From 2396dae9a653591fd820153688d39119e81daf74 Mon Sep 17 00:00:00 2001
From: h7x4 <h7x4@nani.wtf>
Date: Tue, 8 Apr 2025 14:36:55 +0200
Subject: [PATCH] filterOverrides: init

---
 flake.nix               |  9 ++---
 src/filterOverrides.nix | 73 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+), 4 deletions(-)
 create mode 100644 src/filterOverrides.nix

diff --git a/flake.nix b/flake.nix
index ac9f9e4..8ea6191 100644
--- a/flake.nix
+++ b/flake.nix
@@ -10,13 +10,14 @@
   in {
     inherit util;
 
+    collect = import ./src/collect.nix lib;
+    filterAttrs = import ./src/filterAttrs.nix lib;
+    filterOverrides = import ./src/filterOverrides.nix lib;
+    findFirstIndex = import ./src/findFirstIndex.nix lib;
     genAttrs = import ./src/genAttrs.nix lib;
     getAttrs = import ./src/getAttrs.nix lib;
+    overrideExisting = import ./src/overrideExisting.nix lib;
     subtractLists = import ./src/subtractLists.nix lib;
     unique = import ./src/unique.nix lib;
-    overrideExisting = import ./src/overrideExisting.nix lib;
-    findFirstIndex = import ./src/findFirstIndex.nix lib;
-    filterAttrs = import ./src/filterAttrs.nix lib;
-    collect = import ./src/collect.nix lib;
   };
 }
diff --git a/src/filterOverrides.nix b/src/filterOverrides.nix
new file mode 100644
index 0000000..a7e9590
--- /dev/null
+++ b/src/filterOverrides.nix
@@ -0,0 +1,73 @@
+lib:
+with lib;
+let
+  defaultOverridePriority = 100;
+
+  /**
+    Given a list of config values, process the mkOverride properties,
+    that is, return the values that have the highest (that is,
+    numerically lowest) priority, and strip the mkOverride
+    properties.  For example,
+
+      [ { file = "/1"; value = mkOverride 10 "a"; }
+        { file = "/2"; value = mkOverride 20 "b"; }
+        { file = "/3"; value = "z"; }
+        { file = "/4"; value = mkOverride 10 "d"; }
+      ]
+
+    yields
+
+      [ { file = "/1"; value = "a"; }
+        { file = "/4"; value = "d"; }
+      ]
+
+    Note that "z" has the default priority 100.
+
+    # Inputs
+
+    `defs`
+
+    : 1\. Function argument
+  */
+  filterOverridesOld = let
+    filterOverrides' =
+      defs:
+      let
+        getPrio =
+          def: if def.value._type or "" == "override" then def.value.priority else defaultOverridePriority;
+        highestPrio = foldl' (prio: def: min (getPrio def) prio) 9999 defs;
+        strip =
+          def: if def.value._type or "" == "override" then def // { value = def.value.content; } else def;
+      in
+      {
+        values = concatMap (def: if getPrio def == highestPrio then [ (strip def) ] else [ ]) defs;
+        inherit highestPrio;
+      };
+  in defs: (filterOverrides' defs).values;
+
+  filterOverridesNew = let
+    filterOverrides' =
+      defs:
+      let
+        normalizedList = map (def: if def.value._type or null == "override" then {
+          prio = def.value.priority;
+          ${toString def.value.priority} = def.value.content;
+        } else {
+          prio = defaultOverridePriority;
+          ${toString defaultOverridePriority} = def.value;
+        }) defs;
+
+        highestPriority = foldl' min 9999 (catAttrs "prio" normalizedList);
+      in
+      {
+        values = catAttrs (toString highestPriority) normalizedList;
+        inherit highestPriority;
+      };
+  in defs: (filterOverrides' defs).values;
+
+  bigdata = (builtins.genList (x: { file = "asdf"; value = mkOverride x (toString x); }) 999)
+         ++ (builtins.genList (x: { file = "qwerty"; value = toString x; }) 999);
+in {
+  old = filterOverridesOld bigdata;
+  new = filterOverridesNew bigdata;
+}