Describe nix dev environment using nix flakes

.gitignore

@@ -7,3 +7,5 @@ engine_manager
 temp
 docs/build
 include/UI.h
+src/resources.c
+result

Makefile

@@ -3,7 +3,7 @@ STD		?= c17
 GTK		= gtk+-3.0
 RSVG	= librsvg-2.0
 GIO		= gio-unix-2.0 gio-2.0
-PKGCONF	= $(shell which pkg-config)
+PKGCONF	?= $(shell which pkg-config)
 CFLAGS	+= -Wall -Wextra -Wpedantic -Wno-overlength-strings -std=$(STD) -O3 `$(PKGCONF) --cflags $(GTK) $(RSVG) $(GIO)`
 LDFLAGS	+= `$(PKGCONF) --libs $(GTK) $(RSVG) $(GIO)` -lm
 
@@ -38,7 +38,10 @@ UI = $(DATADIR)/window.glade $(DATADIR)/selected.css
 
 all: prepare engine_manager $(OBJECTS)
 	$(CC) $(CFLAGS) -rdynamic -o GTKChess $(OBJECTS) $(LDFLAGS)
-	gio set -t string GTKChess metadata::custom-icon file://$(PWD)/data/textures/classic/WKnight.svg
+#	FIXME: `nix build` fails with error: 
+#	gio: Setting attribute metadata::custom-icon not supported
+#
+#	gio set -t string GTKChess metadata::custom-icon file://$(PWD)/src/textures/classic/WKnight.svg
 
 engine_manager: $(OBJDIR)/engine_manager.o
 	$(CC) $(CFLAGS) -o engine_manager $< $(LDFLAGS) -pthread
@@ -85,4 +88,4 @@ docs: $(DOCDIR)/source
 
 read: docs
 	xdg-open $(DOCDIR)/build/html/index.html &> /dev/null
-
+

flake.nix

@@ -0,0 +1,62 @@
+{
+  description = "A nix flake for GTK-Chess, UCI chess engine GUI written in C.";
+  nixConfig = {
+    extra-experimental-features = [ "nix-command" "flakes" ];
+    extra-substituters = [ "https://cache.zw3rk.com" ];
+    extra-trusted-public-keys = [ "loony-tools:pr9m4BkM/5/eSTZlkQyRt57Jz7OMBxNSUiMC4FkcNfk=" ];
+
+    bash-prompt = "\\[\\e[0m\\][\\[\\e[0;2m\\]nix-develop \\[\\e[0;1m\\]gtk-chess@\\[\\033[33m\\]$(git rev-parse --abbrev-ref HEAD) \\[\\e[0;32m\\]\\w\\[\\e[0m\\]]\\[\\e[0m\\]$ \\[\\e[0m\\]";
+  };
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs?ref=22.11";
+  };
+
+  outputs = { self, nixpkgs }:
+    let
+      supportedSystems = [ "x86_64-linux" "x86_64-darwin" ];
+      perSystem = nixpkgs.lib.genAttrs supportedSystems;
+      allNixpkgs = perSystem (system: import nixpkgs { inherit system; });
+      nixpkgsFor = system: allNixpkgs.${system};
+
+      nativeBuildInputs = perSystem (system:
+        with nixpkgsFor system; [ clang gnumake pkg-config which libxml2 ]
+      );
+
+      buildInputs = perSystem (system:
+        with nixpkgsFor system; [ gtk3 librsvg glib ]
+      );
+
+      inputsCombined = perSystem (system:
+        nativeBuildInputs.${system} ++ buildInputs.${system}
+      );
+    in
+    {
+      defaultPackage = perSystem (system: self.packages.${system}.gtkChess);
+
+      packages = perSystem (system:
+        with nixpkgsFor system; {
+          gtkChess = stdenv.mkDerivation {
+            name = "GTK-Chess";
+            version = "dev";
+            src = ./.;
+            nativeBuildInputs = nativeBuildInputs.${system};
+            buildInputs = buildInputs.${system};
+            buildPhase = "make all";
+            installPhase = "mkdir -p $out/bin; cp GTKChess $out/bin";
+          };
+        }
+      );
+
+      devShells = perSystem (system: {
+        default =
+          with nixpkgsFor system; mkShell {
+            buildInputs = [ cppcheck ] ++ inputsCombined.${system};
+          };
+      });
+
+      formatter = perSystem (system:
+        nixpkgs.legacyPackages.${system}.nixpkgs-fmt
+      );
+    };
+}