#!/usr/bin/env bash
# Build BackstageCapture DLL for Windows x64 using MinGW cross-compiler (C++).
# Run from the repository root or from Docker.
#
# BackstageCapture hooks IDXGISwapChain::Present to capture frames from the GPU
# process. It uses MinHook for hooking and ReflectiveLoader for injection.
#
# Requirements:
#   - x86_64-w64-mingw32-g++ (C++ mode needed for COM vtable calls / __uuidof)
#   - MinHook source under BackstageCapture/Minhook/
#
# If MinHook source is not available, you can pre-build the DLL with MSVC
# on Windows using scripts\build-backstage-capture-dll.bat and place the output at:
#   Overlord-Server/dist-clients/BackstageCapture.x64.dll

set -euo pipefail
SCRIPT_DIR="$(cd -- "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
ROOT="$(cd -- "$SCRIPT_DIR/.." && pwd)"
cd "$ROOT"

# C++ compiler for COM / __uuidof support
CXX="${CXX:-x86_64-w64-mingw32-g++}"
CC="${CC:-x86_64-w64-mingw32-gcc}"
SRC_DIR="${BACKSTAGE_CAPTURE_SRC_DIR:-BackstageCapture/src}"
OUT_DIR="${BACKSTAGE_CAPTURE_OUT_DIR:-Overlord-Server/dist-clients}"
DLL_NAME="BackstageCapture.x64.dll"
MINHOOK_REPO="${MINHOOK_REPO:-https://github.com/TsudaKageyu/minhook.git}"
MINHOOK_REF="${MINHOOK_REF:-master}"
BACKSTAGE_FETCH_MINHOOK="${BACKSTAGE_FETCH_MINHOOK:-1}"
MINHOOK_STATIC_DIR="${MINHOOK_STATIC_DIR:-BackstageCapture/Minhook}"

mkdir -p "$OUT_DIR"

MINHOOK_DIR="$SRC_DIR/minhook"

stage_minhook_tree() {
  local source_root="$1"
  local include_root="${2:-$1}"

  mkdir -p "$MINHOOK_DIR/hde"
  cp -f "$source_root/buffer.c" "$MINHOOK_DIR/" 2>/dev/null || true
  cp -f "$source_root/buffer.h" "$MINHOOK_DIR/" 2>/dev/null || true
  cp -f "$source_root/hook.c" "$MINHOOK_DIR/" 2>/dev/null || true
  cp -f "$source_root/trampoline.c" "$MINHOOK_DIR/" 2>/dev/null || true
  cp -f "$source_root/trampoline.h" "$MINHOOK_DIR/" 2>/dev/null || true
  cp -f "$source_root/hde/hde64.c" "$MINHOOK_DIR/hde/" 2>/dev/null || true
  cp -f "$source_root/hde/hde64.h" "$MINHOOK_DIR/hde/" 2>/dev/null || true
  cp -f "$source_root/hde/hde32.c" "$MINHOOK_DIR/hde/" 2>/dev/null || true
  cp -f "$source_root/hde/hde32.h" "$MINHOOK_DIR/hde/" 2>/dev/null || true
  cp -f "$source_root/hde/pstdint.h" "$MINHOOK_DIR/hde/" 2>/dev/null || true
  cp -f "$source_root/hde/table64.h" "$MINHOOK_DIR/hde/" 2>/dev/null || true
  cp -f "$source_root/hde/table32.h" "$MINHOOK_DIR/hde/" 2>/dev/null || true

  mkdir -p "$SRC_DIR/include"
  if [ -f "$source_root/MinHook.h" ]; then
    cp -f "$source_root/MinHook.h" "$MINHOOK_DIR/MinHook.h" 2>/dev/null || true
    cp -f "$source_root/MinHook.h" "$SRC_DIR/include/MinHook.h" 2>/dev/null || true
  elif [ -f "$include_root/MinHook.h" ]; then
    cp -f "$include_root/MinHook.h" "$MINHOOK_DIR/MinHook.h" 2>/dev/null || true
    cp -f "$include_root/MinHook.h" "$SRC_DIR/include/MinHook.h" 2>/dev/null || true
  fi
}

stage_minhook_from_static_dir() {
  local candidate_src=""
  local candidate_include=""

  for dir in "$MINHOOK_STATIC_DIR" "BackstageCapture/Minhook" "BackstageCapture/minhook"; do
    if [ -f "$dir/hook.c" ] && [ -f "$dir/hde/hde64.c" ]; then
      candidate_src="$dir"
      candidate_include="$dir"
      break
    fi

