from ..modules import db

from wtforms.validators import ValidationError

import json
from sqlalchemy.ext import mutable

class JsonEncodedDict(db.TypeDecorator):
    """Enables JSON storage by encoding and decoding on the fly."""
    impl = db.Text

    def process_bind_param(self, value, dialect):
        if value is None:
            return '{}'
        else:
            return json.dumps(value)

    def process_result_value(self, value, dialect):
        if value is None:
            return {}
        else:
            return json.loads(value)

mutable.MutableDict.associate_with(JsonEncodedDict)

def value(min:int=0, max:int=None):
    if not max:
        message = f'Value must be greater than {min}.'
    else:
        message = f'Value must be between {min} and {max}.'
    def length(form, field):
        value = field.data or 0
        if value < min or max != None and value > max:
            raise ValidationError(message)
    return length