"""Collection of functions to coerce conversion of types with an intelligent guess."""
try:
    from collections.abc import Mapping
except ImportError:
    from collections import Mapping
from itertools import chain
from re import IGNORECASE, compile

from enum import Enum

from .compat import NoneType, integer_types, isiterable
from .decorators import memoizedproperty
from .exceptions import AuxlibError

__all__ = ["boolify", "typify", "maybecall", "listify", "numberify"]

BOOLISH_TRUE = ("true", "yes", "on", "y")
BOOLISH_FALSE = ("false", "off", "n", "no", "non", "none", "")
NULL_STRINGS = ("none", "~", "null", "\0")
BOOL_COERCEABLE_TYPES = (*integer_types, bool, float, complex, list, set, dict, tuple)
NUMBER_TYPES = (*integer_types, float, complex)
NUMBER_TYPES_SET = {*NUMBER_TYPES}
STRING_TYPES_SET = {str}

NO_MATCH = object()


class TypeCoercionError(AuxlibError, ValueError):

    def __init__(self, value, msg, *args, **kwargs):
        self.value = value
        super(TypeCoercionError, self).__init__(msg, *args, **kwargs)


class _Regex(object):

    @memoizedproperty
    def BOOLEAN_TRUE(self):
        return compile(r'^true$|^yes$|^on$', IGNORECASE), True

    @memoizedproperty
    def BOOLEAN_FALSE(self):
        return compile(r'^false$|^no$|^off$', IGNORECASE), False

    @memoizedproperty
    def NONE(self):
        return compile(r'^none$|^null$', IGNORECASE), None

    @memoizedproperty
    def INT(self):
        return compile(r'^[-+]?\d+$'), int

    @memoizedproperty
    def BIN(self):
        return compile(r'^[-+]?0[bB][01]+$'), bin

    @memoizedproperty
    def OCT(self):
        return compile(r'^[-+]?0[oO][0-7]+$'), oct

    @memoizedproperty
    def HEX(self):
        return compile(r'^[-+]?0[xX][0-9a-fA-F]+$'), hex

    @memoizedproperty
    def FLOAT(self):
        return compile(r'^[-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?$'), float

    @memoizedproperty
    def COMPLEX(self):
        return (compile(r'^(?:[-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?)?'  # maybe first float
                        r'[-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?j$'),     # second float with j
                complex)

    @property
    def numbers(self):
        yield self.INT
        yield self.FLOAT
        yield self.BIN
        yield self.OCT
        yield self.HEX
        yield self.COMPLEX

    @property
    def boolean(self):
        yield self.BOOLEAN_TRUE
        yield self.BOOLEAN_FALSE

    @property
    def none(self):
        yield self.NONE

    def convert_number(self, value_string):
        return self._convert(value_string, (self.numbers, ))

    def convert(self, value_string):
        return self._convert(value_string, (self.boolean, self.none, self.numbers, ))

    def _convert(self, value_string, type_list):
        return next((typish(value_string) if callable(typish) else typish
                     for regex, typish in chain.from_iterable(type_list)
                     if regex.match(value_string)),
                    NO_MATCH)


_REGEX = _Regex()


def numberify(value):
    """

    Examples:
        >>> [numberify(x) for x in ('1234', 1234, '0755', 0o0755, False, 0, '0', True, 1, '1')]
          [1234, 1234, 755, 493, 0, 0, 0, 1, 1, 1]
        >>> [numberify(x) for x in ('12.34', 12.34, 1.2+3.5j, '1.2+3.5j')]
        [12.34, 12.34, (1.2+3.5j), (1.2+3.5j)]

    """
    if isinstance(value, bool):
        return int(value)
    if isinstance(value, NUMBER_TYPES):
        return value
    candidate = _REGEX.convert_number(value)
    if candidate is not NO_MATCH:
        return candidate
    raise TypeCoercionError(value, "Cannot convert {0} to a number.".format(value))


def boolify(value, nullable=False, return_string=False):
    """Convert a number, string, or sequence type into a pure boolean.

