{% extends "base.html" %}
{% set active_page = "scan" %}

{% block content %}
<div class="card">
    <h2>Scan-Upload</h2>
    <p class="text-muted" style="margin-bottom:1rem;">
        Mehrseitige PDF hochladen. Trennseiten mit QR-Code werden automatisch erkannt und die einzelnen Dokumente gesendet.
    </p>

    <!-- Upload Zone -->
    <div id="uploadZone" class="upload-zone" onclick="document.getElementById('fileInput').click()">
        <div class="upload-icon">&#128196;</div>
        <div class="upload-text">PDF hierher ziehen oder klicken zum Auswählen</div>
        <div class="upload-hint">Unterstützt große Dateien (1 GB+)</div>
        <input type="file" id="fileInput" accept=".pdf,application/pdf" style="display:none;">
    </div>

    <!-- Upload Progress -->
    <div id="uploadProgress" style="display:none;">
        <div class="progress-header">
            <span id="uploadFilename"></span>
            <span id="uploadPercent">0%</span>
        </div>
        <div class="progress-bar-track">
            <div id="uploadBar" class="progress-bar-fill" style="width:0%"></div>
        </div>
        <div id="uploadStatus" class="text-muted" style="margin-top:0.3rem;font-size:0.85rem;"></div>
    </div>

    <!-- Processing Progress -->
    <div id="processProgress" style="display:none;">
        <div class="progress-header">
            <span>Verarbeitung</span>
            <span id="processStage"></span>
        </div>
        <div class="progress-bar-track">
            <div id="processBar" class="progress-bar-fill progress-bar-processing" style="width:0%"></div>
        </div>
        <div id="processStatus" class="text-muted" style="margin-top:0.3rem;font-size:0.85rem;"></div>
    </div>

    <!-- Result -->
    <div id="resultArea" style="display:none;"></div>
</div>

<div class="card">
    <h2>Trennseiten</h2>
    <p class="text-muted" style="margin-bottom:1rem;">
        Trennseiten ausdrucken und zwischen die Dokumente legen, bevor der Stapel gescannt wird.
    </p>
    <a href="/api/separator-pdf" class="btn btn-secondary" download>Trennseiten-PDF herunterladen</a>
</div>

<script>
const CHUNK_SIZE = 10 * 1024 * 1024; // 10 MB
let currentUploadId = null;

// Drag & Drop
const zone = document.getElementById('uploadZone');
const fileInput = document.getElementById('fileInput');

zone.addEventListener('dragover', (e) => {
    e.preventDefault();
    zone.classList.add('upload-zone-active');
});

zone.addEventListener('dragleave', () => {
    zone.classList.remove('upload-zone-active');
});

zone.addEventListener('drop', (e) => {
    e.preventDefault();
    zone.classList.remove('upload-zone-active');
    const files = e.dataTransfer.files;
    if (files.length > 0) handleFile(files[0]);
});

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

function formatBytes(bytes) {
    if (bytes < 1024) return bytes + ' B';
    if (bytes < 1024 * 1024) return (bytes / 1024).toFixed(1) + ' KB';
    if (bytes < 1024 * 1024 * 1024) return (bytes / (1024 * 1024)).toFixed(1) + ' MB';
    return (bytes / (1024 * 1024 * 1024)).toFixed(2) + ' GB';
}

function generateUUID() {
    return crypto.randomUUID ? crypto.randomUUID() : 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
        const r = Math.random() * 16 | 0;
        return (c === 'x' ? r : (r & 0x3 | 0x8)).toString(16);
    });
}

async function handleFile(file) {
    if (!file.name.toLowerCase().endsWith('.pdf')) {
        showResult('Bitte eine PDF-Datei auswählen.', 'error');
        return;
    }

    // Reset UI
    document.getElementById('resultArea').style.display = 'none';
    document.getElementById('processProgress').style.display = 'none';
    zone.style.display = 'none';

    const uploadId = generateUUID();
    currentUploadId = uploadId;

    const totalChunks = Math.ceil(file.size / CHUNK_SIZE);
    const uploadProgress = document.getElementById('uploadProgress');
    const uploadBar = document.getElementById('uploadBar');
    const uploadPercent = document.getElementById('uploadPercent');
    const uploadStatus = document.getElementById('uploadStatus');
    const uploadFilename = document.getElementById('uploadFilename');

    uploadFilename.textContent = file.name + ' (' + formatBytes(file.size) + ')';
    uploadBar.style.width = '0%';
    uploadPercent.textContent = '0%';
    uploadStatus.textContent = 'Upload wird gestartet...';
    uploadProgress.style.display = '';

