alot: support contact completion

Make choice of contact completion easier.

modules/accounts/email.nix

@@ -1,4 +1,4 @@
-{ config, lib, ... }:
+{ config, lib, pkgs, ... }:
 
 with lib;
 
@@ -379,7 +379,7 @@ in
     accounts = mkOption {
       type = types.attrsOf (types.submodule [
         mailAccountOpts
-        (import ../programs/alot-accounts.nix)
+        (import ../programs/alot-accounts.nix pkgs)
         (import ../programs/astroid-accounts.nix)
         (import ../programs/mbsync-accounts.nix)
         (import ../programs/msmtp-accounts.nix)

modules/programs/alot-accounts.nix

@@ -1,3 +1,4 @@
+pkgs:
 { config, lib, ... }:
 
 with lib;
@@ -13,6 +14,34 @@ with lib;
       '';
     };
 
+    contactCompletion = mkOption {
+      type = types.attrsOf types.str;
+      default = {
+        type = "shellcommand";
+        command = "'${pkgs.notmuch}/bin/notmuch address --format=json --output=recipients  date:6M..'";
+        regexp =
+          "'\[?{"
+          + ''"name": "(?P<name>.*)", ''
+          + ''"address": "(?P<email>.+)", ''
+          + ''"name-addr": ".*"''
+          + "}[,\]]?'";
+        shellcommand_external_filtering = "False";
+      };
+      example = literalExample ''
+        {
+          type = "shellcommand";
+          command = "abook --mutt-query";
+          regexp = "'^(?P<email>[^@]+@[^\t]+)\t+(?P<name>[^\t]+)'";
+          ignorecase = "True";
+        }
+      '';
+      description = ''
+       Contact completion configuration as expected per alot.
+       See <link xlink:href="http://alot.readthedocs.io/en/latest/configuration/contacts_completion.html">alot's wiki</link> for
+       explanation about possible values.
+      '';
+    };
+
     extraConfig = mkOption {
       type = types.lines;
       default = "";

modules/programs/alot.nix

@@ -33,6 +33,8 @@ let
             boolStr (signature.showSignature == "attach");
         }
       )
+      ++ [ "[[[abook]]]" ]
+      ++ mapAttrsToList (n: v: n + "=" + v) alot.contactCompletion
     )
     + "\n"
     + alot.extraConfig;