set -euo pipefail

ulimit -s ${MAIN_STACK_SIZE:-8192}
DIFF=diff
if diff --color --help >/dev/null 2>&1; then
    DIFF="diff --color";
fi

function fail {
    echo $1
    exit 1
}

INTERACTIVE=no
if [ $1 == "-i" ]; then
    INTERACTIVE=yes
    shift
fi
f="$1"
shift
[ $# -eq 0 ] || fail "Usage: test_single.sh [-i] test-file.lean"

function lean_has_llvm_support {
    lean --features | grep -q "LLVM"
}

function compile_lean_c_backend {
    lean --c="$f.c" "$f" || fail "Failed to compile $f into C file"
    leanc ${LEANC_OPTS-} -O3 -DNDEBUG -o "$f.out" "$@" "$f.c" || fail "Failed to compile C file $f.c"
}

function compile_lean_llvm_backend {
    set -o xtrace
    rm "*.ll" || true # remove debugging files.
    rm "*.bc" || true # remove bitcode files
    rm "*.o" || true # remove object files
    lean --bc="$f.linked.bc" "$f" || fail "Failed to compile $f into bitcode file"
    leanc ${LEANC_OPTS-} -O3 -DNDEBUG -o "$f.out" "$@" "$f.linked.bc" || fail "Failed to link object file '$f.linked.bc'"
    set +o xtrace
}

function exec_capture_raw {
    # backtraces are system-specific, strip them (might be captured in `#guard_msgs`)
    LEAN_BACKTRACE=0 "$@" 2>&1 > "$f.produced.out"
}

# produces filtered output intended for usage with `diff_produced`
function exec_capture {
    # backtraces are system-specific, strip them
    # mvar suffixes like in `?m.123` are deterministic but prone to change on minor changes, so strip them
    # similarly, links to the language reference may have URL components depending on the toolchain, so normalize those
    LEAN_BACKTRACE=0 "$@" 2>&1 \
      | perl -pe 's/(\?(\w|_\w+))\.[0-9]+/\1/g' \
      | perl -pe 's/https:\/\/lean-lang\.org\/doc\/reference\/(v?[0-9.]+(-rc[0-9]+)?|latest)/REFERENCE/g'  > "$f.produced.out"
}


# Remark: `${var+x}` is a parameter expansion which evaluates to nothing if `var` is unset, and substitutes the string `x` otherwise.
function check_ret {
    [ -n "${expected_ret+x}" ] || expected_ret=0
    [ -f "$f.expected.ret" ] && expected_ret=$(< "$f.expected.ret")
    if [ -n "$expected_ret" ] && [ $ret -ne $expected_ret ]; then
        echo "Unexpected return code $ret executing '$@'; expected $expected_ret. Output:"
        cat "$f.produced.out"
        exit 1
    fi
}

function exec_check_raw {
    ret=0
    exec_capture_raw "$@" || ret=$?
    check_ret "$@"
}

# produces filtered output intended for usage with `diff_produced`
function exec_check {
    ret=0
    exec_capture "$@" || ret=$?
    check_ret "$@"
}

function diff_produced {
    if test -f "$f.expected.out"; then
        if $DIFF -au --strip-trailing-cr -I "executing external script" "$f.expected.out" "$f.produced.out"; then
            :
        else
            echo "ERROR: file $f.produced.out does not match $f.expected.out"
            if [ $INTERACTIVE == "yes" ]; then
                meld "$f.produced.out" "$f.expected.out"
                if diff -I "executing external script" "$f.expected.out" "$f.produced.out"; then
                    echo "-- mismatch was fixed"
                fi
            fi
            exit 1
        fi
    else
        echo "ERROR: file $f.expected.out does not exist"
        if [ $INTERACTIVE == "yes" ]; then
            read -p "copy $f.produced.out (y/n)? "
            if [ $REPLY == "y" ]; then
                cp -- "$f.produced.out" "$f.expected.out"
                echo "-- copied $f.produced.out --> $f.expected.out"
            fi
        fi
        exit 1
    fi
}