import os
import sys
from logging.config import fileConfig

from sqlalchemy import pool
from sqlalchemy import create_engine  # Add create_engine import

from alembic import context

from core.database import Base  # Import your Base


# --- Add project root to sys.path ---
# This assumes alembic/env.py is one level down from the project root (backend/)
PROJECT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
sys.path.insert(0, PROJECT_DIR)
# -----------------------------------

# 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)

# --- Construct DB URL from environment variables ---
# Use environment variables similar to docker-compose
db_user = os.getenv("POSTGRES_USER", "maia")  # Default to 'maia' if not set
db_password = os.getenv("POSTGRES_PASSWORD", "maia")  # Default to 'maia' if not set
db_host = os.getenv("DB_HOST", "db")  # Default to 'db' service name
db_port = os.getenv("DB_PORT", "5432")  # Default to '5432'
db_name = os.getenv("DB_NAME", "maia")  # Default to 'maia'

# Construct the URL, falling back to alembic.ini if needed
url = os.getenv("DB_URL")
if not url:
    # Try constructing from parts if DB_URL isn't set
    url = f"postgresql://{db_user}:{db_password}@{db_host}:{db_port}/{db_name}"
    # As a final fallback, use the URL from alembic.ini
    config_url = config.get_main_option("sqlalchemy.url")
    if not url and config_url:
        url = config_url

# Update the config object so engine_from_config can potentially use it,
# though we'll primarily use the constructed 'url' directly.
config.set_main_option("sqlalchemy.url", url)
# ----------------------------------------------------

# add your model's MetaData object here
# for 'autogenerate' support
# from myapp import mymodel
# target_metadata = mymodel.Base.metadata
# --- Set target_metadata ---
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.

    """
    context.configure(
        url=url,  # Use the constructed 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.

    """
    # Create engine directly using the constructed URL
    connectable = create_engine(url, poolclass=pool.NullPool)
    # Original approach using engine_from_config:
    # 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()