Added method for creating base parameters consistently.

src/Weatherstack/Service/Extensions/CreateBaseParameters.cs

@@ -0,0 +1,44 @@
+using System;
+
+namespace Weatherstack;
+
+public static partial class WeatherstackServiceExtensions
+{
+    private static Dictionary<string, string> CreateBaseParameters(
+        this IWeatherstackService source,
+        UnitPreference? unitPreference = null,
+        LanguagePreference? languagePreference = null)
+    {
+        var token = source.GetToken();
+        var parameters = new Dictionary<string, string>
+        {
+            ["access_key"] = token
+        };
+
+        parameters.AddUnitPreference(unitPreference);
+        parameters.AddLanguagePreference(languagePreference);
+        return parameters;
+    }
+
+    private static void AddUnitPreference(
+        this IDictionary<string, string> parameters,
+        UnitPreference? unitPreference)
+    {
+        if (!unitPreference.HasValue)
+            return;
+
+        var literalValue = UnitPreferenceAdapter.Convert(unitPreference.Value);
+        parameters["units"] = literalValue;
+    }
+
+    private static void AddLanguagePreference(
+        this IDictionary<string, string> parameters,
+        LanguagePreference? languagePreference)
+    {
+        if (!languagePreference.HasValue)
+            return;
+
+        var isoCode = LanguagePreferenceAdapter.Convert(languagePreference.Value);
+        parameters["language"] = isoCode;
+    }
+}