nix: add package & NixOS module

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I5bfbacb984356f912f1f40d6209f0a896a6a6964

nix/package.nix

@@ -0,0 +1,54 @@
+{
+  lib,
+  rustPlatform,
+  makeWrapper,
+  ...
+}: let
+  pname = "pscand";
+  version = "0.1.0";
+  src = let
+    fs = lib.fileset;
+    s = ../.;
+  in
+    lib.cleanSourceWith {
+      src = fs.toSource {
+        root = s;
+        fileset = fs.unions [
+          (s + /crates)
+          (s + /scanners)
+          (s + /Cargo.lock)
+          (s + /Cargo.toml)
+        ];
+      };
+    };
+in
+  rustPlatform.buildRustPackage {
+    inherit pname version src;
+    cargoLock.lockFile = ../Cargo.lock;
+
+    nativeBuildInputs = [
+      makeWrapper
+    ];
+
+    postFixup = let
+      scannerDir = "${placeholder "out"}/lib/pscand/scanners";
+    in ''
+      mkdir -p ${scannerDir}
+      for scanner in scanners/**/target/release/*.so; do
+        if [ -f "$scanner" ]; then
+          install -Dm755 "$scanner" "${scannerDir}/$(basename "$scanner")"
+        fi
+      done
+
+      wrapProgram "$out/bin/pscand" \
+        --set PSCAND_SCANNER_DIRS "${scannerDir}"
+    '';
+
+    meta = {
+      description = "Pluggable System Condition Monitoring Daemon";
+      homepage = "https://github.com/notashelf/pscand";
+      license = lib.licenses.mpl20;
+      maintainers = with lib.maintainers; [NotAShelf];
+      platforms = lib.platforms.linux;
+    };
+  }