import os
import time

import boto3
from botocore.exceptions import ClientError
from dotenv import load_dotenv


# Load env file if it exists
load_dotenv(verbose=True)

ENVIRONMENT = os.environ.get('Environment', 'dev')

def delete_queues_with_no_messages(client, queue_url):
    # Double check that queue is still empty
    print('getting messages of empty queue')
    empty_queue = get_queues_with_no_messages(client, [queue_url])
    if empty_queue and empty_queue == [queue_url]:
        print(f'Queue is still empty: {queue_url}. Deleting...')
        client.delete_queue(QueueUrl=queue_url)
        print(f'Queue has been deleted: {queue_url}')
    else:
        print(f'Queue is no longer empty: {queue_url}. Skipping...')
        

def get_queues_with_no_messages(client, queue_urls=None):
    # There are generally < 1000 queues for an encoder type. Be simple.
    if not queue_urls:
        queues = client.list_queues(
            QueueNamePrefix=f'{ENVIRONMENT}-encoding18',
            MaxResults=1000
        )
        queue_urls = queues['QueueUrls']
    else:
        print(queue_urls)
    
    empty_queue_urls = []
    for queue_url in queue_urls:
        response = client.get_queue_attributes(
            QueueUrl=queue_url,
            AttributeNames=[
                'ApproximateNumberOfMessagesNotVisible',
                'ApproximateNumberOfMessages',
            ]
        )
        queue_attributes = response['Attributes']
        if sum([
            int(queue_attributes['ApproximateNumberOfMessagesNotVisible']),
            int(queue_attributes['ApproximateNumberOfMessages'])]) == 0:
            empty_queue_urls.append(queue_url)
        else:
            print(
                f'queue {queue_url} is NOT empty: details: {queue_attributes}.')

    return empty_queue_urls
    
    

def main():
    sqs_client = boto3.client('sqs', region_name='us-east-1')
    events_client = boto3.client('events', region_name='us-east-1')
    
    print('Disabling renew manager Cloudwatch event')
    events_client.disable_rule(
        Name=f'{ENVIRONMENT}-lambda-renew-manager-fargate-event'
    )
    print('Renew manager Cloudwatch event has been disabled.')
    
    print('Sleeping for a minute to let running renew lambdas finish')
    time.sleep(60)
    
    try:
        empty_queue_urls = get_queues_with_no_messages(sqs_client)
        print(f'Empty queues are {empty_queue_urls}')
        
        # Delete empty queues
        for queue_url in empty_queue_urls:
            delete_queues_with_no_messages(sqs_client, queue_url)
    except ClientError as error:
        raise SystemExit(f'Error deleting SQS queues: {error}')
    finally:
        """
        https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_CreateQueue.html
        Need to wait one minute so that queue can be recreated with same name by
        subsequent renew lambdas and not hit AWS limits.
        """
        time.sleep(60)
        print('Enabling renew manager Cloudwatch event')
        events_client.enable_rule(
            Name=f'{ENVIRONMENT}-lambda-renew-manager-fargate-event'
        )
        print('Renew manager Cloudwatch event has been enabled.')


if __name__ == "__main__":
    main()