From e068286f1551c53f45090065c6608d799dfac893 Mon Sep 17 00:00:00 2001
From: Christian Kratky <christian.kratky@googlemail.com>
Date: Fri, 17 May 2019 20:57:15 +0200
Subject: [PATCH] Add subscribe options builder.

---
 .../Subscribing/MqttClientSubscribeOptions.cs |  2 +-
 .../MqttClientSubscribeOptionsBuilder.cs      | 87 +++++++++++++++++++
 2 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 Source/MQTTnet/Client/Subscribing/MqttClientSubscribeOptionsBuilder.cs

diff --git a/Source/MQTTnet/Client/Subscribing/MqttClientSubscribeOptions.cs b/Source/MQTTnet/Client/Subscribing/MqttClientSubscribeOptions.cs
index 49cf551..dc4be2f 100644
--- a/Source/MQTTnet/Client/Subscribing/MqttClientSubscribeOptions.cs
+++ b/Source/MQTTnet/Client/Subscribing/MqttClientSubscribeOptions.cs
@@ -9,6 +9,6 @@ namespace MQTTnet.Client.Subscribing
 
         public uint? SubscriptionIdentifier { get; set; }
 
-        public List<MqttUserProperty> UserProperties { get; set; } = new List<MqttUserProperty>();
+        public List<MqttUserProperty> UserProperties { get; set; }
     }
 }
diff --git a/Source/MQTTnet/Client/Subscribing/MqttClientSubscribeOptionsBuilder.cs b/Source/MQTTnet/Client/Subscribing/MqttClientSubscribeOptionsBuilder.cs
new file mode 100644
index 0000000..c33f931
--- /dev/null
+++ b/Source/MQTTnet/Client/Subscribing/MqttClientSubscribeOptionsBuilder.cs
@@ -0,0 +1,87 @@
+using System;
+using System.Collections.Generic;
+using MQTTnet.Packets;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Client.Subscribing
+{
+    public class MqttClientSubscribeOptionsBuilder
+    {
+        private readonly MqttClientSubscribeOptions _subscribeOptions = new MqttClientSubscribeOptions();
+
+        public MqttClientSubscribeOptionsBuilder WithUserProperty(string name, string value)
+        {
+            if (name == null) throw new ArgumentNullException(nameof(name));
+            if (value == null) throw new ArgumentNullException(nameof(value));
+
+            if (_subscribeOptions.UserProperties == null)
+            {
+                _subscribeOptions.UserProperties = new List<MqttUserProperty>();
+            }
+
+            _subscribeOptions.UserProperties.Add(new MqttUserProperty(name, value));
+
+            return this;
+        }
+
+        public MqttClientSubscribeOptionsBuilder WithSubscriptionIdentifier(uint? subscriptionIdentifier)
+        {
+            _subscribeOptions.SubscriptionIdentifier = subscriptionIdentifier;
+
+            return this;
+        }
+
+        public MqttClientSubscribeOptionsBuilder WithTopicFilter(
+            string topic,
+            MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce,
+            bool? noLocal = null,
+            bool? retainAsPublished = null,
+            MqttRetainHandling? retainHandling = null)
+        {
+            return WithTopicFilter(new TopicFilter
+            {
+                Topic = topic,
+                QualityOfServiceLevel = qualityOfServiceLevel,
+                NoLocal = noLocal,
+                RetainAsPublished = retainAsPublished,
+                RetainHandling = retainHandling
+            });
+        }
+
+        public MqttClientSubscribeOptionsBuilder WithTopicFilter(Action<TopicFilterBuilder> topicFilterBuilder)
+        {
+            if (topicFilterBuilder == null) throw new ArgumentNullException(nameof(topicFilterBuilder));
+
+            var internalTopicFilterBuilder = new TopicFilterBuilder();
+            topicFilterBuilder(internalTopicFilterBuilder);
+
+            return WithTopicFilter(internalTopicFilterBuilder);
+        }
+
+        public MqttClientSubscribeOptionsBuilder WithTopicFilter(TopicFilterBuilder topicFilterBuilder)
+        {
+            if (topicFilterBuilder == null) throw new ArgumentNullException(nameof(topicFilterBuilder));
+
+            return WithTopicFilter(topicFilterBuilder.Build());
+        }
+
+        public MqttClientSubscribeOptionsBuilder WithTopicFilter(TopicFilter topicFilter)
+        {
+            if (topicFilter == null) throw new ArgumentNullException(nameof(topicFilter));
+
+            if (_subscribeOptions.TopicFilters == null)
+            {
+                _subscribeOptions.TopicFilters = new List<TopicFilter>();
+            }
+
+            _subscribeOptions.TopicFilters.Add(topicFilter);
+
+            return this;
+        }
+
+        public MqttClientSubscribeOptions Build()
+        {
+            return _subscribeOptions;
+        }
+    }
+}