nuget-to-nix: init

Adapted from `pkgs/games/osu-lazer/update.sh`.

Restore the packages to a directory with `--packages`, then run
`./nuget-to-nix.sh [path to packages] > deps.nix`.

pkgs/build-support/nuget-to-nix/default.nix

@@ -0,0 +1,5 @@
+{ runCommandNoCC }:
+
+runCommandNoCC "nuget-to-nix" { preferLocalBuild = true; } ''
+  install -D -m755 ${./nuget-to-nix.sh} $out/bin/nuget-to-nix
+''

pkgs/build-support/nuget-to-nix/nuget-to-nix.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+if [ $# -eq 0 ]; then
+  >&2 echo "Usage: $0 [packages directory] > deps.nix"
+  exit 1
+fi
+
+pkgs=$1
+
+echo "{ fetchNuGet }: ["
+
+while read pkg_spec; do
+  { read pkg_name; read pkg_version; } < <(
+    # Build version part should be ignored: `3.0.0-beta2.20059.3+77df2220` -> `3.0.0-beta2.20059.3`
+    sed -nE 's/.*<id>([^<]*).*/\1/p; s/.*<version>([^<+]*).*/\1/p' "$pkg_spec")
+  pkg_sha256="$(nix-hash --type sha256 --flat --base32 "$(dirname "$pkg_spec")"/*.nupkg)"
+
+  echo "  (fetchNuGet { name = \"$pkg_name\"; version = \"$pkg_version\"; sha256 = \"$pkg_sha256\"; })"
+done < <(find $1 -name '*.nuspec' | sort)
+
+echo "]"

pkgs/top-level/all-packages.nix

@@ -581,6 +581,7 @@ with pkgs;
 
   fetchNuGet = callPackage ../build-support/fetchnuget { };
   buildDotnetPackage = callPackage ../build-support/build-dotnet-package { };
+  nuget-to-nix = callPackage ../build-support/nuget-to-nix { };
 
   fetchgx = callPackage ../build-support/fetchgx { };