import re
import typing
import json
from itertools import chain

from sqlparse import tokens
from sqlparse.sql import Token, Parenthesis, Comparison, IdentifierList, Identifier, Function

from ..exceptions import SQLDecodeError
from .sql_tokens import SQLToken, SQLStatement
from . import query


def re_index(value: str):
    match = re.match(r'%\(([0-9]+)\)s', value, flags=re.IGNORECASE)
    if match:
        index = int(match.group(1))
    else:
        match = re.match(r'NULL', value, flags=re.IGNORECASE)
        if not match:
            raise SQLDecodeError
        index = None
    return index


class _Op:

    def __init__(
            self,
            statement: SQLStatement,
            query: 'query.SelectQuery',
            params: tuple = None,
            name='generic'):
        super().__init__()
        self.lhs: typing.Optional[_Op] = None
        self.rhs: typing.Optional[_Op] = None

        if params is not None:
            self.params = params
        else:
            self.params = query.params
        self.query = query
        self.left_table = query.left_table

        self.statement = statement
        self.is_negated = False
        self._name = name
        self.precedence = OPERATOR_PRECEDENCE[name]

    def negate(self):
        raise NotImplementedError

    def to_mongo(self):
        raise NotImplementedError


class _UnaryOp(_Op):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._op = None

    def negate(self):
        raise NotImplementedError

    def evaluate(self):
        self.rhs.evaluate()

    def to_mongo(self):
        return self.rhs.to_mongo()


class _BinaryOp(_Op):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        identifier = SQLToken.token2sql(self.statement.prev_token, self.query)
        self._field = identifier.field

    def negate(self):
        raise SQLDecodeError('Negating IN/NOT IN not supported')

    def to_mongo(self):
        raise NotImplementedError

    def evaluate(self):
        pass

class _InNotInOp(_BinaryOp):

    def _fill_in(self, token):
        self._in = []

        # Check for nested
        if token[1].ttype == tokens.DML:
            from .converters import NestedInQueryConverter

            self.query.nested_query = NestedInQueryConverter(token, self.query, 0)
            return

        for index in SQLToken.token2sql(token, self.query):
            if index is not None:
                self._in.append(self.params[index])
            else:
                self._in.append(None)

    def negate(self):
        raise SQLDecodeError('Negating IN/NOT IN not supported')

    def to_mongo(self):
        raise NotImplementedError

    def _to_mongo(self, op):
        if self.query.nested_query is not None:
            return {
                '$expr': {
                    op: ['$' + self._field, '$_nested_in']
                }
            }

        else:
            return {self._field: {op: self._in}}


class NotInOp(_InNotInOp):

    def __init__(self, *args, **kwargs):
        super().__init__(name='NOT IN', *args, **kwargs)
        tok = self.statement.next()
        if not tok.match(tokens.Keyword, 'IN'):
            raise SQLDecodeError
        self._fill_in(self.statement.next())

    def to_mongo(self):
        op = '$nin' if not self.is_negated else '$in'
        return self._to_mongo(op)

    def negate(self):
        self.is_negated = True


class InOp(_InNotInOp):

    def __init__(self, *args, **kwargs):
        super().__init__(name='IN', *args, **kwargs)
        self._fill_in(self.statement.next())

    def to_mongo(self):
        op = '$in' if not self.is_negated else '$nin'
        return self._to_mongo(op)

    def negate(self):
        self.is_negated = True


class LikeOp(_BinaryOp):

    def __init__(self, *args, **kwargs):
        super().__init__(name='LIKE', *args, **kwargs)
        self._regex = None
        self._make_regex(self.statement.next())

    def check_embedded(self, to_match):
        try:
            check_dict = to_match
            replace_chars = "\\%'"
            for c in replace_chars:
                if c == "'":
                    check_dict = check_dict.replace("'", '"')
                else:
                    check_dict = check_dict.replace(c, "")
            check_dict = json.loads(check_dict)
            if isinstance(check_dict, dict):
                return check_dict
            else:
                return to_match
        except Exception as e:
            return to_match

    def _make_regex(self, token):
        index = SQLToken.placeholder_index(token)

        to_match = self.params[index]
        to_match = self.check_embedded(to_match)
        if isinstance(to_match, str):
            to_match = to_match.replace('%', '.*')
            self._regex = '^' + to_match + '$'
        elif isinstance(to_match, dict):
            field_ext, to_match = next(iter(to_match.items()))
            self._field += '.' + field_ext
            self._regex = to_match
        else:
            raise SQLDecodeError
            
    def to_mongo(self):
        return {self._field: {'$regex': self._regex}}


class iLikeOp(LikeOp):
    def to_mongo(self):
        return {self._field: {
            '$regex': self._regex,
            '$options': 'im'
        }}


