#!/usr/bin/env bash
# Summary: Writes specified version(s) to the specified file if the version(s) exist
# Usage: pyenv version-file-write <file> <version>
# If the specified version is not installed, only display error message and return error code.
# If only a single version="system" is specified and installed, display previous version (if any) and remove file.

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

PYENV_VERSION_FILE="$1"
shift || true
versions=("$@")

if [ -z "$versions" ] || [ -z "$PYENV_VERSION_FILE" ]; then
  pyenv-help --usage version-file-write >&2
  exit 1
fi

# Make sure the specified version(s) are installed.
# Use pyenv-prefix loop logic.
if [ -n "$1" ]; then
  OLDIFS="$IFS"
  {
    IFS=:
    export PYENV_VERSION="$*"
  }
  IFS="$OLDIFS"
elif [ -z "$PYENV_VERSION" ]; then
  PYENV_VERSION="$(pyenv-version-name)"
fi

PYENV_VERSIONS=()
OLDIFS="$IFS"
{
  IFS=:
  for version in ${PYENV_VERSION}; do
    if ! INSTALLED="$(pyenv-installed "$version" 2>&1)"; then
      echo "$INSTALLED" >&2
      exit 1
    fi
    PYENV_VERSIONS=("${PYENV_VERSIONS[@]}" "$INSTALLED")
  done
}
IFS="$OLDIFS"

# Special case: only system was specified and found
if [ "$1" = "system" ]; then
  if [ -f "$PYENV_VERSION_FILE" ]; then
    if previous="$(head -1 "$PYENV_VERSION_FILE" | grep -E "^[0-9]+\.[0-9]+\.[0-9]+$")"; then
      echo "pyenv: using system version instead of $previous now"
    fi
    rm "$PYENV_VERSION_FILE"
  fi
else
  # Write the version out to disk.
  # Create an empty file. Using "rm" might cause a permission error.
  > "$PYENV_VERSION_FILE"
  for version in "${PYENV_VERSIONS[@]}"; do
    echo "$version" >> "$PYENV_VERSION_FILE"
  done
fi