from ..extensions import db
from ..tools.logs import write

from flask import jsonify
from sqlalchemy.exc import SQLAlchemyError
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

def get_time_options():
    time_options = [
        ('none', 'None'),
        ('60', '1 hour'),
        ('90', '1 hour 30 minutes'),
        ('120', '2 hours')
    ]
    return time_options

def get_dataset_choices():
    from ..models import Dataset
    try: datasets = Dataset.query.all()
    except SQLAlchemyError as exception:
        write('system.log', f'Database error when fetching dataset lists: {exception}')
        return []
    dataset_choices = []
    for dataset in datasets:
        label = dataset.get_name()
        label = f'{label} (Default)' if dataset.default else label
        choice = (dataset.id, label)
        dataset_choices.append(choice)
    return dataset_choices

def send_errors_to_client(form):
    errors = [*form.errors.values()]
    return jsonify({ 'error': errors}), 400