Started on environment, This is for #5

src/HotUI/Controls/View.cs

@@ -5,6 +5,8 @@ using System.Linq;
 namespace HotUI {
 
 	public class View {
+		internal static readonly EnvironmentData Environment = new EnvironmentData ();
+		internal readonly EnvironmentData Context = new EnvironmentData ();
 		View parent;
 		public View Parent {
 			get => parent;
@@ -23,6 +25,7 @@ namespace HotUI {
 		protected State State { get; set; }
 		public View (bool hasConstructors)
 		{
+			Context.View = this;
 			State = StateBuilder.CurrentState ?? new State {
 				StateChanged = ResetView
 			};
@@ -77,7 +80,7 @@ namespace HotUI {
 				State.SetParent (this);
 				State.StartProperty ();
 				var view = Body.Invoke ();
-				view.Parent = this.Parent;
+				view.Parent = this;
 				var props = State.EndProperty ();
 				var propCount = props.Length;
 				if (propCount > 0) {
@@ -99,5 +102,13 @@ namespace HotUI {
 #endif
 			ViewHandler?.UpdateValue (property, value);
 		}
+
+		public static void SetGlobalEnvironment (string key, object value) => Environment.SetValue (key, value);
+		public static void SetGlobalEnvironment (IDictionary<string, object> data)
+		{
+			foreach(var pair in data)
+				Environment.SetValue (pair.Key, pair.Value);
+		}
+		public static T GetGlobalEnvironment<T> (string key) => Environment.GetValue<T> (key);
 	}
 }

src/HotUI/EnvironmentData.cs

@@ -0,0 +1,52 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace HotUI {
+
+	public static class EnvironmentKeys {
+		public const string DocumentsFolder = "DocumentsFolder";
+		public const string UserFolder = "UserFolder";
+		public const string OS = "OS";
+	}
+
+	class EnvironmentData : BindingObject {
+
+		public View View { get; internal set; }
+
+		protected ICollection<string> GetAllKeys ()
+		{
+			//This is the global Environment
+			if (View?.Parent == null)
+				return dictionary.Keys;
+
+			//TODO: we need a fancy way of collapsing this. This may be too slow
+			var keys = new HashSet<string> ();
+			var localKeys = dictionary?.Keys;
+			if (localKeys != null)
+				foreach (var k in localKeys)
+					keys.Add (k);
+
+			var parentKeys = View?.Parent?.Context?.GetAllKeys () ?? View.Environment.GetAllKeys ();
+			if (parentKeys != null)
+				foreach (var k in parentKeys)
+					keys.Add (k);
+			return keys;
+		}
+
+		public T GetValue<T> (string key)
+		{
+			try {
+				var value = GetValue (key);
+				if (value == null)
+					value = View?.Parent?.Context?.GetValue (key) ?? View.Environment.GetValue (key);
+				return (T)value;
+			} catch (Exception ex) {
+				return default;
+			}
+		}
+
+		public void SetValue (string key, object value) => SetProperty (value, key);
+	}
+}

src/HotUI/Helpers/ViewExtensions.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Collections.Generic;
+
 namespace HotUI {
 	public static class ViewExtensions {
 
@@ -7,6 +9,21 @@ namespace HotUI {
 			listview.ItemSelected = (o) => selected?.Invoke ((T)o);
 			return listview;
 		}
-		
+
+		public static T SetEnvironment<T>(this T view, string key, object value) where T: View
+		{
+			view.Context.SetValue (key, value);
+			return view;
+		}
+
+		public static T SetEnvironment<T> (this T view, IDictionary<string, object> data) where T : View
+		{
+			foreach (var pair in data)
+				view.Context.SetValue (pair.Key, pair.Value);
+			return view;
+		}
+
+		public static T GetEnvironment<T> (this View view, string key) => view.Context.GetValue<T> (key);
+
 	}
 }

src/HotUI/HotUI.cs

@@ -0,0 +1,3 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo ("HotUI.Tests")]

tests/HotUI.Tests/EnvironmentTests.cs

@@ -0,0 +1,121 @@
+using System;
+using Xunit;
+
+namespace HotUI.Tests {
+	public class EnvironmentTests {
+
+		[Fact]
+		public void CanSetAndReadGlobalEnvironment()
+		{
+			View.Environment.dictionary.Clear ();
+
+			const string myStringConstant = "myString";
+			const string myStringKey = "myString";
+
+			//Not set so should be null
+			var environmentEntry = View.GetGlobalEnvironment<string> (myStringKey);
+
+			Assert.Null (environmentEntry);
+
+			View.SetGlobalEnvironment (myStringKey, myStringConstant);
+
+			environmentEntry = View.GetGlobalEnvironment<string> (myStringKey);
+
+			Assert.Equal (myStringConstant, environmentEntry);
+
+		}
+
+
+		[Fact]
+		public void CanSetAndReadGlobalEnvironmentFromView ()
+		{
+			const string myStringConstant = "myString";
+			const string myStringKey = "myString";
+
+			View.SetGlobalEnvironment (myStringKey, myStringConstant);
+
+			var myView = new View ();
+		
+			var environmentEntry = myView.GetEnvironment<string> (myStringKey);
+
+			Assert.Equal (myStringConstant, environmentEntry);
+
+		}
+
+		[Fact]
+		public void ViewEnvironmentOverwritesGlobal ()
+		{
+			const string myStringConstant = "myString";
+			const string myStringKey = "myString";
+			const string parentStringValue = "myParentString";
+
+			View.SetGlobalEnvironment (myStringKey, myStringConstant);
+
+			var myView = new View ().SetEnvironment(myStringKey,parentStringValue);
+
+			var environmentEntry = myView.GetEnvironment<string> (myStringKey);
+
+			Assert.Equal (parentStringValue, environmentEntry);
+
+		}
+
+
+		[Fact]
+		public void NestedViewGetsValueFromParent ()
+		{
+
+			const string myStringConstant = "myString";
+			const string myStringKey = "myString";
+			const string parentStringValue = "myParentString";
+
+			View.SetGlobalEnvironment (myStringKey, myStringConstant);
+
+			Text text = null;
+
+			var view = new View {
+				Body = () => (text = new Text ())
+			}.SetEnvironment(myStringKey, parentStringValue);
+
+			var viewHandler = new GenericViewHandler ();
+			view.ViewHandler = viewHandler;
+
+			var textHandler = new GenericViewHandler ();
+			text.ViewHandler = textHandler;
+
+			var environmentEntry = text.GetEnvironment<string> (myStringKey);
+			Assert.Equal (parentStringValue, environmentEntry);
+		}
+
+
+		[Fact]
+		public void NestedViewGetsIts ()
+		{
+
+			const string myStringConstant = "myString";
+			const string myStringKey = "myString";
+			const string parentStringValue = "myParentString";
+			const string testStringValue = "myTextString";
+
+			View.SetGlobalEnvironment (myStringKey, myStringConstant);
+
+			Text text1 = null;
+			Text text2 = null;
+
+			var view = new View {
+				Body = () => new VStack {
+					(text1 = new Text ().SetEnvironment(myStringKey,testStringValue)),
+					(text2 = new Text ())
+				}.SetEnvironment (myStringKey, parentStringValue)
+			};
+
+			var viewHandler = new GenericViewHandler ();
+			view.ViewHandler = viewHandler;
+
+			var text1Value = text1.GetEnvironment<string> (myStringKey);
+			Assert.Equal (testStringValue, text1Value);
+
+			var text2Value = text2.GetEnvironment<string> (myStringKey);
+			Assert.Equal (parentStringValue, text2Value);
+		}
+	}
+}