From 3db43afcb4a755221530ff821ec4ac30eca77033 Mon Sep 17 00:00:00 2001
From: Robert Helgesson <robert@rycee.net>
Date: Sat, 29 Jul 2023 19:56:00 +0200
Subject: [PATCH] home-manager: rework news command

This new way of handling news should also work in Nix Flake setups.
---
 home-manager/build-news.nix      |  54 +++++++++++++++
 home-manager/home-manager        | 111 +++++++++++++++++++------------
 home-manager/home-manager.nix    |  58 +---------------
 home-manager/po/home-manager.pot |  47 ++++++-------
 modules/misc/news.nix            |  12 ++++
 modules/po/hm-modules.pot        |   6 +-
 6 files changed, 158 insertions(+), 130 deletions(-)
 create mode 100644 home-manager/build-news.nix

diff --git a/home-manager/build-news.nix b/home-manager/build-news.nix
new file mode 100644
index 000000000..251f56ae4
--- /dev/null
+++ b/home-manager/build-news.nix
@@ -0,0 +1,54 @@
+# Used by the home-manager tool to present news to the user. The content of this
+# file is considered internal and the exported fields may change without
+# warning.
+
+{ newsJsonFile, newsReadIdsFile ? null }:
+
+let
+  inherit (builtins)
+    concatStringsSep filter hasAttr isString length optionalString readFile
+    replaceStrings sort split;
+
+  newsJson = builtins.fromJSON (builtins.readFile newsJsonFile);
+
+  # Sorted and relevant entries.
+  relevantEntries =
+    sort (a: b: a.time > b.time) (filter (e: e.condition) newsJson.entries);
+
+  newsReadIds = if newsReadIdsFile == null then
+    { }
+  else
+    let ids = filter isString (split "\n" (readFile newsReadIdsFile));
+    in builtins.listToAttrs (map (id: {
+      name = id;
+      value = null;
+    }) ids);
+
+  newsIsRead = entry: hasAttr entry.id newsReadIds;
+
+  newsUnread = let pred = entry: entry.condition && !newsIsRead entry;
+  in filter pred relevantEntries;
+
+  prettyTime = t: replaceStrings [ "T" "+00:00" ] [ " " "" ] t;
+
+  layoutNews = entries:
+    let
+      mkTextEntry = entry:
+        let flag = if newsIsRead entry then "read" else "unread";
+        in ''
+          * ${prettyTime entry.time} [${flag}]
+
+            ${replaceStrings [ "\n" ] [ "\n  " ] entry.message}
+        '';
+    in concatStringsSep "\n\n" (map mkTextEntry entries);
+in {
+  meta = {
+    numUnread = length newsUnread;
+    display = newsJson.display;
+    ids = concatStringsSep "\n" (map (e: e.id) newsJson.entries);
+  };
+  news = {
+    all = layoutNews relevantEntries;
+    unread = layoutNews newsUnread;
+  };
+}
diff --git a/home-manager/home-manager b/home-manager/home-manager
index ea8546781..f02a2ce19 100644
--- a/home-manager/home-manager
+++ b/home-manager/home-manager
@@ -529,13 +529,16 @@ function doBuildFlake() {
         "${PASSTHROUGH_OPTS[@]}"
 }
 
-# Presents news to the user. Takes as argument the path to a "news
-# info" file as generated by `buildNews`.
+# Presents news to the user as specified by the `news.display` option.
 function presentNews() {
-    local infoFile="$1"
+    local newsNixFile="$WORK_DIR/news.nix"
+    buildNews "$newsNixFile"
 
-    # shellcheck source=/dev/null
-    . "$infoFile"
+    local newsDisplay
+    newsDisplay="$(nix-instantiate --eval --expr "(import ${newsNixFile}).meta.display" | xargs)"
+
+    local newsNumUnread
+    newsNumUnread="$(nix-instantiate --eval --expr "(import ${newsNixFile}).meta.numUnread" | xargs)"
 