    if [ -f "$dir/src/hook.c" ] && [ -f "$dir/src/hde/hde64.c" ]; then
      candidate_src="$dir/src"
      if [ -f "$dir/include/MinHook.h" ]; then
        candidate_include="$dir/include"
      else
        candidate_include="$dir/src"
      fi
      break
    fi
  done

  if [ -n "$candidate_src" ]; then
    echo "Using static MinHook source from $candidate_src"
    stage_minhook_tree "$candidate_src" "$candidate_include"
    return 0
  fi

  return 1
}

# Verify C++ cross-compiler is available
if ! command -v "$CXX" >/dev/null 2>&1; then
  echo "ERROR: C++ cross compiler not found: $CXX"
  echo "Install mingw-w64 (x86_64-w64-mingw32-g++) in your build image/environment."
  exit 1
fi

fetch_minhook() {
  if [ "$BACKSTAGE_FETCH_MINHOOK" != "1" ]; then
    return 1
  fi

  if ! command -v git >/dev/null 2>&1; then
    echo "WARNING: git is not available; cannot auto-fetch MinHook."
    return 1
  fi

  echo "MinHook source not found; fetching from $MINHOOK_REPO ($MINHOOK_REF) ..."
  local tmpdir
  tmpdir="$(mktemp -d)"

  if ! git clone --depth 1 --branch "$MINHOOK_REF" "$MINHOOK_REPO" "$tmpdir/minhook"; then
    rm -rf "$tmpdir"
    echo "WARNING: Failed to fetch MinHook source."
    return 1
  fi

  stage_minhook_tree "$tmpdir/minhook/src" "$tmpdir/minhook/include"
  cp -f "$tmpdir/minhook/include/MinHook.h" "$MINHOOK_DIR/MinHook.h" 2>/dev/null || true
  mkdir -p "$SRC_DIR/include"
  cp -f "$tmpdir/minhook/include/MinHook.h" "$SRC_DIR/include/MinHook.h" 2>/dev/null || true
  rm -rf "$tmpdir"

  [ -f "$MINHOOK_DIR/hook.c" ]
}

# --- Stage MinHook source ---
if [ ! -d "$MINHOOK_DIR" ]; then
  if ! stage_minhook_from_static_dir && ! fetch_minhook; then
    echo "WARNING: MinHook source not found at $MINHOOK_DIR"
    echo "Attempting to use pre-compiled libMinHook.x64.lib ..."
    echo "(This may fail with MinGW. Build with MSVC on Windows instead.)"
    MINHOOK_OBJS=""
    MINHOOK_LIB="$SRC_DIR/libMinHook.x64.lib"
    MINHOOK_INC=""
  fi
fi

if [ -d "$MINHOOK_DIR" ]; then
  if [ ! -f "$MINHOOK_DIR/hook.c" ] && [ ! -f "$MINHOOK_DIR/MinHook.c" ]; then
    stage_minhook_from_static_dir || fetch_minhook || true
  fi
fi

if [ -d "$MINHOOK_DIR" ] && { [ -f "$MINHOOK_DIR/hook.c" ] || [ -f "$MINHOOK_DIR/MinHook.c" ]; }; then
  echo "Building MinHook from source ..."
  MINHOOK_OBJS=""
  MINHOOK_LIB=""
  MINHOOK_INC="-I$MINHOOK_DIR -I$MINHOOK_DIR/hde"

  if [ -f "$MINHOOK_DIR/hook.c" ] && [ ! -f "$SRC_DIR/include/MinHook.h" ]; then
    mkdir -p "$SRC_DIR/include"
    if [ -f "$MINHOOK_DIR/MinHook.h" ]; then
      cp -f "$MINHOOK_DIR/MinHook.h" "$SRC_DIR/include/MinHook.h"
    elif [ -f "$MINHOOK_DIR/include/MinHook.h" ]; then
      cp -f "$MINHOOK_DIR/include/MinHook.h" "$SRC_DIR/include/MinHook.h"
    fi
  fi

  # MinHook is pure C — compile with gcc
  for src in "$MINHOOK_DIR"/buffer.c "$MINHOOK_DIR"/trampoline.c \
             "$MINHOOK_DIR"/hde/hde64.c "$MINHOOK_DIR"/hde/hde32.c \
             "$MINHOOK_DIR"/hook.c "$MINHOOK_DIR"/MinHook.c; do
    if [ -f "$src" ]; then
      obj="${src%.c}.o"
      "$CC" -c -O2 -DWIN64 -D_WIN64 -fno-stack-protector -fno-asynchronous-unwind-tables $MINHOOK_INC -o "$obj" "$src"
      MINHOOK_OBJS="$MINHOOK_OBJS $obj"
    fi
  done

  if [ -z "${MINHOOK_OBJS// }" ]; then
    echo "WARNING: No MinHook objects were built, falling back to pre-compiled libMinHook.x64.lib"
    MINHOOK_LIB="$SRC_DIR/libMinHook.x64.lib"
    MINHOOK_INC=""
  fi
else
  MINHOOK_OBJS=""
  MINHOOK_LIB="$SRC_DIR/libMinHook.x64.lib"
  MINHOOK_INC=""
fi

