"""
migrations/env.py
──────────────────
Alembic async environment configuration.

Supports:
  • Online mode (direct DB connection) — used by ``alembic upgrade head``
  • Offline mode (SQL script generation) — used by ``alembic upgrade head --sql``
"""
from __future__ import annotations

import asyncio
from logging.config import fileConfig

from alembic import context
from sqlalchemy import pool
from sqlalchemy.engine import Connection
from sqlalchemy.ext.asyncio import async_engine_from_config

# ── Import ORM models so Alembic sees them in metadata ───────────────────────
from src.infrastructure.database.models.base import Base
import src.infrastructure.database.models.ppg_model  # noqa: F401
import src.infrastructure.database.models.prediction_model  # noqa: F401
from src.shared.config import get_settings

# Alembic Config object (from alembic.ini)
config = context.config

# Set up logging from the alembic.ini [loggers] section
if config.config_file_name is not None:
    fileConfig(config.config_file_name)

# Provide the target metadata to Alembic for auto-generation
target_metadata = Base.metadata

# Override sqlalchemy.url from our settings
settings = get_settings()
config.set_main_option("sqlalchemy.url", settings.database_url)


def run_migrations_offline() -> None:
    """Run migrations in 'offline' mode — generates SQL script without DB connection."""
    url = config.get_main_option("sqlalchemy.url")
    context.configure(
        url=url,
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        render_as_batch=True,  # Required for SQLite ALTER TABLE support
    )
    with context.begin_transaction():
        context.run_migrations()


def do_run_migrations(connection: Connection) -> None:
    context.configure(
        connection=connection,
        target_metadata=target_metadata,
        render_as_batch=True,
    )
    with context.begin_transaction():
        context.run_migrations()


async def run_async_migrations() -> None:
    """Run migrations in 'online' mode using async engine."""
    connectable = async_engine_from_config(
        config.get_section(config.config_ini_section, {}),
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,
    )
    async with connectable.connect() as connection:
        await connection.run_sync(do_run_migrations)
    await connectable.dispose()


def run_migrations_online() -> None:
    asyncio.run(run_async_migrations())


if context.is_offline_mode():
    run_migrations_offline()
else:
    run_migrations_online()