From 88ce4f70266dfd097289b92b539eb1522112c6f2 Mon Sep 17 00:00:00 2001
From: zhangqi <2794379662@qq.com>
Date: Wed, 21 Apr 2021 17:00:16 +0800
Subject: [PATCH] =?UTF-8?q?update:=E4=BC=98=E5=8C=96=E4=BA=8C=E7=BB=B4?=
 =?UTF-8?q?=E7=A0=81=E9=95=BF=E5=BA=A6?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Domain/AggregateModel/LinkAggregate/Link.cs   |  7 +-
 .../Commands/CreateLinkCommandHandler.cs      | 11 ++-
 QRCodeService/QRCodeService.csproj            |  4 -
 QRCodeService/Services/IShortCodeService.cs   | 13 ++++
 QRCodeService/Services/ShortCodeService.cs    | 76 +++++++++++++++++++
 QRCodeService/Startup.cs                      |  3 +
 6 files changed, 103 insertions(+), 11 deletions(-)
 create mode 100644 QRCodeService/Services/IShortCodeService.cs
 create mode 100644 QRCodeService/Services/ShortCodeService.cs

diff --git a/Domain/AggregateModel/LinkAggregate/Link.cs b/Domain/AggregateModel/LinkAggregate/Link.cs
index d96533f..f261dd4 100644
--- a/Domain/AggregateModel/LinkAggregate/Link.cs
+++ b/Domain/AggregateModel/LinkAggregate/Link.cs
@@ -33,15 +33,14 @@ namespace Domain.AggregateModel.LinkAggregate
         /// <param name="baseUrl"></param>
         /// <param name="suffixUrl"></param>
         /// <param name="appId">分配的应用id</param>
-        public Link(string baseUrl,string suffixUrl,int appId)
+        public Link(string baseUrl,string suffixUrl,string fullUrl,int appId,string shortCode)
         {
             BaseUrl = baseUrl;
             SuffixUrl = suffixUrl;
-            FullUrl = new Uri(new Uri(baseUrl),suffixUrl).ToString();
+            FullUrl = fullUrl;
+            ShortCode = shortCode;
             AppId = appId;
             Time = DateTime.Now;
-            CalculateShortCode();
-
             AddDomainEvent(new LinkCreatedDomainEvent(this));
         }
         /// <summary>
diff --git a/QRCodeService/Application/Commands/CreateLinkCommandHandler.cs b/QRCodeService/Application/Commands/CreateLinkCommandHandler.cs
index 1a8da27..2cdde0f 100644
--- a/QRCodeService/Application/Commands/CreateLinkCommandHandler.cs
+++ b/QRCodeService/Application/Commands/CreateLinkCommandHandler.cs
@@ -3,6 +3,7 @@ using Domain.AggregateModel.LinkAggregate;
 using Domain.Exceptions;
 using MediatR;
 using Microsoft.Extensions.Logging;
+using QRCodeService.Services;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -17,10 +18,12 @@ namespace QRCodeService.Application.Commands
 
         readonly ILogger<CreateLinkCommandHandler> logger;
         readonly IAppRepository appRepository;
+        private readonly IShortCodeService shortCodeService;
         readonly ILinkRepository linkRepository;
 
-        public CreateLinkCommandHandler(ILinkRepository linkRepository, IAppRepository appRepository, ILogger<CreateLinkCommandHandler> logger)
+        public CreateLinkCommandHandler(IShortCodeService shortCodeService,ILinkRepository linkRepository, IAppRepository appRepository, ILogger<CreateLinkCommandHandler> logger)
         {
+            this.shortCodeService = shortCodeService;
             this.linkRepository = linkRepository;
             this.appRepository = appRepository;
             this.logger = logger;
@@ -33,13 +36,15 @@ namespace QRCodeService.Application.Commands
             {
                 throw new DomainException("app not found");
             }
-            var link = new Link(app.BaseUrl, request.SuffixUrl, request.AppId);
-            var dbLink = await linkRepository.GetAsync(link.ShortCode);
+            var fullUrl = new Uri(new Uri(app.BaseUrl), request.SuffixUrl).ToString();
+            var shortCode = await shortCodeService.GenShortCode(fullUrl);
+            var dbLink = await linkRepository.GetAsync(shortCode);
             if (dbLink != null)
             {
                 logger.LogDebug("use exist link");
                 return dbLink;
             }
+            var link = new Link(app.BaseUrl, request.SuffixUrl,fullUrl, request.AppId, shortCode);
             link = linkRepository.Add(link);
             await linkRepository.UnitOfWork.SaveEntitiesAsync();
             return link;
diff --git a/QRCodeService/QRCodeService.csproj b/QRCodeService/QRCodeService.csproj
index 30f3b49..d9d359b 100644
--- a/QRCodeService/QRCodeService.csproj
+++ b/QRCodeService/QRCodeService.csproj
@@ -51,10 +51,6 @@
     <ProjectReference Include="..\Infrastructure\Infrastructure.csproj" />
   </ItemGroup>
 
