feat: Adding OpenFeature provider for AWS AppConfig

DotnetSdkContrib.sln

@@ -45,6 +45,10 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OpenFeature.Contrib.Provide
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OpenFeature.Contrib.Providers.Flipt.Test", "test\OpenFeature.Contrib.Providers.Flipt.Test\OpenFeature.Contrib.Providers.Flipt.Test.csproj", "{B446D481-B5A3-4509-8933-C4CF6DA9B147}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OpenFeature.Contrib.Providers.AwsAppConfig", "src\OpenFeature.Contrib.Providers.AwsAppConfig\OpenFeature.Contrib.Providers.AwsAppConfig.csproj", "{B83B3CA7-7CFD-4915-A5D9-7A88372EA331}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OpenFeature.Contrib.Providers.AwsAppConfig.Test", "test\OpenFeature.Contrib.Providers.AwsAppConfig.Test\OpenFeature.Contrib.Providers.AwsAppConfig.Test.csproj", "{222FAE13-8472-4B7A-B6D3-BF07953B953A}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -127,6 +131,14 @@ Global
 		{B446D481-B5A3-4509-8933-C4CF6DA9B147}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{B446D481-B5A3-4509-8933-C4CF6DA9B147}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{B446D481-B5A3-4509-8933-C4CF6DA9B147}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B83B3CA7-7CFD-4915-A5D9-7A88372EA331}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B83B3CA7-7CFD-4915-A5D9-7A88372EA331}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B83B3CA7-7CFD-4915-A5D9-7A88372EA331}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B83B3CA7-7CFD-4915-A5D9-7A88372EA331}.Release|Any CPU.Build.0 = Release|Any CPU
+		{222FAE13-8472-4B7A-B6D3-BF07953B953A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{222FAE13-8472-4B7A-B6D3-BF07953B953A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{222FAE13-8472-4B7A-B6D3-BF07953B953A}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{222FAE13-8472-4B7A-B6D3-BF07953B953A}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -151,5 +163,7 @@ Global
 		{F3080350-B0AB-4D59-B416-50CC38C99087} = {B6D3230B-5E4D-4FF1-868E-2F4E325C84FE}
 		{5ECF7DBF-FE64-40A2-BF39-239DE173DA4B} = {0E563821-BD08-4B7F-BF9D-395CAD80F026}
 		{B446D481-B5A3-4509-8933-C4CF6DA9B147} = {B6D3230B-5E4D-4FF1-868E-2F4E325C84FE}
+		{B83B3CA7-7CFD-4915-A5D9-7A88372EA331} = {0E563821-BD08-4B7F-BF9D-395CAD80F026}
+		{222FAE13-8472-4B7A-B6D3-BF07953B953A} = {B6D3230B-5E4D-4FF1-868E-2F4E325C84FE}
 	EndGlobalSection
 EndGlobal

