Merge pull request #192 from crupest/highlight-timeline

Highlight timeline.

1 files changed, 66 insertions, 0 deletions

diff --git a/BackEnd/Timeline/Services/BasicUserService.cs b/BackEnd/Timeline/Services/BasicUserService.cs
new file mode 100644
index 00000000..fbbb6677
--- /dev/null
+++ b/BackEnd/Timeline/Services/BasicUserService.cs
@@ -0,0 +1,66 @@
+using Microsoft.EntityFrameworkCore;

+using System;

+using System.Linq;

+using System.Threading.Tasks;

+using Timeline.Entities;

+using Timeline.Models.Validation;

+using Timeline.Services.Exceptions;

+

+namespace Timeline.Services

+{

+    /// <summary>

+    /// This service provide some basic user features, which should be used internally for other services.

+    /// </summary>

+    public interface IBasicUserService

+    {

+        /// <summary>

+        /// Check if a user exists.

+        /// </summary>

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

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

+        Task<bool> CheckUserExistence(long id);

+

+        /// <summary>

+        /// Get the user id of given username.

+        /// </summary>

+        /// <param name="username">Username of the user.</param>

+        /// <returns>The id of the user.</returns>

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

+        /// <exception cref="ArgumentException">Thrown when <paramref name="username"/> is of bad format.</exception>

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

+        Task<long> GetUserIdByUsername(string username);

+    }

+

+    public class BasicUserService : IBasicUserService

+    {

+        private readonly DatabaseContext _database;

+

+        private readonly UsernameValidator _usernameValidator = new UsernameValidator();

+

+        public BasicUserService(DatabaseContext database)

+        {

+            _database = database;

+        }

+

+        public async Task<bool> CheckUserExistence(long id)

+        {

+            return await _database.Users.AnyAsync(u => u.Id == id);

+        }

+

+        public async Task<long> GetUserIdByUsername(string username)

+        {

+            if (username == null)

+                throw new ArgumentNullException(nameof(username));

+

+            if (!_usernameValidator.Validate(username, out var message))

+                throw new ArgumentException(message);

+

+            var entity = await _database.Users.Where(user => user.Username == username).Select(u => new { u.Id }).SingleOrDefaultAsync();

+

+            if (entity == null)

+                throw new UserNotExistException(username);

+

+            return entity.Id;

+        }

+    }

+}