from pathlib import Path

from sqlalchemy import create_engine, text
from sqlalchemy.orm import DeclarativeBase, sessionmaker

from .config import settings

Path(settings.database_path).parent.mkdir(parents=True, exist_ok=True)

engine = create_engine(
    f"sqlite:///{settings.database_path}",
    connect_args={"check_same_thread": False},
)
SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False)


class Base(DeclarativeBase):
    pass


# Columns added to existing tables after their first release. create_all()
# only creates missing *tables*, so an upgrade on an existing SQLite file
# needs these added by hand — a lightweight alternative to a full migration
# framework, appropriate for this project's scale. Add a new (table, column,
# ddl-type-and-default) tuple here whenever a model gains a field.
_COLUMN_MIGRATIONS = [
    ("market_spikes", "top_keywords_json", "TEXT DEFAULT '[]'"),
]


def _run_column_migrations() -> None:
    with engine.connect() as conn:
        for table, column, ddl in _COLUMN_MIGRATIONS:
            existing = {row[1] for row in conn.execute(text(f"PRAGMA table_info({table})"))}
            if column not in existing:
                conn.execute(text(f"ALTER TABLE {table} ADD COLUMN {column} {ddl}"))
        conn.commit()


def init_db() -> None:
    from . import models  # noqa: F401  (registers tables on Base.metadata)

    Base.metadata.create_all(bind=engine)
    _run_column_migrations()


def get_session():
    session = SessionLocal()
    try:
        yield session
    finally:
        session.close()