from app import db
from marshmallow import Schema, fields, ValidationError, pre_load

authors = db.Table('books_authors',
    db.Column('book_id', db.Integer, db.ForeignKey('books.id'), primary_key=True),
    db.Column('author_id', db.Integer, db.ForeignKey('authors.id'), primary_key=True)
)

tags = db.Table('books_tags',
    db.Column('book_id', db.Integer, db.ForeignKey('books.id'), primary_key=True),
    db.Column('tag_id', db.Integer, db.ForeignKey('tags.id'), primary_key=True)
)

class Book(db.Model):
    __tablename__ = 'books'
    id = db.Column(db.Integer, primary_key = True)
    title = db.Column(db.String(255))
    file = db.Column(db.String(255))
    cover = db.Column(db.String(255))
    fileformat = db.Column(db.String(255))
    category = db.Column(db.String(255))
    authors = db.relationship('Author', secondary=authors, lazy='subquery',
        backref=db.backref('books', lazy=True))
    tags = db.relationship('Tag', secondary=tags, lazy='subquery',
        backref=db.backref('books', lazy=True))

    def __init__(self, title, file, cover, fileformat, category):
        self.title = title
        self.file = file
        self.cover = cover
        self.fileformat = fileformat
        self.category = category


    def __repr__(self):
        return '<Title %r>' % self.title

    def get_id(self):
        return self.id


class Author(db.Model):
    __tablename__ = 'authors'
    id = db.Column(db.Integer(), primary_key=True)
    author_name = db.Column(db.String(50))

    def __init__(self, author_name):
        self.author_name = author_name

class Tag(db.Model):
    __tablename__ = 'tags'
    id = db.Column(db.Integer(), primary_key=True)
    tag = db.Column(db.String(50))

    def __init__(self, tag):
        self.tag = tag

class AuthorSchema(Schema):
    id = fields.Int(dump_only=True)
    author_name = fields.Str()

class BookSchema(Schema):
    id = fields.Int(dump_only=True)
    title = fields.Str()
    file = fields.Str()
    authors = fields.Nested(AuthorSchema, many=True)
    cover = fields.Str()
    fileformat = fields.Str()
    category = fields.Str()



def must_not_be_blank(data):
    if not data:
        raise ValidationError('You forgot to write stuff.')