flake: add pre-commit-hooks

Instead of havin the tool manage versions, use a pinned version.

.pre-commit-config.yaml

@@ -1,21 +0,0 @@
-repos:
-- repo: 'https://github.com/pre-commit/pre-commit-hooks'
-  rev: 'v2.3.0'
-  hooks:
-  - id: 'trailing-whitespace'
-  - id: 'end-of-file-fixer'
-  - id: 'check-yaml'
-  - id: 'check-added-large-files'
-- repo: 'https://github.com/jumanjihouse/pre-commit-hooks'
-  rev: '2.1.4'
-  hooks:
-  - id: 'forbid-binary'
-- repo: 'local'
-  hooks:
-  - id: 'nixpkgs-fmt'
-    name: 'nixpkgs-fmt'
-    description: 'Format nix code with nixpkgs-fmt'
-    entry: 'nixpkgs-fmt'
-    language: 'system'
-    files: '\.nix$'
-    always_run: true

flake.lock

@@ -69,12 +69,37 @@
         "type": "github"
       }
     },
+    "pre-commit-hooks": {
+      "inputs": {
+        "flake-utils": [
+          "futils"
+        ],
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1621411868,
+        "narHash": "sha256-R+7OQ2JYFCb3E7Jl7LhRifzMVCR6Gl8R98zYsNhZtJ8=",
+        "owner": "cachix",
+        "repo": "pre-commit-hooks.nix",
+        "rev": "2e7fac06108b4fc81f5ff9ed9a02bc4f6ede7001",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "ref": "master",
+        "repo": "pre-commit-hooks.nix",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "futils": "futils",
         "home-manager": "home-manager",
         "nixpkgs": "nixpkgs",
-        "nur": "nur"
+        "nur": "nur",
+        "pre-commit-hooks": "pre-commit-hooks"
       }
     }
   },

flake.nix

@@ -31,6 +31,17 @@
       repo = "NUR";
       ref = "master";
     };
+
+    pre-commit-hooks = {
+      type = "github";
+      owner = "cachix";
+      repo = "pre-commit-hooks.nix";
+      ref = "master";
+      inputs = {
+        flake-utils.follows = "futils";
+        nixpkgs.follows = "nixpkgs";
+      };
+    };
   };
 
   outputs =
@@ -40,6 +51,7 @@
     , home-manager
     , nixpkgs
     , nur
+    , pre-commit-hooks
     }:
     let
       inherit (futils.lib) eachDefaultSystem;
@@ -96,6 +108,18 @@
           diff-flake = futils.lib.mkApp { drv = packages.diff-flake; };
         };
 
+        checks = {
+          pre-commit = pre-commit-hooks.lib.${system}.run {
+            src = ./.;
+
+            hooks = {
+              nixpkgs-fmt = {
+                enable = true;
+              };
+            };
+          };
+        };
+
         defaultApp = apps.diff-flake;
 
         devShell = pkgs.mkShell {
@@ -107,6 +131,8 @@
             gnupg
             nixpkgs-fmt
           ];
+
+          inherit (self.checks.${system}.pre-commit) shellHook;
         };
 
         packages = import ./pkgs { inherit pkgs; };