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 "java" // {
        description = ''
          Install and setup the Java development kit.
          <note>
          <para>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:
          </para>
          <programlisting>
            environment.variables.JAVA_HOME = ''${pkgs.jdk.home}/lib/openjdk;
            environment.systemPackages = [ pkgs.jdk ];
          </programlisting>
          </note>
        '';
      };

      package = mkOption {
        default = pkgs.jdk;
        defaultText = "pkgs.jdk";
        description = ''
          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
    '';

  };

}