PollForDecisionTask.hs

{-# LANGUAGE DataKinds                   #-}
{-# LANGUAGE DeriveGeneric               #-}
{-# LANGUAGE FlexibleInstances           #-}
{-# LANGUAGE GeneralizedNewtypeDeriving  #-}
{-# LANGUAGE LambdaCase                  #-}
{-# LANGUAGE NoImplicitPrelude           #-}
{-# LANGUAGE OverloadedStrings           #-}
{-# LANGUAGE RecordWildCards             #-}
{-# LANGUAGE TypeFamilies                #-}

{-# OPTIONS_GHC -fno-warn-unused-imports #-}

-- Module      : Network.AWS.SWF.PollForDecisionTask
-- Copyright   : (c) 2013-2014 Brendan Hay <brendan.g.hay@gmail.com>
-- License     : This Source Code Form is subject to the terms of
--               the Mozilla Public License, v. 2.0.
--               A copy of the MPL can be found in the LICENSE file or
--               you can obtain it at http://mozilla.org/MPL/2.0/.
-- Maintainer  : Brendan Hay <brendan.g.hay@gmail.com>
-- Stability   : experimental
-- Portability : non-portable (GHC extensions)

-- | Used by deciders to get a DecisionTask from the specified decision
-- taskList. A decision task may be returned for any open workflow execution
-- that is using the specified task list. The task includes a paginated view
-- of the history of the workflow execution. The decider should use the
-- workflow type and the history to determine how to properly handle the task.
-- This action initiates a long poll, where the service holds the HTTP
-- connection open and responds as soon a task becomes available. If no
-- decision task is available in the specified task list before the timeout of
-- 60 seconds expires, an empty result is returned. An empty result, in this
-- context, means that a DecisionTask is returned, but that the value of
-- taskToken is an empty string. Deciders should set their client side socket
-- timeout to at least 70 seconds (10 seconds higher than the timeout).
-- Because the number of workflow history events for a single workflow
-- execution might be very large, the result returned might be split up across
-- a number of pages. To retrieve subsequent pages, make additional calls to
-- PollForDecisionTask using the nextPageToken returned by the initial call.
-- Note that you do not call GetWorkflowExecutionHistory with this
-- nextPageToken. Instead, call PollForDecisionTask again. Access Control You
-- can use IAM policies to control this action's access to Amazon SWF
-- resources as follows: Use a Resource element with the domain name to limit
-- the action to only specified domains. Use an Action element to allow or
-- deny permission to call this action. Constrain the taskList.name parameter
-- by using a Condition element with the swf:taskList.name key to allow the
-- action to access only certain task lists. If the caller does not have
-- sufficient permissions to invoke the action, or the parameter values fall
-- outside the specified constraints, the action fails by throwing
-- OperationNotPermitted. For details and example IAM policies, see Using IAM
-- to Manage Access to Amazon SWF Workflows.
--
-- <http://docs.aws.amazon.com/amazonswf/latest/apireference/API_PollForDecisionTask.html>
module Network.AWS.SWF.PollForDecisionTask
    (
    -- * Request
      PollForDecisionTask
    -- ** Request constructor
    , pollForDecisionTask
    -- ** Request lenses
    , pfdtDomain
    , pfdtIdentity
    , pfdtMaximumPageSize
    , pfdtNextPageToken
    , pfdtReverseOrder
    , pfdtTaskList

    -- * Response
    , PollForDecisionTaskResponse
    -- ** Response constructor
    , pollForDecisionTaskResponse
    -- ** Response lenses
    , pfdtrEvents
    , pfdtrNextPageToken
    , pfdtrPreviousStartedEventId
    , pfdtrStartedEventId
    , pfdtrTaskToken
    , pfdtrWorkflowExecution
    , pfdtrWorkflowType
    ) where

import Network.AWS.Prelude
import Network.AWS.Request.JSON
import Network.AWS.SWF.Types
import qualified GHC.Exts

data PollForDecisionTask = PollForDecisionTask
    { _pfdtDomain          :: Text
    , _pfdtIdentity        :: Maybe Text
    , _pfdtMaximumPageSize :: Maybe Nat
    , _pfdtNextPageToken   :: Maybe Text
    , _pfdtReverseOrder    :: Maybe Bool
    , _pfdtTaskList        :: TaskList
    } deriving (Eq, Show)

