#!/usr/bin/env bash

export LC_ALL=C
set -eu -o pipefail

usage() {
    echo ""
    echo "$0 <build stage> <options> <passthrough build arguments>"
    echo ""
    echo "Build a fuzzer in the local repo using the following options:"
    echo ""
    echo "<build stage>:"
    echo " either \"depends\" or \"fuzzer\""
    echo ""
    echo "<options>:"
    echo " -f,--fuzzer <fuzzername> (ignored if building \"depends\")"
    echo " [-s,--sanitizers <sanitizers>]"
    echo " [-i,--instrument <instrument>]"
    echo " [-l,--logfile <logfile>] # default is ./zcash-build-wrapper.log"
    echo " [-h,--help]"
    echo ""
    echo "Where fuzzer is an entry in ./src/fuzzing/*, the default sanitizer"
    echo "is \"address\" and default instrument is ( \"^.*/src/$\" )."
    echo ""
    exit -1
}

die() {
    echo $1
    exit -1
}

# parse command line options

POSITIONAL=()
while [[ $# -gt 0 ]]
do
key="$1"

case $key in
    -f|--fuzzer)
    FUZZER_NAME="$2"
    if [ ! -f "./src/fuzzing/$FUZZER_NAME/fuzz.cpp" ]
    then
        die "Cannot find source code for fuzzer."
    fi
    shift
    shift
    ;;
    -s|--sanitizers)
    LLVM_SANITIZERS="$2"
    shift
    shift
    ;;
    -i|--instrument)
    INSTRUMENT_CODE="$2"
    shift
    shift
    ;;
    -l|--logfile)
    LOGFILE="$2"
    shift
    shift
    ;;
    -h|--help)
    usage
    shift
    ;;
    *)
    POSITIONAL+=("$1")
    shift
    ;;
esac
done

# positional arguments

if [ ${#POSITIONAL[@]} -lt 1 ]
then
    usage
else
    BUILD_STAGE=${POSITIONAL[0]}
fi

case "${BUILD_STAGE:-undefined}" in
    depends)
    FUZZER_NAME=notused
    # fine
    ;;
    fuzzer)
    # fine
    ;;
    *)
    # not fine
    usage
    ;;
esac

# required arguments

if [ "${FUZZER_NAME:-undefined}" = "undefined" ]
then
    usage
fi

# default values

if [ "${LLVM_SANITIZERS:-undefined}" = "undefined" ]
then
    export LLVM_SANITIZERS="address"
fi
if [ "${INSTRUMENT_CODE:-undefined}" = "undefined" ]
then
    export INSTRUMENT_CODE=("^.*\/src")
fi
if [ "${LOGFILE:-undefined}" = "undefined" ]
then
    export LOGFILE=./zcash-build-wrapper.log
fi

set -x

export ZCUTIL=$(realpath "./zcutil")

# overwrite the Linux make profile to use clang instead of GCC:

cat $ZCUTIL/../depends/hosts/linux.mk | sed -e 's/=gcc/=clang/g' | sed -e 's/=g++/=clang++/g' > x
mv x $ZCUTIL/../depends/hosts/linux.mk

# the build_stage distinction helps to layer an intermediate docker
# container for the built dependencies, so we can resume building
# from there assuming no other build arguments have changed

if [ "$BUILD_STAGE" = "depends" ]
then
    # make an empty fuzz file just so we can build dependencies
    > src/fuzz.cpp
else
    cp "./src/fuzzing/$FUZZER_NAME/fuzz.cpp" src/fuzz.cpp || die "Can't copy fuzz.cpp for that fuzzer"
fi

# sneak the variable into zcashd's build.sh

export BUILD_STAGE

# run build.sh with our compiler wrapper, and BUILD_STAGE environment set:

CONFIGURE_FLAGS="--enable-tests=no --disable-bench" \
    "$ZCUTIL/build.sh" \
    -j$(nproc) \
    "CC=$ZCUTIL/libfuzzer/zcash-wrapper-clang" \
    "CXX=$ZCUTIL/libfuzzer/zcash-wrapper-clang++" "${POSITIONAL[@]:1}" || die "Build failed at stage $BUILD_STAGE."