<?php
require_once __DIR__ . '/../config.php';
require_once __DIR__ . '/../includes/functions.php';

if (empty($_SESSION['admin_logged_in'])) {
    header('Location: login.php');
    exit;
}

$pageTitle = 'Produkte verwalten';
$message = '';
$messageType = '';
$categories = getCategories();

function handleImageUpload($fileInputName = 'image_file') {
    if (!isset($_FILES[$fileInputName]) || $_FILES[$fileInputName]['error'] === UPLOAD_ERR_NO_FILE) {
        return ['success' => true, 'filename' => null];
    }

    $file = $_FILES[$fileInputName];
    if ($file['error'] !== UPLOAD_ERR_OK) {
        return ['success' => false, 'message' => 'Upload fehlgeschlagen.'];
    }

    $allowedExtensions = ['jpg', 'jpeg', 'png', 'webp', 'gif'];
    $originalName = basename($file['name']);
    $extension = strtolower(pathinfo($originalName, PATHINFO_EXTENSION));
    if (!in_array($extension, $allowedExtensions, true)) {
        return ['success' => false, 'message' => 'Ungültiger Dateityp.'];
    }

    $finfo = new finfo(FILEINFO_MIME_TYPE);
    $mimeType = $finfo->file($file['tmp_name']);
    $allowedMimes = ['image/jpeg', 'image/png', 'image/webp', 'image/gif'];
    if (!in_array($mimeType, $allowedMimes, true)) {
        return ['success' => false, 'message' => 'Die Datei ist kein gültiges Bild.'];
    }

    $uploadsDir = rtrim(UPLOADS_DIR, '/\\');
    if (!is_dir($uploadsDir) && !mkdir($uploadsDir, 02775, true) && !is_dir($uploadsDir)) {
        return ['success' => false, 'message' => 'Upload-Verzeichnis konnte nicht erstellt werden.'];
    }

    if (is_dir($uploadsDir)) {
        @chmod($uploadsDir, 02775);
    }

    if (!is_writable($uploadsDir)) {
        return ['success' => false, 'message' => 'Upload-Verzeichnis ist nicht beschreibbar: ' . $uploadsDir];
    }

    $safeBaseName = preg_replace('/[^a-zA-Z0-9_-]/', '-', pathinfo($originalName, PATHINFO_FILENAME));
    $safeBaseName = trim((string) $safeBaseName, '-');
    if ($safeBaseName === '') {
        $safeBaseName = 'bild';
    }

    $targetFilename = $safeBaseName . '.' . $extension;
    $targetPath = $uploadsDir . '/' . $targetFilename;
    $counter = 1;
    while (file_exists($targetPath)) {
        $targetFilename = $safeBaseName . '-' . $counter . '.' . $extension;
        $targetPath = $uploadsDir . '/' . $targetFilename;
        $counter++;
    }

    if (!move_uploaded_file($file['tmp_name'], $targetPath)) {
        return ['success' => false, 'message' => 'Bild konnte nicht gespeichert werden.'];
    }

    return ['success' => true, 'filename' => $targetFilename];
}

function buildProductAvailabilityFields($sizesInput, $submittedValues = [], $existingValues = []) {
    $sizes = getProductSizes(['sizes' => (string) $sizesInput]);
    if (empty($sizes)) {
        $sizes = ['Standard'];
    }

    $availabilityLabels = [];
    foreach ($sizes as $size) {
        $fieldName = 'availability_' . str_replace([' ', ','], '_', $size);
        if (isset($submittedValues[$fieldName])) {
            $availabilityLabels[$size] = trim((string) $submittedValues[$fieldName]);
        } else {
            $availabilityLabels[$size] = trim((string) ($existingValues[$size] ?? ''));
        }
    }

    return [
        'sizes' => implode(',', $sizes),
        'availability_labels' => $availabilityLabels,
    ];
}

function getSubmittedProductCategoryIds($submittedValues) {
    $selectedCategoryIds = normalizeProductCategoryIds($submittedValues['categories'] ?? []);
    $validCategoryIds = [];

    foreach ($selectedCategoryIds as $categoryId) {
        if (getCategoryById($categoryId) !== null) {
            $validCategoryIds[] = $categoryId;
        }
    }

    return $validCategoryIds;
}

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $products = getProducts();

    if (empty($categories)) {
        $message = 'Bitte zuerst mindestens eine Kategorie anlegen.';
        $messageType = 'error';
    } elseif (isset($_POST['add_product']) || isset($_POST['update_product'])) {
        $uploadResult = handleImageUpload();
        if (!$uploadResult['success']) {
            $message = $uploadResult['message'];
            $messageType = 'error';
        } else {
            $categoryIds = getSubmittedProductCategoryIds($_POST);
            $existingLabels = [];
            $productId = isset($_POST['product_id']) ? (int) $_POST['product_id'] : 0;
            foreach ($products as $product) {
                if ((int) $product['id'] === $productId) {
                    $existingLabels = $product['availability_labels'] ?? [];
                    break;
                }
            }

