<?php
declare(strict_types=1);

/**
 * Menu helper functions
 */

require_once __DIR__ . '/db.php';

function get_full_menu(bool $availableOnly = false): array {
    $pdo = get_db();
    
    $catStmt = $pdo->query("SELECT * FROM menu_categories ORDER BY sort_order ASC, id ASC");
    $categories = $catStmt->fetchAll() ?: [];

    $itemSql = "SELECT * FROM menu_items";
    if ($availableOnly) {
        $itemSql .= " WHERE is_available = 1";
    }
    $itemSql .= " ORDER BY sort_order ASC, id ASC";
    
    $itemStmt = $pdo->query($itemSql);
    $items = $itemStmt->fetchAll() ?: [];

    // Group items by category_id
    $grouped = [];
    foreach ($categories as $cat) {
        $cat['items'] = [];
        $grouped[$cat['id']] = $cat;
    }

    foreach ($items as $item) {
        if (isset($grouped[$item['category_id']])) {
            $grouped[$item['category_id']]['items'][] = $item;
        }
    }

    return array_values($grouped);
}

function get_all_categories(): array {
    $pdo = get_db();
    $stmt = $pdo->query("SELECT * FROM menu_categories ORDER BY sort_order ASC, id ASC");
    return $stmt->fetchAll() ?: [];
}

function get_category_by_id(int $id): ?array {
    $pdo = get_db();
    $stmt = $pdo->prepare("SELECT * FROM menu_categories WHERE id = ?");
    $stmt->execute([$id]);
    $res = $stmt->fetch();
    return $res ?: null;
}

function category_exists(int $id): bool {
    if ($id <= 0) {
        return false;
    }
    $pdo = get_db();
    $stmt = $pdo->prepare("SELECT 1 FROM menu_categories WHERE id = ?");
    $stmt->execute([$id]);
    return (bool)$stmt->fetchColumn();
}

// Categories are manually reordered via move_category() rather than a typed
// sort_order field, so a new one always joins at the end of the list.
function next_category_sort_order(): int {
    $pdo = get_db();
    return (int) $pdo->query("SELECT COALESCE(MAX(sort_order), -1) + 1 FROM menu_categories")->fetchColumn();
}

function save_category(array $data, ?int $id = null): int {
    $pdo = get_db();
    $name = trim($data['name'] ?? '');
    $description = trim($data['description'] ?? '');

    if ($id && $id > 0) {
        $stmt = $pdo->prepare("UPDATE menu_categories SET name = ?, description = ? WHERE id = ?");
        $stmt->execute([$name, $description, $id]);
        return $id;
    } else {
        $sortOrder = next_category_sort_order();
        $stmt = $pdo->prepare("INSERT INTO menu_categories (name, description, sort_order) VALUES (?, ?, ?)");
        $stmt->execute([$name, $description, $sortOrder]);
        return (int)$pdo->lastInsertId();
    }
}

/**
 * Swap a category with its previous/next neighbor (by current display
 * order) and renumber every category's sort_order sequentially from 0.
 * The renumbering is what keeps values unique and gap-free — it also
 * self-heals any duplicate/stale sort_order left over from before this
 * existed, since the new numbers come purely from display position.
 */
function move_category(int $id, string $direction): array {
    $pdo = get_db();
    $orderedIds = $pdo->query("SELECT id FROM menu_categories ORDER BY sort_order ASC, id ASC")
        ->fetchAll(PDO::FETCH_COLUMN);

    $index = array_search($id, $orderedIds, true);
    if ($index === false) {
        return ['success' => false, 'error' => 'Category not found.'];
    }

    $swapWith = $direction === 'up' ? $index - 1 : $index + 1;
    if ($swapWith < 0 || $swapWith >= count($orderedIds)) {
        return ['success' => false, 'error' => 'Category is already at the ' . ($direction === 'up' ? 'top' : 'bottom') . '.'];
    }

    [$orderedIds[$index], $orderedIds[$swapWith]] = [$orderedIds[$swapWith], $orderedIds[$index]];

    $update = $pdo->prepare("UPDATE menu_categories SET sort_order = ? WHERE id = ?");
    $pdo->beginTransaction();
    foreach ($orderedIds as $position => $categoryId) {
        $update->execute([$position, $categoryId]);
    }
    $pdo->commit();

    return ['success' => true];
}

function delete_category(int $id): bool {
    $pdo = get_db();
    $stmt = $pdo->prepare("DELETE FROM menu_categories WHERE id = ?");
    return $stmt->execute([$id]);
}

function get_menu_item_by_id(int $id): ?array {
    $pdo = get_db();
    $stmt = $pdo->prepare("SELECT * FROM menu_items WHERE id = ?");
    $stmt->execute([$id]);
    $res = $stmt->fetch();
    return $res ?: null;
}

