From faec4b72ad1857ef7504177f8d23febc1df85326 Mon Sep 17 00:00:00 2001
From: Claudiu Farcas <claudiu.farcas@cgm.com>
Date: Mon, 26 Apr 2021 07:57:50 +0300
Subject: [PATCH] CoR design pattern

---
 Program.cs                                    |  6 +-
 .../ChainOfResponsabilitySample.cs            | 99 +++++++++++++++++++
 2 files changed, 104 insertions(+), 1 deletion(-)
 create mode 100644 behavioral/chainofresponsability/ChainOfResponsabilitySample.cs

diff --git a/Program.cs b/Program.cs
index 35d44e7..8b23897 100644
--- a/Program.cs
+++ b/Program.cs
@@ -14,6 +14,7 @@ using design_patterns.structural.decorator;
 using design_patterns.structural.facade;
 using design_patterns.structural.flyweight;
 using design_patterns.structural.proxy;
+using design_patterns.behavioral.chainofresponsability;
 
 namespace design_patterns
 {
@@ -39,7 +40,10 @@ namespace design_patterns
                 // await DecoratorSample.Run();
                 // await FacadeSample.Run();
                 // await FlyweightSample.Run();
-                await ProxySample.Run();
+                // await ProxySample.Run();
+
+                // behavioral
+                await ChainOfResponsabilitySample.Run();
             }
             catch (System.Exception ex)
             {
diff --git a/behavioral/chainofresponsability/ChainOfResponsabilitySample.cs b/behavioral/chainofresponsability/ChainOfResponsabilitySample.cs
new file mode 100644
index 0000000..0994369
--- /dev/null
+++ b/behavioral/chainofresponsability/ChainOfResponsabilitySample.cs
@@ -0,0 +1,99 @@
+using System;
+using System.Threading.Tasks;
+using System.Collections.Generic
+
+namespace design_patterns.behavioral.chainofresponsability
+{
+    /// <summary>
+    /// Chain of Responsibility (CoR) is a behavioral design pattern that 
+    /// lets you pass requests along a chain of handlers. 
+    /// Upon receiving a request, each handler decides either 
+    /// to process the request or to pass it to the next handler in the chain.
+    /// 
+    /// Use it when:
+    /// - your program is expected to process different kinds of requests 
+    ///     in various ways, but the exact types of requests and their sequences
+    ///     are unknown beforehand.
+    /// - it’s essential to execute several handlers in a particular order.
+    /// - the set of handlers and their order are supposed to change at runtime.
+    /// </summary>
+    public class ChainOfResponsabilitySample
+    {
+        public static async Task Run()
+        {
+            Console.WriteLine("Behavioral - ChainOfResponsability");
+
+            var request = new RequestInfo {
+                ID = Guid.NewGuid().ToString(),
+                Data = "request data",
+                Date = DateTime.Now
+            };
+            
+            var handler = new BaseReqHandler { Request = request };
+            handler.Add(new SecurityCheckReqHandler(false));
+            handler.Add(new DataValidationReqHandler());
+
+            handler.Handle();
+
+            handler = new BaseReqHandler { Request = request };
+            handler.Add(new SecurityCheckReqHandler(true));
+            handler.Add(new DataValidationReqHandler());
+
+            handler.Handle();
+        }
+    }
+
+    public interface IReqHandler {
+        RequestInfo Request {get; set;}
+        void Add(IReqHandler reqHandler);
+        void Handle();
+    }
+
+    public class BaseReqHandler : IReqHandler {
+        public virtual RequestInfo Request { get; set; }
+        private IReqHandler next;
+
+        public void Add(IReqHandler reqHandler){
+            if(next!=null) {
+                next.Add(reqHandler);
+            }
+            else
+            {
+                reqHandler.Request = this.Request;
+                next = reqHandler;
+            }
+        }
+        public virtual void Handle() {
+            next?.Handle();
+        }
+    }
+
+    public class DataValidationReqHandler : BaseReqHandler {
+        public override void Handle()
+        {
+            Console.WriteLine($"DataValidating the request {Request.ID}");
+            base.Handle();
+        }
+    }
+    public class SecurityCheckReqHandler : BaseReqHandler {
+        private bool isSecure;
+        public SecurityCheckReqHandler(bool isSecure) => this.isSecure = isSecure;
+
+        public override void Handle()
+        {
+            Console.WriteLine($"SecurityCheck the request {Request.ID}");
+            if(isSecure) {
+                base.Handle();
+            }
+            else {
+                Console.WriteLine("Unauthorized!");
+            }
+        }
+    }
+
+    public class RequestInfo {
+        public string ID { get; set; }
+        public string Data { get; set; }
+        public DateTime Date { get; set; }
+    }
+}
\ No newline at end of file