#!/usr/bin/env bash
set -euo pipefail

cd "$(dirname "$0")"

# LinuxCNC source basis: native bridge object caches compile only project
# canon/kinematics bridge sources that wrap LinuxCNC src/emc/nml_intf/canon.hh
# and src/emc/kinematics implementations; G-code behavior remains in
# LinuxCNC RS274 objects linked by the caller.
linuxcnc_root=${LINUXCNC_ROOT:-../linuxcnc}
cxx=${CXX:-g++}
if [[ -z ${CXX:-} ]] && command -v ccache >/dev/null 2>&1; then
    cxx="ccache $cxx"
fi
build_jobs=${CNC_SIM_BUILD_JOBS:-8}
if ! [[ "$build_jobs" =~ ^[1-9][0-9]*$ ]]; then
    echo "CNC_SIM_BUILD_JOBS must be a positive integer: $build_jobs" >&2
    exit 1
fi
cache_dir=${CNC_SIM_NATIVE_BRIDGE_OBJECT_CACHE_DIR-build/native-bridge-object-cache}
if [[ -z "$cache_dir" ]]; then
    echo "CNC_SIM_NATIVE_BRIDGE_OBJECT_CACHE_DIR must not be empty" >&2
    exit 1
fi
if [[ "$cache_dir" =~ [[:space:]] ]]; then
    echo "CNC_SIM_NATIVE_BRIDGE_OBJECT_CACHE_DIR must not contain whitespace: $cache_dir" >&2
    exit 1
fi
mkdir -p "$cache_dir"
cache_dir=$(cd "$cache_dir" && pwd)
if [[ "$cache_dir" == "/" ]]; then
    echo "CNC_SIM_NATIVE_BRIDGE_OBJECT_CACHE_DIR must not be the filesystem root" >&2
    exit 1
fi
exec 8>"$cache_dir/native-bridge-objects.lock"
flock 8

preflight_cache_dir=${CNC_SIM_PREFLIGHT_CACHE_DIR:-"$cache_dir/preflight-cache"}
LINUXCNC_ROOT="$linuxcnc_root" ./check-linuxcnc-inputs-cached.sh --cache-dir "$preflight_cache_dir" --root-only
linuxcnc_root=$(cd "$linuxcnc_root" && pwd)

source_output=$(./list-linuxcnc-bridge-smoke-project-sources.sh)
mapfile -t sources <<<"$source_output"
common_flag_output=$(
    CNC_SIM_PREFLIGHT_CACHE_DIR="$preflight_cache_dir" \
        LINUXCNC_ROOT="$linuxcnc_root" ./list-linuxcnc-source-common-cxxflags.sh \
        --no-ulapi \
        --core-include \
        --core-src
)
mapfile -t common_flags <<<"$common_flag_output"

objects=()
source_index=0
for source in "${sources[@]}"; do
    objects+=("$cache_dir/source_${source_index}.o")
    source_index=$((source_index + 1))
done

signature="$cache_dir/native-bridge-objects.signature"
next_signature="$cache_dir/native-bridge-objects.signature.next"
{
    printf 'CXX=%s\n' "$cxx"
    printf 'PWD=%s\n' "$PWD"
    printf 'LINUXCNC_ROOT=%s\n' "$linuxcnc_root"
    printf 'BUILD_RULE_VERSION=1\n'
    printf 'COMMON_FLAGS='
    printf ' %s' "${common_flags[@]}"
    printf '\n'
    printf 'SOURCES:\n'
    printf '%s\n' "${sources[@]}"
} > "$next_signature"
if [[ ! -f "$signature" ]] || ! cmp -s "$signature" "$next_signature"; then
    rm -f "$cache_dir"/source_*.o "$cache_dir"/source_*.d
fi
mv "$next_signature" "$signature"

makefile="$cache_dir/native-bridge-objects.mk"
{
    printf 'CXX := %s\n' "$cxx"
    printf 'COMMON_FLAGS :='
    printf ' %s' "${common_flags[@]}"
    printf '\n\n'
    printf 'OBJECTS :='
    printf ' %s' "${objects[@]}"
    printf '\n\n'
    printf 'DEP_FILES :=\n'
    for object in "${objects[@]}"; do
        printf 'DEP_FILES += %s.d\n' "$object"
    done
    printf '\n.PHONY: all\n'
    printf 'all: $(OBJECTS)\n\n'

    source_index=0
    for source in "${sources[@]}"; do
        printf '%s: %s\n' "${objects[$source_index]}" "$source"
        printf '\t@$(CXX) $(COMMON_FLAGS) -MMD -MP -MF %s.d -c %s -o %s\n\n' \
            "${objects[$source_index]}" "$source" "${objects[$source_index]}"
        source_index=$((source_index + 1))
    done
    printf '\n-include $(DEP_FILES)\n'
} > "$makefile"
make --output-sync=target -j"$build_jobs" -f "$makefile" >/dev/null

printf '%s\n' "${objects[@]}"