Started work on authentication abstractions

lib/kiota_abstractions.dart

@@ -7,12 +7,17 @@
 library kiota_abstractions;
 
 import 'dart:async';
+import 'dart:collection';
 import 'dart:math';
 import 'dart:typed_data';
 
 import 'package:kiota_abstractions/src/case_insensitive_map.dart';
 import 'package:std_uritemplate/std_uritemplate.dart';
 
+part 'src/authentication/allowed_hosts_validator.dart';
+part 'src/authentication/access_token_provider.dart';
+part 'src/authentication/anonymous_authentication_provider.dart';
+part 'src/authentication/authentication_provider.dart';
 part 'src/api_client_builder.dart';
 part 'src/base_request_builder.dart';
 part 'src/error_mappings.dart';

lib/src/authentication/access_token_provider.dart

@@ -0,0 +1,14 @@
+part of '../../kiota_abstractions.dart';
+
+/// Defines a contract for obtaining an access token for a given url.
+abstract class AccessTokenProvider {
+  /// Gets an access token for the given url and additional authentication
+  /// context.
+  Future<String> getAuthorizationToken(
+    Uri uri, [
+    Map<String, Object>? additionalAuthenticationContext,
+  ]);
+
+  /// The [AllowedHostsValidator] to use when validating the host of the url.
+  AllowedHostsValidator get allowedHostsValidator;
+}

lib/src/authentication/allowed_hosts_validator.dart

@@ -0,0 +1,41 @@
+part of '../../kiota_abstractions.dart';
+
+/// Validator for handling allowed hosts for authentication.
+class AllowedHostsValidator {
+  /// Initializes a new instance of the [AllowedHostsValidator] class.
+  AllowedHostsValidator([Iterable<String>? validHosts]) {
+    validHosts ??= <String>[];
+    _validateHosts(validHosts);
+    _allowedHosts = HashSet(
+      equals: (a, b) => a.toUpperCase() == b.toUpperCase(),
+      hashCode: (o) => o.toUpperCase().hashCode,
+    )..addAll(validHosts);
+  }
+
+  late final Set<String> _allowedHosts;
+
+  /// Gets the allowed hosts.
+  Iterable<String> get allowedHosts => _allowedHosts;
+
+  /// Sets the allowed hosts.
+  set allowedHosts(Iterable<String> value) {
+    _validateHosts(value);
+    _allowedHosts = HashSet(
+      equals: (a, b) => a.toUpperCase() == b.toUpperCase(),
+      hashCode: (o) => o.toUpperCase().hashCode,
+    )..addAll(value);
+  }
+
+  /// Validates that the given [uri] is valid.
+  bool isUrlHostValid(Uri uri) {
+    return _allowedHosts.isEmpty || _allowedHosts.contains(uri.host);
+  }
+
+  static void _validateHosts(Iterable<String> hostsToValidate) {
+    if (hostsToValidate
+        .map((e) => e.toLowerCase())
+        .any((x) => x.startsWith('http://') || x.startsWith('https://'))) {
+      throw ArgumentError('Host should not contain http or https prefix');
+    }
+  }
+}

lib/src/authentication/anonymous_authentication_provider.dart

@@ -0,0 +1,9 @@
+part of '../../kiota_abstractions.dart';
+
+/// This authentication provider does not perform any authentication.
+class AnonymousAuthenticationProvider implements AuthenticationProvider {
+  @override
+  Future<void> authenticateRequest(RequestInformation request, [Map<String, Object>? additionalAuthenticationContext]) {
+    return Future<void>.value();
+  }
+}

lib/src/authentication/authentication_provider.dart

@@ -0,0 +1,11 @@
+part of '../../kiota_abstractions.dart';
+
+/// Authenticates the application request.
+abstract class AuthenticationProvider {
+  /// Authenticates the give [request] with the given
+  /// [additionalAuthenticationContext].
+  Future<void> authenticateRequest(
+    RequestInformation request, [
+    Map<String, Object>? additionalAuthenticationContext,
+  ]);
+}