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1 files changed, 240 insertions, 0 deletions

diff --git a/BackEnd/Timeline/Services/User/UserPermissionService.cs b/BackEnd/Timeline/Services/User/UserPermissionService.cs
new file mode 100644
index 00000000..f292142d
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+++ b/BackEnd/Timeline/Services/User/UserPermissionService.cs
@@ -0,0 +1,240 @@
+using Microsoft.EntityFrameworkCore;

+using System;

+using System.Collections;

+using System.Collections.Generic;

+using System.Linq;

+using System.Threading.Tasks;

+using Timeline.Entities;

+

+namespace Timeline.Services.User

+{

+    public enum UserPermission

+    {

+        /// <summary>

+        /// This permission allows to manage user (creating, deleting or modifying).

+        /// </summary>

+        UserManagement,

+        /// <summary>

+        /// This permission allows to view and modify all timelines.

+        /// </summary>

+        AllTimelineManagement,

+        /// <summary>

+        /// This permission allow to add or remove highlight timelines.

+        /// </summary>

+        HighlightTimelineManagement

+    }

+

+    /// <summary>

+    /// Represents a user's permissions.

+    /// </summary>

+    public class UserPermissions : IEnumerable<UserPermission>, IEquatable<UserPermissions>

+    {

+        public static UserPermissions AllPermissions { get; } = new UserPermissions(Enum.GetValues<UserPermission>());

+

+        /// <summary>

+        /// Create an instance containing given permissions.

+        /// </summary>

+        /// <param name="permissions">Permission list.</param>

+        public UserPermissions(params UserPermission[] permissions) : this(permissions as IEnumerable<UserPermission>)

+        {

+

+        }

+

+        /// <summary>

+        /// Create an instance containing given permissions.

+        /// </summary>

+        /// <param name="permissions">Permission list.</param>

+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="permissions"/> is null.</exception>

+        public UserPermissions(IEnumerable<UserPermission> permissions)

+        {

+            if (permissions == null) throw new ArgumentNullException(nameof(permissions));

+            _permissions = new SortedSet<UserPermission>(permissions);

+        }

+

+        private readonly SortedSet<UserPermission> _permissions = new();

+

+        /// <summary>

+        /// Check if a permission is contained in the list.

+        /// </summary>

+        /// <param name="permission">The permission to check.</param>

+        /// <returns>True if contains. Otherwise false.</returns>

+        public bool Contains(UserPermission permission)

+        {

+            return _permissions.Contains(permission);

+        }

+

+        /// <summary>

+        /// To a serializable string list.

+        /// </summary>

+        /// <returns>A string list.</returns>

+        public List<string> ToStringList()

+        {

+            return _permissions.Select(p => p.ToString()).ToList();

+        }

+

+        /// <summary>

+        /// Convert a string list to user permissions.

+        /// </summary>

+        /// <param name="list">The string list.</param>

+        /// <returns>An instance.</returns>

+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="list"/> is null.</exception>

+        /// <exception cref="ArgumentException">Thrown when there is unknown permission name.</exception>

+        public static UserPermissions FromStringList(IEnumerable<string> list)

+        {

+            List<UserPermission> permissions = new();

+

+            foreach (var value in list)

+            {

+                if (Enum.TryParse<UserPermission>(value, false, out var result))

+                {

+                    permissions.Add(result);

+                }

+                else

+                {

+                    throw new ArgumentException("Unknown permission name.", nameof(list));

+                }

+            }

+

+            return new UserPermissions(permissions);

+        }

+

+        public IEnumerator<UserPermission> GetEnumerator()

+        {

+            return _permissions.GetEnumerator();

+        }

+

+        IEnumerator IEnumerable.GetEnumerator()

+        {

+            return ((IEnumerable)_permissions).GetEnumerator();

+        }

+

+        public bool Equals(UserPermissions? other)

+        {

+            if (other == null)

+                return false;

+

+            return _permissions.SequenceEqual(other._permissions);

+        }

+

+        public override bool Equals(object? obj)

+        {

+            return Equals(obj as UserPermissions);

+        }

+

+        public override int GetHashCode()

+        {

+            int result = 0;

+            foreach (var permission in Enum.GetValues<UserPermission>())

+            {

+                if (_permissions.Contains(permission))

+                {

+                    result += 1;

+                }

+                result <<= 1;

+            }

+            return result;

+        }

+    }

+

+    public interface IUserPermissionService

+    {

+        /// <summary>

+        /// Get permissions of a user.

