#!/bin/sh

if [ $# -eq 0 ]; then
    echo "usage: $0 /path/to/exercise/example"
    exit 1
fi

exampledir=$(cd "$1" && pwd)

examplename=$(basename "$exampledir")
exercisedir=$(cd "$exampledir/../.." && pwd)
exercisename=$(basename "$exercisedir")
xhaskell=$(cd "$(dirname "$0")/.." && pwd)

# We would ideally use a tmpdir here,
# but stack will invalidate its cache if the path changes,
# so the best alternative seems to be to put it in xhaskell.
buildfolder="${xhaskell}/build/${exercisename}/${examplename}"
mkdir -p "${buildfolder}"
cleanup() {
    rm -r "${xhaskell}/build"
}
trap cleanup EXIT INT TERM

cp -R -L ${exercisedir}/stack.yaml ${exercisedir}/test ${exampledir}/* "${buildfolder}"

cd $buildfolder

if [ -n "$TRAVIS" ]; then
    cachedir="$HOME"
else
    cachedir="$xhaskell"
fi
examplecache="${cachedir}/.foldercache/${exercisename}/${examplename}/.stack-work"
mkdir -p "$examplecache"
ln -f -s "$examplecache"

exampletype=$(echo "$examplename" | cut -d- -f1)

runstack () {
    # SET_RESOLVER passed by .travis.yml - sets --resolver if not current.
    stack "$@" ${SET_RESOLVER} `# Select the correct resolver. `\
               --install-ghc   `# Download GHC if not in cache.`\
               --no-terminal   `# Terminal detection is broken.`\
               --pedantic      `# Enable -Wall and -Werror.    `
}

if [ "$exampletype" = "success" ]; then
    echo "testing ${exampledir} - should succeed"
    # Implicit exit value: this is last thing in this path,
    # so the script's exit value = stack's exit value.
    # If statements are reordered, please preserve this property.
    runstack "test"
elif [ "$exampletype" = "fail" ]; then
    echo "testing ${exampledir} - should build, but fail tests"
    if ! runstack "build"; then
        echo "${exampledir} build failed unexpectedly"
        exit 1
    fi
    if runstack "test"; then
        echo "${exampledir} test succeeded unexpectedly"
        exit 1
    fi
elif [ "$exampletype" = "error" ]; then
    echo "testing ${exampledir} - should fail to build"
    if runstack "test" "--no-run-tests"; then
        echo "${exampledir} build succeeded unexpectedly"
        exit 1
    fi
else
    echo "unknown example type: ${exampledir}"
    exit 1
fi