from ..extensions import db
from ..tools.encryption import decrypt, encrypt
from ..tools.logs import write

from flask import current_app as app
from flask.helpers import flash
from flask_login import current_user
from sqlalchemy.exc import SQLAlchemyError
from werkzeug.utils import secure_filename

from datetime import datetime
from json import dump
from os import path, remove
from pathlib import Path
from uuid import uuid4

class Dataset(db.Model):

    id = db.Column(db.String(36), primary_key=True)
    name = db.Column(db.String(128), nullable=False)
    tests = db.relationship('Test', backref='dataset')
    creator_id = db.Column(db.String(36), db.ForeignKey('user.id'))
    date = db.Column(db.DateTime, nullable=False)
    default = db.Column(db.Boolean, default=False, nullable=True)
    accessed = db.Column(db.DateTime, nullable=True)
    locked = db.Column(db.Boolean, default=False, nullable=True)

    def __repr__(self):
        return f'<Dataset {self.id}>.'

    @property
    def generate_id(self): raise AttributeError('generate_id is not a readable attribute.')

    generate_id.setter
    def generate_id(self): self.id = uuid4().hex

    @property
    def set_name(self): raise AttributeError('set_name is not a readable attribute.')
    
    set_name.setter
    def set_name(self, name:str): self.name = encrypt(name)
    
    def get_name(self): return decrypt(self.name)

    def make_default(self):
        try:
            for dataset in Dataset.query.all(): dataset.default = False
        except (SQLAlchemyError, ConnectionError) as exception:
            write('system.log', f'Database error when setting default dataset {self.id}: {exception}')
            return False, f'Database error {exception}.'
        self.default = True
        try: db.session.commit()
        except (SQLAlchemyError, ConnectionError) as exception:
            db.session.rollback()
            write('system.log', f'Database error when setting default dataset {self.id}: {exception}')
            return False, f'Database error {exception}.'
        write('system.log', f'Dataset {self.id} set as default by {current_user.get_username()}.')
        flash(message='Dataset set as default.', category='success')
        return True, f'Dataset set as default.'
    
    def delete(self):
        if self.default:
            message = 'Cannot delete the default dataset.'
            flash(message, 'error')
            return False, message
        try:
            if Dataset.query.count() == 1:
                message = 'Cannot delete the only dataset.'
                flash(message, 'error')
                return False, message
        except (SQLAlchemyError, ConnectionError) as exception:
            write('system.log', f'Database error when setting default dataset {self.id}: {exception}')
            return False, f'Database error {exception}.'
        write('system.log', f'Dataset {self.id} deleted by {current_user.get_username()}.')
        filename = secure_filename('.'.join([self.id,'json']))
        data = Path(app.config.get('DATA'))
        file_path = path.join(data, 'questions', filename)
        try:
            db.session.delete(self)
            db.session.commit()
        except (SQLAlchemyError, ConnectionError) as exception:
            db.session.rollback()
            write('system.log', f'Database error when trying to delete dataset {self.id}: {exception}')
            return False, f'Database error: {exception}'
        remove(file_path)
        return True, 'Dataset deleted.'
    
    def create(self, data:list, default:bool=False):
        self.generate_id()
        timestamp = datetime.now()
        file_path = self.get_file()
        with open(file_path, 'w') as file:
            dump(data, file, indent=2)
        self.date = timestamp
        self.creator = current_user
        if default: self.make_default()
        write('system.log', f'New dataset {self.get_name()} added by {current_user.get_username()}.')
        try:
            db.session.add(self)
            db.session.commit()
        except (SQLAlchemyError, ConnectionError) as exception:
            db.session.rollback()
            write('system.log', f'Database error when trying to crreate dataset {self.id}: {exception}')
            return False, f'Database error: {exception}'
        return True, 'Dataset created.'

    def check_file(self):
        filename = secure_filename('.'.join([self.id,'json']))
        data = Path(app.config.get('DATA'))
        file_path = path.join(data, 'questions', filename)
        if not path.isfile(file_path): return False, 'Data file is missing.'
        return True, 'Data file found.'

    def get_file(self):
        filename = secure_filename('.'.join([self.id,'json']))
        data = Path(app.config.get('DATA'))
        file_path = path.join(data, 'questions', filename)
        return file_path
    
    def update(self, data:list=None, default:bool=False):
        self.date = datetime.now()
        if default: self.make_default()
        file_path = self.get_file()
        with open(file_path, 'w') as file:
            dump(data, file, indent=2)
        write('system.log', f'Dataset {self.id} edited by {current_user.get_username()}.')
        flash(f'Dataset {self.get_name()} successfully edited.', 'success')
        try:
            db.session.add(self)
            db.session.commit()
        except (SQLAlchemyError, ConnectionError) as exception:
            db.session.rollback()
            write('system.log', f'Database error when trying to update dataset {self.id}: {exception}')
            return False, f'Database error: {exception}'
        return True, 'Dataset successfully edited.'