from __future__ import generator_stop
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, scoped_session
from .psiturk_config import PsiturkConfig
import sys

config = PsiturkConfig()
config.load_config()

DATABASE = config.get('Database Parameters', 'database_url')

if 'mysql://' in DATABASE.lower():
    try:
        __import__('imp').find_module('pymysql')
    except ImportError:
        print("To use a MySQL database you need to install "
              "the `pymysql` python package.  Try `pip install "
              "pymysql`.")
        sys.exit()
    # internally use `mysql+pymysql://` so sqlalchemy talks to
    # the pymysql package
    DATABASE = DATABASE.replace('mysql://', 'mysql+pymysql://')

engine = create_engine(DATABASE, echo=False, pool_recycle=3600)
db_session = scoped_session(sessionmaker(autocommit=False,
                                         autoflush=False,
                                         bind=engine))


def init_db():
    from .models import Base
    # print "Initializing db if necessary."
    Base.metadata.create_all(bind=engine)


def truncate_tables():
    from .models import Base
    for table in Base.metadata.sorted_tables:
        db_session.execute(table.delete(bind=engine))
    db_session.commit()


def migrate_db():
    result = _populate_hits_table()
    return result


def _populate_hits_table():
    from .models import Participant, Hit

    # all non-debug unique hitids from the Participant table
    participants = Participant.query.\
        filter(~Participant.uniqueid.contains('debug')).\
        distinct(Participant.hitid)
    participant_table_hitids = [p.hitid for p in participants]

    # all unique hitids from the Hits table
    hit_table_hitids = [hit.hitid for hit in Hit.query.distinct(Hit.hitid)]

    # participant table hitids missing from the Hits table
    hit_table_missing_hitids = list(set(participant_table_hitids) - set(hit_table_hitids))

    dicts = [dict(hitid=hitid) for hitid in hit_table_missing_hitids]
    db_session.bulk_insert_mappings(Hit, dicts)
    db_session.commit()

    return {'message': f'Hit table (`{Hit.__table__.name}`) updated with {len(hit_table_missing_hitids)} hitids from Participant table (`{Participant.__table__.name}`)'}