2 files changed, 109 insertions, 0 deletions
diff --git a/BackEnd/Timeline/Helpers/SecureRandomExtensions.cs b/BackEnd/Timeline/Helpers/SecureRandomExtensions.cs
new file mode 100644
index 00000000..b4f3f7f0
--- /dev/null
+++ b/BackEnd/Timeline/Helpers/SecureRandomExtensions.cs
@@ -0,0 +1,29 @@
+using System;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace Timeline.Helpers
+{
+    public static class SecureRandomExtensions
+    {
+        private static readonly char[] AlphaDigitString = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray();
+
+        public static string GenerateAlphaDigitString(this RandomNumberGenerator randomNumberGenerator, int length)
+        {
+            if (length <= 0) throw new ArgumentOutOfRangeException(nameof(length));
+
+            var buffer = new byte[length];
+            randomNumberGenerator.GetBytes(buffer);
+
+            StringBuilder stringBuilder = new();
+
+            foreach (byte b in buffer)
+            {
+                stringBuilder.Append(AlphaDigitString[b % AlphaDigitString.Length]);
+            }
+
+            return stringBuilder.ToString();
+        }
+    }
+}
+
diff --git a/BackEnd/Timeline/Services/User/RegisterCode/RegisterCodeService.cs b/BackEnd/Timeline/Services/User/RegisterCode/RegisterCodeService.cs
new file mode 100644
index 00000000..eb8bc37a
--- /dev/null
+++ b/BackEnd/Timeline/Services/User/RegisterCode/RegisterCodeService.cs
@@ -0,0 +1,80 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore;
+using Timeline.Entities;
+using Timeline.Helpers;
+
+namespace Timeline.Services.User.RegisterCode
+{
+    public class RegisterCodeService : IRegisterCodeService, IDisposable
+    {
+        private readonly DatabaseContext _databaseContext;
+        private readonly RandomNumberGenerator _randomNumberGenerator;
+
+        public RegisterCodeService(DatabaseContext databaseContext)
+        {
+            _databaseContext = databaseContext;
+            _randomNumberGenerator = RandomNumberGenerator.Create();
+        }
+
+        public async Task<string> CreateNewCode(long userId)
+        {
+            var oldEntity = await _databaseContext.RegisterCodes.Where(r => r.OwnerId == userId && r.Enabled).SingleOrDefaultAsync();
+
+            if (oldEntity is not null)
+            {
+                oldEntity.Enabled = false;
+            }
+
+            var newEntity = new Entities.RegisterCode()
+            {
+                Code = _randomNumberGenerator.GenerateAlphaDigitString(6),
+                OwnerId = userId,
+                Enabled = true
+            };
+            _databaseContext.RegisterCodes.Add(newEntity);
+
+            await _databaseContext.SaveChangesAsync();
+
+            return newEntity.Code;
+        }
+
+        public Task<UserRegisterInfo> CreateRegisterInfo(long userId, long introducerId, string registerCode, DateTime registerTime)
+        {
+            throw new NotImplementedException();
+        }
+
+        public void Dispose()
+        {
+            _randomNumberGenerator.Dispose();
+        }
+
+        public async Task<long?> GetCodeOwner(string code, bool onlyEnabled = true)
+        {
+            var entity = await _databaseContext.RegisterCodes.Where(r => r.Code == code).SingleOrDefaultAsync();
+            if (entity is null) return null;
+            if (onlyEnabled && !entity.Enabled) return null;
+            return entity.OwnerId;
+        }
+
+        public async Task<string?> GetCurrentCode(long userId)
+        {
+            var entity = await _databaseContext.RegisterCodes.Where(r => r.OwnerId == userId && r.Enabled).SingleOrDefaultAsync();
+            return entity?.Code;
+        }
+
+        public Task<UserRegisterInfo?> GetUserRegisterInfo(long userId)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task<List<UserRegisterInfo>> GetUserRegisterInfoOfIntroducer(long introducerId)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}
+