name: Nix

# Builds pandoc with the flake (haskell-flake) on Linux and macOS.
on:
  push:
    paths:
    - 'stack.yaml'
    - 'pandoc.cabal'
    - 'flake.nix'
    - 'flake.lock'
    branches:
    - 'main'
  pull_request:
  workflow_dispatch:

permissions:
  contents: read

concurrency:
  group: nix-${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

jobs:
  nix-build:
    name: nix build (${{ matrix.os }})
    runs-on: ${{ matrix.os }}
    strategy:
      fail-fast: false
      matrix:
        os:
        - ubuntu-latest
        - macos-latest
    steps:
    - uses: actions/checkout@v7

    - uses: cachix/install-nix-action@v31
      with:
        extra_nix_config: |
          experimental-features = nix-command flakes
          accept-flake-config = true

    # Cache the /nix/store across runs so dependencies don't recompile.
    - uses: nix-community/cache-nix-action@v7
      with:
        primary-key: nix-${{ matrix.os }}-${{ hashFiles('flake.lock', 'flake.nix', '**/*.cabal', 'cabal.project') }}
        restore-prefixes-first-match: nix-${{ matrix.os }}-

    - name: nix build
      run: nix build .#default --print-build-logs

    - name: pandoc --version
      run: nix run .#default -- --version