feat(blame): add bindings and api

lib/src/bindings/blame.dart

@@ -0,0 +1,104 @@
+import 'dart:ffi';
+import 'package:ffi/ffi.dart';
+import '../error.dart';
+import '../oid.dart';
+import '../util.dart';
+import 'libgit2_bindings.dart';
+
+/// Get the blame for a single file.
+///
+/// Throws a [LibGit2Error] if error occured.
+Pointer<git_blame> file({
+  required Pointer<git_repository> repoPointer,
+  required String path,
+  int? flags,
+  int? minMatchCharacters,
+  Oid? newestCommit,
+  Oid? oldestCommit,
+  int? minLine,
+  int? maxLine,
+}) {
+  final out = calloc<Pointer<git_blame>>();
+  final pathC = path.toNativeUtf8().cast<Int8>();
+  final options = calloc<git_blame_options>();
+  final optionsError = libgit2.git_blame_options_init(
+    options,
+    GIT_BLAME_OPTIONS_VERSION,
+  );
+
+  if (optionsError < 0) {
+    throw LibGit2Error(libgit2.git_error_last());
+  }
+
+  if (flags != null) {
+    options.ref.flags = flags;
+  }
+
+  if (minMatchCharacters != null) {
+    options.ref.min_match_characters = minMatchCharacters;
+  }
+
+  if (newestCommit != null) {
+    options.ref.newest_commit = newestCommit.pointer.ref;
+  }
+
+  if (oldestCommit != null) {
+    options.ref.oldest_commit = oldestCommit.pointer.ref;
+  }
+
+  if (minLine != null) {
+    options.ref.min_line = minLine;
+  }
+
+  if (maxLine != null) {
+    options.ref.max_line = maxLine;
+  }
+
+  final error = libgit2.git_blame_file(out, repoPointer, pathC, options);
+
+  if (error < 0) {
+    throw LibGit2Error(libgit2.git_error_last());
+  } else {
+    return out.value;
+  }
+}
+
+/// Gets the number of hunks that exist in the blame structure.
+int hunkCount(Pointer<git_blame> blame) {
+  return libgit2.git_blame_get_hunk_count(blame);
+}
+
+/// Gets the blame hunk at the given index.
+///
+/// Throws [RangeError] if index out of range.
+Pointer<git_blame_hunk> getHunkByIndex({
+  required Pointer<git_blame> blamePointer,
+  required int index,
+}) {
+  final result = libgit2.git_blame_get_hunk_byindex(blamePointer, index);
+
+  if (result == nullptr) {
+    throw RangeError('$index is out of bounds');
+  } else {
+    return result;
+  }
+}
+
+/// Gets the hunk that relates to the given line number (1-based) in the newest commit.
+///
+/// Throws [RangeError] if [lineNumber] is out of range.
+Pointer<git_blame_hunk> getHunkByLine({
+  required Pointer<git_blame> blamePointer,
+  required int lineNumber,
+}) {
+  final result = libgit2.git_blame_get_hunk_byline(blamePointer, lineNumber);
+
+  if (result == nullptr) {
+    throw RangeError('$lineNumber is out of bounds');
+  } else {
+    return result;
+  }
+}
+
+/// Free memory allocated for blame object.
+void free(Pointer<git_blame> blame) => libgit2.git_blame_free(blame);