from datetime import datetime, timedelta
import requests
import json
import uuid
import logging
import time
from concurrent.futures import ThreadPoolExecutor

from airflow import DAG
from airflow.operators.python import PythonOperator, BranchPythonOperator
from airflow.operators.dummy import DummyOperator
from airflow.utils.dates import days_ago
from airflow.models import Variable, DagRun
from airflow.utils.session import create_session
from airflow.utils.state import State

# Configure logging
logger = logging.getLogger(__name__)


def is_dag_already_running(**context):
    """
    Check if there are other active DAG runs to prevent duplicate execution
    """
    dag_id = context["dag"].dag_id
    run_id = context["run_id"]

    with create_session() as session:
        # Count running instances of this DAG excluding the current run
        running_dags = (
            session.query(DagRun)
            .filter(
                DagRun.dag_id == dag_id,
                DagRun.run_id != run_id,
                DagRun.state == State.RUNNING,
            )
            .count()
        )

    if running_dags > 0:
        logger.info(
            f"Found {running_dags} other running instance(s) of this DAG. Skipping execution."
        )
        return "skip_execution"
    else:
        logger.info("No other running instances found. Proceeding with execution.")
        return "fetch_daily_maximo_data"


def fetch_daily_maximo_data(**context):
    """
    Fetch data from the Maximo endpoint using GET method with async pattern
    """
    # Generate request ID for tracking
    request_id = str(uuid.uuid4())

    # Connection configuration
    base_url = "http://10.47.0.65/envelope"
    endpoint = "/fetch-maximo-daily"
    fetch_url = f"{base_url}{endpoint}"

    # Log before sending request
    logger.info(f"Sending async GET request to {fetch_url} (Request ID: {request_id})")

    # Request headers
    headers = {
        "Content-Type": "application/json",
        "X-Request-ID": request_id,
    }

    # Create a response callback function
    def response_callback(future):
        try:
            # Get the response from the future, with a short timeout just to confirm
            # the request was properly initiated
            response = future.result(timeout=10)
            logger.info(
                f"Request initiated successfully (Request ID: {request_id}), status: {response.status_code}"
            )

            # We don't wait for the full response processing, as it may take longer than Airflow's task timeout

        except requests.exceptions.Timeout:
            logger.error(f"Request connection timed out (Request ID: {request_id})")
        except Exception as e:
            logger.error(
                f"Error initiating request (Request ID: {request_id}): {str(e)}"
            )

    # Using ThreadPoolExecutor for async operation
    with ThreadPoolExecutor(max_workers=1) as executor:
        # Submit request to executor with a longer timeout for the overall operation
        future = executor.submit(
            requests.get,
            url=fetch_url,
            headers=headers,
            timeout=600,  # Increased timeout to 10 minutes for the actual API call
        )

        # Add callback that will execute when future completes
        future.add_done_callback(response_callback)

        # Don't wait for future to complete, let it run in background
        logger.info(f"Async request has been dispatched (Request ID: {request_id})")

    # Push the request details to XCom for tracking
    result_dict = {
        "request_id": request_id,
        "status": "initiated",
        "timestamp": datetime.now().isoformat(),
        "message": "Fetch Daily Maximo request initiated asynchronously",
    }

    ti = context["ti"]
    ti.xcom_push(key="fetch_result", value=result_dict)

    return result_dict


def process_response(**context):
    """
    Process the response from the Maximo API
    In async mode, this simply acknowledges the request was made
    """
    ti = context["ti"]
    result = ti.xcom_pull(task_ids="fetch_daily_maximo_data", key="fetch_result")

    if result:
        logger.info(f"Processing async request result: {result}")
        # Since we're using fire-and-forget pattern, we just acknowledge the request was made

        # In production, you might want to implement a separate DAG or task
        # to check the status of the asynchronous job later

        return True
    return False


# Define default arguments for the DAG
default_args = {
    "owner": "airflow",
    "depends_on_past": False,
    "email_on_failure": True,
    "email_on_retry": False,
    "retries": 3,
    "retry_delay": timedelta(minutes=5),
}

# Define the DAG
dag = DAG(
    "fetch_daily_maximo_data",
    default_args=default_args,
    description="A DAG to fetch data from Maximo API endpoint asynchronously on a daily schedule",
    # Schedule to run daily at 21:00 GMT
    schedule_interval="0 14 * * *",  # UTC (14:00 WIB)
    start_date=days_ago(1),
    tags=["maximo", "api", "fetch", "continuous", "daily", "async"],
    catchup=False,
)

# Branch operator to check if we should proceed or skip
check_running = BranchPythonOperator(
    task_id="check_if_already_running",
    python_callable=is_dag_already_running,
    provide_context=True,
    dag=dag,
)

# Skip execution dummy task
skip_execution = DummyOperator(
    task_id="skip_execution",
    dag=dag,
)

# Define the task to fetch data from Maximo using PythonOperator
fetch_task = PythonOperator(
    task_id="fetch_daily_maximo_data",
    python_callable=fetch_daily_maximo_data,
    provide_context=True,
    dag=dag,
)

# Define task to process the response
process_task = PythonOperator(
    task_id="process_response",
    python_callable=process_response,
    provide_context=True,
    dag=dag,
)

# Set task dependencies
check_running >> [skip_execution, fetch_task]
fetch_task >> process_task