feat(nix): add flake.nix, packaging rootbeer

.gitignore

@@ -6,3 +6,4 @@ docs/.doxygen/
 docs/_build
 subprojects/*
 !subprojects/*.wrap
+result

flake.nix

@@ -0,0 +1,111 @@
+{
+  description = "A Nix flake for the tale/rootbeer system configuration tool";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+    flake-parts = {
+      url = "github:hercules-ci/flake-parts";
+      inputs.nixpkgs-lib.follows = "nixpkgs";
+    };
+
+    systems = {
+      url = "github:nix-systems/default";
+    };
+  };
+
+  outputs = inputs: inputs.flake-parts.lib.mkFlake { inherit inputs; } {
+    systems = import inputs.systems;
+    perSystem = { self', lib, pkgs, system, ... }: {
+      packages = {
+        rootbeer = let
+          # NOTE: as per <./meson.build>
+          version = "0.0.1";
+          source-with-meson-deps = pkgs.stdenv.mkDerivation {
+            pname = "rootbeer-deps";
+            inherit version;
+
+            src = lib.cleanSource ./.;
+
+            nativeBuildInputs = [
+              pkgs.pkg-config
+              pkgs.meson
+              pkgs.cmake
+              pkgs.git
+              pkgs.cacert
+              pkgs.ninja
+            ];
+
+            outputHashAlgo = "sha256";
+            outputHashMode = "recursive";
+            outputHash = "sha256-DdbXF0LdCptpY5zDApOUDHonDlMjRl7ut9m/46Lj+74=";
+
+            phases = [
+              "installPhase"
+            ];
+
+            installPhase = ''
+              # Copy over the raw source in the output, since we'll do the vendoring work there
+              mkdir -p $out
+              cd $out
+              cp --no-preserve=mode -r $src/. .
+
+              # Set the SSL certificate file for network access
+              export NIX_SSL_CERT_FILE=${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt
+
+              # Download the subprojects the `meson` way (using networking, hence the FOD)
+              ${pkgs.lib.getExe pkgs.meson} subprojects download \
+                cjson luajit
+
+              # Clean up `git` metadata from the downloaded dependencies
+              find subprojects -type d -name .git -prune -execdir rm -r {} +
+            '';
+          };
+        in pkgs.stdenv.mkDerivation {
+          pname = "rootbeer";
+          inherit version;
+
+          src = source-with-meson-deps;
+
+          nativeBuildInputs = [
+            pkgs.pkg-config
+            pkgs.ninja
+            pkgs.meson
+            pkgs.autoPatchelfHook
+          ];
+
+          buildInputs = [
+          ];
+
+          postInstall = ''
+            # Manually install the main executable, left in the `src` directory, for some reason
+            mkdir -p $out/bin
+            cp ./src/rootbeer_cli/rb $out/bin/
+
+            # Install provided libraries
+            # TODO: not sure what the structure of those should be for other consumers
+            mkdir -p $out/lib/rootbeer
+            cp -r ./src/librootbeer/. $out/lib/rootbeer/
+          '';
+
+          meta = with pkgs.lib; {
+            description = "A tool to deterministically manage your system using Lua";
+            homepage = "Deterministically manage your system using Lua!";
+            # NOTE: as per <./meson.build>
+            license = licenses.mit;
+            platforms = platforms.all;
+            maintainers = with maintainers; [ ];
+          };
+        };
+
+        default = self'.packages.rootbeer;
+      };
+
+      devShells = {
+        default = pkgs.mkShell {
+          packages = self'.packages.rootbeer.buildInputs ++ self'.packages.rootbeer.nativeBuildInputs;
+        };
+      };
+    };
+  };
+}