import re
import enum
import decimal
import unicodedata
from sqlalchemy import inspect
from sqlalchemy.orm import exc, class_mapper
from sqlalchemy.orm.attributes import get_history
from werkzeug.exceptions import abort


def get_object_or_404(model, *criterion):
    try:
        rv = model.query.filter(*criterion).one()
    except (exc.NoResultFound, exc.MultipleResultsFound):
        abort(404)
    else:
        return rv


def strip_accents(text):
    """
    Strip accents from input String.

    :param text: The input string.
    :type text: String.

    :returns: The processed String.
    :rtype: String.
    """
    try:
        text = unicode(text, 'utf-8')
    except (TypeError, NameError): # unicode is a default on python 3
        pass
    text = unicodedata.normalize('NFD', text)
    text = text.encode('ascii', 'ignore')
    text = text.decode("utf-8")
    return str(text)


def text_to_id(text):
    """
    Convert input text to id.

    :param text: The input string.
    :type text: String.

    :returns: The processed String.
    :rtype: String.
    """
    text = strip_accents(text.lower())
    text = re.sub('[ ]+', '_', text)
    text = re.sub('[^0-9a-zA-Z_-]', '', text)
    return text


diff_sanitization_rules = [
    (enum.Enum, lambda v: v.name),
    (decimal.Decimal, float),
]


def get_diff(target, blacklist=['created', 'updated']):
    state_before = {}
    state_after = {}
    inspr = inspect(target)
    attrs = class_mapper(target.__class__).column_attrs
    for attr in attrs:
        if attr.key in blacklist:
            continue

        hist = getattr(inspr.attrs, attr.key).history
        if hist.has_changes():
            state_before[attr.key] = get_history(target, attr.key)[2].pop()
            state_after[attr.key] = getattr(target, attr.key)

            for data in [state_before, state_after]:
                for t, c in diff_sanitization_rules:
                    if isinstance(data[attr.key], t):
                        data[attr.key] = c(data[attr.key])

            if state_after[attr.key] == state_before[attr.key] or (state_after[attr.key] in ['', None] and state_before[attr.key] in ['', None]):
                state_after.pop(attr.key)
                state_before.pop(attr.key)

    return state_before, state_after