__all__ = ['BaseConstructor', 'SafeConstructor', 'Constructor',
    'ConstructorError']

from .error import *
from .nodes import *

import collections, datetime, base64, binascii, re, sys, types

class ConstructorError(MarkedYAMLError):
    pass

class BaseConstructor:

    yaml_constructors = {}
    yaml_multi_constructors = {}

    def __init__(self):
        self.constructed_objects = {}
        self.recursive_objects = {}
        self.state_generators = []
        self.deep_construct = False

    def check_data(self):
        # If there are more documents available?
        return self.check_node()

    def get_data(self):
        # Construct and return the next document.
        if self.check_node():
            return self.construct_document(self.get_node())

    def get_single_data(self):
        # Ensure that the stream contains a single document and construct it.
        node = self.get_single_node()
        if node is not None:
            return self.construct_document(node)
        return None

    def construct_document(self, node):
        data = self.construct_object(node)
        while self.state_generators:
            state_generators = self.state_generators
            self.state_generators = []
            for generator in state_generators:
                for dummy in generator:
                    pass
        self.constructed_objects = {}
        self.recursive_objects = {}
        self.deep_construct = False
        return data

    def construct_object(self, node, deep=False):
        if node in self.constructed_objects:
            return self.constructed_objects[node]
        if deep:
            old_deep = self.deep_construct
            self.deep_construct = True
        if node in self.recursive_objects:
            raise ConstructorError(None, None,
                    "found unconstructable recursive node", node.start_mark)
        self.recursive_objects[node] = None
        constructor = None
        tag_suffix = None
        if node.tag in self.yaml_constructors:
            constructor = self.yaml_constructors[node.tag]
        else:
            for tag_prefix in self.yaml_multi_constructors:
                if node.tag.startswith(tag_prefix):
                    tag_suffix = node.tag[len(tag_prefix):]
                    constructor = self.yaml_multi_constructors[tag_prefix]
                    break
            else:
                if None in self.yaml_multi_constructors:
                    tag_suffix = node.tag
                    constructor = self.yaml_multi_constructors[None]
                elif None in self.yaml_constructors:
                    constructor = self.yaml_constructors[None]
                elif isinstance(node, ScalarNode):
                    constructor = self.__class__.construct_scalar
                elif isinstance(node, SequenceNode):
                    constructor = self.__class__.construct_sequence
                elif isinstance(node, MappingNode):
                    constructor = self.__class__.construct_mapping
        if tag_suffix is None:
            data = constructor(self, node)
        else:
            data = constructor(self, tag_suffix, node)
        if isinstance(data, types.GeneratorType):
            generator = data
            data = next(generator)
            if self.deep_construct:
                for dummy in generator:
                    pass
            else:
                self.state_generators.append(generator)
        self.constructed_objects[node] = data
        del self.recursive_objects[node]
        if deep:
            self.deep_construct = old_deep
        return data

    def construct_scalar(self, node):
        if not isinstance(node, ScalarNode):
            raise ConstructorError(None, None,
                    "expected a scalar node, but found %s" % node.id,
                    node.start_mark)
        return node.value

    def construct_sequence(self, node, deep=False):
        if not isinstance(node, SequenceNode):
            raise ConstructorError(None, None,
                    "expected a sequence node, but found %s" % node.id,
                    node.start_mark)
        return [self.construct_object(child, deep=deep)
                for child in node.value]

    def construct_mapping(self, node, deep=False):
        if not isinstance(node, MappingNode):
            raise ConstructorError(None, None,
                    "expected a mapping node, but found %s" % node.id,
                    node.start_mark)
        mapping = {}
        for key_node, value_node in node.value:
            key = self.construct_object(key_node, deep=deep)
            if not isinstance(key, collections.Hashable):
                raise ConstructorError("while constructing a mapping", node.start_mark,
                        "found unhashable key", key_node.start_mark)
            value = self.construct_object(value_node, deep=deep)
            mapping[key] = value
        return mapping

    def construct_pairs(self, node, deep=False):
        if not isinstance(node, MappingNode):
            raise ConstructorError(None, None,
                    "expected a mapping node, but found %s" % node.id,
                    node.start_mark)
        pairs = []
        for key_node, value_node in node.value:
            key = self.construct_object(key_node, deep=deep)
            value = self.construct_object(value_node, deep=deep)
            pairs.append((key, value))
        return pairs

    @classmethod
    def add_constructor(cls, tag, constructor):
        if not 'yaml_constructors' in cls.__dict__:
            cls.yaml_constructors = cls.yaml_constructors.copy()
        cls.yaml_constructors[tag] = constructor

    @classmethod
    def add_multi_constructor(cls, tag_prefix, multi_constructor):
        if not 'yaml_multi_constructors' in cls.__dict__:
            cls.yaml_multi_constructors = cls.yaml_multi_constructors.copy()
        cls.yaml_multi_constructors[tag_prefix] = multi_constructor

class SafeConstructor(BaseConstructor):

    def construct_scalar(self, node):
        if isinstance(node, MappingNode):
            for key_node, value_node in node.value:
                if key_node.tag == 'tag:yaml.org,2002:value':
                    return self.construct_scalar(value_node)
        return super().construct_scalar(node)

