1 files changed, 65 insertions, 0 deletions
diff --git a/gitlint-core/gitlint/hooks.py b/gitlint-core/gitlint/hooks.py
new file mode 100644
index 0000000..98ded18
--- /dev/null
+++ b/gitlint-core/gitlint/hooks.py
@@ -0,0 +1,65 @@
+import os
+import shutil
+import stat
+
+from gitlint.exception import GitlintError
+from gitlint.git import git_hooks_dir
+from gitlint.utils import FILE_ENCODING
+
+COMMIT_MSG_HOOK_SRC_PATH = os.path.join(os.path.dirname(os.path.realpath(__file__)), "files", "commit-msg")
+COMMIT_MSG_HOOK_DST_PATH = "commit-msg"
+GITLINT_HOOK_IDENTIFIER = "### gitlint commit-msg hook start ###\n"
+
+
+class GitHookInstallerError(GitlintError):
+    pass
+
+
+class GitHookInstaller:
+    """Utility class that provides methods for installing and uninstalling the gitlint commitmsg hook."""
+
+    @staticmethod
+    def commit_msg_hook_path(lint_config):
+        return os.path.join(git_hooks_dir(lint_config.target), COMMIT_MSG_HOOK_DST_PATH)
+
+    @staticmethod
+    def _assert_git_repo(target):
+        """Asserts that a given target directory is a git repository"""
+        hooks_dir = git_hooks_dir(target)
+        if not os.path.isdir(hooks_dir):
+            raise GitHookInstallerError(f"{target} is not a git repository.")
+
+    @staticmethod
+    def install_commit_msg_hook(lint_config):
+        GitHookInstaller._assert_git_repo(lint_config.target)
+        dest_path = GitHookInstaller.commit_msg_hook_path(lint_config)
+        if os.path.exists(dest_path):
+            raise GitHookInstallerError(
+                f"There is already a commit-msg hook file present in {dest_path}.\n"
+                "gitlint currently does not support appending to an existing commit-msg file."
+            )
+
+        # copy hook file
+        shutil.copy(COMMIT_MSG_HOOK_SRC_PATH, dest_path)
+        # make hook executable
+        st = os.stat(dest_path)
+        os.chmod(dest_path, st.st_mode | stat.S_IEXEC)
+
+    @staticmethod
+    def uninstall_commit_msg_hook(lint_config):
+        GitHookInstaller._assert_git_repo(lint_config.target)
+        dest_path = GitHookInstaller.commit_msg_hook_path(lint_config)
+        if not os.path.exists(dest_path):
+            raise GitHookInstallerError(f"There is no commit-msg hook present in {dest_path}.")
+
+        with open(dest_path, encoding=FILE_ENCODING) as fp:
+            lines = fp.readlines()
+            if len(lines) < 2 or lines[1] != GITLINT_HOOK_IDENTIFIER:  # noqa: PLR2004 (Magic value used in comparison)
+                msg = (
+                    f"The commit-msg hook in {dest_path} was not installed by gitlint (or it was modified).\n"
+                    "Uninstallation of 3th party or modified gitlint hooks is not supported."
+                )
+                raise GitHookInstallerError(msg)
+
+        # If we are sure it's a gitlint hook, go ahead and remove it
+        os.remove(dest_path)