Allow building current code with flake

flake.nix

@@ -17,17 +17,12 @@
     // flake-utils.lib.eachDefaultSystem (
       system:
       let
-        pkgs = import nixpkgs {
-          inherit system;
-          config = {
-            allowAliases = false;
-          };
-          overlays = [ self.overlays.default ];
-        };
-      in
-      {
-        # check that copyparty builds with all optionals turned on
-        checks.copyparty-full = self.packages.${system}.copyparty.override {
+        lib = import "${nixpkgs}/lib";
+        inherit (self) lastModifiedDate;
+        year = lib.toIntBase10 (builtins.substring 0 4 lastModifiedDate);
+        month = lib.toIntBase10 (builtins.substring 4 2 lastModifiedDate);
+        day = lib.toIntBase10 (builtins.substring 6 2 lastModifiedDate);
+        fullAttrs = {
           withHashedPasswords = true;
           withCertgen = true;
           withThumbnails = true;
@@ -38,10 +33,45 @@
           withFTPS = true;
           withSMB = true;
         };
+        pkgs = import nixpkgs {
+          inherit system;
+          config = {
+            allowAliases = false;
+          };
+          overlays = [ self.overlays.default ] ++ lib.singleton (final: prev: {
+            # This is here in flake.nix rather than common/packages/nix because it needs to access the flake metadata to get the date of the most recent commit (lastModifiedDate)
+            copyparty-unstable = final.copyparty.overrideAttrs (finalAttrs: previousAttrs: {
+              version = "${previousAttrs.version}-unstable-${self.lastModifiedDate}";
+              src = self;
+              postPatch = ''
+                old_src="$(mktemp -d)"
+                tar -C "$old_src" -xvf ${previousAttrs.src}
+                cp -r "$old_src"/*/copyparty/web/deps/* copyparty/web/deps
+                sed -i 's/^BUILD_DT =.*$/BUILD_DT = (${toString year}, ${toString month}, ${toString day})/' copyparty/__version__.py
+                sed -i 's/^CODENAME =.*$/CODENAME = "unstable"/' copyparty/__version__.py
+              '';
+            });
+
+            copyparty-full = final.copyparty.overrideAttrs fullAttrs;
+            copyparty-unstable-full = final.copyparty-unstable.overrideAttrs fullAttrs;
+          });
+        };
+      in
+      {
+        # check that copyparty builds with all optionals turned on
+        checks = {
+          inherit (pkgs)
+            copyparty-full
+            copyparty-unstable-full
+            ;
+        };
 
         packages = {
           inherit (pkgs)
             copyparty
+            copyparty-full
+            copyparty-unstable
+            copyparty-unstable-full
             ;
           default = self.packages.${system}.copyparty;
         };