nixpkgs/nixos/modules/programs/java.nix

# This module provides JAVA_HOME, with a different way to install java
# system-wide.

{ config, lib, pkgs, ... }:

with lib;

let
  cfg = config.programs.java;
in

{

  options = {

    programs.java = {

      enable = mkEnableOption (lib.mdDoc "java") // {
        description = lib.mdDoc ''
          Install and setup the Java development kit.

          ::: {.note}
          This adds JAVA_HOME to the global environment, by sourcing the
          jdk's setup-hook on shell init. It is equivalent to starting a shell
          through 'nix-shell -p jdk', or roughly the following system-wide
          configuration:

              environment.variables.JAVA_HOME = ''${pkgs.jdk.home}/lib/openjdk;
              environment.systemPackages = [ pkgs.jdk ];
          :::
        '';
      };

      package = mkOption {
        default = pkgs.jdk;
        defaultText = literalExpression "pkgs.jdk";
        description = lib.mdDoc ''
          Java package to install. Typical values are pkgs.jdk or pkgs.jre.
        '';
        type = types.package;
      };

    };

  };

  config = mkIf cfg.enable {

    environment.systemPackages = [ cfg.package ];

    environment.shellInit = ''
      test -e ${cfg.package}/nix-support/setup-hook && source ${cfg.package}/nix-support/setup-hook
    '';

  };

}