from logging.config import fileConfig

from sqlalchemy import engine_from_config
from sqlalchemy import pool

from alembic import context

from custos_precificacao.config import DATABASE_URL
from custos_precificacao.models import Base

# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config
# `producao.migrar()` pode passar a URL por `attributes` (o resto usa DATABASE_URL do ambiente/.env).
# "%" precisa ser duplicado no configparser (senhas com caracteres especiais vêm URL-encoded: %40 etc.)
config.set_main_option("sqlalchemy.url", (config.attributes.get("url") or DATABASE_URL).replace("%", "%%"))

# 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)

target_metadata = Base.metadata

# other values from the config, defined by the needs of env.py,
# can be acquired:
# my_important_option = config.get_main_option("my_important_option")
# ... etc.


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.

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

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


def _schemas_dos_planejamentos(connection) -> list[tuple[str, str]]:
    """(schema comum, schema do Planejamento) de cada Planejamento que já tem schema próprio. Vazio fora do Postgres ou
    antes da migration `e8c1b7a45d93` (que cria a coluna)."""
    if connection.dialect.name != "postgresql":
        return []
    from sqlalchemy import text

    comum = connection.execute(text("select current_schema()")).scalar()
    coluna = connection.execute(
        text(
            "select 1 from information_schema.columns "
            "where table_schema = :s and table_name = 'planejamento' and column_name = 'schema'"
        ),
        {"s": comum},
    ).first()
    if coluna is None:
        return []
    return [(comum, s) for s in connection.execute(text("select schema from planejamento where schema is not null order by id")).scalars()]


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

    A revisão roda uma vez no schema comum e depois uma vez em cada schema de Planejamento (`plan_<id>`), cada um com a
    sua tabela `alembic_version`; ver a convenção no docstring de e8c1b7a45d93.
    """
    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
        )

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

        for comum, schema in _schemas_dos_planejamentos(connection):
            connection.exec_driver_sql(f'SET search_path TO "{schema}", "{comum}"')
            context.configure(
                connection=connection, target_metadata=target_metadata, version_table_schema=schema
            )
            with context.begin_transaction():
                context.run_migrations()
            connection.commit()
        connection.exec_driver_sql("RESET search_path")
        connection.commit()


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