+        /// </summary>

+        /// <param name="userId">The id of the user.</param>

+        /// <param name="checkUserExistence">Whether check the user's existence.</param>

+        /// <returns>The permission list.</returns>

+        /// <exception cref="UserNotExistException">Thrown when <paramref name="checkUserExistence"/> is true and user does not exist.</exception>

+        Task<UserPermissions> GetPermissionsOfUserAsync(long userId, bool checkUserExistence = true);

+

+        /// <summary>

+        /// Add a permission to user.

+        /// </summary>

+        /// <param name="userId">The id of the user.</param>

+        /// <param name="permission">The new permission.</param>

+        /// <exception cref="UserNotExistException">Thrown when user does not exist.</exception>

+        /// <exception cref="InvalidOperationOnRootUserException">Thrown when change root user's permission.</exception>

+        Task AddPermissionToUserAsync(long userId, UserPermission permission);

+

+        /// <summary>

+        /// Remove a permission from user.

+        /// </summary>

+        /// <param name="userId">The id of the user.</param>

+        /// <param name="permission">The permission.</param>

+        /// <param name="checkUserExistence">Whether check the user's existence.</param>

+        /// <exception cref="UserNotExistException">Thrown when <paramref name="checkUserExistence"/> is true and user does not exist.</exception>

+        /// <exception cref="InvalidOperationOnRootUserException">Thrown when change root user's permission.</exception>

+        Task RemovePermissionFromUserAsync(long userId, UserPermission permission, bool checkUserExistence = true);

+    }

+

+    public class UserPermissionService : IUserPermissionService

+    {

+        private readonly DatabaseContext _database;

+

+        public UserPermissionService(DatabaseContext database)

+        {

+            _database = database;

+        }

+

+        private async Task CheckUserExistence(long userId, bool checkUserExistence)

+        {

+            if (checkUserExistence)

+            {

+                var existence = await _database.Users.AnyAsync(u => u.Id == userId);

+                if (!existence)

+                {

+                    throw new UserNotExistException(userId);

+                }

+            }

+        }

+

+        public async Task<UserPermissions> GetPermissionsOfUserAsync(long userId, bool checkUserExistence = true)

+        {

+            if (userId == 1) // The init administrator account.

+            {

+                return UserPermissions.AllPermissions;

+            }

+

+            await CheckUserExistence(userId, checkUserExistence);

+

+            var permissionNameList = await _database.UserPermission.Where(e => e.UserId == userId).Select(e => e.Permission).ToListAsync();

+

+            return UserPermissions.FromStringList(permissionNameList);

+        }

+

+        public async Task AddPermissionToUserAsync(long userId, UserPermission permission)

+        {

+            if (userId == 1)

+                throw new InvalidOperationOnRootUserException("Can't change root user's permission.");

+

+            await CheckUserExistence(userId, true);

+

+            var alreadyHas = await _database.UserPermission

+                .AnyAsync(e => e.UserId == userId && e.Permission == permission.ToString());

+

+            if (alreadyHas) return;

+

+            _database.UserPermission.Add(new UserPermissionEntity { UserId = userId, Permission = permission.ToString() });

+

+            await _database.SaveChangesAsync();

+        }

+

+        public async Task RemovePermissionFromUserAsync(long userId, UserPermission permission, bool checkUserExistence = true)

+        {

+            if (userId == 1)

+                throw new InvalidOperationOnRootUserException("Can't change root user's permission.");

+

+            await CheckUserExistence(userId, checkUserExistence);

+

+            var entity = await _database.UserPermission

+                .Where(e => e.UserId == userId && e.Permission == permission.ToString())

+                .SingleOrDefaultAsync();

+

+            if (entity == null) return;

+

+            _database.UserPermission.Remove(entity);

+

+            await _database.SaveChangesAsync();

+        }

+    }

+}