mu: add module

.github/CODEOWNERS

@@ -83,6 +83,8 @@
 
 /modules/programs/mpv.nix                             @tadeokondrak
 
+/modules/programs/mu.nix                              @KarlJoad
+
 /modules/programs/ncmpcpp.nix                         @olmokramer
 /tests/modules/programs/ncmpcpp                       @olmokramer
 /tests/modules/programs/ncmpcpp-linux                 @olmokramer

modules/misc/news.nix

@@ -1680,6 +1680,13 @@ in
           A new module is available: 'programs.pet'.
         '';
       }
+
+      {
+        time = "2020-09-29T21:21:44+00:00";
+        message = ''
+          A new module is available: 'programs.mu'.
+        '';
+      }
     ];
   };
 }

modules/modules.nix

@@ -90,6 +90,7 @@ let
     (loadModule ./programs/mercurial.nix { })
     (loadModule ./programs/mpv.nix { })
     (loadModule ./programs/msmtp.nix { })
+    (loadModule ./programs/mu.nix { })
     (loadModule ./programs/ncmpcpp.nix { })
     (loadModule ./programs/ne.nix { })
     (loadModule ./programs/neomutt.nix { })

modules/programs/mu.nix

@@ -0,0 +1,57 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  cfg = config.programs.mu;
+
+  # Used to generate command line arguments that mu can operate with.
+  genCmdMaildir = path: "--maildir=" + path;
+
+  # Takes the list of accounts with mu.enable = true, and generates a
+  # command-line flag for initializing the mu database.
+  myAddresses = let
+    # List of account sets where mu.enable = true.
+    muAccounts =
+      filter (a: a.mu.enable) (attrValues config.accounts.email.accounts);
+    addrs = map (a: a.address) muAccounts;
+    # Prefix --my-address= to each account's address with mu.enable.
+    addMyAddress = map (addr: "--my-address=" + addr) addrs;
+  in concatStringsSep " " addMyAddress;
+
+in {
+  meta.maintainers = [ maintainers.KarlJoad ];
+
+  options = {
+    programs.mu = {
+      enable = mkEnableOption "mu, a maildir indexer and searcher";
+
+      # No options/config file present for mu, and program author will not be
+      # adding one soon. See https://github.com/djcb/mu/issues/882 for more
+      # information about this.
+    };
+
+    accounts.email.accounts = mkOption {
+      type = with types;
+        attrsOf
+        (submodule { options.mu.enable = mkEnableOption "mu indexing"; });
+    };
+  };
+
+  config = mkIf cfg.enable {
+    home.packages = [ pkgs.mu ];
+
+    home.activation.runMuInit = let
+      maildirOption = genCmdMaildir config.accounts.email.maildirBasePath;
+      dbLocation = config.xdg.cacheHome + "/mu";
+    in hm.dag.entryAfter [ "writeBoundary" ] ''
+      # If the database directory exists, then `mu init` should NOT be run.
+      # In theory, mu is the only thing that creates that directory, and it is
+      # only created during the initial index.
+      if [[ ! -d "${dbLocation}" ]]; then
+        $DRY_RUN_CMD mu init ${maildirOption} $VERBOSE_ARG;
+      fi
+    '';
+  };
+}