Add ability to specify chart generation url for self hosted QuickChart (#5)

* Add ability to specify chart generation url for self hosted QuickChart

* Add more configuration setting:

if user specify: a host only, default to https:443,
	         a host and http, set port to 80
	         a host and https, set port to 443

Co-authored-by: Duca Diana <dduca@globebmg.com>

QuickChart/QuickChart.cs

@@ -31,7 +31,7 @@ namespace QuickChart
 
         private static readonly HttpClient Client = new HttpClient();
 
-        public Chart()
+        public Chart(string scheme = null, string host = null, int? port = null)
         {
             Width = 500;
             Height = 300;
@@ -39,9 +39,40 @@ namespace QuickChart
             Format = "png";
             BackgroundColor = "transparent";
 
-            Scheme = "https";
+            if (host != null)
-            Host = "quickchart.io";
+            {
-            Port = 443;
+                Host = host;
+                if (scheme != null)
+                {
+                    Scheme = scheme;
+                    if (port.HasValue)
+                    {
+                        Port = port.Value;
+                    }
+                    else
+                    {
+                        if(scheme == "http")
+                        {
+                            Port = 80;
+                        }
+                        else
+                        {
+                            Port = 443;
+                        }
+                    }
+                }
+                else
+                {
+                    Scheme = "https";
+                    Port = 443;
+                }
+            }
+            else
+            {
+                Scheme = "https";
+                Host = "quickchart.io";
+                Port = 443;
+            }
         }
 
         public string GetUrl()

QuickChartTest/QuickChartTest.cs

@@ -113,5 +113,32 @@ namespace QuickChartTest
             Assert.Contains("h=300", url);
             Assert.Contains("v=2.9.4", url);
         }
+
+        [Fact]
+        public void TestWithSelfHostingQuickChart()
+        {
+            var scheme = "http";
+            var host = "localhost";
+            var port = 47000;
+            Chart qc = new Chart(scheme, host, port);
+            qc.Width = 500;
+            qc.Height = 300;
+            qc.Config = @"{
+                type: 'bar',
+                data: {
+                    labels: ['Q1', 'Q2', 'Q3', 'Q4'],
+                    datasets: [{
+                        label: 'Users',
+                        data: [50, 60, 70, 180]
+                    }]
+                }[]
+            }";
+
+            string url = qc.GetUrl();
+            Assert.Contains($"{scheme}://{host}:{port}/chart", url);
+            Assert.Contains("w=500", url);
+            Assert.Contains("h=300", url);
+            Assert.DoesNotContain("key=", url);
+        }
     }
 }