news: create an individual file for each news entry (#6747)

The current way to define a news entry in Home-Manager is error prone
(since you need to type the date manually) and also it is common cause
of conflicts after merges because all entries are defined in the same
file.

This commit fixes this: we can now create individual news entries for
each new entry. A script `create-news-entry.sh` also helps to create it
in the correct format (with the correct filenames and structure).

modules/misc/news.nix

@@ -45,6 +45,13 @@ let
       id = lib.mkDefault (builtins.hashString "sha256" config.message);
     };
   });
+
+  isNixFile = n: v: v == "regular" && lib.hasSuffix ".nix" n;
+  # builtins.attrNames return the values in alphabetical order
+  newsFiles =
+    builtins.attrNames (lib.filterAttrs isNixFile (builtins.readDir ./news));
+  newsEntries =
+    builtins.map (newsFile: import (./news + "/${newsFile}")) newsFiles;
 in {
   meta.maintainers = [ lib.maintainers.rycee ];
 
@@ -96,15 +103,8 @@ in {
     news.json.output = pkgs.writeText "hm-news.json"
       (builtins.toJSON { inherit (cfg) display entries; });
 
-    # Add news entries in chronological order (i.e., latest time
-    # should be at the bottom of the list). The time should be
-    # formatted as given in the output of
-    #
-    #     date --iso-8601=second --universal
-    #
-    # On darwin (or BSD like systems) use
-    #
-    #     date -u +'%Y-%m-%dT%H:%M:%S+00:00'
+    # DO NOT define new entries here, instead use the `./create-news-entry.sh`
+    # script and create an individual news file inside `news` sub-directory.
     news.entries = [
       {
         time = "2021-06-02T04:24:10+00:00";
@@ -2231,6 +2231,6 @@ in {
           See https://github.com/ivaaaan/smug for more information.
         '';
       }
-    ];
+    ] ++ newsEntries;
   };
 }

modules/misc/news/2025-04-02_13-01-34.nix

@@ -0,0 +1,10 @@
+{
+  time = "2025-04-02T13:01:34+00:00";
+  condition = true;
+  message = ''
+    A new way to define news is available.
+
+    Instead of editing the previous news.nix file, you can now define entries
+    using individual files. This should reduce the number of merge conflicts.
+  '';
+}

modules/misc/news/create-news-entry.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env nix-shell
+#! nix-shell -I https://github.com/NixOS/nixpkgs/archive/05f0934825c2a0750d4888c4735f9420c906b388.tar.gz -i bash -p coreutils
+
+DATE="$(date --iso-8601=second --universal)"
+FILENAME="$(date --date="$DATE" +"%Y-%m-%d_%H-%M-%S").nix"
+DIRNAME="$(dirname -- "${BASH_SOURCE[0]}")"
+
+cd "$DIRNAME" || {
+  >&2 echo "Failed to change to the script directory: $DIRNAME"
+  exit 1
+}
+
+cat - << EOF > "$FILENAME"
+{
+  time = "$DATE";
+  condition = true;
+  message = ''
+    PLACEHOLDER
+  '';
+}
+EOF
+
+echo "Successfully created a news file: $DIRNAME/$FILENAME"
+echo "You can open the file above in your text editor and edit now."