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

VSCODE_DIR=/opt/vscode
PRODUCT_JSON="${VSCODE_DIR}/resources/app/product.json"
RELEASES_API='https://update.code.visualstudio.com/api/releases/stable'

installed_version() {
  if [[ ! -f "${PRODUCT_JSON}" ]]; then
    return 0
  fi
  python3 -c "import json; print(json.load(open('${PRODUCT_JSON}'))['version'])"
}

latest_version() {
  curl -fsSL "${RELEASES_API}" | python3 -c 'import json, sys; print(json.load(sys.stdin)[0])'
}

vscode_arch() {
  case "$(uname -m)" in
    x86_64) echo linux-x64 ;;
    aarch64) echo linux-arm64 ;;
    *)
      echo "unsupported architecture: $(uname -m)" >&2
      exit 1
      ;;
  esac
}

needs_upgrade() {
  local installed="$1" latest="$2"

  [[ -z "${installed}" ]] && return 0
  [[ "${installed}" == "${latest}" ]] && return 1
  [[ "$(printf '%s\n' "${installed}" "${latest}" | sort -V | head -n1)" == "${installed}" ]]
}

installed="$(installed_version || true)"
latest="$(latest_version)"

if ! needs_upgrade "${installed}" "${latest}"; then
  if [[ -z "${installed}" ]]; then
    echo "VS Code is not installed at ${VSCODE_DIR}"
  else
    echo "VS Code ${installed} is up to date"
  fi
  exit 0
fi

echo "Upgrading VS Code: ${installed:-not installed} -> ${latest}"

arch="$(vscode_arch)"
tmp="$(mktemp -d)"
trap 'rm -rf "${tmp}"' EXIT

archive="${tmp}/vscode.tar.gz"
curl -fsSL "https://update.code.visualstudio.com/${latest}/${arch}/stable" -o "${archive}"
tar -xzf "${archive}" -C "${tmp}"

extract_dir="$(find "${tmp}" -maxdepth 1 -type d -name 'VSCode-linux-*' -print -quit)"
if [[ -z "${extract_dir}" ]]; then
  echo "failed to find extracted VS Code directory" >&2
  exit 1
fi

mkdir -p "$(dirname "${VSCODE_DIR}")"
if [[ -d "${VSCODE_DIR}" ]]; then
  rm -rf "${VSCODE_DIR}.old"
  mv "${VSCODE_DIR}" "${VSCODE_DIR}.old"
fi
mv "${extract_dir}" "${VSCODE_DIR}"
rm -rf "${VSCODE_DIR}.old"

echo "VS Code upgraded to ${latest}"