name: CI

on:
  push:
  pull_request:

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: nixbuild/nix-quick-install-action@v5
        with:
          nix_version: 2.4pre20201205_a5d85d0
          nix_conf: experimental-features = nix-command flakes
      - uses: actions/checkout@v2
      # TODO reuse cache even when key changes and then do GC
      - uses: actions/cache@v2
        id: cache-nix
        with:
          path:  ~/nix
          key: ${{ hashFiles('flake.nix') }}-${{ hashFiles('flake.lock') }}-${{ hashFiles('deps.nix') }}
      - name: Extract the cache
        if: steps.cache-nix.outputs.cache-hit
        run: sudo mkdir -p /nix && sudo rsync --recursive --archive ~/nix/ /nix
      - name: Build
        run: 'outpath="$(nix build --print-build-logs --no-link --json .# | jq -r .[0].outputs.out)" && echo "tinyquiz-build=$outpath" >> $GITHUB_ENV'
      - uses: actions/upload-artifact@v2
        with:
          path: ${{ env.tinyquiz-build }}/**
          retention-days: 7
          if-no-files-found: error
      - name: Prepare /nix/store for caching
        if: '!steps.cache-nix.outputs.cache-hit'
        run: sudo rsync --recursive --archive /nix/ ~/nix