import mysql.connector
import threading
from secret_handler import return_credentials
import os
import time
import sys


db_username = return_credentials("/etc/secrets/db_username")
db_password = return_credentials("/etc/secrets/db_password")
db_host = os.getenv("BACKEND_API_DB_HOST","localhost")
db_database = os.getenv("BACKEND_API_DB_DATABASE","app")

MAX_RETRIES = 5
RETRY_DELAY = 5

MYSQL_CONFIG = {
	"host": db_host,
	"user": db_username,
	"password": db_password,
	"database": db_database
}

_pool_lock = threading.Lock()
_connection_pool = None


def create_connection_pool():
	global _connection_pool
	for attempt in range(1, MAX_RETRIES+1):
		try:
			print(f"[MySQL] Attempt {attempt} to connect...")
			pool  = mysql.connector.pooling.MySQLConnectionPool(
				pool_name="mypool",
				pool_size=5,
				pool_reset_session=True,
				**MYSQL_CONFIG
			)
			with _pool_lock:
				_connection_pool = pool
			print("[MySQL] Connection pool created successfully.")
			return
		except mysql.connector.Error as e:
			print(f"[MySQL] Attempt {attempt} failed: {e}")
			if attempt < MAX_RETRIES:
				time.sleep(RETRY_DELAY)
	print(f"[MySQL] Failed to connect after {MAX_RETRIES} attempts — exiting.")
	sys.exit(1)


def close_connection_pool():
	global _connection_pool
	with _pool_lock:
		if _connection_pool:
			_connection_pool = None
			print("[MySQL] Connection pool closed.")


def get_connection_pool():
	global _connection_pool
	with _pool_lock:
		if _connection_pool is None:
			create_connection_pool()
	return _connection_pool


def get_db():
	pool = get_connection_pool()
	try:
		conn = pool.get_connection()
		if not conn.is_connected():
			conn.reconnect(attempts=MAX_RETRIES, delay=RETRY_DELAY)
	except Exception:
		create_connection_pool()
		pool = get_connection_pool()
		conn = pool.get_connection()
	try:
		yield conn
	finally:
		conn.close()