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/UserTokenManager.cs | 97 +++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 BackEnd/Timeline/Services/UserTokenManager.cs

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

diff --git a/BackEnd/Timeline/Services/UserTokenManager.cs b/BackEnd/Timeline/Services/UserTokenManager.cs
new file mode 100644
index 00000000..813dae67
--- /dev/null
+++ b/BackEnd/Timeline/Services/UserTokenManager.cs
@@ -0,0 +1,97 @@
+using Microsoft.Extensions.Logging;
+using System;
+using System.Threading.Tasks;
+using Timeline.Helpers;
+using Timeline.Models;
+using Timeline.Services.Exceptions;
+
+namespace Timeline.Services
+{
+    public class UserTokenCreateResult
+    {
+        public string Token { get; set; } = default!;
+        public User User { get; set; } = default!;
+    }
+
+    public interface IUserTokenManager
+    {
+        /// <summary>
+        /// Try to create a token for given username and password.
+        /// </summary>
+        /// <param name="username">The username.</param>
+        /// <param name="password">The password.</param>
+        /// <param name="expireAt">The expire time of the token.</param>
+        /// <returns>The created token and the user info.</returns>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="username"/> or <paramref name="password"/> is null.</exception>
+        /// <exception cref="ArgumentException">Thrown when <paramref name="username"/> is of bad format.</exception>
+        /// <exception cref="UserNotExistException">Thrown when the user with <paramref name="username"/> does not exist.</exception>
+        /// <exception cref="BadPasswordException">Thrown when <paramref name="password"/> is wrong.</exception>
+        public Task<UserTokenCreateResult> CreateToken(string username, string password, DateTime? expireAt = null);
+
+        /// <summary>
+        /// Verify a token and get the saved user info. This also check the database for existence of the user.
+        /// </summary>
+        /// <param name="token">The token.</param>
+        /// <returns>The user stored in token.</returns>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="token"/> is null.</exception>
+        /// <exception cref="UserTokenTimeExpireException">Thrown when the token is expired.</exception>
+        /// <exception cref="UserTokenBadVersionException">Thrown when the token is of bad version.</exception>
+        /// <exception cref="UserTokenBadFormatException">Thrown when the token is of bad format.</exception>
+        /// <exception cref="UserNotExistException">Thrown when the user specified by the token does not exist. Usually the user had been deleted after the token was issued.</exception>
+        public Task<User> VerifyToken(string token);
+    }
+
+    public class UserTokenManager : IUserTokenManager
+    {
+        private readonly ILogger<UserTokenManager> _logger;
+        private readonly IUserService _userService;
+        private readonly IUserTokenService _userTokenService;
+        private readonly IClock _clock;
+
+        public UserTokenManager(ILogger<UserTokenManager> logger, IUserService userService, IUserTokenService userTokenService, IClock clock)
+        {
+            _logger = logger;
+            _userService = userService;
+            _userTokenService = userTokenService;
+            _clock = clock;
+        }
+
+        public async Task<UserTokenCreateResult> CreateToken(string username, string password, DateTime? expireAt = null)
+        {
+            expireAt = expireAt?.MyToUtc();
+
+            if (username == null)
+                throw new ArgumentNullException(nameof(username));
+            if (password == null)
+                throw new ArgumentNullException(nameof(password));
+
+            var user = await _userService.VerifyCredential(username, password);
+            var token = _userTokenService.GenerateToken(new UserTokenInfo { Id = user.Id!.Value, Version = user.Version!.Value, ExpireAt = expireAt });
+
+            return new UserTokenCreateResult { Token = token, User = user };
+        }
+
+
+        public async Task<User> VerifyToken(string token)
+        {
+            if (token == null)
+                throw new ArgumentNullException(nameof(token));
+
+            var tokenInfo = _userTokenService.VerifyToken(token);
+
+            if (tokenInfo.ExpireAt.HasValue)
+            {
+                var currentTime = _clock.GetCurrentTime();
+                if (tokenInfo.ExpireAt < currentTime)
+                    throw new UserTokenTimeExpireException(token, tokenInfo.ExpireAt.Value, currentTime);
+            }
+
+            var user = await _userService.GetUserById(tokenInfo.Id);
+
+            if (tokenInfo.Version < user.Version)
+                throw new UserTokenBadVersionException(token, tokenInfo.Version, user.Version.Value);
+
+            return user;
+        }
+    }
+}
-- 
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