home-manager/modules/programs/lieer.nix

{
  config,
  lib,
  pkgs,
  ...
}:
let
  inherit (lib)
    concatStringsSep
    mkIf
    mkOption
    mkRenamedOptionModule
    types
    ;

  cfg = config.programs.lieer;

  lieerAccounts = lib.filter (a: a.lieer.enable) (lib.attrValues config.accounts.email.accounts);

  nonGmailAccounts = map (a: a.name) (lib.filter (a: a.flavor != "gmail.com") lieerAccounts);

  nonGmailConfigHelp = map (
    name: ''accounts.email.accounts.${name}.flavor = "gmail.com";''
  ) nonGmailAccounts;

  missingNotmuchAccounts = map (a: a.name) (
    lib.filter (a: !a.notmuch.enable && a.lieer.notmuchSetupWarning) lieerAccounts
  );

  notmuchConfigHelp = map (
    name: "accounts.email.accounts.${name}.notmuch.enable = true;"
  ) missingNotmuchAccounts;

  settingsFormat = pkgs.formats.json { };

  configFile = account: {
    name = "${account.maildir.absPath}/.gmailieer.json";
    value.source = settingsFormat.generate "lieer-${account.address}.json" (
      { account = account.address; } // account.lieer.settings
    );
  };

  settingsOpts = {
    drop_non_existing_label = mkOption {
      type = types.bool;
      default = false;
      description = ''
        Allow missing labels on the Gmail side to be dropped.
      '';
    };

    file_extension = mkOption {
      type = types.str;
      default = "";
      example = "mbox";
      description = ''
        Extension to include in local file names, which can be useful
        for indexing with third-party programs.
      '';
    };

    ignore_empty_history = mkOption {
      type = types.bool;
      default = false;
      description = ''
        Work around a Gmail API quirk where an empty change history
        is sometimes returned.

        See this
        [GitHub issue](https://github.com/gauteh/lieer/issues/120)
        for more details.
      '';
    };

    ignore_remote_labels = mkOption {
      type = types.listOf types.str;
      default = [
        "CATEGORY_FORUMS"
        "CATEGORY_PROMOTIONS"
        "CATEGORY_UPDATES"
        "CATEGORY_SOCIAL"
        "CATEGORY_PERSONAL"
      ];
      description = ''
        Set Gmail labels to ignore when syncing from remote labels to
        local tags (before translations).
      '';
    };

    ignore_tags = mkOption {
      type = types.listOf types.str;
      default = [ ];
      description = ''
        Set labels to ignore when syncing from local tags to
        remote labels (after translations).
      '';
    };

    local_trash_tag = mkOption {
      type = types.str;
      default = "trash";
      description = ''
        Local tag to which the remote Gmail 'TRASH' label is translated.
      '';
    };

    remove_local_messages = mkOption {
      type = types.bool;
      default = true;
      description = ''
        Remove local messages that have been deleted on the remote.
      '';
    };

    replace_slash_with_dot = mkOption {
      type = types.bool;
      default = false;
      description = ''
        Replace '/' with '.' in Gmail labels.
      '';
    };

    timeout = mkOption {
      type = types.ints.unsigned;
      default = 600;
      description = ''
        HTTP timeout in seconds. 0 means forever or system timeout.
      '';
    };
  };

  syncOpts = {
    enable = lib.mkEnableOption "lieer synchronization service";

    frequency = mkOption {
      type = types.str;
      default = "*:0/5";
      description = ''
        How often to synchronize the account.

        This value is passed to the systemd timer configuration as the
        onCalendar option. See
        {manpage}`systemd.time(7)`
        for more information about the format.
      '';
    };
  };

  lieerOpts = {
    enable = lib.mkEnableOption "lieer Gmail synchronization for notmuch";

    notmuchSetupWarning = mkOption {
      type = types.bool;
      default = true;
      description = ''
        Warn if Notmuch is not also enabled for this account.

        This can safely be disabled if {command}`notmuch init`
        has been used to configure this account outside of Home
        Manager.
      '';
    };

    settings = mkOption {
      type = types.submodule {
        freeformType = settingsFormat.type;
        options = settingsOpts;
      };
      default = { };
      description = ''
        Settings which are applied to {file}`.gmailieer.json`
        for the account.

        See the [lieer manual](https://github.com/gauteh/lieer/)
        for documentation of settings not explicitly covered by this module.
      '';
    };

    sync = syncOpts;
  };

  lieerModule = types.submodule {
    imports = [
      (mkRenamedOptionModule
        [ "lieer" "dropNonExistingLabels" ]
        [
          "lieer"
          "settings"
          "drop_non_existing_label"
        ]
      )
      (mkRenamedOptionModule
        [ "lieer" "ignoreTagsRemote" ]
        [
          "lieer"
          "settings"
          "ignore_remote_labels"
        ]
      )
      (mkRenamedOptionModule
        [ "lieer" "ignoreTagsLocal" ]
        [
          "lieer"
          "settings"
          "ignore_tags"
        ]
      )
      (mkRenamedOptionModule
        [ "lieer" "timeout" ]
        [
          "lieer"
          "settings"
          "timeout"
        ]
      )
      (mkRenamedOptionModule
        [ "lieer" "replaceSlashWithDot" ]
        [
          "lieer"
          "settings"
          "replace_slash_with_dot"
        ]
      )
    ];

    options = {
      lieer = lieerOpts;

      warnings = mkOption {
        type = types.listOf types.str;
        default = [ ];
        internal = true;
        visible = false;
      };
    };
  };
in
{
  meta.maintainers = [ lib.maintainers.tadfisher ];

  options = {
    programs.lieer = {
      enable = lib.mkEnableOption "lieer Gmail synchronization for notmuch";

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

    accounts.email.accounts = mkOption { type = with types; attrsOf lieerModule; };
  };

  config = mkIf cfg.enable (
    lib.mkMerge [
      (mkIf (missingNotmuchAccounts != [ ]) {
        warnings = [
          ''
            lieer is enabled for the following email accounts, but notmuch is not:

                ${concatStringsSep "\n    " missingNotmuchAccounts}

            Notmuch can be enabled with:

                ${concatStringsSep "\n    " notmuchConfigHelp}

            If you have configured notmuch outside of Home Manager, you can suppress this
            warning with:

                programs.lieer.notmuchSetupWarning = false;
          ''
        ];
      })

      {
        assertions = [
          {
            assertion = nonGmailAccounts == [ ];
            message = ''
              lieer is enabled for non-Gmail accounts:

                  ${concatStringsSep "\n    " nonGmailAccounts}

              If these accounts are actually Gmail accounts, you can
              fix this error with:

                  ${concatStringsSep "\n    " nonGmailConfigHelp}
            '';
          }
        ];

        warnings = lib.flatten (map (account: account.warnings) lieerAccounts);

        home.packages = [ cfg.package ];

        # Notmuch should ignore non-mail files created by lieer.
        programs.notmuch.new.ignore = [ "/.*[.](json|lock|bak)$/" ];

        home.file = lib.listToAttrs (map configFile lieerAccounts);
      }
    ]
  );
}