import enum

from sqlalchemy import Column, Integer, String, TIMESTAMP, Text, ForeignKey, Enum, UniqueConstraint, func
from sqlalchemy.orm import relationship

from .base import Base


class BookStatusEnum(enum.Enum):
    available = 'available'
    borrowed = 'borrowed'
    reserved = 'reserved'


class Book(Base):
    __tablename__  = 'book'
    __table_args__ = (UniqueConstraint('isbn'),)

    id             = Column(Integer, primary_key=True, autoincrement=True)
    author_id      = Column(Integer, ForeignKey('author.id'), nullable=False)
    title          = Column(String(100), nullable=False)
    description    = Column(Text, nullable=False)
    year_published = Column(String(4), nullable=False)
    isbn           = Column(String(13), nullable=False, unique=True)
    status         = Column(Enum(BookStatusEnum), nullable=False, default=BookStatusEnum.available)
    created_at     = Column(TIMESTAMP, nullable=False, server_default=func.now())
    last_updated   = Column(TIMESTAMP, nullable=False, server_default=func.now())

    author                   = relationship('Author', back_populates='books')
    categories               = relationship('BookCategory',secondary='book_category_link',back_populates='books')

    def to_dict(self):
        book_dict = {col.name: getattr(self, col.name) for col in self.__table__.columns}
        
        book_dict['author'] = {
            'first_name': self.author.first_name,
            'last_name': self.author.last_name
        }

        book_dict['categories'] = [category.name for category in self.categories]
        
        return book_dict

__all__ = ["Book", "BookStatusEnum"]