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

# Verify that a Bun binary doesn't use CPU instructions beyond its baseline target.
# Uses QEMU user-mode emulation with restricted CPU features.
# Any illegal instruction (SIGILL) causes exit code 132 and fails the build.
#
# QEMU must be pre-installed in the CI image (see .buildkite/Dockerfile and
# scripts/bootstrap.sh).

ARCH=""
BINARY=""

while [[ $# -gt 0 ]]; do
  case $1 in
    --arch) ARCH="$2"; shift 2 ;;
    --binary) BINARY="$2"; shift 2 ;;
    *) echo "Unknown arg: $1"; exit 1 ;;
  esac
done

if [ -z "$ARCH" ] || [ -z "$BINARY" ]; then
  echo "Usage: $0 --arch <x64|aarch64> --binary <path>"
  exit 1
fi

if [ ! -f "$BINARY" ]; then
  echo "ERROR: Binary not found: $BINARY"
  exit 1
fi

# Select QEMU binary and CPU model
HOST_ARCH=$(uname -m)
if [ "$ARCH" = "x64" ]; then
  QEMU_BIN="qemu-x86_64"
  if [ -f "/usr/bin/qemu-x86_64-static" ]; then
    QEMU_BIN="qemu-x86_64-static"
  fi
  QEMU_CPU="Nehalem"
  CPU_DESC="Nehalem (SSE4.2, no AVX/AVX2/AVX512)"
elif [ "$ARCH" = "aarch64" ]; then
  QEMU_BIN="qemu-aarch64"
  if [ -f "/usr/bin/qemu-aarch64-static" ]; then
    QEMU_BIN="qemu-aarch64-static"
  fi
  # cortex-a53 is ARMv8.0-A (no LSE atomics, no SVE). It's the most widely
  # supported ARMv8.0 model across QEMU versions.
  QEMU_CPU="cortex-a53"
  CPU_DESC="Cortex-A53 (ARMv8.0-A+CRC, no LSE/SVE)"
else
  echo "ERROR: Unknown arch: $ARCH"
  exit 1
fi

if ! command -v "$QEMU_BIN" &>/dev/null; then
  echo "ERROR: $QEMU_BIN not found. It must be pre-installed in the CI image."
  exit 1
fi

BINARY_NAME=$(basename "$BINARY")

echo "--- Verifying $BINARY_NAME on $CPU_DESC"
echo "    Binary: $BINARY"
echo "    QEMU:   $QEMU_BIN -cpu $QEMU_CPU"
echo "    Host:   $HOST_ARCH"
echo ""

run_test() {
  local label="$1"
  shift
  echo "+++ $BINARY_NAME: $label"
  if "$QEMU_BIN" -cpu "$QEMU_CPU" "$@"; then
    echo "    PASS"
    return 0
  else
    local exit_code=$?
    echo ""
    if [ $exit_code -eq 132 ]; then
      echo "    FAIL: Illegal instruction (SIGILL)"
      echo ""
      echo "    The $BINARY_NAME binary uses CPU instructions not available on $QEMU_CPU."
      if [ "$ARCH" = "x64" ]; then
        echo "    The baseline x64 build targets Nehalem (SSE4.2)."
        echo "    AVX, AVX2, and AVX512 instructions are not allowed."
      else
        echo "    The aarch64 build targets Cortex-A53 (ARMv8.0-A+CRC)."
        echo "    LSE atomics, SVE, and dotprod instructions are not allowed."
      fi
    else
      echo "    FAIL: exit code $exit_code"
    fi
    exit $exit_code
  fi
}

run_test "bun --version" "$BINARY" --version
run_test "bun -e eval" "$BINARY" -e "console.log(JSON.stringify({ok:1+1}))"

echo ""
echo "    All checks passed for $BINARY_NAME on $QEMU_CPU."