#!/bin/bash
# PR构建专用：只构建不推送，只读缓存不写，用于PR阶段验证Dockerfile
set -eu

NO_CACHE_FLAG=""
if [ "$1" = "--no-cache" ]; then
  NO_CACHE_FLAG="--no-cache"
  shift
fi

DOCKERFILE="$1"
IMAGE_TAG="$2"
CACHE_REF="$3"
shift 3
BUILD_ARGS=""
for arg in "$@"; do
  BUILD_ARGS="$BUILD_ARGS --build-arg $arg"
done

BUILDER_NAME="ci-pr-builder-${GITHUB_RUN_ID:-local}"
if ! docker buildx inspect "$BUILDER_NAME" > /dev/null 2>&1; then
  docker buildx create --use --name "$BUILDER_NAME" --driver docker-container
else
  docker buildx use "$BUILDER_NAME"
fi
docker buildx inspect --bootstrap

CACHE_NAME=$(echo "$CACHE_REF" | tr "/" "_" | tr ":" "-")
LOCAL_CACHE_DIR="/tmp/buildx-cache/${CACHE_NAME}"
mkdir -p "$LOCAL_CACHE_DIR"

echo "=== PR Build: build only, no push, read-only cache ==="
echo "Dockerfile: ${DOCKERFILE}"
echo "Image tag: ${IMAGE_TAG}"
echo ""

build_with_retry() {
  local attempt=1
  local max_attempts=2
  while [ $attempt -le $max_attempts ]; do
    local build_output
    local exit_code
    set +e
    build_output=$(docker buildx build \
      $NO_CACHE_FLAG \
      $BUILD_ARGS \
      --cache-from "type=local,src=${LOCAL_CACHE_DIR}" \
      --cache-from "type=registry,ref=${CACHE_REF}" \
      -f "${DOCKERFILE}" \
      -t "${IMAGE_TAG}" \
      --load \
      . 2>&1)
    exit_code=$?
    set -e
    if [ $exit_code -eq 0 ]; then
      echo "$build_output"
      return 0
    fi
    if echo "$build_output" | grep -qE "parent snapshot.*not found|snapshot.*does not exist|cache.*corrupt|failed to compute cache key"; then
      echo "$build_output"
      echo "Local cache corrupted, cleaning and retrying ($attempt/$max_attempts)..."
      rm -rf "${LOCAL_CACHE_DIR}"
      mkdir -p "${LOCAL_CACHE_DIR}"
      docker buildx prune -f -a >/dev/null 2>&1 || true
      attempt=$((attempt + 1))
    else
      echo "$build_output"
      return $exit_code
    fi
  done
  echo "Local cache failed, building with registry cache only..."
  docker buildx build \
    $NO_CACHE_FLAG \
    $BUILD_ARGS \
    --cache-from "type=registry,ref=${CACHE_REF}" \
    -f "${DOCKERFILE}" \
    -t "${IMAGE_TAG}" \
    --load \
    .
}

build_with_retry
echo ""
echo "PR build OK (not pushed): ${IMAGE_TAG}"