import os

from dotenv import load_dotenv
load_dotenv()

from logging.config import fileConfig

from sqlalchemy import pool, create_engine

from alembic import context
from core.models import Base

# Migrations run as the schema owner (wikitcg), which is a different role from the
# one the app runs as (wikitcg_app, DML only). Deliberately no fallback to
# DATABASE_URL: falling back would connect as the app role and fail somewhere deep
# inside a CREATE/ALTER with a permissions error, instead of telling you plainly
# that the environment is misconfigured.
MIGRATION_DATABASE_URL = os.environ.get("MIGRATION_DATABASE_URL")
if not MIGRATION_DATABASE_URL:
  raise RuntimeError(
    "MIGRATION_DATABASE_URL is not set. Migrations must run as the schema owner "
    "(wikitcg), not as the application role (wikitcg_app), which has no DDL "
    "rights. In Docker: docker compose run --rm backend alembic upgrade head"
  )

# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config

# Note: the URL is passed straight to create_engine / context.configure rather than
# through config.set_main_option. alembic.ini is a configparser file, so a password
# containing '%' would be mangled by interpolation on the way through.

# Interpret the config file for Python logging.
# This line sets up loggers basically.
if config.config_file_name is not None:
  fileConfig(config.config_file_name)

# add your model's MetaData object here
# for 'autogenerate' support
target_metadata = Base.metadata


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

  This configures the context with just a URL
  and not an Engine, though an Engine is acceptable
  here as well.  By skipping the Engine creation
  we don't even need a DBAPI to be available.

  Calls to context.execute() here emit the given string to the
  script output.

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

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


def run_migrations_online() -> None:
  """Run migrations in 'online' mode.

  In this scenario we need to create an Engine
  and associate a connection with the context.

  """
  connectable = create_engine(MIGRATION_DATABASE_URL, poolclass=pool.NullPool)

  with connectable.connect() as connection:
    context.configure(
      connection=connection, target_metadata=target_metadata
    )

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


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