{
  description = "Base dev env for Java";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = {
    self,
    nixpkgs,
    flake-utils,
  }:
    flake-utils.lib.eachDefaultSystem (system: let
      pkgs = nixpkgs.legacyPackages.${system};
    in {
      devShells.default = pkgs.mkShell {
        packages = with pkgs; [
          jdk21
          maven
          gradle
          jdt-language-server # LSP for editors
        ];

        shellHook = ''
          echo "Java $(java -version 2>&1 | head -1)"

          alias jbuild='find src -name "*.java" | xargs javac -d out && echo "Build success"'
          alias jrun='jbuild && java -cp out src.Main'
          alias jclean='rm -rf out && echo "Cleaned"'

          mkdir -p out

          echo "  jbuild  — compile all sources"
          echo "  jrun    — compile and run"
          echo "  jclean  — remove compiled output"
        '';
      };
    });
}