     # shellcheck disable=2154
     if [[ $newsNumUnread -eq 0 ]]; then
@@ -601,12 +604,9 @@ function doBuild() {
             ${NO_OUT_LINK+--no-out-link} \
             --attr activationPackage \
         || return
-
-        local newsInfo
-        newsInfo=$(buildNews)
-
-        presentNews "$newsInfo"
     fi
+
+    presentNews
 }
 
 function doSwitch() {
@@ -632,12 +632,9 @@ function doSwitch() {
             --out-link "$generation" \
             --attr activationPackage \
             && "$generation/activate" || return
-
-        local newsInfo
-        newsInfo=$(buildNews)
-
-        presentNews "$newsInfo"
     fi
+
+    presentNews
 }
 
 function doListGens() {
@@ -718,62 +715,88 @@ function newsReadIdsFile() {
     echo "$path"
 }
 
-# Builds news meta information to be sourced into this script.
+# Builds the Home Manager news data file.
 #
 # Note, we suppress build output to remove unnecessary verbosity. We
 # put the output in the work directory to avoid the risk of an
 # unfortunately timed GC removing it.
 function buildNews() {
-    setFlakeAttribute
+    local newsNixFile="$1"
+    local newsJsonFile="$WORK_DIR/news.json"
+
     if [[ -v FLAKE_CONFIG_URI ]]; then
-        # translators: Here "flake" is a noun that refers to the Nix Flakes feature.
-        _iError "Sorry, this command is not yet supported in flake setup" >&2
-        exit 1
+        # TODO: Use check=false to make it more likely that the build succeeds.
+        doBuildFlake \
+            "$FLAKE_CONFIG_URI.config.news.json.output" \
+            --quiet \
+            --out-link "$newsJsonFile" \
+            || return
+    else
+        doBuildAttr \
+            --out-link "$newsJsonFile" \
+            --arg check false \
+            --attr config.news.json.output \
+            > /dev/null \
+        || return
     fi
 
-    local output
-    output="$WORK_DIR/news-info.sh"
+    local extraArgs=()
 
-    doBuildAttr \
-        --out-link "$output" \
-        --no-build-output \
-        --quiet \
-        --arg check false \
-        --argstr newsReadIdsFile "$(newsReadIdsFile)" \
-        --attr newsInfo \
-        > /dev/null
+    for p in "${EXTRA_NIX_PATH[@]}"; do
+        extraArgs=("${extraArgs[@]}" "-I" "$p")
+    done
 
-    echo "$output"
+    local readIdsFile
+    readIdsFile=$(newsReadIdsFile)
+
+    nix-instantiate \
+        --no-build-output --strict \
+        --eval '<home-manager/home-manager/build-news.nix>' \
+        --arg newsJsonFile "$newsJsonFile" \
+        --arg newsReadIdsFile "$readIdsFile" \
+        "${extraArgs[@]}" \
+        > "$newsNixFile"
 }
 
 function doShowNews() {
     setWorkDir
+    setFlakeAttribute
 
-    local infoFile
-    infoFile=$(buildNews) || return 1
+    local newsNixFile="$WORK_DIR/news.nix"
+    buildNews "$newsNixFile"
 
-    # shellcheck source=/dev/null
-    . "$infoFile"
+    local readIdsFile
+    readIdsFile=$(newsReadIdsFile)
 
-    # shellcheck disable=2154
+    local news
+
+    # shellcheck disable=2154,2046
     case $1 in
         --all)
-            ${PAGER:-less} "$newsFileAll"
+            news="$(nix-instantiate --quiet --eval --expr "(import ${newsNixFile}).news.all")"
             ;;
         --unread)
-            ${PAGER:-less} "$newsFileUnread"
+            news="$(nix-instantiate --quiet --eval --expr "(import ${newsNixFile}).news.unread")"
             ;;
         *)
             _i 'Unknown argument %s' "$1"
             return 1
     esac
 
-    # shellcheck disable=2154
-    if [[ -s "$newsUnreadIdsFile" ]]; then
-        local newsReadIdsFile
-        newsReadIdsFile="$(newsReadIdsFile)"
-        cat "$newsUnreadIdsFile" >> "$newsReadIdsFile"
-    fi
+    # Prints the news without surrounding quotes.
+    echo -e "${news:1:-1}" | ${PAGER:-less}
+
+    local allIds
+    allIds="$(nix-instantiate --quiet --eval --expr "(import ${newsNixFile}).meta.ids")"
+    allIds="${allIds:1:-1}"    # Trim surrounding quotes.
+
+    local readIdsFileNew="$WORK_DIR/news-read-ids.new"
+    {
+      cat "$readIdsFile"
+      echo -e "$allIds"
+    } | sort | uniq > "$readIdsFileNew"
+
+    mv -f "$readIdsFileNew" "$readIdsFile"
 }
 
 function doUninstall() {
diff --git a/home-manager/home-manager.nix b/home-manager/home-manager.nix
index 6f2f4b667..13a638fd8 100644
--- a/home-manager/home-manager.nix
+++ b/home-manager/home-manager.nix
@@ -15,60 +15,4 @@ let
     check = check;
   };
 