-- | 'PollForDecisionTask' constructor.
--
-- The fields accessible through corresponding lenses are:
--
-- * 'pfdtDomain' @::@ 'Text'
--
-- * 'pfdtIdentity' @::@ 'Maybe' 'Text'
--
-- * 'pfdtMaximumPageSize' @::@ 'Maybe' 'Natural'
--
-- * 'pfdtNextPageToken' @::@ 'Maybe' 'Text'
--
-- * 'pfdtReverseOrder' @::@ 'Maybe' 'Bool'
--
-- * 'pfdtTaskList' @::@ 'TaskList'
--
pollForDecisionTask :: Text -- ^ 'pfdtDomain'
                    -> TaskList -- ^ 'pfdtTaskList'
                    -> PollForDecisionTask
pollForDecisionTask p1 p2 = PollForDecisionTask
    { _pfdtDomain          = p1
    , _pfdtTaskList        = p2
    , _pfdtIdentity        = Nothing
    , _pfdtNextPageToken   = Nothing
    , _pfdtMaximumPageSize = Nothing
    , _pfdtReverseOrder    = Nothing
    }

-- | The name of the domain containing the task lists to poll.
pfdtDomain :: Lens' PollForDecisionTask Text
pfdtDomain = lens _pfdtDomain (\s a -> s { _pfdtDomain = a })

-- | Identity of the decider making the request, which is recorded in the
-- DecisionTaskStarted event in the workflow history. This enables
-- diagnostic tracing when problems arise. The form of this identity is user
-- defined.
pfdtIdentity :: Lens' PollForDecisionTask (Maybe Text)
pfdtIdentity = lens _pfdtIdentity (\s a -> s { _pfdtIdentity = a })

-- | The maximum number of history events returned in each page. The default
-- is 100, but the caller can override this value to a page size smaller
-- than the default. You cannot specify a page size greater than 100. Note
-- that the number of events may be less than the maxiumum page size, in
-- which case, the returned page will have fewer results than the
-- maximumPageSize specified.
pfdtMaximumPageSize :: Lens' PollForDecisionTask (Maybe Natural)
pfdtMaximumPageSize =
    lens _pfdtMaximumPageSize (\s a -> s { _pfdtMaximumPageSize = a })
        . mapping _Nat

-- | If on a previous call to this method a NextPageToken was returned, the
-- results are being paginated. To get the next page of results, repeat the
-- call with the returned token and all other arguments unchanged. .
pfdtNextPageToken :: Lens' PollForDecisionTask (Maybe Text)
pfdtNextPageToken =
    lens _pfdtNextPageToken (\s a -> s { _pfdtNextPageToken = a })

-- | When set to true, returns the events in reverse order. By default the
-- results are returned in ascending order of the eventTimestamp of the
-- events.
pfdtReverseOrder :: Lens' PollForDecisionTask (Maybe Bool)
pfdtReverseOrder = lens _pfdtReverseOrder (\s a -> s { _pfdtReverseOrder = a })

-- | Specifies the task list to poll for decision tasks. The specified string
-- must not start or end with whitespace. It must not contain a : (colon), /
-- (slash), | (vertical bar), or any control characters (\u0000-\u001f |
-- \u007f - \u009f). Also, it must not contain the literal string
-- &quot;arn&quot;.
pfdtTaskList :: Lens' PollForDecisionTask TaskList
pfdtTaskList = lens _pfdtTaskList (\s a -> s { _pfdtTaskList = a })

data PollForDecisionTaskResponse = PollForDecisionTaskResponse
    { _pfdtrEvents                 :: List "events" HistoryEvent
    , _pfdtrNextPageToken          :: Maybe Text
    , _pfdtrPreviousStartedEventId :: Maybe Integer
    , _pfdtrStartedEventId         :: Integer
    , _pfdtrTaskToken              :: Text
    , _pfdtrWorkflowExecution      :: WorkflowExecution
    , _pfdtrWorkflowType           :: WorkflowType
    } deriving (Eq, Show)

-- | 'PollForDecisionTaskResponse' constructor.
--
-- The fields accessible through corresponding lenses are:
--
-- * 'pfdtrEvents' @::@ ['HistoryEvent']
--
-- * 'pfdtrNextPageToken' @::@ 'Maybe' 'Text'
--
-- * 'pfdtrPreviousStartedEventId' @::@ 'Maybe' 'Integer'
--
-- * 'pfdtrStartedEventId' @::@ 'Integer'
--
-- * 'pfdtrTaskToken' @::@ 'Text'
--
-- * 'pfdtrWorkflowExecution' @::@ 'WorkflowExecution'
--
-- * 'pfdtrWorkflowType' @::@ 'WorkflowType'
--
pollForDecisionTaskResponse :: Text -- ^ 'pfdtrTaskToken'
                            -> Integer -- ^ 'pfdtrStartedEventId'
                            -> WorkflowExecution -- ^ 'pfdtrWorkflowExecution'
                            -> WorkflowType -- ^ 'pfdtrWorkflowType'
                            -> PollForDecisionTaskResponse
pollForDecisionTaskResponse p1 p2 p3 p4 = PollForDecisionTaskResponse
    { _pfdtrTaskToken              = p1
    , _pfdtrStartedEventId         = p2
    , _pfdtrWorkflowExecution      = p3
    , _pfdtrWorkflowType           = p4
    , _pfdtrEvents                 = mempty
    , _pfdtrNextPageToken          = Nothing
    , _pfdtrPreviousStartedEventId = Nothing
    }

