From 079d2226148b191d35aeaeff831ab49df0d7c1f0 Mon Sep 17 00:00:00 2001
From: Tim Van Baak <tim.vanbaak@gmail.com>
Date: Sun, 28 Jul 2024 20:09:17 -0700
Subject: [PATCH] Support bundling nixos configurations

---
 default.nix | 105 ++++++++++++++++++++++++++++++++--------------------
 flake.nix   |  12 ++++--
 2 files changed, 73 insertions(+), 44 deletions(-)

diff --git a/default.nix b/default.nix
index ba24632..8ebf9c8 100644
--- a/default.nix
+++ b/default.nix
@@ -3,8 +3,11 @@ let
   inherit (builtins)
     genericClosure
     hasAttr
+    head
     length
     map
+    match
+    tail
     ;
   inherit (pkgs) runCommandLocal writeText;
   inherit (pkgs.lib)
@@ -19,18 +22,32 @@ let
     ;
 in
 rec {
-  drvOutputs = drv: if hasAttr "outputs" drv then map (out: drv.${out}) drv.outputs else [ drv ];
+  # Map a drv or list of drvs to a list of output drvs
+  drvOutputs = drv:
+    if isList drv then
+      concatMap drvOutputs drv
+    else if hasAttr "outputs" drv then
+      map (out: drv.${out}) drv.outputs
+    else [ drv ];
+
+  # Map a drv or list of drvs to the outputs of referenced derivations
   drvDeps =
     drv:
-    mapAttrsToList (
-      k: v:
-      if isDerivation v then
-        (drvOutputs v)
-      else if isList v then
-        concatMap drvOutputs (filter isDerivation v)
-      else
-        [ ]
-    ) drv;
+    if isList drv then
+      concatMap drvDeps drv
+    else
+      mapAttrsToList (
+        k: v:
+        if isDerivation v then
+          (drvOutputs v)
+        else if isList v then
+          concatMap drvOutputs (filter isDerivation v)
+        else
+          [ ]
+      ) drv;
+
+  # Get the reference closure of a derivation or list of derivations
+  # This may miss dependencies that are only in-closure from string context
   drvClosure =
     let
       wrap = drv: {
@@ -43,50 +60,58 @@ rec {
       startSet = map wrap (drvOutputs drv);
       operator = obj: map wrap (concatLists (drvDeps obj.drv.drvAttrs));
     });
+
   maintainable = drv: hasAttr "meta" drv && hasAttr "maintainers" drv.meta;
   drvMaintainers = drv: if maintainable drv then drv.meta.maintainers else [ ];
-  nobodyMaintains =
-    drv: hasAttr "meta" drv && hasAttr "maintainers" drv.meta && (length drv.meta.maintainers) == 0;
+
+  # Construct a link to a derivation's source in github:NixOS/nixpkgs
+  drvSource = drv:
+  let
+    parts = match "/nix/store/[^/]+/(.*):([0-9]*)" drv.meta.position;
+  in
+  if hasAttr "meta" drv && hasAttr "position" drv.meta then
+    "https://github.com/NixOS/nixpkgs/blob/master/${head parts}#L${head (tail parts)}"
+  else
+    "";
+
+  mainInfo = drv: {
+    name = drv.name;
+    maintainers = map (main: toString main.github) (drvMaintainers drv);
+    source = drvSource drv;
+  };
+
   stringJoin = objToString: objs: writeText "txt" (concatLines (map objToString objs));
 
+  closureInfo = drv: map mainInfo (filter maintainable (drvClosure drv));
+
   allMaintainers =
     drv:
     let
-      closure = drvClosure drv;
-      maintainers = concatMap drvMaintainers closure;
-      mainToString = m: "${m.name} (${m.email})";
+      info = closureInfo drv;
+      infoToString = info: "${info.name} ${concatStringsSep "," info.maintainers}";
     in
-    runCommandLocal "uniq-maintainers.txt" { } ''
-      <${stringJoin mainToString maintainers} sort | uniq -c > $out
+    runCommandLocal "all-maintainers.txt" { } ''
+      <${stringJoin infoToString info} sort -u | ${pkgs.unixtools.column}/bin/column -t > $out
     '';
 
   noMaintainers =
     drv:
     let
-      closure = drvClosure drv;
-      unmaintained = filter nobodyMaintains closure;
-      drvToString = drv: "${drv.name} ${drv.meta.position}";
+      info = closureInfo drv;
+      unmaintained = filter (info: (length info.maintainers) == 0) info;
+      infoToString = info: "${info.name} ${info.source}";
     in
-    runCommandLocal "no-maintainers.txt" { } ''
-      <${stringJoin drvToString unmaintained} sort -u \
-        | sed 's/\/nix\/store\/[^/]*/https:\/\/github.com\/NixOS\/nixpkgs\/blob\/master/' \
-        | sed 's/.nix:\(.*\)$/.nix#L\1/' \
-        | ${pkgs.unixtools.column}/bin/column -t \
-        > $out
+    runCommandLocal "unmaintained.txt" { } ''
+      <${stringJoin infoToString unmaintained} sort -u | ${pkgs.unixtools.column}/bin/column -t > $out
     '';
 
-  listMaintainers =
-    drv:
-    let
-      closure = drvClosure drv;
-      maintainableDrvs = filter maintainable closure;
-      maintainersToString =
-        maintainers: concatStringsSep "," (map (main: toString main.github) maintainers);
-      drvToString = drv: "${drv.name} ${maintainersToString (drvMaintainers drv)}";
-    in
-    runCommandLocal "maintainers.txt" { } ''
-      <${stringJoin drvToString maintainableDrvs} sort -u \
-        | ${pkgs.unixtools.column}/bin/column -t \
-        > $out
-    '';
+  expandInput =
+    input:
+    if (input.class or null == "nixos") && (input._type or null == "configuration") then
+      [
+        input.config.system.build.toplevel
+        input.config.environment.systemPackages
+      ]
+    else
+      input;
 }
diff --git a/flake.nix b/flake.nix
index 8e8245f..bed8963 100644
--- a/flake.nix
+++ b/flake.nix
@@ -5,13 +5,17 @@
       system = "x86_64-linux";
       pkgs = nixpkgs.legacyPackages.${system};
       lib = import ./default.nix { inherit pkgs; };
+      inherit (lib)
+        allMaintainers
+        expandInput
+        noMaintainers
+        ;
     in
     {
       bundlers."x86_64-linux" = rec {
-        default = adopt;
-        maintainers = lib.allMaintainers;
-        adopt = lib.noMaintainers;
-        list = lib.listMaintainers;
+        default = unmaintained;
+        all = drv: allMaintainers (expandInput drv);
+        unmaintained = drv: noMaintainers (expandInput drv);
       };
 
       formatter."x86_64-linux" = pkgs.nixfmt-rfc-style;