// Items are manually reordered via move_menu_item() rather than a typed
// sort_order field, so a new one always joins at the end of its category.
function next_item_sort_order(int $categoryId): int {
    $pdo = get_db();
    $stmt = $pdo->prepare("SELECT COALESCE(MAX(sort_order), -1) + 1 FROM menu_items WHERE category_id = ?");
    $stmt->execute([$categoryId]);
    return (int) $stmt->fetchColumn();
}

function save_menu_item(array $data, ?int $id = null): int {
    $pdo = get_db();
    $categoryId = (int)($data['category_id'] ?? 0);
    $name = trim($data['name'] ?? '');
    $description = trim($data['description'] ?? '');
    $price = trim($data['price'] ?? '');
    $badge = trim($data['badge'] ?? '');
    $isAvailable = !empty($data['is_available']) ? 1 : 0;

    if ($id && $id > 0) {
        $existing = get_menu_item_by_id($id);
        // Keep its existing position when the category is unchanged; if the
        // item was reassigned to a different category, it joins at the end
        // of that category rather than keeping a sort_order that was only
        // ever meaningful among its old category's items.
        $sortOrder = ($existing && (int) $existing['category_id'] === $categoryId)
            ? (int) $existing['sort_order']
            : next_item_sort_order($categoryId);

        $stmt = $pdo->prepare("
            UPDATE menu_items SET
                category_id = ?, name = ?, description = ?, price = ?,
                badge = ?, is_available = ?, sort_order = ?, updated_at = CURRENT_TIMESTAMP
            WHERE id = ?
        ");
        $stmt->execute([$categoryId, $name, $description, $price, $badge, $isAvailable, $sortOrder, $id]);
        return $id;
    } else {
        $sortOrder = next_item_sort_order($categoryId);
        $stmt = $pdo->prepare("
            INSERT INTO menu_items (category_id, name, description, price, badge, is_available, sort_order)
            VALUES (?, ?, ?, ?, ?, ?, ?)
        ");
        $stmt->execute([$categoryId, $name, $description, $price, $badge, $isAvailable, $sortOrder]);
        return (int)$pdo->lastInsertId();
    }
}

/**
 * Swap a menu item with its previous/next neighbor within its own category
 * (by current display order) and renumber that category's items
 * sequentially from 0. See move_category() for why renumbering matters.
 */
function move_menu_item(int $id, string $direction): array {
    $item = get_menu_item_by_id($id);
    if (!$item) {
        return ['success' => false, 'error' => 'Menu item not found.'];
    }

    $pdo = get_db();
    $categoryId = (int) $item['category_id'];
    $stmt = $pdo->prepare("SELECT id FROM menu_items WHERE category_id = ? ORDER BY sort_order ASC, id ASC");
    $stmt->execute([$categoryId]);
    $orderedIds = $stmt->fetchAll(PDO::FETCH_COLUMN);

    $index = array_search($id, $orderedIds, true);
    if ($index === false) {
        return ['success' => false, 'error' => 'Menu item not found.'];
    }

    $swapWith = $direction === 'up' ? $index - 1 : $index + 1;
    if ($swapWith < 0 || $swapWith >= count($orderedIds)) {
        return ['success' => false, 'error' => 'Item is already at the ' . ($direction === 'up' ? 'top' : 'bottom') . '.'];
    }

    [$orderedIds[$index], $orderedIds[$swapWith]] = [$orderedIds[$swapWith], $orderedIds[$index]];

    $update = $pdo->prepare("UPDATE menu_items SET sort_order = ? WHERE id = ?");
    $pdo->beginTransaction();
    foreach ($orderedIds as $position => $itemId) {
        $update->execute([$position, $itemId]);
    }
    $pdo->commit();

    return ['success' => true];
}

function toggle_menu_item_availability(int $id): bool {
    $pdo = get_db();
    $stmt = $pdo->prepare("UPDATE menu_items SET is_available = CASE WHEN is_available = 1 THEN 0 ELSE 1 END, updated_at = CURRENT_TIMESTAMP WHERE id = ?");
    return $stmt->execute([$id]);
}

function delete_menu_item(int $id): bool {
    $pdo = get_db();
    $stmt = $pdo->prepare("DELETE FROM menu_items WHERE id = ?");
    return $stmt->execute([$id]);
}