factorio: use actual args instead of sample in download help

Makes it easier for the user since they should no longer have to
manually replace things. Remove the note about the name as it may no
longer be true, and the user now has to care less since the values are
more easily copy-pastable.

Author: amarshall

pkgs/by-name/fa/factorio/package.nix

@@ -40,46 +40,44 @@ let
 
   mods = args.mods or [ ];
 
-  helpMsg = ''
-
-    ===FETCH FAILED===
-    Please ensure you have set the username and token with config.nix, or
-    /etc/nix/nixpkgs-config.nix if on NixOS.
-
-    Your token can be seen at https://factorio.com/profile (after logging in). It is
-    not as sensitive as your password, but should still be safeguarded. There is a
-    link on that page to revoke/invalidate the token, if you believe it has been
-    leaked or wish to take precautions.
-
-    Example:
-    {
-      packageOverrides = pkgs: {
-        factorio = pkgs.factorio.override {
-          username = "FactorioPlayer1654";
-          token = "d5ad5a8971267c895c0da598688761";
+  helpMsg =
+    { dlName, storeName }:
+    ''
+
+      ===FETCH FAILED===
+      Please ensure you have set the username and token with config.nix, or
+      /etc/nix/nixpkgs-config.nix if on NixOS.
+
+      Your token can be seen at https://factorio.com/profile (after logging in). It is
+      not as sensitive as your password, but should still be safeguarded. There is a
+      link on that page to revoke/invalidate the token, if you believe it has been
+      leaked or wish to take precautions.
+
+      Example:
+      {
+        packageOverrides = pkgs: {
+          factorio = pkgs.factorio.override {
+            username = "FactorioPlayer1654";
+            token = "d5ad5a8971267c895c0da598688761";
+          };
         };
-      };
-    }
+      }
 
-    Alternatively, instead of providing the username+token, you may manually
-    download the release through https://factorio.com/download , then add it to
-    the store using e.g.:
+      Alternatively, instead of providing the username+token, you may manually
+      download the release through https://factorio.com/download , then add it to
+      the store using e.g.:
 
-      releaseType=alpha
-      version=0.17.74
-      nix-prefetch-url file://\''$HOME/Downloads/factorio_\''${releaseType}_x64_\''${version}.tar.xz --name factorio_\''${releaseType}_x64-\''${version}.tar.xz
+        nix-prefetch-url file://\''$HOME/Downloads/${dlName} --name ${storeName}
 
-    Note the ultimate "_" is replaced with "-" in the --name arg!
+      If you go this route you might want to tell Nix to explicitly hold on to the
+      source tarball. Otherwise it could get GC'd from the Nix store and you'd
+      have to redownload it next time the package wants to rebuild to use a newer
+      dependency. E.g. if you're using NixOS:
 
-    If you go this route you might want to tell Nix to explicitly hold on to the
-    source tarball. Otherwise it could get GC'd from the Nix store and you'd
-    have to redownload it next time the package wants to rebuild to use a newer
-    dependency. E.g. if you're using NixOS:
-
-      system.extraDependencies = [
-        factorio.src
-      ];
-  '';
+        system.extraDependencies = [
+          factorio.src
+        ];
+    '';
 
   desktopItem = makeDesktopItem {
     name = "factorio";
@@ -155,7 +153,10 @@ let
                   '';
               failureHook = ''
                 cat <<EOF
-                ${helpMsg}
+                ${helpMsg {
+                  dlName = if candidateHashFilenames != [ ] then builtins.head candidateHashFilenames else name;
+                  storeName = name;
+                }}
                 EOF
               '';
             })