import os
import time

import mysql.connector
from mysql.connector import Error


def _get_required_env(name: str) -> str:
    value = os.getenv(name)
    if value is None or value == "":
        raise RuntimeError(f"Missing required environment variable: {name}")
    return value


class DB:
    def __init__(self):
        self.config = {
            'host': _get_required_env('DB_HOST'),
            'user': _get_required_env('DB_USER'),
            'password': _get_required_env('DB_PASSWORD'),
            'database': _get_required_env('DB_NAME'),
            'port': int(_get_required_env('DB_PORT')),
            'connection_timeout': int(_get_required_env('DB_CONNECTION_TIMEOUT'))
        }
        self.connect_retries = max(1, int(_get_required_env('DB_CONNECT_RETRIES')))
        self.connect_retry_delay = float(_get_required_env('DB_CONNECT_RETRY_DELAY'))
        self.init_database()
    
    def get_connection(self):
        """Get MySQL database connection."""
        for attempt in range(1, self.connect_retries + 1):
            try:
                connection = mysql.connector.connect(**self.config)
                return connection
            except Error as e:
                print(f"Error connecting to MySQL: {e}")
                if attempt < self.connect_retries:
                    print(
                        f"Retrying MySQL connection ({attempt}/{self.connect_retries}) "
                        f"in {self.connect_retry_delay} seconds..."
                    )
                    time.sleep(self.connect_retry_delay)
        return None
    
    def init_database(self):
        """Initialize the database connection."""
        connection = self.get_connection()
        if connection is None:
            raise Exception("Failed to connect to database")
        cursor = None
        try:
            cursor = connection.cursor()
            # Test connection by checking if required tables exist
            cursor.execute("SHOW TABLES LIKE 'acc'")
            if not cursor.fetchone():
                raise Exception("Table 'acc' does not exist")
            
            cursor.execute("SHOW TABLES LIKE 'user'")
            if not cursor.fetchone():
                raise Exception("Table 'user' does not exist")
            
            # print("Database connection verified - required tables exist")
            
        except Error as e:
            print(f"Error verifying database: {e}")
            raise Exception(f"Database verification failed: {e}")
        finally:
            if cursor is not None:
                cursor.close()
            if connection.is_connected():
                connection.close()
    
    def query(self, query, params=None):
        """Execute a query and return results."""
        connection = self.get_connection()
        if connection is None:
            return []
        cursor = None
        try:
            cursor = connection.cursor(dictionary=True)
            
            if params:
                cursor.execute(query, params)
            else:
                cursor.execute(query)
            
            results = cursor.fetchall()
            return results
            
        except Error as e:
            print(f"Error executing query: {e}")
            return []
        finally:
            if cursor is not None:
                cursor.close()
            if connection.is_connected():
                connection.close()
    
    def execute(self, query, params=None):
        """Execute a query that modifies data (INSERT, UPDATE, DELETE) and return success status."""
        connection = self.get_connection()
        if connection is None:
            return False
        cursor = None
        try:
            cursor = connection.cursor()
            
            if params:
                cursor.execute(query, params)
            else:
                cursor.execute(query)
            
            connection.commit()
            return True
            
        except Error as e:
            print(f"Error executing query: {e}")
            return False
        finally:
            if cursor is not None:
                cursor.close()
            if connection.is_connected():
                connection.close()