feat: prototype config api

lib/src/config.dart

@@ -0,0 +1,58 @@
+import 'dart:ffi';
+import 'package:ffi/ffi.dart';
+import 'bindings/libgit2_bindings.dart';
+import 'bindings/config.dart' as config;
+import 'util.dart';
+
+/// [Config] provides management of global configuration options
+/// (system, global, XDG, excluding repository config)
+class Config {
+  /// Initializes a new instance of [Config] class.
+  ///
+  /// If [path] isn't provided, opens global, XDG and system config files.
+  ///
+  /// [path] should point to single on-disk file; it's expected to be a native
+  /// Git config file following the default Git config syntax (see man git-config).
+  ///
+  /// [Config] object should be closed with [close] function to release allocated memory.
+  Config({this.path}) {
+    libgit2.git_libgit2_init();
+
+    if (path == null) {
+      configPointer = config.openDefault();
+    } else {
+      configPointer = config.open(path!);
+    }
+
+    libgit2.git_libgit2_shutdown();
+  }
+
+  /// Path to on-disk config file provided by user.
+  String? path;
+
+  /// Pointer to memory address for allocated config object.
+  late Pointer<Pointer<git_config>> configPointer;
+
+  /// Get boolean value of `key` [variable]
+  bool getBool(String variable) {
+    return config.getBool(configPointer.value, variable);
+  }
+
+  ///Get integer value of `key` [variable]
+  int getInt(String variable) {
+    return config.getInt(configPointer.value, variable);
+  }
+
+  ///Get string value of `key` [variable]
+  String getString(String variable) {
+    return config.getString(configPointer.value, variable);
+  }
+
+  /// Set value of config key
+  // TODO
+
+  /// Releases memory allocated for config object.
+  void close() {
+    calloc.free(configPointer);
+  }
+}