from __future__ import annotations

import asyncio
import os
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

from db.models import Base

config = context.config

if config.config_file_name is not None:
    fileConfig(config.config_file_name)

target_metadata = Base.metadata


def _get_database_url() -> str:
    configured_url = config.get_main_option("sqlalchemy.url")
    if configured_url:
        return configured_url

    env_url = os.getenv("DATABASE_URL")
    if env_url:
        return env_url

    user = os.getenv("POSTGRES_USER", "postgres")
    password = os.getenv("POSTGRES_PASSWORD", "postgres")
    host = os.getenv("POSTGRES_HOST", "localhost")
    port = os.getenv("POSTGRES_PORT", "5432")
    db_name = os.getenv("POSTGRES_DB", "postgres")
    return f"postgresql+asyncpg://{user}:{password}@{host}:{port}/{db_name}"


def run_migrations_offline() -> None:
    """Run migrations in 'offline' mode."""

    context.configure(
        url=_get_database_url(),
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        compare_type=True,
    )

    with context.begin_transaction():
        context.run_migrations()


def do_run_migrations(connection: Connection) -> None:
    context.configure(
        connection=connection,
        target_metadata=target_metadata,
        compare_type=True,
    )

    with context.begin_transaction():
        context.run_migrations()


async def run_async_migrations() -> None:
    configuration = config.get_section(config.config_ini_section) or {}
    configuration["sqlalchemy.url"] = _get_database_url()

    connectable = async_engine_from_config(
        configuration,
        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:
    """Run migrations in 'online' mode."""

    connectable = config.attributes.get("connection", None)
    if connectable is None:
        asyncio.run(run_async_migrations())
    else:
        do_run_migrations(connectable)


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