name: Nix Flake actions

on:
  pull_request:
    types: [opened, reopened, synchronize]
  push:
    branches: [main, master]

jobs:
  nix-matrix:
    runs-on: ubuntu-latest
    outputs:
      matrix: ${{ steps.set-matrix.outputs.matrix }}
    steps:
      - uses: actions/checkout@v3
      - uses: cachix/install-nix-action@v22
      - id: set-matrix
        name: Generate Nix Matrix
        run: |
          set -Eeu
          echo "matrix=$(nix eval --json '.#githubActions.matrix')" >> "$GITHUB_OUTPUT"