name: nix

on:
  pull_request:
  push:
    branches:
      - master

jobs:
  nix-build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkouts code
        uses: actions/checkout@v3

      - name: Caches Nix store
        uses: actions/cache@v3
        id: nix-cache
        with:
          path: /tmp/nix-cache
          key: nix-${{ hashFiles('**/flake.*') }}

      - name: Installs Nix
        uses: cachix/install-nix-action@v18
        with:
          extra_nix_config: |
            experimental-features = nix-command flakes

      - name: Imports Nix store cache
        if: ${{ steps.nix-cache.outputs.cache-hit == 'true' }}
        run: nix-store --import < /tmp/nix-cache

      - name: Builds the project
        run: nix build

      - name: Exports Nix store cache
        if: ${{ steps.nix-cache.outputs.cache-hit != 'true' }}
        run: nix-store --export $(find /nix/store -maxdepth 1 -name '*-*') > /tmp/nix-cache