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

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

PYTHON_BIN="${PYTHON_BIN:-python3}"
REQUIREMENTS_FILE="${REQUIREMENTS_FILE:-${SCRIPT_DIR}/offline-runtime-requirements.txt}"
WHEELHOUSE_DIR="${WHEELHOUSE_DIR:-${SCRIPT_DIR}/wheelhouse}"
PIP_INDEX_URL="${PIP_INDEX_URL:-https://pypi.org/simple}"

# The supplied backend image is CPython 3.12 on Debian x86_64. These values can
# be overridden when building an offline bundle for a different image/CPU.
TARGET_PLATFORM="${TARGET_PLATFORM:-manylinux2014_x86_64}"
TARGET_PYTHON_VERSION="${TARGET_PYTHON_VERSION:-312}"
TARGET_IMPLEMENTATION="${TARGET_IMPLEMENTATION:-cp}"
TARGET_ABI="${TARGET_ABI:-cp312}"

die() {
  echo "ERROR: $*" >&2
  exit 1
}

require_cmd() {
  command -v "$1" >/dev/null 2>&1 || die "command not found: $1"
}

require_wheel() {
  local pattern="$1"
  compgen -G "${WHEELHOUSE_DIR}/${pattern}" >/dev/null || die "wheel not downloaded: ${pattern}"
}

require_cmd "${PYTHON_BIN}"
require_cmd sha256sum
[ -f "${REQUIREMENTS_FILE}" ] || die "requirements file not found: ${REQUIREMENTS_FILE}"
"${PYTHON_BIN}" -m pip --version >/dev/null 2>&1 || die "pip is not available for ${PYTHON_BIN}"

mkdir -p "${WHEELHOUSE_DIR}"

download_args=(
  download
  --dest "${WHEELHOUSE_DIR}"
  --only-binary=:all:
  --platform "${TARGET_PLATFORM}"
  --python-version "${TARGET_PYTHON_VERSION}"
  --implementation "${TARGET_IMPLEMENTATION}"
  --abi "${TARGET_ABI}"
)

echo "Downloading Linux/Python runtime wheels"
echo "  requirements: ${REQUIREMENTS_FILE}"
echo "  destination:  ${WHEELHOUSE_DIR}"
echo "  platform:     ${TARGET_PLATFORM}"
echo "  Python/ABI:   ${TARGET_PYTHON_VERSION}/${TARGET_ABI}"

"${PYTHON_BIN}" -m pip "${download_args[@]}" \
  --index-url "${PIP_INDEX_URL}" \
  --requirement "${REQUIREMENTS_FILE}"

require_wheel 'croniter-6.2.2-*.whl'
require_wheel 'hindsight_client-0.6.2-*.whl'
require_wheel 'redis-5.2.1-*.whl'
require_wheel 'aiomysql-0.3.2-*.whl'
require_wheel 'pymysql-1.2.0-*.whl'
require_wheel 'sqlalchemy-2.0.51-*.whl'
require_wheel 'greenlet-3.2.5-*.whl'

# Resolve the same requirements a second time using only wheelhouse. This
# catches a missing transitive dependency before the bundle reaches offline.
verify_dir="$(mktemp -d)"
cleanup() {
  if [ -n "${verify_dir:-}" ] && [ -d "${verify_dir}" ]; then
    rm -rf -- "${verify_dir}"
  fi
}
trap cleanup EXIT

verify_args=(
  download
  --dest "${verify_dir}"
  --no-index
  --find-links "${WHEELHOUSE_DIR}"
  --only-binary=:all:
  --platform "${TARGET_PLATFORM}"
  --python-version "${TARGET_PYTHON_VERSION}"
  --implementation "${TARGET_IMPLEMENTATION}"
  --abi "${TARGET_ABI}"
  --requirement "${REQUIREMENTS_FILE}"
)
"${PYTHON_BIN}" -m pip "${verify_args[@]}" >/dev/null

shopt -s nullglob
wheels=("${WHEELHOUSE_DIR}"/*.whl)
[ "${#wheels[@]}" -gt 0 ] || die "wheelhouse is empty: ${WHEELHOUSE_DIR}"
(
  cd "${WHEELHOUSE_DIR}"
  sha256sum -- *.whl | LC_ALL=C sort > SHA256SUMS
)

echo
echo "Wheelhouse is complete for the pinned runtime requirements."
echo "  wheel count: ${#wheels[@]}"
echo "  checksums:   ${WHEELHOUSE_DIR}/SHA256SUMS"
echo "Copy the wheelhouse directory with the deployment bundle."