import os
from logging.config import fileConfig
from urllib.parse import unquote

from sqlalchemy import create_engine, pool
from sqlalchemy.engine.url import make_url

from alembic import context
from src.models import Base

# Alembic Config object
config = context.config

# Override sqlalchemy.url from environment if set
database_url = os.environ.get("DATABASE_URL")
if database_url:
    # Alembic needs the synchronous driver; asyncpg -> psycopg2
    database_url = database_url.replace("postgresql+asyncpg://", "postgresql://")
    # Decode URL-encoded characters (e.g. %40 -> @)
    database_url = unquote(database_url)
    config.set_main_option("sqlalchemy.url", database_url)

# Set up Python logging from the config file
if config.config_file_name is not None:
    fileConfig(config.config_file_name)

target_metadata = Base.metadata


def run_migrations_offline() -> None:
    """Run migrations in 'offline' mode."""
    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 run_migrations_online() -> None:
    """Run migrations in 'online' mode.
    
    Use create_engine directly to bypass ConfigParser URL parsing
    which mishandles special characters in passwords.
    """
    url = config.get_main_option("sqlalchemy.url")
    # Ensure dialect is postgresql (not postgres)
    if url.startswith("postgres://"):
        url = "postgresql://" + url[len("postgres://"):]
    connectable = create_engine(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()