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

if [[ "${VOXELFORGE_LIMITED_BUILD:-0}" != "1" ]]; then
    exec taskset -c 0-11 prlimit --as=6442450944 -- env VOXELFORGE_LIMITED_BUILD=1 "$0" "$@"
fi

SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
ROOT="$SCRIPT_DIR"
PROJECT_ROOT="$(cd -- "$ROOT/.." && pwd)"
VERIFY_DIR="$ROOT/Tools/verify"
COMPILER="clang++-19"
VARIANT="clang19"
FP_CONTRACT="off"
JOBS=12
SANITIZERS=""
EXCLUDE_UNSIGNED_OVERFLOW=0

while (($#)); do
    case "$1" in
        --compiler=*) COMPILER="${1#*=}" ;;
        --variant=*) VARIANT="${1#*=}" ;;
        --fp-contract=*) FP_CONTRACT="${1#*=}" ;;
        --jobs=*) JOBS="${1#*=}" ;;
        --sanitize=*) SANITIZERS="${1#*=}" ;;
        --exclude-unsigned-integer-overflow) EXCLUDE_UNSIGNED_OVERFLOW=1 ;;
        *) printf 'Unknown build option: %s\n' "$1" >&2; exit 2 ;;
    esac
    shift
done

if [[ ! "$JOBS" =~ ^[0-9]+$ ]] || ((JOBS < 1 || JOBS > 12)); then
    printf 'jobs must be from 1 to 12\n' >&2
    exit 2
fi
if [[ "$FP_CONTRACT" != "default" && "$FP_CONTRACT" != "off" && "$FP_CONTRACT" != "on" && "$FP_CONTRACT" != "fast" ]]; then
    printf 'fp-contract must be default, off, on, or fast\n' >&2
    exit 2
fi
command -v "$COMPILER" >/dev/null || { printf 'Compiler not found: %s\n' "$COMPILER" >&2; exit 2; }
command -v ar >/dev/null || { printf 'ar not found\n' >&2; exit 2; }
command -v pkg-config >/dev/null || { printf 'pkg-config not found\n' >&2; exit 2; }
pkg-config --exists egl glesv2 libpng || { printf 'EGL, GLESv2, and libpng development files are required\n' >&2; exit 2; }

BUILD_ROOT="${VOXELFORGE_BUILD_ROOT:-$ROOT/Build}"
BIN_DIR="${VOXELFORGE_BIN_DIR:-$ROOT/bin/linux}"
BUILD_DIR="$BUILD_ROOT/linux-$VARIANT"
mkdir -p "$BUILD_DIR/wrappers" "$BUILD_DIR/objects" "$BIN_DIR"

STAMP_HELPER="$VERIFY_DIR/source_stamp.py"
STAMP_ARGS=()
if [[ "${VOXELFORGE_INCLUDE_UNREAL_ADAPTER:-0}" == "1" ]]; then
    STAMP_ARGS+=(--include-unreal-adapter)
fi
SOURCE_STAMP="$(python3 -B "$STAMP_HELPER" stamp --root "$PROJECT_ROOT" "${STAMP_ARGS[@]}")"
python3 -B "$STAMP_HELPER" write-manifest --root "$PROJECT_ROOT" --output "$BUILD_DIR/source-manifest.txt" "${STAMP_ARGS[@]}" >/dev/null
printf 'Source stamp: %s\n' "$SOURCE_STAMP"

INCLUDES=(
    "-I$ROOT/Core/include"
    "-I$ROOT/Core/src"
    "-I$ROOT/Compat"
    "-I$ROOT/Source"
    "-I$ROOT/Source/VoxelForge/Public"
    "-I$ROOT/Source/VoxelForge/Private"
)
OPT_LEVEL=-O2
LINK_FLAGS=()
if [[ -n "$SANITIZERS" ]]; then
    OPT_LEVEL=-O1
    LINK_FLAGS+=("-fsanitize=$SANITIZERS" -fno-sanitize-recover=undefined)
    if ((EXCLUDE_UNSIGNED_OVERFLOW)); then
        LINK_FLAGS+=(-fno-sanitize=unsigned-integer-overflow)
    fi
fi

FLAGS=(
    -std=c++20 "$OPT_LEVEL" -mavx2 -mfma -fno-fast-math
    -fexceptions -pthread "${INCLUDES[@]}"
    "-DVOXELFORGE_SOURCE_STAMP=\"$SOURCE_STAMP\""
)
FLAGS+=("${LINK_FLAGS[@]}")
if [[ "$FP_CONTRACT" != "default" ]]; then
    FLAGS+=("-ffp-contract=$FP_CONTRACT")
fi
if [[ "$($COMPILER --version | head -n 1)" == *clang* ]]; then
    FLAGS+=(-Wno-c++11-narrowing)
else
    FLAGS+=(-Wno-narrowing)
fi

