# Copyright (c) 2014 TrilioData, Inc.
# All Rights Reserved.

"""
System-level utilities and helper functions.
"""

import logging
import sys
import six

LOG = logging.getLogger(__name__)


def int_from_bool_as_string(subject):
    """
    Interpret a string as a boolean and return either 1 or 0.

    Any string value in:

        ('True', 'true', 'On', 'on', '1')

    is interpreted as a boolean True.

    Useful for JSON-decoded stuff and config file parsing
    """
    return bool_from_string(subject) and 1 or 0


def bool_from_string(subject):
    """
    Interpret a string as a boolean.

    Any string value in:

        ('True', 'true', 'On', 'on', 'Yes', 'yes', '1')

    is interpreted as a boolean True.

    Useful for JSON-decoded stuff and config file parsing
    """
    if isinstance(subject, bool):
        return subject
    if isinstance(subject, six.string_types):
        if subject.strip().lower() in ("true", "on", "yes", "1"):
            return True
    return False


def safe_decode(text, incoming=None, errors="strict"):
    """
    Decodes incoming str using `incoming` if they're
    not already unicode.

    :param incoming: Text's current encoding
    :param errors: Errors handling policy. See here for valid
        values http://docs.python.org/2/library/codecs.html
    :returns: text or a unicode `incoming` encoded
                representation of it.
    :raises TypeError: If text is not an isntance of basestring
    """
    if not isinstance(text, six.string_types):
        raise TypeError("%s can't be decoded" % type(text))

    if isinstance(text, str):
        return text

    if not incoming:
        incoming = sys.stdin.encoding or sys.getdefaultencoding()

    try:
        return text.decode(incoming, errors)
    except UnicodeDecodeError:
        # Note(flaper87) If we get here, it means that
        # sys.stdin.encoding / sys.getdefaultencoding
        # didn't return a suitable encoding to decode
        # text. This happens mostly when global LANG
        # var is not set correctly and there's no
        # default encoding. In this case, most likely
        # python will use ASCII or ANSI encoders as
        # default encodings but they won't be capable
        # of decoding non-ASCII characters.
        #
        # Also, UTF-8 is being used since it's an ASCII
        # extension.
        return text.decode("utf-8", errors)


def safe_encode(text, incoming=None, encoding="utf-8", errors="strict"):
    """
    Encodes incoming str/unicode using `encoding`. If
    incoming is not specified, text is expected to
    be encoded with current python's default encoding.
    (`sys.getdefaultencoding`)

    :param incoming: Text's current encoding
    :param encoding: Expected encoding for text (Default UTF-8)
    :param errors: Errors handling policy. See here for valid
        values http://docs.python.org/2/library/codecs.html
    :returns: text or a bytestring `encoding` encoded
                representation of it.
    :raises TypeError: If text is not an isntance of basestring
    """
    if not isinstance(text, six.string_types):
        raise TypeError("%s can't be encoded" % type(text))

    if not incoming:
        incoming = sys.stdin.encoding or sys.getdefaultencoding()

    if isinstance(text, six.text_type):
        return text.encode(encoding, errors)
    elif text and encoding != incoming:
        # Decode text before encoding it with `encoding`
        text = safe_decode(text, incoming, errors)
        return text.encode(encoding, errors)

    return text