home-manager/modules/programs/opam.nix

{ config, lib, pkgs, ... }:
let cfg = config.programs.opam;
in {
  meta.maintainers = [ ];

  options.programs.opam = {
    enable = lib.mkEnableOption "Opam";

    package = lib.mkPackageOption pkgs "opam" { };

    enableBashIntegration =
      lib.hm.shell.mkBashIntegrationOption { inherit config; };

    enableFishIntegration =
      lib.hm.shell.mkFishIntegrationOption { inherit config; };

    enableZshIntegration =
      lib.hm.shell.mkZshIntegrationOption { inherit config; };
  };

  config = lib.mkIf cfg.enable {
    home.packages = [ cfg.package ];

    programs.bash.initExtra = lib.mkIf cfg.enableBashIntegration ''
      eval "$(${cfg.package}/bin/opam env --shell=bash)"
    '';

    programs.zsh.initContent = lib.mkIf cfg.enableZshIntegration ''
      eval "$(${cfg.package}/bin/opam env --shell=zsh)"
    '';

    programs.fish.shellInit = lib.mkIf cfg.enableFishIntegration ''
      eval (${cfg.package}/bin/opam env --shell=fish)
    '';
  };
}