# --- Compile BackstageCapture sources ---
# DXGICapture.c is compiled as C++ for COM vtable calls and __uuidof
CXXFLAGS="-O2 -DWIN64 -D_WIN64 -DNDEBUG -D_WINDOWS -D_USRDLL"
CXXFLAGS="$CXXFLAGS -DBackstageCapture_EXPORTS -DWIN_X64"
CXXFLAGS="$CXXFLAGS -DREFLECTIVEDLLINJECTION_VIA_LOADREMOTELIBRARYR"
CXXFLAGS="$CXXFLAGS -DREFLECTIVEDLLINJECTION_CUSTOM_DLLMAIN"
CXXFLAGS="$CXXFLAGS -fno-stack-protector"
CXXFLAGS="$CXXFLAGS -fno-exceptions -fno-rtti"
CXXFLAGS="$CXXFLAGS -I$SRC_DIR"
if [ -n "${MINHOOK_INC:-}" ]; then
  CXXFLAGS="$CXXFLAGS $MINHOOK_INC"
fi

# C flags for ReflectiveLoader (pure C, no C++)
# Keep -fno-asynchronous-unwind-tables only for the loader shellcode
LOADER_CFLAGS="-O2 -DWIN64 -D_WIN64 -DNDEBUG -D_WINDOWS -D_USRDLL"
LOADER_CFLAGS="$LOADER_CFLAGS -DBackstageCapture_EXPORTS -DWIN_X64"
LOADER_CFLAGS="$LOADER_CFLAGS -DREFLECTIVEDLLINJECTION_VIA_LOADREMOTELIBRARYR"
LOADER_CFLAGS="$LOADER_CFLAGS -DREFLECTIVEDLLINJECTION_CUSTOM_DLLMAIN"
LOADER_CFLAGS="$LOADER_CFLAGS -fno-stack-protector"
LOADER_CFLAGS="$LOADER_CFLAGS -fno-asynchronous-unwind-tables"
LOADER_CFLAGS="$LOADER_CFLAGS -I$SRC_DIR"
if [ -n "${MINHOOK_INC:-}" ]; then
  LOADER_CFLAGS="$LOADER_CFLAGS $MINHOOK_INC"
fi

echo "Compiling ReflectiveLoader.c ..."
"$CC" -c $LOADER_CFLAGS -o "$SRC_DIR/ReflectiveLoader.o" "$SRC_DIR/ReflectiveLoader.c"

echo "Compiling ReflectiveDll.c (C++) ..."
"$CXX" -c $CXXFLAGS -include "$SRC_DIR/seh_compat.h" -o "$SRC_DIR/ReflectiveDll.o" "$SRC_DIR/ReflectiveDll.c"

echo "Compiling DXGICapture.c (C++) ..."
"$CXX" -c $CXXFLAGS -include "$SRC_DIR/seh_compat.h" -o "$SRC_DIR/DXGICapture.o" "$SRC_DIR/DXGICapture.c"

echo "Linking $DLL_NAME ..."
LINK_OBJS="$SRC_DIR/ReflectiveLoader.o $SRC_DIR/ReflectiveDll.o $SRC_DIR/DXGICapture.o"
if [ -n "${MINHOOK_OBJS:-}" ]; then
  LINK_OBJS="$LINK_OBJS $MINHOOK_OBJS"
fi
LINK_LIBS="-lkernel32 -luser32 -ladvapi32 -ld3d11 -ldxgi"
if [ -n "${MINHOOK_LIB:-}" ] && [ -f "${MINHOOK_LIB}" ]; then
  LINK_LIBS="$LINK_LIBS $MINHOOK_LIB"
fi

"$CXX" -shared -o "$OUT_DIR/$DLL_NAME" $LINK_OBJS $LINK_LIBS \
  -Wl,--entry,DllMain \
  -Wl,--disable-runtime-pseudo-reloc \
  -fno-stack-protector \
  -fno-exceptions -fno-rtti \
  -static-libgcc -static-libstdc++ \
  -s

echo "Built: $OUT_DIR/$DLL_NAME"
ls -la "$OUT_DIR/$DLL_NAME"

# Clean up object files
rm -f "$SRC_DIR"/*.o
if [ -d "$MINHOOK_DIR" ]; then
  find "$MINHOOK_DIR" -name '*.o' -delete
fi

echo "Done."