From 257ade944e49559b898fc548f6e65e65d3319d7e Mon Sep 17 00:00:00 2001
From: Franck Cuny <franck@fcuny.net>
Date: Sun, 17 Aug 2025 19:41:36 -0700
Subject: manage the repository with nix

Add a flake.nix to manage the development shell, the formatters, add
some pre-commit checks, and such.

This might evolve a bit over time but this is a good starting point.
---
 flake.nix | 114 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 flake.nix

(limited to 'flake.nix')

diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..d0c01b3
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,114 @@
+{
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-25.05";
+    flake-utils.url = "github:numtide/flake-utils";
+    treefmt-nix = {
+      url = "github:numtide/treefmt-nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    pre-commit-hooks = {
+      url = "github:cachix/git-hooks.nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+  outputs =
+    {
+      self,
+      nixpkgs,
+      treefmt-nix,
+      flake-utils,
+      pre-commit-hooks,
+    }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = import nixpkgs { inherit system; };
+
+        treefmtEval = treefmt-nix.lib.evalModule pkgs ./treefmt.nix;
+
+        ciPackagesBackend = with pkgs; [
+          go # Need that obviously
+          gofumpt # Go formatter
+          golangci-lint # Local/CI linter
+          gotestsum # Pretty tester
+          goperf # Go performance suite
+        ];
+
+        devPackages = with pkgs; [
+          gopls
+          gotools
+        ];
+      in
+      {
+        formatter = treefmtEval.config.build.wrapper;
+
+        checks = {
+          # Throws an error if any of the source files are not correctly formatted
+          # when you run `nix flake check --print-build-logs`. Useful for CI
+          treefmt = treefmtEval.config.build.check self;
+          pre-commit-check = pre-commit-hooks.lib.${system}.run {
+            src = ./.;
+            hooks = {
+              format = {
+                enable = true;
+                name = "Format with treefmt";
+                pass_filenames = true;
+                entry = "${treefmtEval.config.build.wrapper}/bin/treefmt";
+                stages = [
+                  "pre-commit"
+                  "pre-push"
+                ];
+              };
+              golangci-lint = {
+                enable = true;
+                package = pkgs.golangci-lint;
+                pass_filenames = true;
+                stages = [ "pre-push" ];
+              };
+              unit-tests-go = {
+                enable = true;
+                name = "Run unit tests";
+                entry = "gotestsum --format testdox ./...";
+                pass_filenames = false;
+                stages = [ "pre-push" ];
+                types = [ "go" ];
+              };
+            };
+          };
+
+          # ci =
+          #   pkgs.runCommand "ci-runner"
+          #     {
+          #       nativeBuildInputs = [ ci-script ] ++ ciPackages; # Include ci-script and ciPackages
+          #       inherit (self.checks.${system}.pre-commit-check) shellHook; # Reuse pre-commit shellHook if needed
+          #     }
+          #     ''
+          #       echo "Running CI script with essential packages..."
+          #       # Ensure the ci-script is executable and in PATH for this check
+          #       export PATH=$out/bin:$PATH
+          #       run-ci
+          #       touch $out # Ensure the output path is created
+          #     '';
+        };
+
+        devShells = {
+          default = pkgs.mkShell {
+            buildInputs =
+              [ ] ++ ciPackagesBackend ++ devPackages ++ self.checks.${system}.pre-commit-check.enabledPackages;
+
+            shellHook = ''
+              ${self.checks.${system}.pre-commit-check.shellHook}
+            '';
+          };
+
+          ci-backend = pkgs.mkShell {
+            buildInputs = [ ] ++ ciPackagesBackend;
+            CI = true;
+            shellHook = ''
+              echo "Entering CI backend shell. Only essential CI tools available."
+            '';
+          };
+        };
+      }
+    );
+}
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