import sqlalchemy
import os

from wizard import shell

# We're going to use sqlalchemy.engine.url.URL as our database
# info intermediate object

def connect(url):
    """Convenience method for connecting to a MySQL database."""
    engine = sqlalchemy.create_engine(url)
    meta = sqlalchemy.MetaData()
    meta.bind = engine
    meta.reflect()
    return meta

def fill_url(url):
    """
    If the URL has a database name but no other values, it will
    use the global configuration, and then try the database name.
    """
    if not url:
        return None
    if not url.database:
        # it's hopeless
        return url
    # omitted port and query
    if any((url.host, url.username, url.password)):
        # don't try for defaults if a few of these were set
        return url
    # this is hook stuff
    if url.driver == "mysql":
        try:
            url.host, url.username, url.password = shell.Shell().eval("/mit/scripts/sql/bin/get-password").split()
            return url
        except shell.CallError:
            pass
    dsn = os.getenv("WIZARD_DSN")
    old_url = url
    url = sqlalchemy.engine.url.make_url(dsn)
    url.database = old_url.database
    return url