From ab9cc41caf44d1f1d465d8028e4bc0096fd73238 Mon Sep 17 00:00:00 2001
From: Nicolas Mattia <nicolas@nmattia.com>
Date: Fri, 24 Jul 2020 13:06:32 +0200
Subject: [PATCH] Add CI check for formatting

---
 default.nix | 18 ++++++++++++++++++
 script/fmt  |  8 +++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/default.nix b/default.nix
index 245ffd9..77584e4 100644
--- a/default.nix
+++ b/default.nix
@@ -198,6 +198,24 @@ rec
   tests-github = pkgs.callPackage ./tests/github { inherit niv; };
   tests-git = pkgs.callPackage ./tests/git { inherit niv; };
 
+  fmt-check =
+    pkgs.stdenv.mkDerivation
+      {
+        name = "fmt-check";
+        buildInputs = [ pkgs.ormolu pkgs.glibcLocales ];
+        src = niv-source;
+        phases = [ "unpackPhase" "checkPhase" ];
+        LANG = "en_US.UTF-8";
+        checkPhase = ''
+          cp ${./script/fmt} ./fmt
+          patchShebangs ./fmt
+          chmod +x fmt
+          bash fmt -c
+          touch $out
+        '';
+        doCheck = true;
+      };
+
   readme = pkgs.runCommand "README.md" { nativeBuildInputs = [ niv ]; }
     ''
       cp ${./README.tpl.md} $out
diff --git a/script/fmt b/script/fmt
index 16116a3..651ee5a 100755
--- a/script/fmt
+++ b/script/fmt
@@ -1,4 +1,9 @@
-#!/usr/bin/env bash
+#!/usr/bin/env nix-shell
+#!nix-shell -i bash
+#!nix-shell -I nixpkgs=./nix
+#!nix-shell -p ormolu
+#!nix-shell -p glibcLocales
+#!nix-shell --keep GITHUB_TOKEN
 ###
 ### fmt - Format Haskell files with Ormolu
 ###
@@ -40,6 +45,7 @@ fmt() {
         if [ "$mode" == "check" ]; then
             exit 1
         fi
+        echo "Please run ./script/fmt"
     fi
 }