{ config, lib, pkgs, ... }:
let
  inherit (lib)
    mkOption mkRenamedOptionModule mkRemovedOptionModule mkEnableOption types
    mkPackageOption mkIf mkAfter getExe;

  cfg = config.programs.direnv;

  tomlFormat = pkgs.formats.toml { };

in {
  imports = [
    (mkRenamedOptionModule [
      "programs"
      "direnv"
      "enableNixDirenvIntegration"
    ] [ "programs" "direnv" "nix-direnv" "enable" ])
    (mkRemovedOptionModule [ "programs" "direnv" "nix-direnv" "enableFlakes" ]
      "Flake support is now always enabled.")
  ];

  meta.maintainers = [ lib.maintainers.rycee ];

  options.programs.direnv = {
    enable = mkEnableOption "direnv, the environment switcher";

    package = mkPackageOption pkgs "direnv" { };

    config = mkOption {
      type = tomlFormat.type;
      default = { };
      description = ''
        Configuration written to
        {file}`$XDG_CONFIG_HOME/direnv/direnv.toml`.

        See
        {manpage}`direnv.toml(1)`.
        for the full list of options.
      '';
    };

    stdlib = mkOption {
      type = types.lines;
      default = "";
      description = ''
        Custom stdlib written to
        {file}`$XDG_CONFIG_HOME/direnv/direnvrc`.
      '';
    };

    enableBashIntegration = mkOption {
      default = true;
      type = types.bool;
      description = ''
        Whether to enable Bash integration.
      '';
    };

    enableZshIntegration = mkOption {
      default = true;
      type = types.bool;
      description = ''
        Whether to enable Zsh integration.
      '';
    };

    enableFishIntegration = mkOption {
      default = true;
      type = types.bool;
      readOnly = true;
      description = ''
        Whether to enable Fish integration. Note, enabling the direnv module
        will always active its functionality for Fish since the direnv package
        automatically gets loaded in Fish. If this is not the case try adding
        ```nix
          environment.pathsToLink = [ "/share/fish" ];
        ```
        to the system configuration.
      '';
    };

    enableNushellIntegration = mkOption {
      default = true;
      type = types.bool;
      description = ''
        Whether to enable Nushell integration.
      '';
    };

    nix-direnv = {
      enable = mkEnableOption ''
        [nix-direnv](https://github.com/nix-community/nix-direnv),
        a fast, persistent use_nix implementation for direnv'';

      package = mkPackageOption pkgs "nix-direnv" { };
    };

    silent = mkEnableOption "silent mode, that is, disabling direnv logging";
  };

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

    xdg.configFile."direnv/direnv.toml" = mkIf (cfg.config != { }) {
      source = tomlFormat.generate "direnv-config" cfg.config;
    };

    xdg.configFile."direnv/lib/hm-nix-direnv.sh" = mkIf cfg.nix-direnv.enable {
      source = "${cfg.nix-direnv.package}/share/nix-direnv/direnvrc";
    };

    xdg.configFile."direnv/direnvrc" =
      lib.mkIf (cfg.stdlib != "") { text = cfg.stdlib; };

    programs.bash.initExtra = mkIf cfg.enableBashIntegration (
      # Using mkAfter to make it more likely to appear after other
      # manipulations of the prompt.
      mkAfter ''
        eval "$(${getExe cfg.package} hook bash)"
      '');

    programs.zsh.initExtra = mkIf cfg.enableZshIntegration ''
      eval "$(${getExe cfg.package} hook zsh)"
    '';

    programs.fish.interactiveShellInit = mkIf cfg.enableFishIntegration (
      # Using mkAfter to make it more likely to appear after other
      # manipulations of the prompt.
      mkAfter ''
        ${getExe cfg.package} hook fish | source
      '');

    programs.nushell.extraConfig = mkIf cfg.enableNushellIntegration (let
      # We want to get the stdout from direnv even if it exits with non-zero,
      # because it will have the DIRENV_ internal variables defined.
      #
      # However, nushell's current implementation of try-catch is subtly
      # broken with external commands in pipelines[0].
      #
      # This means we don't have a good way to ignore the exit code
      # without using do | complete, which has a side effect of also
      # capturing stderr, which we don't want.
      #
      # So, as a workaround, we wrap nushell in a second script that
      # just ignores the exit code and does nothing else, allowing
      # nushell to capture our stdout, but letting stderr go through
      # and not causing a spurious "command failed" message.
      #
      # [0]: https://github.com/nushell/nushell/issues/13868
      #
      # FIXME: remove the wrapper once the upstream issue is fixed

      direnvWrapped = pkgs.writeShellScript "direnv-wrapped" ''
        ${getExe cfg.package} export json || true
      '';
      # Using mkAfter to make it more likely to appear after other
      # manipulations of the prompt.
    in mkAfter ''
      $env.config = ($env.config? | default {})
      $env.config.hooks = ($env.config.hooks? | default {})
      $env.config.hooks.pre_prompt = (
          $env.config.hooks.pre_prompt?
          | default []
          | append {||
              let direnv = (
                  ${direnvWrapped}
                  | from json --strict
                  | default {}
              )
              if ($direnv | is-empty) {
                  return
              }
              $direnv
              | items {|key, value|
                  {
                      key: $key
                      value: (do (
                          $env.ENV_CONVERSIONS?
                          | default {}
                          | get -i $key
                          | get -i from_string
                          | default {|x| $x}
                      ) $value)
                  }
              }
              | transpose -ird
              | load-env
          }
      )
    '');

    home.sessionVariables = lib.mkIf cfg.silent { DIRENV_LOG_FORMAT = ""; };
  };
}