from sqlalchemy import *
from migrate import *
import migrate.changeset


def upgrade(migrate_engine):
    metadata = MetaData()
    metadata.bind = migrate_engine

    harvest_source_table = Table('harvest_source', metadata, autoload=True)
    package_table = Table('package', metadata, autoload=True)

    harvested_document_table = Table('harvested_document', metadata,
        Column('url', UnicodeText, nullable=False),
        Column('guid', UnicodeText, default=''),
        Column('source_id', UnicodeText, ForeignKey('harvest_source.id')),
        Column('package_id', UnicodeText, ForeignKey('package.id')),
    )
    
    harvested_document_table.c.url.drop()
    harvested_document_table.c.guid.create(harvested_document_table)
    harvested_document_table.c.source_id.create(harvested_document_table)
    harvested_document_table.c.package_id.create(harvested_document_table)

def downgrade(migrate_engine):
    raise NotImplementedError()

