import abc
from . import actions, exceptions

LOG_TRUNCATE = 1024


class Message(object):
    __metaclass__ = abc.ABCMeta
    logattrs = []

    def __init__(self, tokens):
        track = set([])
        for i in tokens:
            if i.unique_name:
                if i.unique_name in track:
                    raise exceptions.ParseException(
                        "Message has multiple %s clauses, "
                        "but should only have one." % i.unique_name,
                        0, 0
                    )
                else:
                    track.add(i.unique_name)
        self.tokens = tokens

    def copy(self):
        return self.__class__(self.tokens[:])

    def toks(self, klass):
        """
            Fetch all tokens that are instances of klass
        """
        return [i for i in self.tokens if isinstance(i, klass)]

    def tok(self, klass):
        """
            Fetch first token that is an instance of klass
        """
        l = self.toks(klass)
        if l:
            return l[0]

    def length(self, settings):
        """
            Calculate the length of the base message without any applied
            actions.
        """
        return sum(len(x) for x in self.values(settings))

    def preview_safe(self):
        """
            Return a copy of this message that issafe for previews.
        """
        tokens = [i for i in self.tokens if not isinstance(i, actions.PauseAt)]
        return self.__class__(tokens)

    def maximum_length(self, settings):
        """
            Calculate the maximum length of the base message with all applied
            actions.
        """
        l = self.length(settings)
        for i in self.actions:
            if isinstance(i, actions.InjectAt):
                l += len(i.value.get_generator(settings))
        return l

    @classmethod
    def expr(klass): # pragma: no cover
        pass

    def log(self, settings):
        """
            A dictionary that should be logged if this message is served.
        """
        ret = {}
        for i in self.logattrs:
            v = getattr(self, i)
            # Careful not to log any VALUE specs without sanitizing them first.
            # We truncate at 1k.
            if hasattr(v, "values"):
                v = [x[:LOG_TRUNCATE] for x in v.values(settings)]
                v = "".join(v).encode("string_escape")
            elif hasattr(v, "__len__"):
                v = v[:LOG_TRUNCATE]
                v = v.encode("string_escape")
            ret[i] = v
        ret["spec"] = self.spec()
        return ret

    def freeze(self, settings):
        r = self.resolve(settings)
        return self.__class__([i.freeze(settings) for i in r.tokens])

    def __repr__(self):
        return self.spec()