version: "2.1"

env: &env
    environment:
      LC_ALL: "C.UTF-8"
      GHC_OPTS: "-O0 -Wall -fno-warn-unused-do-bind -Wincomplete-record-updates -Wnoncanonical-monad-instances -Wnoncanonical-monadfail-instances -Wincomplete-uni-patterns -Werror=missing-home-modules -Widentities -Wcpp-undef -fhide-source-paths"
    docker:
      - image: fpco/stack-build:lts

#-----------------------------------------------------------------------------
# Common utility stuff, not to be modified usually
#-----------------------------------------------------------------------------

preinstall: &preinstall
  run: |
      echo 'export PATH=/opt/cabal/bin:$PATH' >> $BASH_ENV
      source $BASH_ENV
      apt-get update

restore: &restore
  # Needs to happen after installing ca-certificates
  restore_cache:
    key: v1-{{ .Environment.CIRCLE_JOB }}-{{ .Branch }}

save: &save
  save_cache:
      key: v1-{{ .Environment.CIRCLE_JOB }}-{{ .Branch }}
      paths:
        - ~/.cabal
        - ~/.ghc
        - ~/.local
        - ~/.stack

commands:
  cabal_build:
    parameters:
      ghcversion:
        type: string
    steps:
      - checkout
      - *preinstall
      - *restore
      - run:
          name: install ghc
          command: apt-get install -y ghc-<< paramaters.ghcversion >>
      - run: |
          set -e
          apt-get install -y cabal-install-2.4
          cabal v2-update
          TMPDIR=`mktemp -d -t circleci.XXXXXXX`
          cabal v2-sdist --output-dir=${TMPDIR}
          cd ${TMPDIR}
          tar xvzf *.tar.gz
          cd *
          cabal v2-build -j2 --dependencies-only --enable-tests --ghc-options="${GHC_OPTS}" all
          cabal v2-build -j2 --enable-tests --ghc-options="${GHC_OPTS}" all 2>build.log
          # fail if we had warnings in local build
          # this is to work around the fact that cabal v2 doesn't allow
          # us to use -Werror for just local build:
          # https://github.com/haskell/cabal/issues/4247
          ! grep -q "warning:" build.log
          cabal v2-test --ghc-options="${GHC_OPTS}" 2>build.log
          cabal v2-haddock --ghc-options="${GHC_OPTS}"
          cabal check
      - *save

#-----------------------------------------------------------------------------
# Build matrix
#-----------------------------------------------------------------------------

jobs:
  cabal-ghc-8_6_3:
      <<: *env
      steps:
          - cabal_build:
              ghcversion: 8.6.3

  cabal-ghc-8_4_4:
      <<: *env
      steps:
          - cabal_build:
              ghcversion: 8.4.4

  cabal-ghc-8_2_2:
      <<: *env
      steps:
          - cabal_build:
              ghcversion: 8.2.2

  cabal-ghc-8_0_2:
      <<: *env
      steps:
          - cabal_build:
              ghcversion: 8.0.2

  cabal-ghc-7_10_3:
      <<: *env
      steps:
          - cabal_build:
              ghcversion: 7.10.3

  stack-ghc-8_6:
      <<: *env
      steps:
        - checkout
        - *preinstall
        - *restore
        - run: |
            set -e
            apt-get install -y ghc-8.6.3
            stack update
            stack test --system-ghc --ghc-options="${GHC_OPTS} -Werror" .
        - *save

workflows:
  version: "2.1"
  build:
    jobs:
      - cabal-ghc-8_6_3
      - cabal-ghc-8_4_4
      - cabal-ghc-8_2_2
      - cabal-ghc-8_0_2
      - cabal-ghc-7_10_3
      - stack-ghc-8_6