"""Script that starts SWF execution from AWS Lambda.

Code writen in python 2.7 (AWS Lambda for now supports only that version).
Functions such as urllib.unquote_plus won't work in python 3+.
"""

import json
from os import environ
import urllib
import uuid

import boto3


SWF_DOMAIN = environ.get('SWF_DOMAIN') or 'dev'
SWF_REGION_NAME = 'us-east-1'
SWF_WORKFLOW_ID_PATTERN = 'ows_ft_etl_theatrical_cuts_{cid}'
SWF_WORKFLOW_NAME = 'ows_ft_etl_theatrical_cuts'
SWF_WORKFLOW_TIMEOUT = '3600'
SWF_WORKFLOW_VERSION = '1.0'


def lambda_handler(event, context):
    """Event handler.

    Process event triggered by Object creation on S3.

    Args:
        event (dict): AWS Lambda event data.
        context (LambdaContext): AWS Lambda context.

    Returns:
        dict: dict containing the runId of the execution.
    """
    bucket = event['Records'][0]['s3']['bucket']['name']
    key = urllib.unquote_plus(
        event['Records'][0]['s3']['object']['key'].encode('utf8'))

    correlation_id = str(uuid.uuid1())

    swf_context = {
        'correlation_id': correlation_id,
        's3_key': key,
        's3_bucket': bucket
    }

    swf = boto3.client('swf', region_name=SWF_REGION_NAME)
    response = swf.start_workflow_execution(
        input=json.dumps(swf_context),
        domain=SWF_DOMAIN,
        taskList={'name': SWF_WORKFLOW_NAME},
        executionStartToCloseTimeout=SWF_WORKFLOW_TIMEOUT,
        workflowId=SWF_WORKFLOW_ID_PATTERN.format(cid=correlation_id),
        workflowType={
            'name': SWF_WORKFLOW_NAME,
            'version': SWF_WORKFLOW_VERSION})

    return response