-  newsReadIds = if newsReadIdsFile == null then
-    { }
-  else
-    let ids = splitString "\n" (fileContents newsReadIdsFile);
-    in builtins.listToAttrs (map (id: {
-      name = id;
-      value = null;
-    }) ids);
-
-  newsIsRead = entry: builtins.hasAttr entry.id newsReadIds;
-
-  newsFiltered = let pred = entry: entry.condition && !newsIsRead entry;
-  in filter pred env.newsEntries;
-
-  newsNumUnread = length newsFiltered;
-
-  newsFileUnread = pkgs.writeText "news-unread.txt" (concatMapStringsSep "\n\n"
-    (entry:
-      let
-        time =
-          replaceStrings [ "T" ] [ " " ] (removeSuffix "+00:00" entry.time);
-      in ''
-        * ${time}
-
-          ${replaceStrings [ "\n" ] [ "\n  " ] entry.message}
-      '') newsFiltered);
-
-  newsFileAll = pkgs.writeText "news-all.txt" (concatMapStringsSep "\n\n"
-    (entry:
-      let
-        flag = if newsIsRead entry then "read" else "unread";
-        time =
-          replaceStrings [ "T" ] [ " " ] (removeSuffix "+00:00" entry.time);
-      in ''
-        * ${time} [${flag}]
-
-          ${replaceStrings [ "\n" ] [ "\n  " ] entry.message}
-      '') env.newsEntries);
-
-  # File where each line corresponds to an unread news entry
-  # identifier. If non-empty then the file ends in "\n".
-  newsUnreadIdsFile = pkgs.writeText "news-unread-ids"
-    (let text = concatMapStringsSep "\n" (entry: entry.id) newsFiltered;
-    in text + optionalString (text != "") "\n");
-
-  newsInfo = pkgs.writeText "news-info.sh" ''
-    local newsNumUnread=${toString newsNumUnread}
-    local newsDisplay="${env.newsDisplay}"
-    local newsFileAll="${newsFileAll}"
-    local newsFileUnread="${newsFileUnread}"
-    local newsUnreadIdsFile="${newsUnreadIdsFile}"
-  '';
-
-in {
-  inherit (env) activationPackage;
-  inherit newsInfo;
-}
+in { inherit (env) activationPackage config; }
diff --git a/home-manager/po/home-manager.pot b/home-manager/po/home-manager.pot
index 2260e4e7d..df8aaf283 100644
--- a/home-manager/po/home-manager.pot
+++ b/home-manager/po/home-manager.pot
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: Home Manager\n"
 "Report-Msgid-Bugs-To: https://github.com/nix-community/home-manager/issues\n"
-"POT-Creation-Date: 2023-07-16 10:09+0200\n"
+"POT-Creation-Date: 2023-07-30 09:08+0200\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -78,11 +78,11 @@ msgid "Can't inspect options of a flake configuration"
 msgstr ""
 
 #: home-manager/home-manager:281 home-manager/home-manager:304
-#: home-manager/home-manager:1000
+#: home-manager/home-manager:1023
 msgid "%s: unknown option '%s'"
 msgstr ""
 
-#: home-manager/home-manager:286 home-manager/home-manager:1001
+#: home-manager/home-manager:286 home-manager/home-manager:1024
 msgid "Run '%s --help' for usage help"
 msgstr ""
 
@@ -124,7 +124,7 @@ msgstr ""
 msgid "Can't instantiate a flake configuration"
 msgstr ""
 
-#: home-manager/home-manager:549
+#: home-manager/home-manager:552
 msgid ""
 "There is %d unread and relevant news item.\n"
 "Read it by running the command \"%s news\"."
@@ -134,77 +134,72 @@ msgid_plural ""
 msgstr[0] ""
 msgstr[1] ""
 
