count] of Object.entries(data.counts)) {
                const item = document.createElement('div');
                item.className = 'object-item';
                item.innerHTML = `
                    <span class="obj-name">${name}</span>
                    <span class="obj-count">${count}</span>
                `;
                objectList.innerHTML += item.outerHTML;
            }
        } else {
            resultVid.src = data.result_url;
            resultVid.style.display = 'block';
            resultImg.style.display = 'none';
            totalCount.textContent = '-'; // Video counts are harder to aggregate simply
            objectList.innerHTML = '<p style="color: var(--text-dim)">Summary detection for video complete. Check video for visual bounding boxes.</p>';
        }

        downloadBtn.href = data.result_url;

        // Scroll to results
        results.scrollIntoView({ behavior: 'smooth' });
    }
});