    def flatten_mapping(self, node):
        merge = []
        index = 0
        while index < len(node.value):
            key_node, value_node = node.value[index]
            if key_node.tag == 'tag:yaml.org,2002:merge':
                del node.value[index]
                if isinstance(value_node, MappingNode):
                    self.flatten_mapping(value_node)
                    merge.extend(value_node.value)
                elif isinstance(value_node, SequenceNode):
                    submerge = []
                    for subnode in value_node.value:
                        if not isinstance(subnode, MappingNode):
                            raise ConstructorError("while constructing a mapping",
                                    node.start_mark,
                                    "expected a mapping for merging, but found %s"
                                    % subnode.id, subnode.start_mark)
                        self.flatten_mapping(subnode)
                        submerge.append(subnode.value)
                    submerge.reverse()
                    for value in submerge:
                        merge.extend(value)
                else:
                    raise ConstructorError("while constructing a mapping", node.start_mark,
                            "expected a mapping or list of mappings for merging, but found %s"
                            % value_node.id, value_node.start_mark)
            elif key_node.tag == 'tag:yaml.org,2002:value':
                key_node.tag = 'tag:yaml.org,2002:str'
                index += 1
            else:
                index += 1
        if merge:
            node.value = merge + node.value

    def construct_mapping(self, node, deep=False):
        if isinstance(node, MappingNode):
            self.flatten_mapping(node)
        return super().construct_mapping(node, deep=deep)

    def construct_yaml_null(self, node):
        self.construct_scalar(node)
        return None

    bool_values = {
        'yes':      True,
        'no':       False,
        'true':     True,
        'false':    False,
        'on':       True,
        'off':      False,
    }

    def construct_yaml_bool(self, node):
        value = self.construct_scalar(node)
        return self.bool_values[value.lower()]

    def construct_yaml_int(self, node):
        value = self.construct_scalar(node)
        value = value.replace('_', '')
        sign = +1
        if value[0] == '-':
            sign = -1
        if value[0] in '+-':
            value = value[1:]
        if value == '0':
            return 0
        elif value.startswith('0b'):
            return sign*int(value[2:], 2)
        elif value.startswith('0x'):
            return sign*int(value[2:], 16)
        elif value[0] == '0':
            return sign*int(value, 8)
        elif ':' in value:
            digits = [int(part) for part in value.split(':')]
            digits.reverse()
            base = 1
            value = 0
            for digit in digits:
                value += digit*base
                base *= 60
            return sign*value
        else:
            return sign*int(value)

    inf_value = 1e300
    while inf_value != inf_value*inf_value:
        inf_value *= inf_value
    nan_value = -inf_value/inf_value   # Trying to make a quiet NaN (like C99).

    def construct_yaml_float(self, node):
        value = self.construct_scalar(node)
        value = value.replace('_', '').lower()
        sign = +1
        if value[0] == '-':
            sign = -1
        if value[0] in '+-':
            value = value[1:]
        if value == '.inf':
            return sign*self.inf_value
        elif value == '.nan':
            return self.nan_value
        elif ':' in value:
            digits = [float(part) for part in value.split(':')]
            digits.reverse()
            base = 1
            value = 0.0
            for digit in digits:
                value += digit*base
                base *= 60
            return sign*value
        else:
            return sign*float(value)

    def construct_yaml_binary(self, node):
        try:
            value = self.construct_scalar(node).encode('ascii')
        except UnicodeEncodeError as exc:
            raise ConstructorError(None, None,
                    "failed to convert base64 data into ascii: %s" % exc,
                    node.start_mark)
        try:
            if hasattr(base64, 'decodebytes'):
                return base64.decodebytes(value)
            else:
                return base64.decodestring(value)
        except binascii.Error as exc:
            raise ConstructorError(None, None,
                    "failed to decode base64 data: %s" % exc, node.start_mark)

    timestamp_regexp = re.compile(
            r'''^(?P<year>[0-9][0-9][0-9][0-9])
                -(?P<month>[0-9][0-9]?)
                -(?P<day>[0-9][0-9]?)
                (?:(?:[Tt]|[ \t]+)
                (?P<hour>[0-9][0-9]?)
                :(?P<minute>[0-9][0-9])
                :(?P<second>[0-9][0-9])
                (?:\.(?P<fraction>[0-9]*))?
                (?:[ \t]*(?P<tz>Z|(?P<tz_sign>[-+])(?P<tz_hour>[0-9][0-9]?)
                (?::(?P<tz_minute>[0-9][0-9]))?))?)?$''', re.X)

    def construct_yaml_timestamp(self, node):
        value = self.construct_scalar(node)
        match = self.timestamp_regexp.match(node.value)
        values = match.groupdict()
        year = int(values['year'])
        month = int(values['month'])
        day = int(values['day'])
        if not values['hour']:
            return datetime.date(year, month, day)
        hour = int(values['hour'])
        minute = int(values['minute'])
        second = int(values['second'])
        fraction = 0
        if values['fraction']:
            fraction = values['fraction'][:6]
            while len(fraction) < 6:
                fraction += '0'
            fraction = int(fraction)
        delta = None
        if values['tz_sign']:
            tz_hour = int(values['tz_hour'])
            tz_minute = int(values['tz_minute'] or 0)
            delta = datetime.timedelta(hours=tz_hour, minutes=tz_minute)
            if values['tz_sign'] == '-':
                delta = -delta
        data = datetime.datetime(year, month, day, hour, minute, second, fraction)
        if delta:
            data -= delta
        return data

    def construct_yaml_omap(self, node):
        # Note: we do not check for duplicate keys, because it's too
        # CPU-expensive.
        omap = []
        yield omap
        if not isinstance(node, SequenceNode):
            raise ConstructorError("while constructing an ordered map", node.start_mark,
                    "expected a sequence, but found %s" % node.id, node.start_mark)