feat: nix flake (#1)

flake.nix

@@ -0,0 +1,25 @@
+{
+  inputs.nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+
+  outputs =
+    { nixpkgs, ... }:
+    let
+      forAllSystems =
+        function:
+        nixpkgs.lib.genAttrs nixpkgs.lib.systems.flakeExposed (
+          system: function nixpkgs.legacyPackages.${system}
+        );
+    in
+    {
+      formatter = forAllSystems (pkgs: pkgs.nixfmt-rfc-style);
+
+      devShells = forAllSystems (pkgs: {
+        default = pkgs.callPackage ./nix/shell.nix { };
+      });
+
+      packages = forAllSystems (pkgs: rec {
+        default = purr;
+        purr = pkgs.callPackage ./nix/default.nix { };
+      });
+    };
+}

nix/default.nix

@@ -0,0 +1,26 @@
+{
+  lib,
+  rustPlatform,
+  pkg-config,
+  openssl,
+  stdenv,
+  darwin,
+}:
+rustPlatform.buildRustPackage {
+  pname = "purr";
+  inherit ((lib.importTOML ../Cargo.toml).package) version;
+
+  src = ../.;
+  cargoLock.lockFile = ../Cargo.lock;
+
+  nativeBuildInputs = [ pkg-config ];
+
+  buildInputs = [ openssl ] ++ lib.optionals stdenv.isDarwin [ darwin.apple_sdk.frameworks.Security ];
+
+  meta = with lib; {
+    description = "Utility commands for managing userstyles";
+    homepage = "https://github.com/uncenter/purr";
+    license = licenses.mit;
+    mainProgram = "purr";
+  };
+}

nix/shell.nix

@@ -0,0 +1,16 @@
+{
+  clippy,
+  rustfmt,
+  callPackage,
+  rust-analyzer,
+}:
+let
+  mainPkg = callPackage ./default.nix { };
+in
+mainPkg.overrideAttrs (oa: {
+  nativeBuildInputs = [
+    clippy
+    rustfmt
+    rust-analyzer
+  ] ++ (oa.nativeBuildInputs or [ ]);
+})