feat: make lib configurable

2026-03-04 04:58:55 +01:00
commit 765ad16b4f
3 changed files with 317 additions and 0 deletions
--- a/flake.nix
+++ b/flake.nix
@@ -0,0 +1,180 @@
+# flake.nix — devshell-lib
+{
+  description = "Shared devshell boilerplate library";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
+    git-hooks.url = "github:cachix/git-hooks.nix";
+    treefmt-nix.url = "github:numtide/treefmt-nix";
+  };
+
+  outputs =
+    {
+      self,
+      nixpkgs,
+      treefmt-nix,
+      git-hooks,
+      ...
+    }:
+    let
+      supportedSystems = [
+        "x86_64-linux"
+        "aarch64-linux"
+        "x86_64-darwin"
+        "aarch64-darwin"
+      ];
+      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
+    in
+    {
+      lib = {
+        mkDevShell =
+          {
+            system,
+            extraPackages ? [ ],
+            extraShellHook ? "",
+            additionalHooks ? { },
+            tools ? [ ],
+            # tools = list of { name, bin, versionCmd, color? }
+            # e.g. { name = "Bun"; bin = "${pkgs.bun}/bin/bun"; versionCmd = "--version"; color = "YELLOW"; }
+            formatters ? { },
+            # formatters = treefmt-nix programs attrset, merged over { nixfmt.enable = true; }
+            # e.g. { gofmt.enable = true; shfmt.enable = true; }
+            formatterSettings ? { },
+            # formatterSettings = treefmt-nix settings.formatter attrset
+            # e.g. { shfmt.options = [ "-i" "2" "-s" "-w" ]; }
+            features ? { },
+            # features = opt-in lib-managed behaviours
+            # features.oxfmt = true  →  adds pkgs.oxfmt + pkgs.oxlint, enables oxfmt in treefmt
+          }:
+          let
+            pkgs = import nixpkgs { inherit system; };
+
+            oxfmtEnabled = features.oxfmt or false;
+            oxfmtPackages = pkgs.lib.optionals oxfmtEnabled [
+              pkgs.oxfmt
+              pkgs.oxlint
+            ];
+            oxfmtFormatters = pkgs.lib.optionalAttrs oxfmtEnabled {
+              oxfmt.enable = true;
+            };
+
+            treefmtEval = treefmt-nix.lib.evalModule pkgs {
+              projectRootFile = "flake.nix";
+              programs = {
+                nixfmt.enable = true; # always on — every repo has a flake.nix
+              }
+              // oxfmtFormatters
+              // formatters;
+              settings.formatter = { } // formatterSettings;
+            };
+
+            pre-commit-check = git-hooks.lib.${system}.run {
+              src = ./.;
+              hooks = {
+                treefmt = {
+                  enable = true;
+                  entry = "${treefmtEval.config.build.wrapper}/bin/treefmt";
+                  pass_filenames = true;
+                };
+                gitlint.enable = true;
+                gitleaks = {
+                  enable = true;
+                  entry = "${pkgs.gitleaks}/bin/gitleaks protect --staged";
+                  pass_filenames = false;
+                };
+                tests = {
+                  enable = true;
+                  entry = "echo 'No tests defined yet.'";
+                  pass_filenames = false;
+                  stages = [ "pre-push" ];
+                };
+              }
+              // additionalHooks;
+            };
+
+            toolBannerScript = pkgs.lib.concatMapStrings (
+              t:
+              let
+                colorVar = "$" + (t.color or "YELLOW");
+              in
+              ''
+                if command -v ${t.bin} >/dev/null 2>&1; then
+                  printf "  $CYAN ${t.name}:$RESET\t${colorVar}%s$RESET\n" "$(${t.bin} ${t.versionCmd})"
+                fi
+              ''
+            ) tools;
+
+          in
+          {
+            inherit pre-commit-check;
+
+            formatter = treefmtEval.config.build.wrapper;
+
+            shell = pkgs.mkShell {
+              packages = extraPackages ++ oxfmtPackages;
+
+              buildInputs = pre-commit-check.enabledPackages;
+
+              shellHook = ''
+                ${pre-commit-check.shellHook}
+
+                if [ -t 1 ]; then
+                  command -v tput >/dev/null 2>&1 && tput clear || printf '\033c'
+                fi
+
+                GREEN='\033[1;32m'
+                CYAN='\033[1;36m'
+                YELLOW='\033[1;33m'
+                BLUE='\033[1;34m'
+                RESET='\033[0m'
+
+                printf "\n$GREEN 🚀 Dev shell ready$RESET\n\n"
+                ${toolBannerScript}
+                printf "\n"
+
+                ${extraShellHook}
+              '';
+            };
+          };
+      };
+
+      # Dogfood: this repo's own dev shell using the lib above
+      devShells = forAllSystems (
+        system:
+        let
+          pkgs = import nixpkgs { inherit system; };
+          env = self.lib.mkDevShell {
+            inherit system;
+            extraPackages = with pkgs; [
+              nixfmt
+              gitlint
+              gitleaks
+            ];
+            tools = [
+              {
+                name = "Nix";
+                bin = "${pkgs.nix}/bin/nix";
+                versionCmd = "--version";
+                color = "YELLOW";
+              }
+            ];
+          };
+        in
+        {
+          default = env.shell;
+        }
+      );
+
+      checks = forAllSystems (
+        system:
+        let
+          env = self.lib.mkDevShell { inherit system; };
+        in
+        {
+          inherit (env) pre-commit-check;
+        }
+      );
+
+      formatter = forAllSystems (system: (self.lib.mkDevShell { inherit system; }).formatter);
+    };
+}