import sqlite3
import sys
import os
import logging

# Add parent path to import config
sys.path.append(os.path.abspath(os.path.join(os.path.dirname(__file__), "../..")))
from backend.config import settings

logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')
logger = logging.getLogger(__name__)

# Extract DB file path from SQLAlchemy URL
DB_FILE = settings.DATABASE_URL.replace("sqlite:///", "")

def get_db_connection():
    """Establishes a connection to the SQLite database."""
    return sqlite3.connect(DB_FILE)

def get_table_columns(cursor, table_name):
    """Returns a list of column names for a given table."""
    cursor.execute(f"PRAGMA table_info({table_name})")
    return [row[1] for row in cursor.fetchall()]

def migrate_industries_table():
    """
    Adds the new schema columns to the 'industries' table if they don't exist.
    This ensures backward compatibility with older database files.
    """
    logger.info(f"Connecting to database at {DB_FILE} to run migrations...")
    conn = get_db_connection()
    cursor = conn.cursor()

    try:
        logger.info("Checking 'industries' table schema...")
        columns = get_table_columns(cursor, "industries")
        logger.info(f"Found existing columns: {columns}")

        migrations_to_run = {
            "metric_type": "TEXT",
            "scraper_search_term": "TEXT",
            "standardization_logic": "TEXT",
            "proxy_factor": "FLOAT" 
            # min_requirement, whale_threshold, scraper_keywords already exist from v0.6.0
        }

        for col, col_type in migrations_to_run.items():
            if col not in columns:
                logger.info(f"Adding column '{col}' ({col_type}) to 'industries' table...")
                cursor.execute(f"ALTER TABLE industries ADD COLUMN {col} {col_type}")
            else:
                logger.info(f"Column '{col}' already exists. Skipping.")

        # Also, we need to handle the removal of old columns if necessary (safer to leave them)
        # We will also fix the proxy_factor type if it was TEXT
        # This is more complex, for now let's just add.
        
        conn.commit()
        logger.info("Migrations for 'industries' table completed successfully.")

    except Exception as e:
        logger.error(f"An error occurred during migration: {e}", exc_info=True)
        conn.rollback()
    finally:
        conn.close()


if __name__ == "__main__":
    if not os.path.exists(DB_FILE):
        logger.error(f"Database file not found at {DB_FILE}. Cannot run migration. Please ensure the old database is in place.")
    else:
        migrate_industries_table()