#!/usr/bin/env bash

PYTHON_VIRTUALENV_VERSION="20120927"

set -E
exec 3<&2 # preserve original stderr at fd 3


lib() {
  parse_options() {
    OPTIONS=()
    ARGUMENTS=()
    local arg option index

    for arg in "$@"; do
      if [ "${arg:0:1}" = "-" ]; then
        if [ "${arg:1:1}" = "-" ]; then
          OPTIONS[${#OPTIONS[*]}]="${arg:2}"
        else
          index=1
          while option="${arg:$index:1}"; do
            [ -n "$option" ] || break
            OPTIONS[${#OPTIONS[*]}]="$option"
            index=$(($index+1))
          done
        fi
      else
        ARGUMENTS[${#ARGUMENTS[*]}]="$arg"
      fi
    done
  }

  if [ "$1" == "--$FUNCNAME" ]; then
    declare -f "$FUNCNAME"
    echo "$FUNCNAME \"\$1\";"
    exit
  fi
}
lib "$1"

resolve_link() {
  $(type -p greadlink readlink | head -1) "$1"
}

abs_dirname() {
  local cwd="$(pwd)"
  local path="$1"

  while [ -n "$path" ]; do
    cd "${path%/*}"
    local name="${path##*/}"
    path="$(resolve_link "$name" || true)"
  done

  pwd
  cd "$cwd"
}

version() {
  echo "python-virtualenv ${PYTHON_VIRTUALENV_VERSION}"
}

usage() {
  { version
    echo "usage: python-virtualenv [-v|--verbose] [VIRTUALENV_OPTIONS] python_prefix virtualenv_path"
  } >&2

  if [ -z "$1" ]; then
    exit 1
  fi
}

unset VERBOSE
PYTHON_VIRTUALENV_ROOT="$(abs_dirname "$0")/.."
VIRTUALENV_OPTIONS=()

parse_options "$@"

for option in "${OPTIONS[@]}"; do
  case "$option" in
  "h" | "help" )
    usage without_exiting
    { echo
      echo "  -v/--verbose     Verbose mode: print compilation status to stdout"
      echo
    } >&2
    exit 0
    ;;
  "v" | "verbose" )
    VERBOSE=true
    ;;
  "version" )
    version
    exit 0
    ;;
  * )
    VIRTUALENV_OPTIONS[${#VIRTUALENV_OPTIONS[*]}]="--$option"
    ;;
  esac
done

PYTHON_PREFIX="${ARGUMENTS[0]}"
if [ -z "$PYTHON_PREFIX" ]; then
  usage
elif [ ! -x "${PYTHON_PREFIX}/bin/python" ]; then
  echo "python-virtualenv: python not found: ${PYTHON_PREFIX}" >&2
  exit 1
fi

VIRTUALENV_PATH="${ARGUMENTS[1]}"
if [ -z "$VIRTUALENV_PATH" ]; then
  usage
fi

BOOTSTRAP_PYTHON_BIN="${PYTHON_PREFIX}/bin/python"
PYTHON_BIN="${VIRTUALENV_PATH}/bin/python"

# find canonical name of python executable.
# virtualenv will create "bin/python" executable as same name as its bootstraped python.
if test -L "${BOOTSTRAP_PYTHON_BIN}"; then
  while test -L "${BOOTSTRAP_PYTHON_BIN}"; do # retrieve symlinks
    BOOTSTRAP_PYTHON_BIN="$(dirname "${BOOTSTRAP_PYTHON_BIN}")/$(resolve_link "${BOOTSTRAP_PYTHON_BIN}")"
  done
else
# python 2.6 and older don't have "bin/python" as symlink.
# so we must traverse files like "bin/python*" to obtain canonical name.
  for python in ${PYTHON_PREFIX}/bin/python*; do
    if ( basename "$python" | grep '^python[0-9][0-9]*\.[0-9][0-9]*$' && cmp "$BOOTSTRAP_PYTHON_BIN" "$python" ) >/dev/null; then
      BOOTSTRAP_PYTHON_BIN="${python}"
      break
    fi
  done
fi

# create virtualenv
"${BOOTSTRAP_PYTHON_BIN}" "${PYTHON_VIRTUALENV_ROOT}/libexec/virtualenv.py" "${VIRTUALENV_OPTIONS[@]}" "${VIRTUALENV_PATH}"

# create symlink of `python' bound for actual executable
if [ ! -f "$PYTHON_BIN" ]; then
  if test -f "${VIRTUALENV_PATH}/bin/$(basename "${BOOTSTRAP_PYTHON_BIN}")"; then
    {
      cd ${VIRTUALENV_PATH}/bin
      ln -fs "$(basename "${BOOTSTRAP_PYTHON_BIN}")" python
    }
  fi
fi