"""
SWF Utilities
=============

Utility methods for Amazon simple workflow
"""

import datetime
import json
import time

from processing_accounting.util import logging
from processing_accounting.util import setting

RE_RUN_TAGS = ['re-run']


def wait_for_workflow_to_complete(workflow_executions, max_wait_time=-1):
    """Wait for workflows to finish.

    @todo(pkuong): add custom exception modules building list of custom
        exception classes.

    Args:
        workflow_executions (list): list of workflow execution objects.
        max_wait_time (int): optional wait time. If exceeded, it will throw
            a timeout exception. Default is -1 for waiting forever.

    Raise:
        Exception: workflow ends unexpectedly or wait time has exceeded.
    """

    elapsed_time = 0
    interval = setting.CHECK_WORKFLOW_STATUS_TIME_INTERVAL
    while True:
        all_status = []
        for workflow_execution in workflow_executions:
            execution_info = workflow_execution.describe().get(
                'executionInfo')
            status = execution_info.get('closeStatus')
            workflow_id = execution_info.get('execution').get('workflowId')
            logging.logger.info(
                'Waiting workflows {} to be completed....'.format(
                    workflow_id))
            all_status.append(status == 'COMPLETED')

            # If any workflow has an invalid state, stop the whole thing.
            if status in ['CANCELED', 'FAILED', 'TERMINATED']:
                raise Exception('Workflow ends unexpectedly.')

        if all(all_status):
            return

        # If max_wait_time is set, throw an exception if wait time exceeds.
        if elapsed_time > max_wait_time > -1:
            raise Exception('Wait time has exceeded.')

        time.sleep(interval)
        elapsed_time += interval


def get_swf(session):
    """Get SWF client.

    Args:
        session (boto3.session.Session): AWS session

    Returns:
        botocore.client.SWF: AWS SWF client
    """
    return session.client('swf')


def get_latest_failed_executions(
        domain, latest_date, session, days_range=1, **extra):
    """Get the list of failed workflow executions.

    Args:
        domain (str): SWF domain
        latest_date (datetime.datetime): the latest date to filter
        days_range (int): num days to go back (latest_date - days_range)
        session (boto3.session.Session): AWS session object
        extra (dict): extra keyword arguments for
            swf.list_closed_workflow_executions function

    Returns:
        list: list with execution metadata (dict)
    """

    swf = get_swf(session)
    oldest_date = latest_date - datetime.timedelta(days=days_range)
    main_args = {
        'domain': domain,
        'startTimeFilter': {
            'oldestDate': oldest_date,
            'latestDate': latest_date},
        'closeStatusFilter': {'status': 'FAILED'}
    }
    list_kwargs = {}
    list_kwargs.update(extra)
    list_kwargs.update(main_args)
    next_page_token = True
    failed_executions = []
    while next_page_token:
        resp = swf.list_closed_workflow_executions(**list_kwargs)
        failed_executions.extend(resp.get('executionInfos'))
        next_page_token = resp.get('nextPageToken')
        list_kwargs['nextPageToken'] = next_page_token
    return failed_executions


def get_execution_history(domain, execution, session):
    """Get execution history (events, input, etc).

    Args:
        domain (str): SWF domain
        execution (dict): execution details (workflowId, runId)
        session (boto3.session.Session): AWS session

    Returns:
        dict: execution history (list of events)
    """
    swf = get_swf(session)
    resp = swf.get_workflow_execution_history(
        domain=domain, execution=execution)
    return resp


def get_execution_input(execution_history):
    """Get workflow execution input (context).

    Args:
        execution_history (dict): SWF get workflow execution history response

    Returns:
        dict: workflow execution input
    """
    events = execution_history.get('events')
    if not events:
        return {}

    initial_event = events[0]
    event_attributes = initial_event.get(
        'workflowExecutionStartedEventAttributes')
    if not event_attributes:
        return {}
    workflow_input = json.loads(event_attributes['input'])
    return workflow_input


def get_execution_description(execution, domain_name, session):
    """Get workflow execution description.

    Args:
        execution (dict): execution - workflowId and runId
        domain_name (str): execution domain
        session (boto3.session.Session): AWS session

    Returns:
        dict: AWS response
    """
    swf = get_swf(session)
    resp = swf.describe_workflow_execution(
        domain=domain_name, execution=execution)
    return resp


def re_run_execution(execution, execution_input, domain_name, session):
    """Re-run workflow execution

    Args:
        execution (dict): execution metadata
        execution_input (dict): execution input
        domain_name (str): execution domain
        session (boto3.session.Session): AWS session

    Returns:
        dict: SWF start execution response
    """
    swf = get_swf(session)

    execution_description = get_execution_description(
        execution=execution['execution'],
        domain_name=domain_name,
        session=session)
    execution_configuration = execution_description.get(
        'executionConfiguration', {})

    task_list = execution_configuration.get('taskList')
    start_to_close_timeout = execution_configuration.get(
        'taskStartToCloseTimeout')
    execution_start_to_close_timeout = execution_configuration.get(
        'executionStartToCloseTimeout')
    child_policy = execution_configuration.get('childPolicy', 'TERMINATE')
    try:
        resp = swf.start_workflow_execution(
            domain=domain_name,
            workflowId=execution['execution']['workflowId'],
            workflowType=execution['workflowType'],
            input=json.dumps(execution_input),
            taskList=task_list,
            taskStartToCloseTimeout=start_to_close_timeout,
            executionStartToCloseTimeout=execution_start_to_close_timeout,
            childPolicy=child_policy,
            tagList=RE_RUN_TAGS)
    except swf.exceptions.ClientError as e:
        resp = {
            'ResponseMetadata': {
                'HTTPStatusCode': 304,
                'Message': str(e)}}
    return resp