            $sizeData = buildProductAvailabilityFields($_POST['sizes'] ?? '', $_POST, $existingLabels);

            if (empty($categoryIds)) {
                $message = 'Bitte mindestens eine gültige Kategorie auswählen.';
                $messageType = 'error';
            } else {
                $record = [
                    'name' => sanitize($_POST['name'] ?? ''),
                    'description' => trim((string) ($_POST['description'] ?? '')),
                    'categories' => $categoryIds,
                    'image' => $uploadResult['filename'] !== null ? $uploadResult['filename'] : trim((string) ($_POST['image'] ?? '')),
                    'sizes' => $sizeData['sizes'],
                    'availability_labels' => $sizeData['availability_labels'],
                ];

                if ($record['name'] === '') {
                    $message = 'Bitte einen Produktnamen eingeben.';
                    $messageType = 'error';
                } elseif (isset($_POST['add_product'])) {
                    $newId = empty($products) ? 1 : (max(array_map(function ($product) {
                        return (int) $product['id'];
                    }, $products)) + 1);
                    $record['id'] = $newId;
                    $products[] = $record;
                    saveProducts($products);
                    $message = 'Produkt wurde angelegt.';
                    $messageType = 'success';
                } else {
                    $updated = false;
                    foreach ($products as &$product) {
                        if ((int) $product['id'] === $productId) {
                            $record['id'] = $productId;
                            $product = $record;
                            $updated = true;
                            break;
                        }
                    }
                    unset($product);

                    if ($updated) {
                        saveProducts($products);
                        $message = 'Produkt wurde aktualisiert.';
                        $messageType = 'success';
                    } else {
                        $message = 'Produkt nicht gefunden.';
                        $messageType = 'error';
                    }
                }
            }
        }
    }

    if (isset($_POST['delete_product'])) {
        $productId = (int) ($_POST['product_id'] ?? 0);
        $products = array_values(array_filter($products, function ($product) use ($productId) {
            return (int) $product['id'] !== $productId;
        }));
        saveProducts($products);
        $message = 'Produkt wurde gelöscht.';
        $messageType = 'success';
    }
}

$products = getProducts();
$editingProduct = isset($_GET['edit']) ? getProductById((int) $_GET['edit']) : null;

$bodyClass = 'admin-page';
include __DIR__ . '/../includes/header.php';
?>

<div class="admin-header">
    <h2>Produkte verwalten</h2>
    <div>
        <a href="index.php" class="btn btn-secondary">Zurück zum Dashboard</a>
    </div>
</div>

<?php if ($message !== ''): ?>
    <div class="alert alert-<?php echo escape($messageType); ?>">
        <?php echo escape($message); ?>
    </div>
<?php endif; ?>

<?php
$currentProduct = $editingProduct ?: [
    'id' => '',
    'name' => '',
    'description' => '',
    'categories' => [],
    'sizes' => 'Standard',
    'availability_labels' => ['Standard' => ''],
    'image' => '',
];
$currentSizes = getProductSizes($currentProduct);
if (empty($currentSizes)) {
    $currentSizes = ['Standard'];
}
?>

<div class="panel panel-lg">
    <h3><?php echo $editingProduct ? 'Produkt bearbeiten' : 'Neues Produkt anlegen'; ?></h3>
    <form method="POST" enctype="multipart/form-data">
        <?php if ($editingProduct): ?>
            <input type="hidden" name="product_id" value="<?php echo (int) $editingProduct['id']; ?>">
        <?php endif; ?>

        <div class="form-group">
            <label for="name">Name *</label>
            <input type="text" id="name" name="name" required value="<?php echo escape($currentProduct['name']); ?>">
        </div>

        <div class="form-group">
            <label for="description">Beschreibung</label>
            <textarea id="description" name="description" rows="4"><?php echo escape($currentProduct['description']); ?></textarea>
        </div>

        <div class="form-group">
            <label for="categories">Kategorien *</label>
            <select id="categories" name="categories[]" multiple size="<?php echo max(3, min(8, count($categories))); ?>" required>
                <?php foreach ($categories as $category): ?>
                    <option value="<?php echo escape($category['id']); ?>" <?php echo in_array($category['id'], getProductCategoryIds($currentProduct), true) ? 'selected' : ''; ?>>
                        <?php echo escape($category['label']); ?>
                    </option>
                <?php endforeach; ?>
            </select>
        </div>

