From 2126268791fdf9001c2b7f6b96f05c98e222f8a7 Mon Sep 17 00:00:00 2001
From: David Arnold <dar@xoe.solutions>
Date: Wed, 27 Jan 2021 10:31:17 -0500
Subject: [PATCH] shell: use devshell-native pre-commit hooks

---
 .pre-commit-config.yaml |  5 -----
 flake.lock              |  6 +++---
 shell/default.nix       | 29 +++++++++++++++++++++++------
 3 files changed, 26 insertions(+), 14 deletions(-)
 delete mode 100644 .pre-commit-config.yaml

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
deleted file mode 100644
index f1ed697..0000000
--- a/.pre-commit-config.yaml
+++ /dev/null
@@ -1,5 +0,0 @@
-repos:
--   repo: https://github.com/nix-community/nixpkgs-fmt
-    rev: master
-    hooks:
-    -   id: nixpkgs-fmt
diff --git a/flake.lock b/flake.lock
index dfab41b..67f47de 100644
--- a/flake.lock
+++ b/flake.lock
@@ -23,11 +23,11 @@
     },
     "devshell": {
       "locked": {
-        "lastModified": 1607956014,
-        "narHash": "sha256-kcmh1ZO56GFYStDeM2VngJSvx/e8aKhFSYqLwfiq+Es=",
+        "lastModified": 1611739118,
+        "narHash": "sha256-QjLEfLSiiWDdURFMkke/W7iJsA0unI3pg+91ubvmjbI=",
         "owner": "numtide",
         "repo": "devshell",
-        "rev": "17f46732ce299daa2977be2978f60d258c2d1b41",
+        "rev": "d7a5ebc22aa89a40a96b413a8fc616178920567c",
         "type": "github"
       },
       "original": {
diff --git a/shell/default.nix b/shell/default.nix
index 31e01c2..8a795ea 100644
--- a/shell/default.nix
+++ b/shell/default.nix
@@ -34,7 +34,7 @@ let
 
   name = "flk";
 in
-pkgs.mkDevShell {
+pkgs.devshell.mkShell {
   inherit name;
 
   packages = with pkgs; with installPkgs; [
@@ -48,6 +48,28 @@ pkgs.mkDevShell {
 
   env = { inherit name; };
 
+  git.hooks = with pkgs; {
+    enable = true;
+    pre-commit.text = ''
+      if ${git}/bin/git rev-parse --verify HEAD >/dev/null 2>&1
+      then
+        against=HEAD
+      else
+        # Initial commit: diff against an empty tree object
+        against=$(${git}/bin/git hash-object -t tree /dev/null)
+      fi
+      # Redirect output to stderr.
+      exec 1>&2
+
+      # Format staged nix files.
+      exec ${nixpkgs-fmt}/bin/nixpkgs-fmt \
+        $(
+           ${git}/bin/git diff-index --name-only --cached $against -- \
+           | ${ripgrep}/bin/rg '\.nix$'
+         )
+    '';
+  };
+
   commands = with pkgs; [
     {
       name = nixpkgs-fmt.pname;
@@ -61,11 +83,6 @@ pkgs.mkDevShell {
       category = "main";
       package = flk;
     }
-    {
-      name = "hooks";
-      help = "install git hooks";
-      command = "pre-commit install";
-    }
     {
       name = "grip";
       help = python38Packages.grip.meta.description;