recoll: add module

modules/misc/news.nix

@@ -624,6 +624,14 @@ in
           A new module is available: 'xsession.windowManager.spectrwm'.
         '';
       }
+
+      {
+        time = "2022-07-27T12:22:37+00:00";
+        condition = hostPlatform.isLinux;
+        message = ''
+          A new module is available: 'services.recoll'.
+        '';
+      }
     ];
   };
 }

modules/modules.nix

@@ -242,6 +242,7 @@ let
     ./services/poweralertd.nix
     ./services/pulseeffects.nix
     ./services/random-background.nix
+    ./services/recoll.nix
     ./services/redshift-gammastep/gammastep.nix
     ./services/redshift-gammastep/redshift.nix
     ./services/rsibreak.nix

modules/services/recoll.nix

@@ -0,0 +1,192 @@
+{ config, options, lib, pkgs, ... }:
+
+with lib;
+
+# TODO: Fix the formatting of the resulting config.
+let
+  cfg = config.services.recoll;
+
+  # The key-value generator for Recoll config format. For future references,
+  # see the example configuration from the package (i.e.,
+  # `$out/share/recoll/examples/recoll.conf`).
+  mkRecollConfKeyValue = generators.mkKeyValueDefault {
+    mkValueString = v:
+      if v == true then
+        "1"
+      else if v == false then
+        "0"
+      else if isList v then
+        concatStringsSep " " v
+      else
+        generators.mkValueStringDefault { } v;
+  } " = ";
+
+  # A modified version of 'lib.generators.toINI' that also accepts top-level
+  # attributes as non-attrsets.
+  toRecollConf = { listsAsDuplicateKeys ? false }:
+    attr:
+    let
+      toKeyValue = generators.toKeyValue {
+        inherit listsAsDuplicateKeys;
+        mkKeyValue = mkRecollConfKeyValue;
+      };
+      mkSectionName = name: strings.escape [ "[" "]" ] name;
+      convert = k: v:
+        if isAttrs v then
+          ''
+            [${mkSectionName k}]
+          '' + toKeyValue v
+        else
+          toKeyValue { "${k}" = v; };
+
+      # TODO: Improve this chunk of code, pls.
+      # There's a possibility of attributes with attrsets overriding other
+      # top-level attributes with non-attrsets so we're forcing the attrsets to
+      # come last.
+      _config = mapAttrsToList convert (filterAttrs (k: v: !isAttrs v) attr);
+      _config' = mapAttrsToList convert (filterAttrs (k: v: isAttrs v) attr);
+      config = _config ++ _config';
+    in concatStringsSep "\n" config;
+
+  # A specific type for Recoll config format. Taken from `pkgs.formats`
+  # implementation from nixpkgs. See the 'Nix-representable formats' from the
+  # NixOS manual for more information.
+  recollConfFormat = { }: {
+    type = with types;
+      let
+        valueType = nullOr (oneOf [
+          bool
+          float
+          int
+          path
+          str
+          (attrsOf valueType)
+          (listOf valueType)
+        ]) // {
+          description = "Recoll config value";
+        };
+      in attrsOf valueType;
+
+    generate = name: value: pkgs.writeText name (toRecollConf { } value);
+  };
+
+  # The actual object we're going to use for this module. This is for the sake
+  # of consistency (and dogfooding the settings format implementation).
+  settingsFormat = recollConfFormat { };
+in {
+  meta.maintainers = [ maintainers.foo-dogsquared ];
+
+  options.services.recoll = {
+    enable = mkEnableOption "Recoll file index service";
+
+    package = mkOption {
+      type = types.package;
+      default = pkgs.recoll;
+      defaultText = literalExpression "pkgs.recoll";
+      description = ''
+        Package providing the <literal>recoll</literal> binary.
+      '';
+      example = literalExpression "(pkgs.recoll.override { withGui = false; })";
+    };
+
+    startAt = mkOption {
+      type = types.str;
+      default = "hourly";
+      example = "00/2:00";
+      description = ''
+        When or how often the periodic update should run. Must be the format
+        described from
+        <citerefentry>
+          <refentrytitle>systemd.time</refentrytitle>
+          <manvolnum>7</manvolnum>
+        </citerefentry>.
+      '';
+    };
+
+    settings = mkOption {
+      type = settingsFormat.type;
+      default = { };
+      description = ''
+        The configuration to be written at
+        <filename>''${config.services.recoll.configDir}/recoll.conf</filename>.
+
+        See
+        <citerefentry>
+          <refentrytitle>recoll</refentrytitle>
+          <manvolnum>5</manvolnum>
+        </citerefentry> for more details about the configuration.
+      '';
+      example = literalExpression ''
+        {
+          nocjk = true;
+          loglevel = 5;
+          topdirs = [ "~/Downloads" "~/Documents" "~/projects" ];
+
+          "~/Downloads" = {
+            "skippedNames+" = [ "*.iso" ];
+          };
+
+          "~/projects" = {
+            "skippedNames+" = [ "node_modules" "target" "result" ];
+          };
+        }
+      '';
+    };
+
+    configDir = mkOption {
+      type = types.str;
+      default = "${config.home.homeDirectory}/.recoll";
+      defaultText = literalExpression "\${config.home.homeDirectory}/.recoll";
+      example = literalExpression "\${config.xdg.configHome}/recoll";
+      description = ''
+        The directory to contain Recoll configuration files. This will be set
+        as <literal>RECOLL_CONFDIR</literal>.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    assertions = [
+      (lib.hm.assertions.assertPlatform "services.recoll" pkgs
+        lib.platforms.linux)
+    ];
+
+    home.packages = [ cfg.package ];
+
+    home.sessionVariables = { RECOLL_CONFDIR = cfg.configDir; };
+
+    home.file."${cfg.configDir}/recoll.conf".source =
+      settingsFormat.generate "recoll-conf-${config.home.username}"
+      cfg.settings;
+
+    systemd.user.services.recollindex = {
+      Unit = {
+        Description = "Recoll index update";
+        Documentation = [
+          "man:recoll"
+          "man:recollindex"
+          "https://www.lesbonscomptes.com/recoll/usermanual/"
+        ];
+      };
+
+      Service = {
+        ExecStart = "${cfg.package}/bin/recollindex";
+        Environment = [ "RECOLL_CONFDIR=${escapeShellArg cfg.configDir}" ];
+      };
+    };
+
+    systemd.user.timers.recollindex = {
+      Unit = {
+        Description = "Recoll index update";
+        PartOf = [ "default.target" ];
+      };
+
+      Timer = {
+        Persistent = true;
+        OnCalendar = cfg.startAt;
+      };
+
+      Install.WantedBy = [ "timers.target" ];
+    };
+  };
+}