-#: home-manager/home-manager:563
+#: home-manager/home-manager:566
 msgid "Unknown \"news.display\" setting \"%s\"."
 msgstr ""
 
-#: home-manager/home-manager:570
+#: home-manager/home-manager:573
 #, sh-format
 msgid "Please set the $EDITOR environment variable"
 msgstr ""
 
-#: home-manager/home-manager:585
+#: home-manager/home-manager:588
 msgid "Cannot run build in read-only directory"
 msgstr ""
 
-#: home-manager/home-manager:669
+#: home-manager/home-manager:666
 msgid "No generation with ID %s"
 msgstr ""
 
-#: home-manager/home-manager:671
+#: home-manager/home-manager:668
 msgid "Cannot remove the current generation %s"
 msgstr ""
 
-#: home-manager/home-manager:673
+#: home-manager/home-manager:670
 msgid "Removing generation %s"
 msgstr ""
 
-#: home-manager/home-manager:692
+#: home-manager/home-manager:689
 msgid "No generations to expire"
 msgstr ""
 
-#: home-manager/home-manager:703
+#: home-manager/home-manager:700
 msgid "No home-manager packages seem to be installed."
 msgstr ""
 
-#. translators: Here "flake" is a noun that refers to the Nix Flakes feature.
-#: home-manager/home-manager:730
-msgid "Sorry, this command is not yet supported in flake setup"
-msgstr ""
-
-#: home-manager/home-manager:767
+#: home-manager/home-manager:781
 msgid "Unknown argument %s"
 msgstr ""
 
-#: home-manager/home-manager:783
+#: home-manager/home-manager:805
 msgid "This will remove Home Manager from your system."
 msgstr ""
 
-#: home-manager/home-manager:786
+#: home-manager/home-manager:808
 msgid "This is a dry run, nothing will actually be uninstalled."
 msgstr ""
 
-#: home-manager/home-manager:790
+#: home-manager/home-manager:812
 msgid "Really uninstall Home Manager?"
 msgstr ""
 
-#: home-manager/home-manager:796
+#: home-manager/home-manager:818
 msgid "Switching to empty Home Manager configuration..."
 msgstr ""
 
-#: home-manager/home-manager:823
+#: home-manager/home-manager:846
 msgid "Yay!"
 msgstr ""
 
-#: home-manager/home-manager:828
+#: home-manager/home-manager:851
 msgid "Home Manager is uninstalled but your home.nix is left untouched."
 msgstr ""
 
-#: home-manager/home-manager:1040
+#: home-manager/home-manager:1063
 msgid "expire-generations expects one argument, got %d."
 msgstr ""
 
-#: home-manager/home-manager:1062
+#: home-manager/home-manager:1085
 msgid "Unknown command: %s"
 msgstr ""
 
diff --git a/modules/misc/news.nix b/modules/misc/news.nix
index 61d186da0..0538d767b 100644
--- a/modules/misc/news.nix
+++ b/modules/misc/news.nix
@@ -85,10 +85,22 @@ in
         default = [ ];
         description = "News entries.";
       };
+
+      json = {
+        output = mkOption {
+          internal = true;
+          type = types.package;
+          description = "The generated JSON file package.";
+        };
+      };
     };
   };
 
   config = {
+    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
diff --git a/modules/po/hm-modules.pot b/modules/po/hm-modules.pot
index 2b4030b6c..8fdef9e6e 100644
--- a/modules/po/hm-modules.pot
+++ b/modules/po/hm-modules.pot
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: Home Manager Modules\n"
 "Report-Msgid-Bugs-To: https://github.com/nix-community/home-manager/issues\n"
-"POT-Creation-Date: 2023-07-16 10:09+0200\n"
+"POT-Creation-Date: 2023-07-30 09:08+0200\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -33,7 +33,7 @@ msgstr ""
 msgid "No change so reusing latest profile generation %s"
 msgstr ""
 
-#: modules/home-environment.nix:634
+#: modules/home-environment.nix:626
 msgid ""
 "Oops, Nix failed to install your new Home Manager profile!\n"
 "\n"
@@ -49,7 +49,7 @@ msgid ""
 "Then try activating your Home Manager configuration again."
 msgstr ""
 
-#: modules/home-environment.nix:667
+#: modules/home-environment.nix:659
 msgid "Activating %s"
 msgstr ""