Add derivation for static website

flake.nix

@@ -3,13 +3,46 @@
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
+    flutils.url = "github:numtide/flake-utils";
   };
 
-  outputs = { self, nixpkgs }: {
+  outputs = { self, nixpkgs, flutils }: flutils.lib.eachDefaultSystem (system:
+    let
+      pkgs = nixpkgs.legacyPackages.${system};
 
-    packages.x86_64-linux.hello = nixpkgs.legacyPackages.x86_64-linux.hello;
+      gems = pkgs.bundlerEnv {
+        name = "blog-pim";
+        gemdir = ./src;
+      };
 
-    packages.x86_64-linux.default = self.packages.x86_64-linux.hello;
+      patch-feed-date = pkgs.stdenv.mkDerivation {
+        name = "path-feed-date";
+        propagatedBuildInputs = [ pkgs.python3 ];
+        dontUnpack = true;
+        installPhase = "install -Dm755 ${./patch-feed-date.py} $out/bin/patch-feed-date";
+      };
+    in
+    {
+      packages.website = pkgs.stdenv.mkDerivation {
+        name = "blog-pim";
+        src = ./src;
+        sourceRoot = "src";
 
-  };
+        buildInputs = [
+          gems
+          gems.wrappedRuby
+          patch-feed-date
+        ];
+
+        buildPhase = ''
+          bundle exec jekyll build
+        '';
+
+        installPhase = ''
+          mkdir -p $out
+          cp -r _site/* $out/
+          patch-feed-date --file _site/feed.xml > $out/feed.xml
+        '';
+      };
+    });
 }