Use git to resolve the correct hooks path

Author: qgadrian

lib/git.ex

@@ -1,37 +1,24 @@
 defmodule GitHooks.Git do
   @moduledoc false
 
-  alias Mix.Project
-
   @doc false
   @spec resolve_git_path() :: any
   def resolve_git_path do
     :git_hooks
     |> Application.get_env(:git_path)
     |> case do
       nil ->
-        path = Path.join(Project.deps_path(), "/../.git")
-
-        if File.dir?(path) do
-          path
-        else
-          resolve_git_submodule_path(path)
-        end
+        {path, 0} = System.cmd("git", ["rev-parse", "--git-path", "hooks"])
+        String.replace(path, "\n", "")
 
       custom_path ->
         custom_path
     end
   end
 
-  @spec resolve_git_submodule_path(String.t()) :: any
-  defp resolve_git_submodule_path(git_path) do
-    with {:ok, contents} <- File.read(git_path),
-         %{"dir" => submodule_dir} <- Regex.named_captures(~r/^gitdir:\s+(?<dir>.*)$/, contents) do
-      Project.deps_path()
-      |> Path.join("/../" <> submodule_dir)
-    else
-      _error ->
-        raise "Error resolving git submodule path '#{git_path}'"
-    end
+  @spec git_hooks_path_for(path :: String.t()) :: String.t()
+  def git_hooks_path_for(path) do
+    __MODULE__.resolve_git_path()
+    |> Path.join("/#{path}")
   end
 end

lib/git/path.ex

@@ -0,0 +1,52 @@
+defmodule GitHooks.Git.Path do
+  @moduledoc false
+
+  alias GitHooks.Git
+
+  @doc false
+  @spec resolve_git_hooks_path() :: any
+  def resolve_git_hooks_path do
+    :git_hooks
+    |> Application.get_env(:git_path)
+    |> case do
+      nil -> resolve_git_hooks_path_based_on_git_version()
+      custom_path -> custom_path
+    end
+  end
+
+  @spec git_hooks_path_for(path :: String.t()) :: String.t()
+  def git_hooks_path_for(path) do
+    __MODULE__.resolve_git_hooks_path()
+    |> Path.join("/#{path}")
+    |> String.replace(~r/\/+/, "/")
+  end
+
+  #
+  # Private functions
+  #
+
+  # https://stackoverflow.com/questions/10848191/git-submodule-commit-hooks
+  #
+  # Git 2.10+
+  # `git rev-parse --git-path hooks`
+  # Pre Git 2.10+
+  # `git rev-parse --git-dir /hooks`
+  #
+  # This will support as well changes on the default /hooks path
+  # git config core.hooksPath .githooks/
+
+  @spec resolve_git_hooks_path_based_on_git_version() :: String.t()
+  defp resolve_git_hooks_path_based_on_git_version() do
+    Git.git_version()
+    |> Version.compare(Version.parse!("2.10.0"))
+    |> case do
+      :lt ->
+        {path, 0} = System.cmd("git", ["rev-parse", "--git-dir", "hooks"])
+        String.replace(path, "\n", "")
+
+      _gt_or_eq ->
+        {path, 0} = System.cmd("git", ["rev-parse", "--git-path", "hooks"])
+        String.replace(path, "\n", "")
+    end
+  end
+end

lib/mix/tasks/git_hooks/install.ex

@@ -21,7 +21,7 @@ defmodule Mix.Tasks.GitHooks.Install do
   use Mix.Task
 
   alias GitHooks.Config
-  alias GitHooks.Git
+  alias GitHooks.Git.Path, as: GitPath
   alias GitHooks.Printer
 
   @impl true
@@ -55,9 +55,7 @@ defmodule Mix.Tasks.GitHooks.Install do
 
       case File.read(template_file) do
         {:ok, body} ->
-          target_file_path =
-            Git.resolve_git_path()
-            |> Path.join("/hooks/#{git_hook_atom_as_kebab_string}")
+          target_file_path = GitPath.git_hooks_path_for(git_hook_atom_as_kebab_string)
 
           target_file_body =
             body
@@ -85,13 +83,9 @@ defmodule Mix.Tasks.GitHooks.Install do
 
