from sqlalchemy import Column, Table, Integer, MetaData, String, select, create_engine
from sqlalchemy.sql import func
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base


SQLALCHEMY_DATABASE_URL = "sqlite:///./sql_app.db"

engine = create_engine(
    SQLALCHEMY_DATABASE_URL, connect_args={"check_same_thread": False}
)

SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)


def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


Base = declarative_base()


class People(Base):
    __tablename__ = "people"

    id = Column(Integer, primary_key=True, index=True)
    name = Column(String)
    age = Column(Integer)
    gender = Column(String)
    country = Column(String)


def create_people_from_list(db, people_list):
    count = 0
    for p in people_list:
        db_people = People(**p.dict())
        db.add(db_people)
        count += 1

    db.commit()
    return count


def get_average_age_by_country(db) -> []:
    return db.query(People.country.label('country'), func.avg(People.age).label('average_age'))\
             .group_by( People.country).all()


def count_people_by_country(db) -> []:
    return db.query(People.country.label('country'), func.count(People.id).label('people_count'))\
             .group_by( People.country).all()


def get_gender_repartition_by_country(db, country) -> []:
    count_women, total = db.query(

        select(func.count(People.id).label('count_women')) \
        .where(People.gender == 'F') \
        .where(People.country == country).subquery(),

        select(func.count(People.id).label('total')) \
        .where(People.country == country).subquery(),

    ).first()
    female_proportion = count_women / total
    return {
        "female_proportion": female_proportion,
        "male_proportion": 1 - female_proportion
    }


meta = MetaData()
Table(
    'people', meta,
    Column('id', Integer, primary_key=True),
    Column('name', String),
    Column('age', Integer),
    Column('gender', String),
    Column('country', String),
)
meta.create_all(engine)