app/api/admin/handlers/roles-handlers.php

<?php

declare(strict_types=1);

/**
 * GET - List all roles with their permissions + all available permissions
 */
function handleGetRole(PDO $pdo): void
{
    // Get all roles with user count (LEFT JOIN instead of correlated subquery)
    $stmt = $pdo->query('
        SELECT r.*, COUNT(u.id) as user_count
        FROM roles r
        LEFT JOIN users u ON u.role_id = r.id
        GROUP BY r.id
        ORDER BY r.id
    ');
    $roles = $stmt->fetchAll();

    // Batch fetch all role-permission mappings in one query (was N+1)
    $stmt = $pdo->query('
        SELECT rp.role_id, p.name
        FROM role_permissions rp
        JOIN permissions p ON p.id = rp.permission_id
    ');
    $allRolePerms = $stmt->fetchAll();

    // Group permissions by role_id
    $permsByRole = [];
    foreach ($allRolePerms as $rp) {
        $permsByRole[$rp['role_id']][] = $rp['name'];
    }

    foreach ($roles as &$role) {
        $role['permissions'] = $permsByRole[$role['id']] ?? [];
        $role['permission_count'] = count($role['permissions']);
    }
    unset($role);

    // Get all available permissions grouped by module
    $stmt = $pdo->query('SELECT id, name, display_name, description FROM permissions ORDER BY id');
    $allPermissions = $stmt->fetchAll();

    $grouped = [];
    foreach ($allPermissions as $perm) {
        $parts = explode('.', $perm['name'], 2);
        $module = $parts[0];
        if (!isset($grouped[$module])) {
            $grouped[$module] = [];
        }
        $grouped[$module][] = $perm;
    }

    successResponse([
        'roles' => $roles,
        'permissions' => $allPermissions,
        'permission_groups' => $grouped,
    ]);
}

/**
 * POST - Create new role
 */
function handleCreateRole(PDO $pdo): void
{
    $input = getJsonInput();

    $name = trim($input['name'] ?? '');
    $displayName = trim($input['display_name'] ?? '');
    $description = trim($input['description'] ?? '');
    $permissions = $input['permissions'] ?? [];

    if (!$name) {
        errorResponse('Název role je povinný');
    }

    if (!$displayName) {
        errorResponse('Zobrazovaný název je povinný');
    }

    // Validate name format (slug)
    if (!preg_match('/^[a-z0-9_-]+$/', $name)) {
        errorResponse('Název role může obsahovat pouze malá písmena, čísla, pomlčky a podtržítka');
    }

    // Check uniqueness
    $stmt = $pdo->prepare('SELECT id FROM roles WHERE name = ?');
    $stmt->execute([$name]);
    if ($stmt->fetch()) {
        errorResponse('Role s tímto názvem již existuje');
    }

    $pdo->beginTransaction();

    try {
        // Create role
        $stmt = $pdo->prepare('
            INSERT INTO roles (name, display_name, description)
            VALUES (?, ?, ?)
        ');
        $stmt->execute([$name, $displayName, $description ?: null]);
        $newRoleId = (int)$pdo->lastInsertId();

        // Assign permissions
        if (!empty($permissions)) {
            $stmt = $pdo->prepare('
                INSERT INTO role_permissions (role_id, permission_id)
                SELECT ?, id FROM permissions WHERE name = ?
            ');
            foreach ($permissions as $permName) {
                $stmt->execute([$newRoleId, $permName]);
            }
        }

        $pdo->commit();

        AuditLog::logCreate('role', $newRoleId, [
            'name' => $name,
            'display_name' => $displayName,
            'permissions' => $permissions,
        ], "Vytvořena role '$displayName'");

        successResponse(['id' => $newRoleId], 'Role byla vytvořena');
    } catch (PDOException $e) {
        $pdo->rollBack();
        throw $e;
    }
}

/**
 * PUT - Update role
 */
function handleUpdateRole(PDO $pdo, int $roleId): void
{
    // Get existing role
    $stmt = $pdo->prepare('SELECT * FROM roles WHERE id = ?');
    $stmt->execute([$roleId]);
    $role = $stmt->fetch();

    if (!$role) {
        errorResponse('Role nebyla nalezena', 404);
    }

    // Block editing admin role name
    if ($role['name'] === 'admin') {
        errorResponse('Roli administrátora nelze upravovat');
    }

    $input = getJsonInput();

    $displayName = trim($input['display_name'] ?? $role['display_name']);
    $description = trim($input['description'] ?? $role['description'] ?? '');
    $permissions = $input['permissions'] ?? null;

    if (!$displayName) {
        errorResponse('Zobrazovaný název je povinný');
    }

    $pdo->beginTransaction();

    try {
        // Update role
        $stmt = $pdo->prepare('
            UPDATE roles SET display_name = ?, description = ?
            WHERE id = ?
        ');
        $stmt->execute([$displayName, $description ?: null, $roleId]);

        // Update permissions if provided
        if ($permissions !== null) {
            // Remove existing permissions
            $stmt = $pdo->prepare('DELETE FROM role_permissions WHERE role_id = ?');
            $stmt->execute([$roleId]);

            // Add new permissions
            if (!empty($permissions)) {
                $stmt = $pdo->prepare('
                    INSERT INTO role_permissions (role_id, permission_id)
                    SELECT ?, id FROM permissions WHERE name = ?
                ');
                foreach ($permissions as $permName) {
                    $stmt->execute([$roleId, $permName]);
                }
            }
        }

        $pdo->commit();

        AuditLog::logUpdate('role', $roleId, [
            'display_name' => $role['display_name'],
        ], [
            'display_name' => $displayName,
            'permissions' => $permissions,
        ], "Upravena role '$displayName'");

        successResponse(null, 'Role byla aktualizována');
    } catch (PDOException $e) {
        $pdo->rollBack();
        throw $e;
    }
}

/**
 * DELETE - Delete role
 */
function handleDeleteRole(PDO $pdo, int $roleId): void
{
    $stmt = $pdo->prepare('SELECT * FROM roles WHERE id = ?');
    $stmt->execute([$roleId]);
    $role = $stmt->fetch();

    if (!$role) {
        errorResponse('Role nebyla nalezena', 404);
    }

    // Block deleting admin role
    if ($role['name'] === 'admin') {
        errorResponse('Roli administrátora nelze smazat');
    }

    // Check if role has users
    $stmt = $pdo->prepare('SELECT COUNT(*) FROM users WHERE role_id = ?');
    $stmt->execute([$roleId]);
    $userCount = $stmt->fetchColumn();

    if ($userCount > 0) {
        errorResponse("Nelze smazat roli s {$userCount} přiřazenými uživateli. Nejprve změňte roli těmto uživatelům.");
    }

    // Delete role (cascade deletes role_permissions)
    $stmt = $pdo->prepare('DELETE FROM roles WHERE id = ?');
    $stmt->execute([$roleId]);

    AuditLog::logDelete('role', $roleId, $role, "Smazána role '{$role['display_name']}'");

    successResponse(null, 'Role byla smazána');
}