From 708f498c4b008d3d6cbe178b5eeebda5f55c4350 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Na=C3=AFm=20Favier?= <n@monade.li>
Date: Wed, 25 Jan 2023 12:58:38 +0100
Subject: [PATCH 1/3] format: improve argument handling

For now, fail if the user tries to format a specific file/directory,
or runs the formatter from within a subdirectory.

Handling these situations is slightly tricky because `find -path` is
not very flexible.
---
 format | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/format b/format
index ef5528b76588..6e0d6100cf35 100755
--- a/format
+++ b/format
@@ -1,16 +1,30 @@
 #! /usr/bin/env nix-shell
 #! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/6616de389ed55fba6eeba60377fc04732d5a207c.tar.gz -i bash -p findutils nixfmt
 
-CHECK_ARG=
+nixfmt_args=()
 
-case $1 in
-    -h)
-        echo "$0 [-c]"
-        ;;
-    -c)
-        CHECK_ARG=-c
-        ;;
-esac
+for arg do
+    case $arg in
+        -h)
+            echo "$0 [-c]"
+            exit
+            ;;
+        -c)
+            nixfmt_args+=("$arg")
+            ;;
+        .)
+            ;;
+        *)
+            echo "unrecognised argument: $arg" >&2
+            exit 1
+            ;;
+    esac
+done
+
+if [[ ! -e flake.nix ]]; then
+    echo "must be run from the root directory" >&2
+    exit 1
+fi
 
 # The excludes are for files touched by open pull requests and we want
 # to avoid merge conflicts.
@@ -24,4 +38,4 @@ find . -name '*.nix' \
   ! -path ./modules/programs/ssh.nix \
   ! -path ./modules/programs/zsh.nix \
   ! -path ./tests/default.nix \
-  -exec nixfmt $CHECK_ARG {} +
+  -exec nixfmt "${nixfmt_args[@]}" {} +

From 8d4fd9bb10de646a477c62f78502954beb459a17 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Na=C3=AFm=20Favier?= <n@monade.li>
Date: Wed, 25 Jan 2023 13:00:41 +0100
Subject: [PATCH 2/3] flake: add formatter

This allows running the formatter with `nix fmt`, added in Nix 2.8.
---
 flake.nix | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/flake.nix b/flake.nix
index 0b7eaa913cf8..5e354f780f28 100644
--- a/flake.nix
+++ b/flake.nix
@@ -55,7 +55,7 @@
                 - 'system'
 
               have been removed. Instead use the arguments 'pkgs' and
-              'modules'. See the 22.11 release notes for more: https://nix-community.github.io/home-manager/release-notes.html#sec-release-22.11-highlights 
+              'modules'. See the 22.11 release notes for more: https://nix-community.github.io/home-manager/release-notes.html#sec-release-22.11-highlights
             '';
 
             throwForRemovedArgs = v:
@@ -93,6 +93,13 @@
           tests = import ./tests { inherit pkgs; };
         in tests.run);
 
+      formatter = forAllSystems (system:
+        let pkgs = nixpkgs.legacyPackages.${system};
+        in pkgs.linkFarm "format" [{
+          name = "bin/format";
+          path = ./format;
+        }]);
+
       packages = forAllSystems (system:
         let
           pkgs = nixpkgs.legacyPackages.${system};

From bbec47d88b558b593037e3c72c59e26b08a846cd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Na=C3=AFm=20Favier?= <n@monade.li>
Date: Sat, 28 Jan 2023 12:17:31 +0100
Subject: [PATCH 3/3] format: use git ls-files

This is cleaner than `find` and allows us to restrict formatting to
particular files or subdirectories.
---
 format | 50 ++++++++++++++++++++++++++++++--------------------
 1 file changed, 30 insertions(+), 20 deletions(-)

diff --git a/format b/format
index 6e0d6100cf35..ff4b32e4761a 100755
--- a/format
+++ b/format
@@ -1,7 +1,8 @@
 #! /usr/bin/env nix-shell
-#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/6616de389ed55fba6eeba60377fc04732d5a207c.tar.gz -i bash -p findutils nixfmt
+#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/6616de389ed55fba6eeba60377fc04732d5a207c.tar.gz -i bash -p git gnugrep gnused findutils nixfmt
 
 nixfmt_args=()
+files=()
 
 for arg do
     case $arg in
@@ -12,30 +13,39 @@ for arg do
         -c)
             nixfmt_args+=("$arg")
             ;;
-        .)
+        -*)
+            echo "unrecognised flag: $arg" >&2
+            exit 1
             ;;
         *)
-            echo "unrecognised argument: $arg" >&2
-            exit 1
+            files+=("$arg")
             ;;
     esac
 done
 
-if [[ ! -e flake.nix ]]; then
-    echo "must be run from the root directory" >&2
-    exit 1
-fi
-
 # The excludes are for files touched by open pull requests and we want
 # to avoid merge conflicts.
-find . -name '*.nix' \
-  ! -path ./modules/default.nix \
-  ! -path ./modules/files.nix \
-  ! -path ./modules/home-environment.nix \
-  ! -path ./modules/lib/default.nix \
-  ! -path ./modules/lib/file-type.nix \
-  ! -path ./modules/misc/news.nix \
-  ! -path ./modules/programs/ssh.nix \
-  ! -path ./modules/programs/zsh.nix \
-  ! -path ./tests/default.nix \
-  -exec nixfmt "${nixfmt_args[@]}" {} +
+excludes=(
+    modules/default.nix
+    modules/files.nix
+    modules/home-environment.nix
+    modules/lib/default.nix
+    modules/lib/file-type.nix
+    modules/misc/news.nix
+    modules/programs/ssh.nix
+    modules/programs/zsh.nix
+    tests/default.nix
+)
+
+exclude_args=()
+for e in "${excludes[@]}"; do
+    exclude_args+=(-e "$e")
+done
+
+git_root=$(git rev-parse --show-toplevel)
+
+git ls-files -z --cached --others --full-name -- "${files[@]}" |
+    grep -z '\.nix$' |
+    grep -z -v "${exclude_args[@]}" |
+    sed -z "s|^|$git_root/|" |
+    xargs -0 nixfmt "${nixfmt_args[@]}"