    Args:
        value (number, string, sequence): pretty much anything

    Returns:
        bool: boolean representation of the given value

    Examples:
        >>> [boolify(x) for x in ('yes', 'no')]
        [True, False]
        >>> [boolify(x) for x in (0.1, 0+0j, True, '0', '0.0', '0.1', '2')]
        [True, False, True, False, False, True, True]
        >>> [boolify(x) for x in ("true", "yes", "on", "y")]
        [True, True, True, True]
        >>> [boolify(x) for x in ("no", "non", "none", "off", "")]
        [False, False, False, False, False]
        >>> [boolify(x) for x in ([], set(), dict(), tuple())]
        [False, False, False, False]
        >>> [boolify(x) for x in ([1], set([False]), dict({'a': 1}), tuple([2]))]
        [True, True, True, True]

    """
    # cast number types naturally
    if isinstance(value, BOOL_COERCEABLE_TYPES):
        return bool(value)
    # try to coerce string into number
    val = str(value).strip().lower().replace(".", "", 1)
    if val.isnumeric():
        return bool(float(val))
    elif val in BOOLISH_TRUE:
        return True
    elif nullable and val in NULL_STRINGS:
        return None
    elif val in BOOLISH_FALSE:
        return False
    else:  # must be False
        try:
            return bool(complex(val))
        except ValueError:
            if isinstance(value, str) and return_string:
                return value
            raise TypeCoercionError(value, "The value %r cannot be boolified." % value)


def boolify_truthy_string_ok(value):
    try:
        return boolify(value)
    except ValueError:
        assert isinstance(value, str), repr(value)
        return True


def typify_str_no_hint(value):
    candidate = _REGEX.convert(value)
    return candidate if candidate is not NO_MATCH else value


def typify(value, type_hint=None):
    """Take a primitive value, usually a string, and try to make a more relevant type out of it.
    An optional type_hint will try to coerce the value to that type.

    Args:
        value (Any): Usually a string, not a sequence
        type_hint (type or Tuple[type]):

    Examples:
        >>> typify('32')
        32
        >>> typify('32', float)
        32.0
        >>> typify('32.0')
        32.0
        >>> typify('32.0.0')
        '32.0.0'
        >>> [typify(x) for x in ('true', 'yes', 'on')]
        [True, True, True]
        >>> [typify(x) for x in ('no', 'FALSe', 'off')]
        [False, False, False]
        >>> [typify(x) for x in ('none', 'None', None)]
        [None, None, None]

    """
    # value must be a string, or there at least needs to be a type hint
    if isinstance(value, str):
        value = value.strip()
    elif type_hint is None:
        # can't do anything because value isn't a string and there's no type hint
        return value

    # now we either have a stripped string, a type hint, or both
    # use the hint if it exists
    if isiterable(type_hint):
        if isinstance(type_hint, type) and issubclass(type_hint, Enum):
            try:
                return type_hint(value)
            except ValueError as e:
                try:
                    return type_hint[value]
                except KeyError:
                    raise TypeCoercionError(value, str(e))
        type_hint = set(type_hint)
        if not (type_hint - NUMBER_TYPES_SET):
            return numberify(value)
        elif not (type_hint - STRING_TYPES_SET):
            return str(value)
        elif not (type_hint - {bool, NoneType}):
            return boolify(value, nullable=True)
        elif not (type_hint - (STRING_TYPES_SET | {bool})):
            return boolify(value, return_string=True)
        elif not (type_hint - (STRING_TYPES_SET | {NoneType})):
            value = str(value)
            return None if value.lower() == 'none' else value
        elif not (type_hint - {bool, int}):
            return typify_str_no_hint(str(value))
        else:
            raise NotImplementedError()
    elif type_hint is not None:
        # coerce using the type hint, or use boolify for bool
        try:
            return boolify(value) if type_hint == bool else type_hint(value)
        except ValueError as e:
            # ValueError: invalid literal for int() with base 10: 'nope'
            raise TypeCoercionError(value, str(e))
    else:
        # no type hint, but we know value is a string, so try to match with the regex patterns
        #   if there's still no match, `typify_str_no_hint` will return `value`
        return typify_str_no_hint(value)


def typify_data_structure(value, type_hint=None):
    if isinstance(value, Mapping):
        return type(value)((k, typify(v, type_hint)) for k, v in value.items())
    elif isiterable(value):
        return type(value)(typify(v, type_hint) for v in value)
    elif isinstance(value, str) and isinstance(type_hint, type) and issubclass(type_hint, str):
        # This block is necessary because if we fall through to typify(), we end up calling
        # .strip() on the str, when sometimes we want to preserve preceding and trailing
        # whitespace.
        return type_hint(value)
    else:
        return typify(value, type_hint)


def maybecall(value):
    return value() if callable(value) else value


def listify(val, return_type=tuple):
    """
    Examples:
        >>> listify('abc', return_type=list)
        ['abc']
        >>> listify(None)
        ()
        >>> listify(False)
        (False,)
        >>> listify(('a', 'b', 'c'), return_type=list)
        ['a', 'b', 'c']
    """
    # TODO: flatlistify((1, 2, 3), 4, (5, 6, 7))
    if val is None:
        return return_type()
    elif isiterable(val):
        return return_type(val)
    else:
        return return_type((val, ))