from logging.config import fileConfig

from sqlalchemy import engine_from_config
from sqlalchemy import pool

from alembic import context

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

# 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
import os
import sys
from pathlib import Path

# Backend root directory adding to path to allow imports
backend_path = Path(__file__).parent.parent
sys.path.append(str(backend_path))

from app.models import Base
from app.config import get_settings

target_metadata = Base.metadata

# Update config with app settings
# Update config with app settings
settings = get_settings()

# 우선적으로 환경변수에서 DB URL을 확인하여 설정 (로컬 마이그레이션용)
env_db_url = os.getenv("DATABASE_URL")
if env_db_url:
    config.set_main_option("sqlalchemy.url", env_db_url)
else:
    config.set_main_option("sqlalchemy.url", settings.get_database_url())

# 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.

    """
    # Debug: Check what URL is actually being used
    # 우선적으로 환경변수에서 DB URL을 확인하여 설정 (로컬 마이그레이션용)
    env_db_url = os.getenv("DATABASE_URL")
    if env_db_url:
        print(f"DEBUG: Using DATABASE_URL from environment: {env_db_url}")
        url = env_db_url
    else:
        url = config.get_main_option("sqlalchemy.url")
        print(f"DEBUG: Using default configuration URL: {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.

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

    """
    # Debug: Check what URL is actually being used
    env_db_url = os.getenv("DATABASE_URL")
    if env_db_url:
        print(f"DEBUG: Using DATABASE_URL from environment: {env_db_url}")
        config.set_main_option("sqlalchemy.url", env_db_url)
    else:
        url = config.get_main_option("sqlalchemy.url")
        print(f"DEBUG: Using default configuration URL: {url}")

    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()


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