From ac769e656b122ff569c3f1534701b71e00fed586 Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Tue, 27 Oct 2020 19:21:35 +0800
Subject: Split front and back end.

---
 BackEnd/Timeline/Services/UserDeleteService.cs | 69 ++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 BackEnd/Timeline/Services/UserDeleteService.cs

(limited to 'BackEnd/Timeline/Services/UserDeleteService.cs')

diff --git a/BackEnd/Timeline/Services/UserDeleteService.cs b/BackEnd/Timeline/Services/UserDeleteService.cs
new file mode 100644
index 00000000..845de573
--- /dev/null
+++ b/BackEnd/Timeline/Services/UserDeleteService.cs
@@ -0,0 +1,69 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Threading.Tasks;
+using Timeline.Entities;
+using Timeline.Helpers;
+using Timeline.Models.Validation;
+using static Timeline.Resources.Services.UserService;
+
+namespace Timeline.Services
+{
+    public interface IUserDeleteService
+    {
+        /// <summary>
+        /// Delete a user of given username.
+        /// </summary>
+        /// <param name="username">Username of the user to delete. Can't be null.</param>
+        /// <returns>True if user is deleted, false if user not exist.</returns>
+        /// <exception cref="ArgumentNullException">Thrown if <paramref name="username"/> is null.</exception>
+        /// <exception cref="ArgumentException">Thrown when <paramref name="username"/> is of bad format.</exception>
+        Task<bool> DeleteUser(string username);
+    }
+
+    public class UserDeleteService : IUserDeleteService
+    {
+        private readonly ILogger<UserDeleteService> _logger;
+
+        private readonly DatabaseContext _databaseContext;
+
+        private readonly ITimelineService _timelineService;
+
+        private readonly UsernameValidator _usernameValidator = new UsernameValidator();
+
+        public UserDeleteService(ILogger<UserDeleteService> logger, DatabaseContext databaseContext, ITimelineService timelineService)
+        {
+            _logger = logger;
+            _databaseContext = databaseContext;
+            _timelineService = timelineService;
+        }
+
+        public async Task<bool> DeleteUser(string username)
+        {
+            if (username == null)
+                throw new ArgumentNullException(nameof(username));
+
+            if (!_usernameValidator.Validate(username, out var message))
+            {
+                throw new ArgumentException(string.Format(CultureInfo.CurrentCulture, ExceptionUsernameBadFormat, message), nameof(username));
+            }
+
+            var user = await _databaseContext.Users.Where(u => u.Username == username).SingleOrDefaultAsync();
+            if (user == null)
+                return false;
+
+            await _timelineService.DeleteAllPostsOfUser(user.Id);
+
+            _databaseContext.Users.Remove(user);
+
+            await _databaseContext.SaveChangesAsync();
+            _logger.LogInformation(Log.Format(LogDatabaseRemove, ("Id", user.Id), ("Username", user.Username)));
+
+            return true;
+        }
+
+    }
+}
-- 
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