redshift-gammastep: support reading latitude and longitude from files

Support reading latitude and longitude from files, which is useful for
reading the values from decrypted runtime files.

The new strNotFloat type catches deprecated str types used for the
latitude and longitude options.

The systemd ExecStart command points to a wrapper script for subshell
invocations.

modules/services/redshift-gammastep/lib/options.nix

@@ -28,7 +28,17 @@ in {
     (mkRenamed [ "brightness" "night" ] "brightness-night")
   ];
 
-  options = {
+  options = let
+    strNotFloat = (pattern:
+      lib.mkOptionType {
+        inherit (lib.types.str) merge;
+
+        check = x: lib.types.str.check x && builtins.match pattern x == null;
+        description = "string not matching the pattern ${pattern}";
+        descriptionClass = "noun";
+        name = "strNotMatching ${lib.strings.escapeNixString pattern}";
+      }) "^-?[0-9]+\\.[0-9]+$";
+  in {
     enable = mkEnableOption programName;
 
     dawnTime = mkOption {
@@ -52,22 +62,30 @@ in {
     };
 
     latitude = mkOption {
-      type = with types; nullOr (either str float);
+      type = with types; nullOr (either float strNotFloat);
       default = null;
       description = ''
         Your current latitude, between `-90.0` and
         `90.0`. Must be provided along with
         longitude.
+
+        Specifying a string retrieves the latitude using the `"$(<
+        "''${config.services.${moduleName}.latitude}")"` command at runtime,
+        which is useful for reading the value from a decrypted runtime file.
       '';
     };
 
     longitude = mkOption {
-      type = with types; nullOr (either str float);
+      type = with types; nullOr (either float strNotFloat);
       default = null;
       description = ''
         Your current longitude, between `-180.0` and
         `180.0`. Must be provided along with
         latitude.
+
+        Specifying a string retrieves the longitude using the `"$(<
+        "''${config.services.${moduleName}.longitude}")"` command at runtime,
+        which is useful for reading the value from a decrypted runtime file.
       '';
     };
 
@@ -152,7 +170,7 @@ in {
           ? ${mainSection}.dusk-time)
           || (cfg.settings.${mainSection}.location-provider) == "geoclue2"
           || ((cfg.settings.${mainSection}.location-provider) == "manual"
-            && (cfg.settings ? manual.lat || cfg.settings ? manual.lon));
+            && (cfg.latitude != null || cfg.longitude != null));
         message = ''
           In order for ${programName} to know the time of action, you need to set one of
             - services.${moduleName}.provider = "geoclue2" for automatically inferring your location
@@ -171,10 +189,6 @@ in {
         dawn-time = mkIf (cfg.dawnTime != null) cfg.dawnTime;
         dusk-time = mkIf (cfg.duskTime != null) cfg.duskTime;
       };
-      manual = mkIf (cfg.provider == "manual") {
-        lat = mkIf (cfg.latitude != null) (toString cfg.latitude);
-        lon = mkIf (cfg.longitude != null) (toString cfg.longitude);
-      };
     };
 
     xdg.configFile.${xdgConfigFilePath}.source =
@@ -200,10 +214,30 @@ in {
         ExecStart = let
           command = if cfg.tray then appletExecutable else mainExecutable;
           configFullPath = config.xdg.configHome + "/${xdgConfigFilePath}";
-        in "${cfg.package}/bin/${command} " + cli.toGNUCommandLineShell { } {
-          v = cfg.enableVerboseLogging;
-          c = configFullPath;
-        };
+        in pkgs.writeShellScript moduleName ''
+          ${cfg.package}/bin/${command} ${
+            cli.toGNUCommandLineShell { } {
+              v = cfg.enableVerboseLogging;
+              c = configFullPath;
+            }
+          } ${
+            optionalString (cfg.provider == "manual"
+              && (cfg.latitude != null || cfg.longitude != null)) ''
+                -l "${
+                  optionalString (cfg.latitude != null)
+                  (if builtins.isFloat cfg.latitude then
+                    toString cfg.latitude
+                  else
+                    ''$(< "${cfg.latitude}")'')
+                }:${
+                  optionalString (cfg.latitude != null)
+                  (if builtins.isFloat cfg.longitude then
+                    toString cfg.longitude
+                  else
+                    ''$(< "${cfg.longitude}")'')
+                }"''
+          }
+        '';
         RestartSec = 3;
         Restart = "on-failure";
       };

tests/modules/services/redshift-gammastep/gammastep-basic-configuration-expected.service

@@ -2,7 +2,7 @@
 WantedBy=graphical-session.target
 
 [Service]
-ExecStart=@gammastep@/bin/gammastep -c /home/hm-user/.config/gammastep/config.ini
+ExecStart=@gammastep@
 Restart=on-failure
 RestartSec=3
 

tests/modules/services/redshift-gammastep/gammastep-basic-configuration-file-expected.conf

@@ -7,7 +7,5 @@ location-provider=manual
 temp-day=5500
 temp-night=3700
 
-[manual]
-
 [randr]
 screen=0

tests/modules/services/redshift-gammastep/redshift-basic-configuration-expected.service

@@ -2,7 +2,7 @@
 WantedBy=graphical-session.target
 
 [Service]
-ExecStart=@redshift@/bin/redshift -c /home/hm-user/.config/redshift/redshift.conf
+ExecStart=@redshift@
 Restart=on-failure
 RestartSec=3
 

tests/modules/services/redshift-gammastep/redshift-basic-configuration-file-expected.conf

@@ -1,7 +1,3 @@
-[manual]
-lat=0.000000
-lon=0.0
-
 [randr]
 screen=0
 

tests/modules/services/redshift-gammastep/redshift-basic-configuration.nix

@@ -6,7 +6,7 @@
       enable = true;
       provider = "manual";
       latitude = 0.0;
-      longitude = "0.0";
+      longitude = "$XDG_RUNTIME_DIR/longitude";
       settings = {
         redshift = {
           adjustment-method = "randr";
@@ -19,6 +19,9 @@
     test.stubs.redshift = { };
 
     nmt.script = ''
+      export XDG_RUNTIME_DIR="$(mktemp --directory)"
+      echo 0.0 > "$XDG_RUNTIME_DIR/longitude"
+
       assertFileContent \
           home-files/.config/redshift/redshift.conf \
           ${./redshift-basic-configuration-file-expected.conf}