name: CI
on:
  pull_request:
  push:
    branches:
    - master
    - dev
    - ci

  workflow_run:
    workflows:
    - sync-channels
    types:
    - completed
    branches:
    - master

jobs:
  check-flake:
    name: Check flake
    if: ${{ github.event.workflow_run.conclusion != 'failure' }}
    runs-on: ubuntu-latest
    steps:
    - name: Checkout
      uses: actions/checkout@v2
      with:
        fetch-depth: 0 # Nix Flakes doesn't work on shallow clones
    - name: Install Nix (flakes, nixpkgs-unstable)
      uses: cachix/install-nix-action@v12
      with:
        install_url: https://github.com/numtide/nix-flakes-installer/releases/download/nix-2.4pre20201221_9fab14a/install
        extra_nix_config: |
          experimental-features = nix-command flakes
        nix_path: nixpkgs=channel:nixpkgs-unstable
    - name: Check flake
      run: nix flake check -v --show-trace --no-update-lock-file

  check-sync-script:
    name: Check sync script
    if: ${{ github.event.workflow_run.conclusion != 'failure' }}
    runs-on: ubuntu-latest
    steps:
    - name: Checkout
      uses: actions/checkout@v2
    - name: Install python
      uses: actions/setup-python@v2
      with:
        python-version: '3.8'
    - name: Install python packages
      run: pip3 install -r ./scripts/requirements.txt
    - name: Clean the latest version of each channel
      run: |
        for channel in stable beta nightly; do
          version=$(sed -nE 's/.*latest = "(.*?)".*/\1/p' "./manifests/$channel/default.nix")
          echo "Remove $channel $version"
          rm "./manifests/$channel/default.nix"
          if [[ "$channel" == "stable" ]]; then
            rm "./manifests/$channel/$version.nix"
          else
            rm "./manifests/$channel/${version%%-*}/$version.nix"
          fi
        done
    - name: Re-fetch latest stable
      run: python3 ./scripts/fetch.py stable
    - name: Re-fetch latest beta
      run: python3 ./scripts/fetch.py beta
    - name: Re-fetch latest nightly
      run: python3 ./scripts/fetch.py nightly
    - name: Check file changes
      run: |
        short_status=$(git status --short)
        echo "$short_status"
        shopt -s extglob
        while read -r change; do
          case "$change" in
            # Okay if there is no change.
            "" ) ;;
            "?? "manifests/@(stable|nightly|beta)/* ) ;;
            "M "manifests/@(renames.nix|targets.nix) ) ;;
            "M "manifests/@(stable|nightly|beta)/default.nix ) ;;
            * )
              echo "Unexpected change: $change"
              exit 1
          esac
        done <<<"$short_status"

  check-build:
    name: Check build Rust
    if: ${{ github.event.workflow_run.conclusion != 'failure' }}
    strategy:
      fail-fast: false
      matrix:
        os: [ubuntu-latest, macos-latest]
        channel: [stable, beta]
        build_pkg: [minimal, default]
    runs-on: ${{ matrix.os }}
    env:
      build_expr: (import <nixpkgs> { overlays = [ (import ./.) ]; }).rust-bin.${{ matrix.channel }}.latest.${{ matrix.build_pkg }}
    steps:
    - name: Checkout
      uses: actions/checkout@v2
    - name: Get locked nixpkgs revision
      id: nixpkgs_rev
      run: |
        rev=$(jq '.nodes.nixpkgs.locked.rev' --raw-output flake.lock)
        echo "Revision: $rev"
        echo "::set-output name=rev::$rev"
    - name: Install Nix
      uses: cachix/install-nix-action@v12
      with:
        nix_path: nixpkgs=https://github.com/NixOS/nixpkgs/archive/${{ steps.nixpkgs_rev.outputs.rev }}.tar.gz
    - name: Instantiate derivation
      id: instantiate
      run: |
        drv_path=$(nix-instantiate -E "$build_expr")
        echo "::set-output name=drv_path::$drv_path"
    - name: Cache derivation status
      id: cache-drv-status
      uses: actions/cache@v2
      with:
        key: drv-check-build-0-${{ steps.instantiate.outputs.drv_path }}
        path: successful
    - name: Build Rust
      if: steps.cache-drv-status.outputs.cache-hit != 'true'
      run: |
        nix-build -E "$build_expr"
        ./result/bin/rustc --version
    - name: Prepare nix-shell
      if: steps.cache-drv-status.outputs.cache-hit != 'true'
      run: nix-shell -p "$build_expr" --pure --command "exit"
    - name: Check `rustc` works
      if: steps.cache-drv-status.outputs.cache-hit != 'true'
      run: |
        echo 'fn main() { println!("hello, world"); }' >./test.rs
        # Use nix-shell to bring propagatedBuildInputs into scope.
        nix-shell -p "$build_expr" --pure --command "rustc test.rs -o test"
        [[ "$(./test)" == "hello, world" ]]
    - name: Check `clippy` works
      if: matrix.build_pkg == 'default' && steps.cache-drv-status.outputs.cache-hit != 'true'
      run: |
        echo 'fn main() { loop { break; } }' >./test.rs
        nix-shell -p "$build_expr" --pure --command 'clippy-driver test.rs -W clippy::never-loop' 2>&1 | tee msg
        [[ ${PIPESTATUS[0]} -eq 0 && "$(cat msg)" == *"warning: this loop never actually loops"* ]]
    - name: Mark a successful build for cache
      if: steps.cache-drv-status.outputs.cache-hit != 'true'
      run: echo "1" >./successful