#!/usr/bin/env bash

set -euo pipefail

TARGET_VERSION="${1:-3.11}"
IFS="." read -r PYTHON_MAJOR PYTHON_MINOR _ <<< "${TARGET_VERSION}"

if [[ -n "${PYTHON_MINOR:-}" ]]; then
  PYTHON_BIN="python${PYTHON_MAJOR}.${PYTHON_MINOR}"
else
  PYTHON_BIN="python${PYTHON_MAJOR}"
fi

if command -v "${PYTHON_BIN}" >/dev/null 2>&1; then
  command -v "${PYTHON_BIN}"
  exit 0
fi

APT_RUNNER=()
if [[ "$(id -u)" -ne 0 ]]; then
  APT_RUNNER=(sudo)
fi

export DEBIAN_FRONTEND=noninteractive

"${APT_RUNNER[@]}" apt-get update >&2
if ! "${APT_RUNNER[@]}" apt-get install -y "${PYTHON_BIN}" "${PYTHON_BIN}-venv" >&2; then
  "${APT_RUNNER[@]}" apt-get install -y software-properties-common >&2
  "${APT_RUNNER[@]}" add-apt-repository -y ppa:deadsnakes/ppa >&2
  "${APT_RUNNER[@]}" apt-get update >&2
  "${APT_RUNNER[@]}" apt-get install -y "${PYTHON_BIN}" "${PYTHON_BIN}-venv" >&2
fi

command -v "${PYTHON_BIN}"