migrate flake to uv2nix

this is a really experimental project that's getting a ton of changes
every day, so I'll have to keep an eye on things. Should work for now
though :-)

packaging/flake.nix

@@ -1,46 +1,58 @@
 {
   description = "Python program to show your google calendar next meeting";
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
 
-  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
-  inputs.flake-utils.url = "github:numtide/flake-utils";
-  inputs.poetry2nix = {
-    url = "github:nix-community/poetry2nix";
-    inputs.nixpkgs.follows = "nixpkgs";
-    inputs.flake-utils.follows = "flake-utils";
+    pyproject-nix = {
+      url = "github:nix-community/pyproject.nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    pyproject-build-systems = {
+      url = "github:pyproject-nix/build-system-pkgs";
+      inputs.pyproject-nix.follows = "pyproject-nix";
+      inputs.uv2nix.follows = "uv2nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    uv2nix = {
+      url = "github:adisbladis/uv2nix";
+      inputs.pyproject-nix.follows = "pyproject-nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
-
   outputs = {
-    self,
     nixpkgs,
     flake-utils,
-    poetry2nix,
+    uv2nix,
+    pyproject-nix,
+    pyproject-build-systems,
+    ...
   }:
     flake-utils.lib.eachDefaultSystem (system: let
-      p2n = import poetry2nix {inherit pkgs;};
-      python = pkgs.python3;
-      projectDir = ../.;
-      overrides = p2n.overrides.withDefaults (final: prev: {
-        # use wheels to build ruff & mypy
-        ruff = prev.ruff.override {
-          preferWheel = true;
-        };
-        mypy = prev.mypy.override {
-          preferWheel = true;
-        };
-      });
-      poetry_env = p2n.mkPoetryEnv {
-        inherit python projectDir overrides;
-      };
-      poetry_app = p2n.mkPoetryApplication {
-        inherit python projectDir overrides;
-      };
+      inherit (nixpkgs) lib;
       pkgs = nixpkgs.legacyPackages.${system};
+      python = pkgs.python312;
+      # setup uv2nix workspace & overlay
+      workspace = uv2nix.lib.workspace.loadWorkspace {workspaceRoot = ../.;};
+      overlay = workspace.mkPyprojectOverlay {
+        # Prefer prebuilt binary wheels as a package source.
+        sourcePreference = "wheel"; # or sourcePreference = "sdist";
+      };
+      pythonSet =
+        # Use base package set from pyproject.nix builders
+        (pkgs.callPackage pyproject-nix.build.packages {
+          inherit python;
+        })
+        .overrideScope
+        (
+          lib.composeManyExtensions [
+            pyproject-build-systems.overlays.default
+            overlay
+          ]
+        );
     in {
       packages = {
-        nextmeeting = poetry_app;
-        default = self.packages.${system}.nextmeeting;
+        ${system}.default = pythonSet.mkVirtualEnv "nextmeeting" workspace.deps.default;
       };
-      devShells.default =
-        pkgs.mkShell {packages = [pkgs.poetry poetry_env];};
     });
 }