CORE_OBJECTS=()
LEGACY_OBJECTS=()
PIDS=()
wait_oldest() {
    local pid="${PIDS[0]}"
    wait "$pid"
    PIDS=("${PIDS[@]:1}")
}
compile_background() {
    local source="$1" output="$2"
    "$COMPILER" "${FLAGS[@]}" -c "$source" -o "$output" &
    PIDS+=("$!")
    if ((${#PIDS[@]} >= JOBS)); then wait_oldest; fi
}

while IFS= read -r source_name || [[ -n "$source_name" ]]; do
    source_name="${source_name%%#*}"
    source_name="${source_name//[[:space:]]/}"
    [[ -z "$source_name" ]] && continue
    source_path="$ROOT/$source_name"
    [[ -f "$source_path" ]] || { printf 'Missing source from core_sources.txt: %s\n' "$source_name" >&2; exit 2; }
    if [[ "$source_name" == "Core/src/VoxelForgeCore.cpp" ]]; then
        object="$BUILD_DIR/objects/VoxelForgeCore.o"
        compile_background "$source_path" "$object"
        CORE_OBJECTS+=("$object")
        continue
    fi
    wrapper_name="vfcore_${source_name//[^A-Za-z0-9]/_}"
    wrapper="$BUILD_DIR/wrappers/$wrapper_name.cpp"
    cat > "$wrapper" <<WRAPPER
#include "CoreNamespacePreamble.h"
namespace vfcore::detail
{
#include "$source_path"
}
WRAPPER
    object="$BUILD_DIR/objects/$wrapper_name.o"
    compile_background "$wrapper" "$object"
    CORE_OBJECTS+=("$object")

    # The same copied compatibility implementations are also needed by the standalone owner
    # loader/mesher host. They are compiled globally for that reference layer, as in Build.ps1.
    legacy_object="$BUILD_DIR/objects/legacy_${wrapper_name}.o"
    compile_background "$source_path" "$legacy_object"
    LEGACY_OBJECTS+=("$legacy_object")
done < "$ROOT/Core/core_sources.txt"

headless_object="$BUILD_DIR/objects/StreamBenchmarkHeadless.o"
compile_background "$ROOT/Source/StreamBenchmarkHeadless.cpp" "$headless_object"
LEGACY_OBJECTS+=("$headless_object")

for pid in "${PIDS[@]}"; do wait "$pid"; done
PIDS=()

CORE_LIBRARY="$BUILD_DIR/libVoxelForgeCore.a"
"$(command -v ar)" rcs "$CORE_LIBRARY" "${CORE_OBJECTS[@]}"
OUTPUT="$BIN_DIR/VoxelForgeCoreHeadless-$VARIANT"
"$COMPILER" -pthread "${LINK_FLAGS[@]}" "${LEGACY_OBJECTS[@]}" "$CORE_LIBRARY" -o "$OUTPUT"
CAPTURE_OUTPUT="$BIN_DIR/VoxelForgeOffscreenCapture-$VARIANT"
"$COMPILER" -std=c++20 -O2 -fno-fast-math -pthread \
    "-DVOXELFORGE_SOURCE_STAMP=\"$SOURCE_STAMP\"" -I"$ROOT/Source" \
    "$ROOT/Source/LinuxOffscreenCapture.cpp" -o "$CAPTURE_OUTPUT" \
    $(pkg-config --cflags --libs egl glesv2 libpng)

POST_BUILD_STAMP="$(python3 -B "$STAMP_HELPER" stamp --root "$PROJECT_ROOT" "${STAMP_ARGS[@]}")"
if [[ "$POST_BUILD_STAMP" != "$SOURCE_STAMP" ]]; then
    printf 'Source changed during build: before=%s after=%s\n' "$SOURCE_STAMP" "$POST_BUILD_STAMP" >&2
    exit 1
fi
printf 'Built Core library: %s\nBuilt headless benchmark: %s\n' "$CORE_LIBRARY" "$OUTPUT"
printf 'Built EGL offscreen capture: %s\n' "$CAPTURE_OUTPUT"
printf 'Compiler: %s | variant: %s | fp-contract: %s | sanitizers: %s | jobs: %s\n' \
    "$COMPILER" "$VARIANT" "$FP_CONTRACT" "${SANITIZERS:-off}" "$JOBS"