from logging.config import fileConfig

from sqlalchemy import engine_from_config, pool

from alembic import context
from modelforge_api.persistence.models import Base
from modelforge_api.settings import get_settings

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


def _database_url() -> str:
    """Where the migration runs, in order of explicitness.

    1. `-x db_url=...` on the command line
    2. a URL the caller set programmatically, or in alembic.ini
    3. MODELFORGE_MIGRATION_DATABASE_URL
    4. MODELFORGE_DATABASE_URL only outside production

    env.py used to overwrite whatever the caller had set with the settings default
    unconditionally, so both explicit forms were silently discarded. A bootstrap or upgrade
    rehearsal aimed at an isolated copy would have migrated the deployment's own database while
    reporting success against the copy.
    """

    supplied = context.get_x_argument(as_dictionary=True).get("db_url")
    if supplied:
        return str(supplied)
    configured = config.get_main_option("sqlalchemy.url", None)
    if configured:
        return configured
    settings = get_settings()
    if settings.migration_database_url is not None:
        return settings.migration_database_url.get_secret_value()
    if settings.env == "production":
        raise RuntimeError(
            "production migrations require MODELFORGE_MIGRATION_DATABASE_URL; the API runtime "
            "credential is intentionally not a migration credential"
        )
    return settings.database_url


config.set_main_option("sqlalchemy.url", _database_url())
target_metadata = Base.metadata


def run_migrations_offline() -> None:
    context.configure(
        url=config.get_main_option("sqlalchemy.url"),
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        compare_type=True,
    )
    with context.begin_transaction():
        context.run_migrations()


def run_migrations_online() -> None:
    connectable = engine_from_config(
        config.get_section(config.config_ini_section, {}),
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,
    )
    with connectable.connect() as connection:
        context.configure(connection=connection, target_metadata=target_metadata, compare_type=True)
        with context.begin_transaction():
            context.run_migrations()


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