-  <ItemGroup>
-    <Folder Include="Services\" />
-  </ItemGroup>
-
   <ProjectExtensions><VisualStudio><UserProperties properties_4launchsettings_1json__JsonSchema="" /></VisualStudio></ProjectExtensions>
 
 </Project>
diff --git a/QRCodeService/Services/IShortCodeService.cs b/QRCodeService/Services/IShortCodeService.cs
new file mode 100644
index 0000000..3386377
--- /dev/null
+++ b/QRCodeService/Services/IShortCodeService.cs
@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace QRCodeService.Services
+{
+    public interface IShortCodeService
+    {
+        Task<string> GenShortCode(string url);
+    }
+}
diff --git a/QRCodeService/Services/ShortCodeService.cs b/QRCodeService/Services/ShortCodeService.cs
new file mode 100644
index 0000000..61cbee4
--- /dev/null
+++ b/QRCodeService/Services/ShortCodeService.cs
@@ -0,0 +1,76 @@
+using Base62;
+using Domain.AggregateModel.LinkAggregate;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace QRCodeService.Services
+{
+    public class ShortCodeService : IShortCodeService
+    {
+        private readonly ILinkRepository linkRepository;
+
+        public ShortCodeService(ILinkRepository linkRepository)
+        {
+            this.linkRepository = linkRepository;
+        }
+
+        public async Task<string> GenShortCode(string url)
+        {
+            var full = 16;
+            var length = 4;
+            var idx = 0;
+
+            while (true)
+            {
+                var code = CalculateShortCode(url, length, idx);
+                var link = await linkRepository.GetAsync(code);
+                if (link == null || link.FullUrl == url)
+                {
+                    return code;
+                }
+                idx++;
+                if (idx * length == full)
+                {
+                    idx = 0;
+                    length = 2 * length;
+                }
+            }
+            
+        }
+        /// <summary>
+        /// 计算短链接
+        /// </summary>
+        /// <param name="url"></param>
+        /// <param name="length">4(四分之一) 8(半) 16(全长)</param>
+        /// <param name="index"></param>
+        /// <returns></returns>
+        private string CalculateShortCode(string url,int length,int index)
+        {
+            using (var md5 = MD5.Create())
+            {
+                var result = md5.ComputeHash(Encoding.UTF8.GetBytes(url));
+                if (length == 4)
+                {
+                    return BitConverter.ToInt32(result, 4 * index).ToBase62();
+                }
+                if(length == 8)
+                {
+                    return BitConverter.ToInt32(result, 8 * index).ToBase62();
+                }
+                if(length == 16)
+                {
+                    return BitConverter.ToInt64(result, 0).ToBase62() + BitConverter.ToInt64(result, 8).ToBase62();
+                }
+                if(length > 16)
+                {
+                    return BitConverter.ToInt64(result, 0).ToBase62() + BitConverter.ToInt64(result, 8).ToBase62() + length.ToBase62();
+                }
+                throw (new ArgumentOutOfRangeException());
+            }
+        }
+    }
+}
diff --git a/QRCodeService/Startup.cs b/QRCodeService/Startup.cs
index 650615e..d403f3a 100644
--- a/QRCodeService/Startup.cs
+++ b/QRCodeService/Startup.cs
@@ -24,6 +24,7 @@ using QRCodeService.Application.Queries;
 using QRCodeService.Application.Validations;
 using QRCodeService.Infrastructure.Middlewares;
 using QRCodeService.Options;
+using QRCodeService.Services;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -90,6 +91,8 @@ namespace QRCodeService
                 options.ForwardedHeaders =
                     ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
             });
+
+            services.AddTransient<IShortCodeService, ShortCodeService>();
         }
 
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.