from contextlib import contextmanager
import datetime
import mimetypes
import os

from flask import current_app
from sqlalchemy import create_engine, Column, Integer, String, DateTime, Text, Index, ForeignKey, Boolean, JSON
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, relation, backref
from sqlalchemy.orm.exc import NoResultFound
from sqlalchemy.exc import IntegrityError
from sqlalchemy.sql import and_

engine = create_engine(current_app.config['DB_URI'])

Base = declarative_base(bind = engine)

class User(Base):
    __tablename__ = 'users'

    id = Column(Integer, primary_key = True)
    username = Column(String, unique = True, index = True)
    jab_id = Column(String(24), unique = True, index = True)
    api_key_date = Column(DateTime, default = datetime.datetime.utcnow)
    files = relation('File', backref = 'user', order_by = 'File.date.desc()')

    def __init__(self, username, jab_id):
        self.username = username
        self.jab_id = jab_id

class UserSession(Base):
    __tablename__ = 'sessions'

    id = Column(Integer, primary_key = True)
    user_id = Column(Integer, ForeignKey('users.id'), index = True)
    access_token = Column(String)
    refresh_token = Column(String)
    updated = Column(DateTime)

    def __init__(self, user_id, access_token, refresh_token):
        self.user_id = user_id
        self.access_token = access_token
        self.refresh_token = refresh_token

class File(Base):
    __tablename__ = 'files'

    id = Column(Integer, primary_key = True)
    hash = Column(String, unique = True, index = True)
    filename = Column(String)
    date = Column(DateTime)
    user_id = Column(Integer, ForeignKey('users.id'), nullable = True)
    ip = Column(String)
    accessed = Column(DateTime)
    scanned = Column(Boolean, nullable=False, default=False)
    blocked_reason = Column(JSON)

    def __init__(self, hash, filename, date, user_id = None, ip = None):
        self.hash = hash
        self.filename = filename
        self.date = date
        self.user_id = user_id
        self.ip = ip

    @staticmethod
    def pretty_size(size):
        if size is None:
            return 'N/A'
        suffixes = (('TiB', 2**40), ('GiB', 2**30), ('MiB', 2**20), ('KiB', 2**10))
        for suf, threshold in suffixes:
            if size >= threshold:
                return '{:.2f} {}'.format(size / threshold, suf)
            else:
                continue
        return '{} B'.format(size)

    def get_path(self):
        return os.path.join(current_app.config['FILE_DIRECTORY'], self.hash + os.path.splitext(self.filename)[1])

    def get_thumb_path(self):
        return os.path.join(current_app.config['THUMB_DIRECTORY'], self.hash + '.jpg')

    def get_size(self):
        try:
            return os.path.getsize(self.get_path())
        except OSError:
            return None

    @property
    def formatted_size(self):
        return self.pretty_size(self.get_size())

    @property
    def formatted_date(self):
        return self.date.strftime('%Y-%m-%d %H:%M:%S UTC')

    def get_mime_type(self):
        return mimetypes.guess_type(self.filename, strict = False)[0] or 'application/octet-stream'

    def is_image(self):
        return self.get_mime_type().startswith('image')

    def is_video(self):
        return self.get_mime_type().startswith('video')

    @property
    def ext(self):
        return os.path.splitext(self.filename)[1]

    @property
    def exists(self):
        return os.path.exists(self.get_path())

Base.metadata.create_all()
Session = sessionmaker(bind = engine, autoflush = True, autocommit = False)

@contextmanager
def session_scope():
    session = Session()
    try:
        session.expire_on_commit = False
        yield session
        session.commit()
    except:
        session.rollback()
        raise
    finally:
        session.close()