#!/usr/bin/env bash
# Summary: Display an installed Python version
# Usage: pyenv installed [<version>]
#
# Displays the installed Python version, searching for shortcuts if necessary.
# If no version is given, `pyenv installed' displays the latest installed version.
# If version is `system`, `system` will be returned if an installed system Python can be found.
# If version is `latest`, the latest installed Python version will be returned (3.12.3).
# If version is `3`, the latest installed Python version of this major version will be returned (3.12.3).
# If version is `12` or `3.12`, the latest installed patch of this minor version will be returned (3.12.3).
# If version is `3.12.3`, the same version will be returned if that patch version is installed (3.12.3).
# If version is not found or no versions are installed, an error message will be returned with an error code.

set -e
[ -n "$PYENV_DEBUG" ] && set -x

# Provide pyenv completions
if [ "$1" = "--complete" ]; then
  echo system
  exec pyenv-versions --bare
fi

majors=({3,2}) # Supported Python versions: 3,2 (latest first)

versions() {
  # Sort correctly (3.10.9 comes before 3.10.10)
  pyenv versions --bare | sort -V | $(type -p ggrep grep | head -1) -F "$query" || true
}

latest_version() {
  versions | tail -1
}

latest_major() {
  # 3 -> latest major 3.12.3
  versions | grep -oE "^$(regex "$1")\\.[0-9]+\\.[0-9]+$" | tail -1
}

latest_minor() {
  # 3.12 -> latest minor 3.12.3
  versions | grep -oE "^$(regex "$1")\\.([0-9]+)$" | tail -1
}

installed() {
  # 3.12.3 -> 3.12.3 if installed (else "")
  versions | grep -oE "^$(regex "$1")$" || true
}

regex() {
  echo "${1//\./\\.}"
}

if [ -n "$1" ]; then
  version="$1"
else
  version="latest"
fi

if [ "$version" = "system" ]; then
  if PYTHON_PATH="$(PYENV_VERSION="${version}" pyenv-which python 2>/dev/null)" || \
      PYTHON_PATH="$(PYENV_VERSION="${version}" pyenv-which python3 2>/dev/null)" || \
      PYTHON_PATH="$(PYENV_VERSION="${version}" pyenv-which python2 2>/dev/null)"; then
    echo "system"
    exit 0
  else
    echo "pyenv: system version not found in PATH" >&2
    exit 1
  fi
fi
if [ "$version" = "latest" ]; then
  LATEST_PATCH=$(latest_version)
  if [ -n "$LATEST_PATCH" ]; then
    echo "$LATEST_PATCH"
    exit 0
  else
    echo "pyenv: no versions installed" >&2
    exit 1
  fi
fi

# Check version=3 (major without minor and patch) => 3.12.3 (latest major version)
# Or version=12 (minor without major and patch) => 3.12.3 (latest patch version)
if grep -q -E "^[0-9]+(\s*)$" <<<"${version}"; then
  for major in "${majors[@]}"; do
    if [ "$version" = "$major" ]; then
      LATEST_MAJOR=$(latest_major "$version")
      if [ -n "$LATEST_MAJOR" ]; then
        echo "$LATEST_MAJOR"
        exit 0
      fi
    else
      LATEST_MINOR=$(latest_minor "$major.$version")
      if [ -n "$LATEST_MINOR" ]; then
        echo "$LATEST_MINOR"
        exit 0
      fi
    fi
  done
fi

# Check version=3.12 (minor without patch) => 3.12.3 (latest patch version)
if grep -q -E "^[0-9]+\.[0-9]+(\s*)$" <<<"${version}"; then
  LATEST_MINOR=$(latest_minor "$version")
  if [ -n "$LATEST_MINOR" ]; then
    echo "$LATEST_MINOR"
    exit 0
  fi
fi

# Check version=3.12.3 (full version number) => 3.12.3 (installed version)
if grep -q -E "^[0-9]+\.[0-9]+\.[0-9]+(\s*)$" <<<"${version}"; then
  INSTALLED=$(installed "$version")
  if [ -n "$INSTALLED" ]; then
    echo "$INSTALLED"
    exit 0
  fi
fi

echo "pyenv: version \`${version}' not installed" >&2
exit 1