-- | A paginated list of history events of the workflow execution. The decider
-- uses this during the processing of the decision task.
pfdtrEvents :: Lens' PollForDecisionTaskResponse [HistoryEvent]
pfdtrEvents = lens _pfdtrEvents (\s a -> s { _pfdtrEvents = a }) . _List

-- | Returns a value if the results are paginated. To get the next page of
-- results, repeat the request specifying this token and all other arguments
-- unchanged.
pfdtrNextPageToken :: Lens' PollForDecisionTaskResponse (Maybe Text)
pfdtrNextPageToken =
    lens _pfdtrNextPageToken (\s a -> s { _pfdtrNextPageToken = a })

-- | The id of the DecisionTaskStarted event of the previous decision task of
-- this workflow execution that was processed by the decider. This can be
-- used to determine the events in the history new since the last decision
-- task received by the decider.
pfdtrPreviousStartedEventId :: Lens' PollForDecisionTaskResponse (Maybe Integer)
pfdtrPreviousStartedEventId =
    lens _pfdtrPreviousStartedEventId
        (\s a -> s { _pfdtrPreviousStartedEventId = a })

-- | The id of the DecisionTaskStarted event recorded in the history.
pfdtrStartedEventId :: Lens' PollForDecisionTaskResponse Integer
pfdtrStartedEventId =
    lens _pfdtrStartedEventId (\s a -> s { _pfdtrStartedEventId = a })

-- | The opaque string used as a handle on the task. This token is used by
-- workers to communicate progress and response information back to the
-- system about the task.
pfdtrTaskToken :: Lens' PollForDecisionTaskResponse Text
pfdtrTaskToken = lens _pfdtrTaskToken (\s a -> s { _pfdtrTaskToken = a })

-- | The workflow execution for which this decision task was created.
pfdtrWorkflowExecution :: Lens' PollForDecisionTaskResponse WorkflowExecution
pfdtrWorkflowExecution =
    lens _pfdtrWorkflowExecution (\s a -> s { _pfdtrWorkflowExecution = a })

-- | The type of the workflow execution for which this decision task was
-- created.
pfdtrWorkflowType :: Lens' PollForDecisionTaskResponse WorkflowType
pfdtrWorkflowType =
    lens _pfdtrWorkflowType (\s a -> s { _pfdtrWorkflowType = a })

instance ToPath PollForDecisionTask where
    toPath = const "/"

instance ToQuery PollForDecisionTask where
    toQuery = const mempty

instance ToHeaders PollForDecisionTask

instance ToJSON PollForDecisionTask where
    toJSON PollForDecisionTask{..} = object
        [ "domain"          .= _pfdtDomain
        , "taskList"        .= _pfdtTaskList
        , "identity"        .= _pfdtIdentity
        , "nextPageToken"   .= _pfdtNextPageToken
        , "maximumPageSize" .= _pfdtMaximumPageSize
        , "reverseOrder"    .= _pfdtReverseOrder
        ]

instance AWSRequest PollForDecisionTask where
    type Sv PollForDecisionTask = SWF
    type Rs PollForDecisionTask = PollForDecisionTaskResponse

    request  = post "PollForDecisionTask"
    response = jsonResponse

instance FromJSON PollForDecisionTaskResponse where
    parseJSON = withObject "PollForDecisionTaskResponse" $ \o -> PollForDecisionTaskResponse
        <$> o .:  "events"
        <*> o .:? "nextPageToken"
        <*> o .:? "previousStartedEventId"
        <*> o .:  "startedEventId"
        <*> o .:  "taskToken"
        <*> o .:  "workflowExecution"
        <*> o .:  "workflowType"

instance AWSPager PollForDecisionTask where
    page rq rs
        | stop (rq ^. pfdtNextPageToken) = Nothing
        | otherwise = (\x -> rq & pfdtNextPageToken ?~ x)
            <$> (rs ^. pfdtrNextPageToken)