# -*- coding: utf-8 -*-
from __future__ import unicode_literals, absolute_import

import logging
import re
import six

from collections import OrderedDict
from inspect import isclass

from .errors import RestError

log = logging.getLogger(__name__)

LEXER = re.compile(r'\{|\}|\,|[\w_:\-\*]+')


class MaskError(RestError):
    '''Raised when an error occurs on mask'''
    pass


class ParseError(MaskError):
    '''Raised when the mask parsing failed'''
    pass


class Mask(OrderedDict):
    '''
    Hold a parsed mask.

    :param str|dict|Mask mask: A mask, parsed or not
    :param bool skip: If ``True``, missing fields won't appear in result
    '''
    def __init__(self, mask=None, skip=False, **kwargs):
        self.skip = skip
        if isinstance(mask, six.string_types):
            super(Mask, self).__init__()
            self.parse(mask)
        elif isinstance(mask, (dict, OrderedDict)):
            super(Mask, self).__init__(mask, **kwargs)
        else:
            self.skip = skip
            super(Mask, self).__init__(**kwargs)

    def parse(self, mask):
        '''
        Parse a fields mask.
        Expect something in the form::

            {field,nested{nested_field,another},last}

        External brackets are optionals so it can also be written::

            field,nested{nested_field,another},last

        All extras characters will be ignored.

        :param str mask: the mask string to parse
        :raises ParseError: when a mask is unparseable/invalid

        '''
        if not mask:
            return

        mask = self.clean(mask)
        fields = self
        previous = None
        stack = []

        for token in LEXER.findall(mask):
            if token == '{':
                if previous not in fields:
                    raise ParseError('Unexpected opening bracket')
                fields[previous] = Mask(skip=self.skip)
                stack.append(fields)
                fields = fields[previous]
            elif token == '}':
                if not stack:
                    raise ParseError('Unexpected closing bracket')
                fields = stack.pop()
            elif token == ',':
                if previous in (',', '{', None):
                    raise ParseError('Unexpected comma')
            else:
                fields[token] = True

            previous = token

        if stack:
            raise ParseError('Missing closing bracket')

    def clean(self, mask):
        '''Remove unecessary characters'''
        mask = mask.replace('\n', '').strip()
        # External brackets are optional
        if mask[0] == '{':
            if mask[-1] != '}':
                raise ParseError('Missing closing bracket')
            mask = mask[1:-1]
        return mask

    def apply(self, data):
        '''
        Apply a fields mask to the data.

        :param data: The data or model to apply mask on
        :raises MaskError: when unable to apply the mask

        '''
        from . import fields
        # Should handle lists
        if isinstance(data, (list, tuple, set)):
            return [self.apply(d) for d in data]
        elif isinstance(data, (fields.Nested, fields.List, fields.Polymorph)):
            return data.clone(self)
        elif type(data) == fields.Raw:
            return fields.Raw(default=data.default, attribute=data.attribute, mask=self)
        elif data == fields.Raw:
            return fields.Raw(mask=self)
        elif isinstance(data, fields.Raw) or isclass(data) and issubclass(data, fields.Raw):
            # Not possible to apply a mask on these remaining fields types
            raise MaskError('Mask is inconsistent with model')
        # Should handle objects
        elif (not isinstance(data, (dict, OrderedDict)) and hasattr(data, '__dict__')):
            data = data.__dict__

        return self.filter_data(data)

    def filter_data(self, data):
        '''
        Handle the data filtering given a parsed mask

        :param dict data: the raw data to filter
        :param list mask: a parsed mask tofilter against
        :param bool skip: whether or not to skip missing fields

        '''
        out = {}
        for field, content in six.iteritems(self):
            if field == '*':
                continue
            elif isinstance(content, Mask):
                nested = data.get(field, None)
                if self.skip and nested is None:
                    continue
                elif nested is None:
                    out[field] = None
                else:
                    out[field] = content.apply(nested)
            elif self.skip and field not in data:
                continue
            else:
                out[field] = data.get(field, None)

        if '*' in self.keys():
            for key, value in six.iteritems(data):
                if key not in out:
                    out[key] = value
        return out

    def __str__(self):
        return '{{{0}}}'.format(','.join([
            ''.join((k, str(v))) if isinstance(v, Mask) else k
            for k, v in six.iteritems(self)
        ]))


def apply(data, mask, skip=False):
    '''
    Apply a fields mask to the data.

    :param data: The data or model to apply mask on
    :param str|Mask mask: the mask (parsed or not) to apply on data
    :param bool skip: If rue, missing field won't appear in result
    :raises MaskError: when unable to apply the mask

    '''
    return Mask(mask, skip).apply(data)