        <div class="form-group">
            <label for="sizes">Größen (kommagetrennt) *</label>
            <input type="text" id="sizes" name="sizes" required value="<?php echo escape($currentProduct['sizes']); ?>" placeholder="Standard" oninput="updateAvailabilityFields()">
            <small>Für Artikel ohne Varianten z. B. <code>Standard</code> oder <code>Einheitsgröße</code>.</small>
        </div>

        <div id="availability-group">
            <?php foreach ($currentSizes as $size): ?>
                <div class="form-group">
                    <label>Lieferhinweis für Größe "<?php echo escape($size); ?>"</label>
                    <textarea name="availability_<?php echo escape(str_replace([' ', ','], '_', $size)); ?>" rows="2" placeholder="Optionaler Hinweis"><?php echo escape($currentProduct['availability_labels'][$size] ?? ''); ?></textarea>
                </div>
            <?php endforeach; ?>
        </div>

        <div class="form-group">
            <label for="image">Bilddateiname</label>
            <input type="text" id="image" name="image" value="<?php echo escape($currentProduct['image']); ?>">
        </div>

        <div class="form-group">
            <label for="image_file">Oder Bild hochladen</label>
            <input type="file" id="image_file" name="image_file" accept=".jpg,.jpeg,.png,.webp,.gif,image/*">
        </div>

        <button type="submit" name="<?php echo $editingProduct ? 'update_product' : 'add_product'; ?>" class="btn">
            <?php echo $editingProduct ? 'Produkt aktualisieren' : 'Produkt anlegen'; ?>
        </button>
        <?php if ($editingProduct): ?>
            <a href="products.php" class="btn btn-secondary">Abbrechen</a>
        <?php endif; ?>
    </form>
</div>

<script>
function updateAvailabilityFields() {
    const sizesInput = document.getElementById('sizes');
    const group = document.getElementById('availability-group');
    const currentValues = {};

    group.querySelectorAll('textarea').forEach((textarea) => {
        currentValues[textarea.name] = textarea.value;
    });

    const sizes = sizesInput.value
        .split(',')
        .map((size) => size.trim())
        .filter((size, index, all) => size && all.indexOf(size) === index);

    const finalSizes = sizes.length > 0 ? sizes : ['Standard'];
    let html = '';

    finalSizes.forEach((size) => {
        const safeName = size.replace(/[ ,]/g, '_');
        const fieldName = 'availability_' + safeName;
        const currentValue = Object.prototype.hasOwnProperty.call(currentValues, fieldName) ? currentValues[fieldName] : '';
        html += '<div class="form-group">';
        html += '<label>Lieferhinweis für Größe "' + size.replace(/"/g, '&quot;') + '"</label>';
        html += '<textarea name="' + fieldName + '" rows="2" placeholder="Optionaler Hinweis">' + currentValue.replace(/</g, '&lt;').replace(/>/g, '&gt;') + '</textarea>';
        html += '</div>';
    });

    group.innerHTML = html;
}
</script>

<h3>Alle Produkte</h3>
<?php if (empty($products)): ?>
    <p>Keine Produkte vorhanden.</p>
<?php else: ?>
    <div class="table-responsive">
        <table class="responsive-table">
            <thead>
                <tr>
                    <th>ID</th>
                    <th>Name</th>
                    <th>Kategorien</th>
                    <th>Größen</th>
                    <th>Lieferhinweise</th>
                    <th>Aktionen</th>
                </tr>
            </thead>
            <tbody>
                <?php foreach ($products as $product): ?>
                    <tr>
                        <td data-label="ID"><?php echo (int) $product['id']; ?></td>
                        <td data-label="Name"><?php echo escape($product['name']); ?></td>
                        <td data-label="Kategorien"><?php echo escape(implode(', ', getCategoryLabels(getProductCategoryIds($product)))); ?></td>
                        <td data-label="Größen"><?php echo escape(implode(', ', getProductSizes($product))); ?></td>
                        <td data-label="Lieferhinweise">
                            <?php
                            $labels = [];
                            foreach (($product['availability_labels'] ?? []) as $size => $label) {
                                if (trim((string) $label) !== '') {
                                    $labels[] = $size . ': ' . $label;
                                }
                            }
                            echo empty($labels) ? 'Keine' : escape(implode(' | ', $labels));
                            ?>
                        </td>
                        <td data-label="Aktionen">
                            <a href="?edit=<?php echo (int) $product['id']; ?>" class="btn btn-small">Bearbeiten</a>
                            <form method="POST" class="inline-form" onsubmit="return confirm('Produkt wirklich löschen?');">
                                <input type="hidden" name="product_id" value="<?php echo (int) $product['id']; ?>">
                                <button type="submit" name="delete_product" class="btn btn-secondary btn-small">Löschen</button>
                            </form>
                        </td>
                    </tr>
                <?php endforeach; ?>
            </tbody>
        </table>
    </div>
<?php endif; ?>

<?php include __DIR__ . '/../includes/footer.php'; ?>