"""
Alembic Environment Configuration for Crypto Trading Bot Platform
"""

import os
import sys
from logging.config import fileConfig
from pathlib import Path

from sqlalchemy import engine_from_config
from sqlalchemy import pool

from alembic import context

# Add project root to path for imports
project_root = Path(__file__).parent.parent.parent
sys.path.insert(0, str(project_root))

# Load environment variables from .env file if it exists
try:
    from dotenv import load_dotenv
    env_file = project_root / '.env'
    if env_file.exists():
        load_dotenv(env_file)
except ImportError:
    # dotenv not available, proceed without it
    pass

# Import our models and database configuration
from database.models import Base
from database.connection import DatabaseConfig

# 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
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 get_database_url():
    """Get database URL from environment variables"""
    # Use DATABASE_URL if set, otherwise construct from individual components
    url = os.getenv('DATABASE_URL')
    if url:
        return url
    
    # Fallback to constructing URL from components
    user = os.getenv('POSTGRES_USER', 'dashboard')
    password = os.getenv('POSTGRES_PASSWORD', '')
    host = os.getenv('POSTGRES_HOST', 'localhost')
    port = os.getenv('POSTGRES_PORT', '5434')
    database = os.getenv('POSTGRES_DB', 'dashboard')
    
    return f"postgresql://{user}:{password}@{host}:{port}/{database}"


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 = get_database_url()
    context.configure(
        url=url,
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        compare_type=True,
        compare_server_default=True,
        render_as_batch=False,  # PostgreSQL supports transactional DDL
    )

    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.

    """
    # Override the sqlalchemy.url in the config with our environment-based URL
    config.set_main_option("sqlalchemy.url", get_database_url())
    
    # Create engine with our database configuration
    db_config = DatabaseConfig()
    engine_config = config.get_section(config.config_ini_section)
    engine_config.update(db_config.get_engine_kwargs())
    
    connectable = engine_from_config(
        engine_config,
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,  # Use NullPool for migrations to avoid connection issues
    )

    with connectable.connect() as connection:
        context.configure(
            connection=connection,
            target_metadata=target_metadata,
            compare_type=True,
            compare_server_default=True,
            render_as_batch=False,  # PostgreSQL supports transactional DDL
            transaction_per_migration=True,  # Each migration in its own transaction
        )

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


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