Umbraco-CMS/src/Umbraco.Core/Services/SectionService.cs

using System;
using System.Collections.Generic;
using System.Linq;
using Umbraco.Core.Models.Sections;
using Umbraco.Core.Services;
using Umbraco.Web.Sections;

namespace Umbraco.Web.Services
{
    public class SectionService : ISectionService
    {
        private readonly IUserService _userService;
        private readonly SectionCollection _sectionCollection;

        public SectionService(
            IUserService userService,
            SectionCollection sectionCollection)
        {
            _userService = userService ?? throw new ArgumentNullException(nameof(userService));
            _sectionCollection = sectionCollection ?? throw new ArgumentNullException(nameof(sectionCollection));
        }

        /// <summary>
        /// The cache storage for all applications
        /// </summary>
        public IEnumerable<ISection> GetSections()
            => _sectionCollection;

        /// <inheritdoc />
        public IEnumerable<ISection> GetAllowedSections(int userId)
        {
            var user = _userService.GetUserById(userId);
            if (user == null)
                throw new InvalidOperationException("No user found with id " + userId);

            return GetSections().Where(x => user.AllowedSections.Contains(x.Alias));
        }

        /// <inheritdoc />
        public ISection GetByAlias(string appAlias)
            => GetSections().FirstOrDefault(t => t.Alias.Equals(appAlias, StringComparison.OrdinalIgnoreCase));
    }
}