src/OpenFeature.Contrib.Providers.AwsAppConfig/AppConfigKey.cs

@@ -0,0 +1,146 @@
+using System;
+using System.Text.RegularExpressions;
+
+namespace OpenFeature.Contrib.Providers.AwsAppConfig
+{
+    /// <summary>
+    /// Represents a key structure for AWS AppConfig feature flags with optional attributes.
+    /// Keys can be in the format "flagKey" or "flagKey:attributeKey"
+    /// </summary>
+    public class AppConfigKey
+    {
+        /// <summary>
+        /// The separator used to split the flag key from its attribute key
+        /// </summary>
+        private const string Separator = ":";
+
+        /// <summary>
+        /// Gets the App config's Configuration Profile ID
+        /// </summary>
+        public string ConfigurationProfileId {get; }
+
+        /// <summary>
+        /// Gets the main feature flag key
+        /// </summary>
+        public string FlagKey { get; }
+
+        /// <summary>
+        /// Gets the optional attribute key associated with the feature flag
+        /// </summary>
+        public string AttributeKey { get; }
+
+        /// <summary>
+        /// Gets whether this key has an attribute component
+        /// </summary>
+        public bool HasAttribute => !string.IsNullOrWhiteSpace(AttributeKey);
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AppConfigKey"/> class that represents a structured key
+        /// for AWS AppConfig feature flags.
+        /// </summary>
+        /// <param name="key">
+        /// The composite key string that must be in the format "configurationProfileId:flagKey[:attributeKey]" where:
+        /// <list type="bullet">
+        ///     <item><description>configurationProfileId - The AWS AppConfig configuration profile identifier</description></item>
+        ///     <item><description>flagKey - The feature flag key name</description></item>
+        ///     <item><description>attributeKey - (Optional) The specific attribute key to access within the feature flag</description></item>
+        /// </list>
+        /// </param>
+        /// <exception cref="ArgumentException">
+        /// Thrown when:
+        /// <list type="bullet">
+        ///     <item><description>The key parameter is null, empty, or consists only of whitespace</description></item>
+        ///     <item><description>The key format is invalid (missing required parts)</description></item>
+        ///     <item><description>The key doesn't contain at least configurationProfileId and flagKey parts</description></item>
+        /// </list>
+        /// </exception>
+        /// <remarks>
+        /// The constructor parses the provided key string and populates the corresponding properties:
+        /// <list type="bullet">
+        ///     <item><description><see cref="ConfigurationProfileId"/> - First part of the key</description></item>
+        ///     <item><description><see cref="FlagKey"/> - Second part of the key</description></item>
+        ///     <item><description><see cref="AttributeKey"/> - Third part of the key (if provided)</description></item>
+        /// </list>
+        /// </remarks>
+        /// <example>
+        /// Valid key formats:
+        /// <code>
+        /// // Basic usage with configuration profile and flag key
+        /// var key1 = new AppConfigKey("myProfile:myFlag");
+        /// 
+        /// // Usage with an attribute key
+        /// var key2 = new AppConfigKey("myProfile:myFlag:myAttribute");
+        /// </code>
+        /// </example>
+        public AppConfigKey(string key)
+        {
+            if(string.IsNullOrWhiteSpace(key))
+            {
+                throw new ArgumentException("Key cannot be null or empty");
+            }
+
+            // Regular expression for validating the format with last part as 0 or 1 or empty
+            string pattern = @"^[^:]+:[^:]+(:[^:]+)?$";
+            var match = Regex.IsMatch(key, pattern);
+
+            if(!match) throw new ArgumentException("Invalid key format. Flag key is expected in configurationProfileId:flagKey[:attributeKey] format");
+
+
+            var parts = key.Split(Separator, StringSplitOptions.RemoveEmptyEntries);
+
+            if(parts.Length < 2 )
+            {
+                throw new ArgumentException("Invalid key format. Flag key is expected in configurationProfileId:flagKey[:attributeKey] format");
+            }
+
+            ConfigurationProfileId = parts[0];
+            FlagKey = parts[1];
+            // At this point, AWS AppConfig allows only value types for attributes. 
+            // Hence ignoring anything afterwords.
+            if (parts.Length > 2)
+            {
+                AttributeKey = parts[2];
+            }   
+        }
+
+        /// <summary>
+        /// Constructs an AppConfigKey using individual components.
+        /// </summary>
+        /// <param name="configurationProfileId">The AWS AppConfig configuration profile identifier</param>
+        /// <param name="flagKey">The feature flag key name</param>
+        /// <param name="attributeKey">Optional. The specific attribute key to access</param>
+        /// <exception cref="ArgumentException">
+        /// Thrown when:
+        /// - configurationProfileId is null, empty, or whitespace
+        /// - flagKey is null, empty, or whitespace
+        /// </exception>
+        public AppConfigKey(string configurationProfileId, string flagKey, string attributeKey = null)
+        {
+            if (string.IsNullOrWhiteSpace(configurationProfileId))
+            {
+                throw new ArgumentNullException("Configuration Profile ID cannot be null or empty");
+            }
+
+            if (string.IsNullOrWhiteSpace(flagKey))
+            {
+                throw new ArgumentNullException("Flag key cannot be null or empty");
+            }
+
+            ConfigurationProfileId = configurationProfileId;
+            FlagKey = flagKey;
+            AttributeKey = attributeKey;
+        }
+
+        /// <summary>
+        /// Converts the AppConfigKey object back to its string representation.
+        /// </summary>
+        /// <returns>
+        /// A string in the format "configurationProfileId:flagKey[:attributeKey]".
+        /// The attributeKey part is only included if it exists.
+        /// </returns>
+        public override string ToString()
+        {
+            return $"{ConfigurationProfileId}{Separator}{FlagKey}{(HasAttribute ? Separator + AttributeKey : "")}";
+        }
+    }
+}