#!/bin/bash

source $(dirname "$0")/activate

PYTHON_VERSION=${PYTHON_VERSION:-}


function python() {
    # call get_python_exe only the first time it is required
    export PYTHON_EXECUTABLE=${PYTHON_EXECUTABLE:-$(python_executable)}
    if [ -x "${PYTHON_EXECUTABLE}" ]; then
        "${PYTHON_EXECUTABLE}" "$@"
    else
        exit 1
    fi
}


function python_executable() {
    local version=${PYTHON_VERSION:-}
    local executables=( $( list_python_executables ) )
    for executable in "${executables[@]}"; do
        if "${executable}" -c "${SELECT_PYTHON_EXECUTABLE_SCRIPT}" "${version}"; then
            echo "${executable}"
            exit 0
        fi
    done
    fail 1 "No such Python executable (PYTHON_VERSION=${PYTHON_VERSION})"
}


function list_python_executables() {
    PATH=${CI_TOOLS_ORIGINAL_PATH} which $(list_python_names) 2> /dev/null
}


function list_python_names() {
    local version=${PYTHON_VERSION}
    if [ "${version}" != "" ]; then
        echo "python${version}"
    fi
    echo python3.7
    echo python3.6
    echo python3
    echo python
}


function fail() {
    local error=$1
    shift
    echo "$@" 1>&2
    exit "${error}"
}


read -r -d '' SELECT_PYTHON_EXECUTABLE_SCRIPT << END_OF_SCRIPT
import sys
version = ".".join(str(i) for i in sys.version_info[:3])
if version.startswith(sys.argv[1]):
    exit(0)
else:
    exit(1)
END_OF_SCRIPT


if [ $(basename "$0") == python ]; then
    set -euo pipefail
    python "$@"
fi