import hashlib
from enum import Enum
import logging

from core.tokenizer import Tokenizer, TokenKind

log = logging.getLogger(__name__)


class ConceptParts(Enum):
    WHERE = "where"
    PRE = "pre"
    POST = "post"
    BODY = "body"


class Concept:
    """
    Default concept object
    A concept is a the base object of our universe
    Everything is a concept
    """
    props_to_serialize = ("id", "is_builtin", "name", "where", "pre", "post", "body", "desc")

    PROPERTY_PREFIX = "__var__"

    def __init__(self, name=None, is_builtin=False, where=None, pre=None, post=None, body=None, desc=None, key=None):
        self.name = name
        self.is_builtin = is_builtin
        self.where = where  # condition to recognize variables in name
        self.pre = pre  # list of pre conditions before calling the main function
        self.post = post  # list of post conditions after calling the main function
        self.body = body  # main method, can also be the value of the concept
        self.desc = desc
        self.id = None
        self.key = key

        self.props = {}  # list of Property for this concept
        self.functions = {}  # list of helper functions

        self.codes = {}  # cached ast for the where, pre, post and body parts

    def __repr__(self):
        return f"({self.id}){self.name}"

    def __eq__(self, other):
        if not isinstance(other, Concept):
            return False
        return self.name == other.name and \
               self.where == other.where and \
               self.pre == other.pre and \
               self.post == other.post and \
               self.body == other.body

    def __hash__(self):
        return hash(self.name)

    def get_key(self):
        return self.key

    def init_key(self, tokens=None):
        """
        Create the key for this concept.
        Must be called only when the concept if fully initialized

        The method is not called set_key to make sure that no other class set the key by mistake
        :param tokens:
        :return:
        """
        if self.key is not None:
            return self.key

        if tokens is None:
            tokens = iter(Tokenizer(self.name))

        variables = list(self.props.keys())

        key = ""
        first = True
        for token in tokens:
            if token.type == TokenKind.EOF:
                break
            if token.type == TokenKind.WHITESPACE:
                continue
            if not first:
                key += " "
            if variables is not None and token.value in variables:
                key += self.PROPERTY_PREFIX + str(variables.index(token.value))
            else:
                key += token.value[1:-1] if token.type == TokenKind.STRING else token.value
            first = False

        self.key = key
        return self

    def add_codes(self, codes):
        """
        Gets the ASTs for 'where', 'pre', 'post' and 'body'
        There ASTs are know when the concept is freshly parsed.
        So the values are kept in cache.

        For concepts loaded from sdp, these ASTs must be created again
        :param codes:
        :return:
        """
        possibles_codes = set(item.value for item in ConceptParts)
        if codes is None:
            return
        for key in codes:
            if key in possibles_codes:
                self.codes[ConceptParts(key)] = codes[key]

        return self

    def get_digest(self):
        """
        Returns the digest of the event
        :return: hexa form of the sha256
        """
        return hashlib.sha256(f"Concept:{self.name}{self.pre}{self.post}{self.body}".encode("utf-8")).hexdigest()

    def to_dict(self):
        """
        Returns a dict representing 'self'
        :return:
        """
        props_as_dict = dict((prop, getattr(self, prop)) for prop in self.props_to_serialize)
        props_as_dict["props"] = [(p, self.props[p].value) for p in self.props]
        return props_as_dict

    def from_dict(self, as_dict):
        """
        Initializes 'self' from a dict
        :param as_dict:
        :return:
        """
        for prop in self.props_to_serialize:
            if prop in as_dict:
                setattr(self, prop, as_dict[prop])
        if "props" in as_dict:
            for n, v in as_dict["props"]:
                self.set_prop(n, v)
        return self

    def update_from(self, other):
        """
        Update self using the properties of another concept
        This method is to mimic the class to instance pattern
        'other' is the class, the template, and 'self' is a new instance
        :param other:
        :return:
        """
        for prop in self.props_to_serialize:
            setattr(self, prop, getattr(other, prop))

        return self

    def set_prop(self, prop_name, prop_value):
        self.props[prop_name] = Property(prop_name, prop_value)

    def set_prop_by_index(self, index, prop_value):
        prop_name = list(self.props.keys())[index]
        self.props[prop_name] = Property(prop_name, prop_value)

class ErrorConcept(Concept):
    NAME = "Error"

    def __init__(self, where=None, pre=None, post=None, body=None, desc=None):
        Concept.__init__(self, self.NAME, is_builtin=True, where=where, pre=pre, post=post, body=body, desc=desc)
        self.key = self.NAME

    def __repr__(self):
        return f"({self.id}){self.name}: {self.body}"


class TooManySuccessConcept(Concept):
    NAME = "Too many successful items"

    def __init__(self, items=None):
        super().__init__(self.NAME, body=items)
        self.key = self.NAME


class ReturnValueConcept(Concept):
    NAME = "Return Value"

    def __init__(self, return_value=None):
        super().__init__(self.NAME, body=return_value)
        self.key = self.NAME

    def __repr__(self):
        return f"({self.id}){self.name}: {self.body}"


class Property:
    """
    Defines a behaviour of Concept
    """

    def __init__(self, name, value):
        self.name = name
        self.value = value

    def __repr__(self):
        return f"{self.name}={self.value}"