    // Chunked upload
    try {
        for (let i = 0; i < totalChunks; i++) {
            const start = i * CHUNK_SIZE;
            const end = Math.min(start + CHUNK_SIZE, file.size);
            const chunk = file.slice(start, end);

            const formData = new FormData();
            formData.append('file', chunk);
            formData.append('chunk_index', i);
            formData.append('total_chunks', totalChunks);
            formData.append('upload_id', uploadId);
            formData.append('filename', file.name);

            const resp = await fetch('/api/scan-upload-chunk', {
                method: 'POST',
                body: formData,
            });

            if (!resp.ok) {
                const errData = await resp.json().catch(() => ({}));
                throw new Error(errData.error || 'Upload fehlgeschlagen (HTTP ' + resp.status + ')');
            }

            const pct = Math.round(((i + 1) / totalChunks) * 100);
            uploadBar.style.width = pct + '%';
            uploadPercent.textContent = pct + '%';
            uploadStatus.textContent = 'Chunk ' + (i + 1) + '/' + totalChunks + ' (' + formatBytes(end) + ' von ' + formatBytes(file.size) + ')';
        }

        uploadStatus.textContent = 'Upload abgeschlossen. Starte Verarbeitung...';
        startProcessing(uploadId);

    } catch (e) {
        showResult('Upload-Fehler: ' + e.message, 'error');
        resetUploadZone();
    }
}

async function startProcessing(uploadId) {
    const processProgress = document.getElementById('processProgress');
    const processBar = document.getElementById('processBar');
    const processStage = document.getElementById('processStage');
    const processStatus = document.getElementById('processStatus');

    processBar.style.width = '0%';
    processStage.textContent = '';
    processStatus.textContent = 'Starte Verarbeitung...';
    processProgress.style.display = '';

    try {
        const resp = await fetch('/api/scan-process', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ upload_id: uploadId }),
        });

        if (!resp.ok) {
            const errData = await resp.json().catch(() => ({}));
            throw new Error(errData.error || 'Verarbeitung konnte nicht gestartet werden');
        }

        // Subscribe to SSE for progress
        listenProgress(uploadId);

    } catch (e) {
        showResult('Fehler: ' + e.message, 'error');
        resetUploadZone();
    }
}

function listenProgress(uploadId) {
    const processBar = document.getElementById('processBar');
    const processStage = document.getElementById('processStage');
    const processStatus = document.getElementById('processStatus');

    const evtSource = new EventSource('/api/scan-status/' + uploadId);

    evtSource.addEventListener('scan', (e) => {
        const data = JSON.parse(e.data);
        const pct = Math.round((data.current / data.total) * 100);
        processBar.style.width = pct + '%';
        processStage.textContent = pct + '%';
        processStatus.textContent = 'Seite ' + data.current + ' von ' + data.total + ' analysiert...';
    });

    evtSource.addEventListener('status', (e) => {
        const data = JSON.parse(e.data);
        processStatus.textContent = data.message || '';
    });

    evtSource.addEventListener('send', (e) => {
        const data = JSON.parse(e.data);
        const pct = Math.round((data.current / data.total) * 100);
        processBar.style.width = pct + '%';
        processStage.textContent = data.current + '/' + data.total;
        processStatus.textContent = 'Dokument ' + data.current + ' von ' + data.total + ' wird gesendet...';
    });

    evtSource.addEventListener('done', (e) => {
        evtSource.close();
        const data = JSON.parse(e.data);
        const result = data.result || {};

        let msg = '';
        if (result.error) {
            msg = result.error;
            showResult(msg, 'error');
        } else {
            msg = result.documents + ' Dokument(e) erkannt';
            if (result.separator_pages > 0) {
                msg += ' (' + result.separator_pages + ' Trennseite(n))';
            }
            msg += ', ' + result.sent + ' gesendet';
            if (result.errors > 0) {
                msg += ', ' + result.errors + ' Fehler';
                showResult(msg, 'warning');
            } else {
                showResult(msg, 'success');
            }
        }

        document.getElementById('processProgress').style.display = 'none';
        resetUploadZone();
    });

    evtSource.addEventListener('error', (e) => {
        // Check if it's an SSE error event from our backend
        try {
            const data = JSON.parse(e.data);
            showResult('Verarbeitungsfehler: ' + (data.message || 'Unbekannter Fehler'), 'error');
        } catch {
            // Connection error
            showResult('Verbindung zum Server verloren.', 'error');
        }
        evtSource.close();
        document.getElementById('processProgress').style.display = 'none';
        resetUploadZone();
    });
}

function showResult(message, type) {
    const area = document.getElementById('resultArea');
    area.innerHTML = '<div class="alert alert-' + type + '">' + escapeHtml(message) + '</div>';
    area.style.display = '';
    document.getElementById('uploadProgress').style.display = 'none';
}

function resetUploadZone() {
    zone.style.display = '';
    fileInput.value = '';
}

function escapeHtml(str) {
    const d = document.createElement('div');
    d.textContent = str;
    return d.innerHTML;
}
</script>
{% endblock %}