   @spec backup_current_hook(String.t(), Keyword.t()) :: {:error, atom} | {:ok, non_neg_integer()}
   defp backup_current_hook(git_hook_to_backup, opts) do
-    source_file_path =
-      Git.resolve_git_path()
-      |> Path.join("/hooks/#{git_hook_to_backup}")
+    source_file_path = GitPath.git_hooks_path_for(git_hook_to_backup)
 
-    target_file_path =
-      Git.resolve_git_path()
-      |> Path.join("/hooks/#{git_hook_to_backup}.pre_git_hooks_backup")
+    target_file_path = GitPath.git_hooks_path_for("/#{git_hook_to_backup}.pre_git_hooks_backup")
 
     unless opts[:quiet] || !Config.verbose?() do
       Printer.info("Backing up git hook file `#{source_file_path}` to `#{target_file_path}`")
@@ -104,8 +98,8 @@ defmodule Mix.Tasks.GitHooks.Install do
   defp track_configured_hooks do
     git_hooks = Config.git_hooks() |> Enum.join(" ")
 
-    Git.resolve_git_path()
-    |> Path.join("/hooks/git_hooks.db")
+    "/git_hooks.db"
+    |> GitPath.git_hooks_path_for()
     |> write_backup(git_hooks)
   end
 
@@ -123,8 +117,8 @@ defmodule Mix.Tasks.GitHooks.Install do
 
   @spec ensure_hooks_folder_exists() :: any
   defp ensure_hooks_folder_exists do
-    Git.resolve_git_path()
-    |> Path.join("/hooks")
+    "/"
+    |> GitPath.git_hooks_path_for()
     |> File.mkdir_p()
   end
 
@@ -134,8 +128,8 @@ defmodule Mix.Tasks.GitHooks.Install do
       Config.git_hooks()
       |> Enum.map(&Atom.to_string/1)
 
-    Git.resolve_git_path()
-    |> Path.join("/git_hooks.db")
+    "/git_hooks.db"
+    |> GitPath.git_hooks_path_for()
     |> File.read()
     |> case do
       {:ok, file} ->
@@ -149,8 +143,8 @@ defmodule Mix.Tasks.GitHooks.Install do
               "Remove old git hook `#{git_hook_atom_as_kebab_string}` and restore backup"
             )
 
-            Git.resolve_git_path()
-            |> Path.join("/hooks/#{git_hook_atom_as_kebab_string}")
+            git_hook_atom_as_kebab_string
+            |> GitPath.git_hooks_path_for()
             |> File.rm()
 
             restore_backup(git_hook_atom_as_kebab_string)
@@ -165,16 +159,9 @@ defmodule Mix.Tasks.GitHooks.Install do
   @spec restore_backup(String.t()) :: any
   defp restore_backup(git_hook_atom_as_kebab_string) do
     backup_path =
-      Path.join(
-        Git.resolve_git_path(),
-        "/hooks/#{git_hook_atom_as_kebab_string}.pre_git_hooks_backup"
-      )
+      GitPath.git_hooks_path_for("/#{git_hook_atom_as_kebab_string}.pre_git_hooks_backup")
 
-    restore_path =
-      Path.join(
-        Git.resolve_git_path(),
-        "/#{git_hook_atom_as_kebab_string}"
-      )
+    restore_path = GitPath.git_hooks_path_for(git_hook_atom_as_kebab_string)
 
     case File.rename(backup_path, restore_path) do
       :ok -> :ok

test/git/path_test.exs

@@ -0,0 +1,11 @@
+defmodule GitHooks.Git.PathTest do
+  use ExUnit.Case
+
+  alias GitHooks.Git.Path
+
+  describe "git_hooks_path_for/1" do
+    test "appends the path to the hooks folder" do
+      assert Path.git_hooks_path_for("/testing") == ".git/hooks/testing"
+    end
+  end
+end