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1 files changed, 125 insertions, 0 deletions

diff --git a/BackEnd/Timeline/Services/Token/SecureRandomUserTokenService.cs b/BackEnd/Timeline/Services/Token/SecureRandomUserTokenService.cs
new file mode 100644
index 00000000..404862d4
--- /dev/null
+++ b/BackEnd/Timeline/Services/Token/SecureRandomUserTokenService.cs
@@ -0,0 +1,125 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using Timeline.Configs;
+using Timeline.Entities;
+
+namespace Timeline.Services.Token
+{
+    public class SecureRandomUserTokenService : IUserTokenService, IDisposable
+    {
+        private DatabaseContext _databaseContext;
+        private ILogger<SecureRandomUserTokenService> _logger;
+        private RandomNumberGenerator _secureRandom;
+        private IOptionsMonitor<TokenOptions> _optionMonitor;
+        private IClock _clock;
+
+        public SecureRandomUserTokenService(DatabaseContext databaseContext, ILogger<SecureRandomUserTokenService> logger, IOptionsMonitor<TokenOptions> optionMonitor, IClock clock)
+        {
+            _databaseContext = databaseContext;
+            _logger = logger;
+            _secureRandom = RandomNumberGenerator.Create();
+            _optionMonitor = optionMonitor;
+            _clock = clock;
+        }
+
+        public void Dispose()
+        {
+            _secureRandom.Dispose();
+        }
+
+        private string GenerateSecureRandomTokenString()
+        {
+            var option = _optionMonitor.CurrentValue;
+            var tokenLength = option.TokenLength ?? 32;
+            var buffer = new byte[tokenLength];
+            _secureRandom.GetBytes(buffer);
+            return Convert.ToHexString(buffer);
+        }
+
+        /// <inheritdoc/>
+        public async Task<string> CreateTokenAsync(long userId, DateTime? expireTime)
+        {
+            var currentTime = _clock.GetCurrentTime();
+
+            if (expireTime is not null && expireTime > currentTime)
+            {
+                _logger.LogWarning("The expire time of the token has already passed.");
+            }
+
+            UserTokenEntity entity = new UserTokenEntity
+            {
+                UserId = userId,
+                Token = GenerateSecureRandomTokenString(),
+                ExpireAt = expireTime,
+                CreateAt = currentTime,
+                Deleted = false
+            };
+
+            _databaseContext.UserTokens.Add(entity);
+            await _databaseContext.SaveChangesAsync();
+
+            _logger.LogInformation("A user token is created with user id {}.", userId);
+
+            return entity.Token;
+        }
+
+        /// <inheritdoc/>
+        public async Task<UserTokenInfo> ValidateTokenAsync(string token)
+        {
+            var entity = await _databaseContext.UserTokens.Where(t => t.Token == token && !t.Deleted).SingleOrDefaultAsync();
+
+            if (entity is null)
+            {
+                throw new UserTokenException(token, Resource.ExceptionUserTokenInvalid);
+            }
+
+            var currentTime = _clock.GetCurrentTime();
+
+            if (entity.ExpireAt.HasValue && entity.ExpireAt > currentTime)
+            {
+                throw new UserTokenExpiredException(token, entity.ExpireAt.Value, currentTime);
+            }
+
+            return new UserTokenInfo()
+            {
+                UserId = entity.UserId,
+                ExpireAt = entity.ExpireAt,
+                CreateAt = entity.CreateAt
+            };
+        }
+
+        /// <inheritdoc/>
+        public async Task<bool> RevokeTokenAsync(string token)
+        {
+            var entity = await _databaseContext.UserTokens.Where(t => t.Token == token && t.Deleted == false).SingleOrDefaultAsync();
+            if (entity is not null)
+            {
+                entity.Deleted = true;
+                await _databaseContext.SaveChangesAsync();
+
+                _logger.LogInformation("A token is revoked with user id {}.", entity.UserId);
+
+                return entity.ExpireAt <= _clock.GetCurrentTime();
+            }
+            return false;
+        }
+
+        /// <inheritdoc/>
+        public async Task RevokeAllTokenByUserIdAsync(long userId)
+        {
+            List<UserTokenEntity> entities = await _databaseContext.UserTokens.Where(t => t.UserId == userId && t.Deleted == false).ToListAsync();
+            foreach (var entity in entities)
+            {
+                entity.Deleted = true;
+            }
+            await _databaseContext.SaveChangesAsync();
+            _logger.LogInformation("All tokens of user with id {} are revoked.", userId);
+        }
+    }
+}
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