from contextlib import contextmanager

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

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

Base = declarative_base(bind = engine)

class Paste(Base):
    __tablename__ = 'paste'

    id = Column(Integer, primary_key = True)
    hash = Column(String, unique = True, index = True)
    nick = Column(String)
    date = Column(DateTime, nullable = False)
    syntax = Column(String)
    title = Column(String)
    text = Column(Text, nullable = False)
    ip = Column(String)

    def __init__(self, hash, nick, date, syntax, title, text, ip=None):
        self.nick = nick
        self.hash = hash
        self.date = date
        self.syntax = syntax
        self.title = title
        self.text = text
        self.ip = ip

    def __repr__(self):
        return '<Paste(%d, "%s", "%s", "%s", "%s")>' % (self.id, self.hash, self.nick, self.date.ctime(), self.title)

class Cache(Base):
    __tablename__ = 'cache'

    id = Column(Integer, primary_key = True)
    paste_hash = Column(String, ForeignKey('paste.hash'), index = True)
    paste = relation(Paste, primaryjoin = paste_hash == Paste.hash, lazy = False)
    syntax_name = Column(String)
    text = Column(Text, nullable = False)

    def __init__(self, hash, syntax_name, text):
        self.paste_hash = hash
        self.syntax_name = syntax_name
        self.text = text

    def __repr__(self):
        return '<Cache(%d, "%s")>' % (self.id, self.paste_hash)

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()