class IsOp(_BinaryOp):

    def __init__(self, *args, **kwargs):
        super().__init__(name='IS', *args, **kwargs)
        token = self.statement
        key = token.next()
        if key.match(tokens.Keyword, 'Null'):
            self._is_null = True
        elif key.match(tokens.Keyword, 'Not null'):
            self._is_null = False
        else:
            raise SQLDecodeError

    def negate(self):
        self.is_negated = True

    def to_mongo(self):
        is_null = not self._is_null if self.is_negated else self._is_null
        return {
            self._field: None if is_null else {'$ne': None}
        }


class BetweenOp(_BinaryOp):

    def __init__(self, *args, **kwargs):
        super().__init__(name='BETWEEN', *args, **kwargs)
        token = self.statement

        lower = token.next()
        lower = SQLToken.placeholder_index(lower)
        self._lower = self.params[lower]

        _and = token.next()
        if not _and.match(tokens.Keyword, 'AND'):
            raise SQLDecodeError

        upper = token.next()
        upper = SQLToken.placeholder_index(upper)
        self._upper = self.params[upper]

    def negate(self):
        self.is_negated = True

    def to_mongo(self):
        if not self.is_negated:
            return {
                self._field: {
                    '$gte': self._lower,
                    '$lte': self._upper
                }
            }
        else:
            return {
                self._field: {
                    '$not': {
                        '$gte': self._lower,
                        '$lte': self._upper
                    }
                }
            }


class NotOp(_UnaryOp):
    def __init__(self, *args, **kwargs):
        super().__init__(name='NOT', *args, **kwargs)

    def negate(self):
        raise SQLDecodeError

    def evaluate(self):
        self.rhs.negate()
        if isinstance(self.rhs, ParenthesisOp):
            self.rhs.evaluate()
        if self.lhs is not None:
            self.lhs.rhs = self.rhs


class _AndOrOp(_Op):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._acc = []

    def negate(self):
        self.is_negated = True

    def op_type(self):
        raise NotImplementedError

    def evaluate(self):
        if not (self.lhs and self.rhs):
            raise SQLDecodeError

        if isinstance(self.lhs, _AndOrOp):
            if self.op_type() == self.lhs.op_type():
                self._acc = self.lhs._acc + self._acc
            else:
                self._acc.insert(0, self.lhs)

        elif isinstance(self.lhs, ParenthesisOp):
            self.lhs.evaluate()
            self._acc.append(self.lhs)

        elif isinstance(self.lhs, _Op):
            self._acc.append(self.lhs)

        else:
            raise SQLDecodeError

        if isinstance(self.rhs, _AndOrOp):
            if self.op_type() == self.rhs.op_type():
                self._acc.extend(self.rhs._acc)
            else:
                self._acc.append(self.rhs)

        elif isinstance(self.rhs, ParenthesisOp):
            self.rhs.evaluate()
            self._acc.append(self.rhs)

        elif isinstance(self.rhs, _Op):
            self._acc.append(self.rhs)

        else:
            raise SQLDecodeError

        if self.lhs.lhs is not None:
            self.lhs.lhs.rhs = self
        if self.rhs.rhs is not None:
            self.rhs.rhs.lhs = self

    def to_mongo(self):
        if self.op_type() == AndOp:
            oper = '$and'
        else:
            oper = '$or'

        docs = [itm.to_mongo() for itm in self._acc]
        return {oper: docs}


class AndOp(_AndOrOp):

    def __init__(self, *args, **kwargs):
        super().__init__(name='AND', *args, **kwargs)

    def op_type(self):
        if not self.is_negated:
            return AndOp
        else:
            return OrOp


class OrOp(_AndOrOp):

    def __init__(self, *args, **kwargs):
        super().__init__(name='OR', *args, **kwargs)

    def op_type(self):
        if not self.is_negated:
            return OrOp
        else:
            return AndOp


class _StatementParser:

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._ops: typing.List[_Op] = []
        self._cmp_ops: typing.List[_Op] = []
        self._op = None

    def _token2op(self,
                  tok: Token,
                  statement: SQLStatement) -> '_Op':
        op = None
        kw = {'statement': statement, 'query': self.query}
        if tok.match(tokens.Keyword, 'AND'):
            op = AndOp(**kw)

        elif tok.match(tokens.Keyword, 'OR'):
            op = OrOp(**kw)

        elif tok.match(tokens.Keyword, 'IN'):
            op = InOp(**kw)

        elif tok.match(tokens.Keyword, 'NOT'):
            if statement.next_token.match(tokens.Keyword, 'IN'):
                op = NotInOp(**kw)
                statement.skip(1)
            else:
                op = NotOp(**kw)

        elif tok.match(tokens.Keyword, 'LIKE'):
            op = LikeOp(**kw)

        elif tok.match(tokens.Keyword, 'iLIKE'):
            op = iLikeOp(**kw)

        elif tok.match(tokens.Keyword, 'BETWEEN'):
            op = BetweenOp(**kw)
            statement.skip(3)

        elif tok.match(tokens.Keyword, 'IS'):
            op = IsOp(**kw)

        elif isinstance(tok, Comparison):
            if isinstance(tok.tokens[0], Function):
                op = FuncOp(tok, self.query)
            else:
                op = CmpOp(tok, self.query)

        elif isinstance(tok, Parenthesis):
            if (tok[1].match(tokens.Name.Placeholder, '.*', regex=True)
                    or tok[1].match(tokens.Keyword, 'Null')
                    or isinstance(tok[1], IdentifierList)
                    or tok[1].ttype == tokens.DML
            ):
                pass
            else:
                op = ParenthesisOp(SQLStatement(tok), self.query)

        elif tok.match(tokens.Punctuation, (')', '(')):
            pass

        elif isinstance(tok, Identifier):
            pass
        else:
            raise SQLDecodeError

        return op

    def _statement2ops(self):
        def link_op():
            if prev_op is not None:
                prev_op.rhs = op
                op.lhs = prev_op

        statement = self.statement

        prev_op = None
        op = None
        for tok in statement:
            op = self._token2op(tok, statement)
            if not op:
                continue
            link_op()
            if isinstance(op, CmpOp):
                self._cmp_ops.append(op)
            if not isinstance(op, (CmpOp, ParenthesisOp)):
                self._op_precedence(op)
            prev_op = op

        if prev_op.lhs is None:
            if isinstance(prev_op, (CmpOp, ParenthesisOp)):
                self._ops.append(prev_op)

    def _op_precedence(self, operator: _Op):
        ops = self._ops
        if not ops:
            ops.append(operator)
            return

        for i in range(len(ops)):
            if operator.precedence > ops[i].precedence:
                ops.insert(i, operator)
                break
        else:
            ops.append(operator)

    def evaluate(self):
        if self._op is not None:
            return

        if not self._ops:
            raise SQLDecodeError

        op = None
        while self._ops:
            op = self._ops.pop(0)
            op.evaluate()
        self._op = op


class WhereOp(_Op, _StatementParser):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.statement.skip(2)
        self._statement2ops()
        self.evaluate()

    def negate(self):
        raise NotImplementedError

    def to_mongo(self):
        return self._op.to_mongo()


class ParenthesisOp(_Op, _StatementParser):

    def to_mongo(self):
        return self._op.to_mongo()

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self._statement2ops()

    def negate(self):
        for op in chain(self._ops, self._cmp_ops):
            op.negate()


class CmpOp(_Op):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._identifier = SQLToken.token2sql(self.statement.left, self.query)

        if isinstance(self.statement.right, Identifier):
            raise SQLDecodeError('Join using WHERE not supported')

        self._operator = OPERATOR_MAP[self.statement.token_next(0)[1].value]
        index = re_index(self.statement.right.value)

        self._constant = self.params[index] if index is not None else None
        if isinstance(self._constant, dict):
            self._field_ext, self._constant = next(iter(self._constant.items()))
        else:
            self._field_ext = None

    def negate(self):
        self.is_negated = True

    def evaluate(self):
        pass

    def to_mongo(self):
        field = self._identifier.field
        if self._field_ext:
            field += '.' + self._field_ext

        if not self.is_negated:
            return {field: {self._operator: self._constant}}
        else:
            return {field: {'$not': {self._operator: self._constant}}}


class FuncOp(CmpOp):

    def to_mongo(self):
        field = self._identifier.field
        if self._field_ext:
            field += '.' + self._field_ext
        func = self.statement.tokens[0].get_name().lower()
        if func == 'day':
            func = 'dayOfMonth'
        return {
            '$expr': {
                self._operator: [
                    {'$' + func: '$' + field},
                    self._constant
                ]
            }
        }


OPERATOR_MAP = {
    '=': '$eq',
    '>': '$gt',
    '<': '$lt',
    '>=': '$gte',
    '<=': '$lte',
}
OPERATOR_PRECEDENCE = {
    'IS': 8,
    'BETWEEN': 7,
    'LIKE': 6,
    'IN': 5,
    'NOT IN': 4,
    'NOT': 3,
    'AND': 2,
    'OR': 1,
    'generic': 0
}