GetRecords.hs

{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE DeriveGeneric      #-}
{-# LANGUAGE OverloadedStrings  #-}
{-# LANGUAGE RecordWildCards    #-}
{-# LANGUAGE TypeFamilies       #-}

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

-- Derived from AWS service descriptions, licensed under Apache 2.0.

-- |
-- Module      : Network.AWS.DynamoDBStreams.GetRecords
-- Copyright   : (c) 2013-2016 Brendan Hay
-- License     : Mozilla Public License, v. 2.0.
-- Maintainer  : Brendan Hay <brendan.g.hay@gmail.com>
-- Stability   : auto-generated
-- Portability : non-portable (GHC extensions)
--
-- Retrieves the stream records from a given shard.
--
-- Specify a shard iterator using the 'ShardIterator' parameter. The shard
-- iterator specifies the position in the shard from which you want to
-- start reading stream records sequentially. If there are no stream
-- records available in the portion of the shard that the iterator points
-- to, 'GetRecords' returns an empty list. Note that it might take multiple
-- calls to get to a portion of the shard that contains stream records.
--
-- GetRecords can retrieve a maximum of 1 MB of data or 2000 stream
-- records, whichever comes first.
module Network.AWS.DynamoDBStreams.GetRecords
    (
    -- * Creating a Request
      getRecords
    , GetRecords
    -- * Request Lenses
    , grLimit
    , grShardIterator

    -- * Destructuring the Response
    , getRecordsResponse
    , GetRecordsResponse
    -- * Response Lenses
    , grrsRecords
    , grrsNextShardIterator
    , grrsResponseStatus
    ) where

import           Network.AWS.DynamoDBStreams.Types
import           Network.AWS.DynamoDBStreams.Types.Product
import           Network.AWS.Lens
import           Network.AWS.Prelude
import           Network.AWS.Request
import           Network.AWS.Response

-- | Represents the input of a /GetRecords/ operation.
--
-- /See:/ 'getRecords' smart constructor.
data GetRecords = GetRecords'
    { _grLimit         :: !(Maybe Nat)
    , _grShardIterator :: !Text
    } deriving (Eq,Read,Show,Data,Typeable,Generic)

-- | Creates a value of 'GetRecords' with the minimum fields required to make a request.
--
-- Use one of the following lenses to modify other fields as desired:
--
-- * 'grLimit'
--
-- * 'grShardIterator'
getRecords
    :: Text -- ^ 'grShardIterator'
    -> GetRecords
getRecords pShardIterator_ =
    GetRecords'
    { _grLimit = Nothing
    , _grShardIterator = pShardIterator_
    }

-- | The maximum number of records to return from the shard. The upper limit
-- is 1000.
grLimit :: Lens' GetRecords (Maybe Natural)
grLimit = lens _grLimit (\ s a -> s{_grLimit = a}) . mapping _Nat;

-- | A shard iterator that was retrieved from a previous GetShardIterator
-- operation. This iterator can be used to access the stream records in
-- this shard.
grShardIterator :: Lens' GetRecords Text
grShardIterator = lens _grShardIterator (\ s a -> s{_grShardIterator = a});

instance AWSRequest GetRecords where
        type Rs GetRecords = GetRecordsResponse
        request = postJSON dynamoDBStreams
        response
          = receiveJSON
              (\ s h x ->
                 GetRecordsResponse' <$>
                   (x .?> "Records" .!@ mempty) <*>
                     (x .?> "NextShardIterator")
                     <*> (pure (fromEnum s)))

instance Hashable GetRecords

instance ToHeaders GetRecords where
        toHeaders
          = const
              (mconcat
                 ["X-Amz-Target" =#
                    ("DynamoDBStreams_20120810.GetRecords" ::
                       ByteString),
                  "Content-Type" =#
                    ("application/x-amz-json-1.0" :: ByteString)])

instance ToJSON GetRecords where
        toJSON GetRecords'{..}
          = object
              (catMaybes
                 [("Limit" .=) <$> _grLimit,
                  Just ("ShardIterator" .= _grShardIterator)])

instance ToPath GetRecords where
        toPath = const "/"

instance ToQuery GetRecords where
        toQuery = const mempty

-- | Represents the output of a /GetRecords/ operation.
--
-- /See:/ 'getRecordsResponse' smart constructor.
data GetRecordsResponse = GetRecordsResponse'
    { _grrsRecords           :: !(Maybe [Record])
    , _grrsNextShardIterator :: !(Maybe Text)
    , _grrsResponseStatus    :: !Int
    } deriving (Eq,Read,Show,Data,Typeable,Generic)

-- | Creates a value of 'GetRecordsResponse' with the minimum fields required to make a request.
--
-- Use one of the following lenses to modify other fields as desired:
--
-- * 'grrsRecords'
--
-- * 'grrsNextShardIterator'
--
-- * 'grrsResponseStatus'
getRecordsResponse
    :: Int -- ^ 'grrsResponseStatus'
    -> GetRecordsResponse
getRecordsResponse pResponseStatus_ =
    GetRecordsResponse'
    { _grrsRecords = Nothing
    , _grrsNextShardIterator = Nothing
    , _grrsResponseStatus = pResponseStatus_
    }

-- | The stream records from the shard, which were retrieved using the shard
-- iterator.
grrsRecords :: Lens' GetRecordsResponse [Record]
grrsRecords = lens _grrsRecords (\ s a -> s{_grrsRecords = a}) . _Default . _Coerce;

-- | The next position in the shard from which to start sequentially reading
-- stream records. If set to 'null', the shard has been closed and the
-- requested iterator will not return any more data.
grrsNextShardIterator :: Lens' GetRecordsResponse (Maybe Text)
grrsNextShardIterator = lens _grrsNextShardIterator (\ s a -> s{_grrsNextShardIterator = a});

-- | The response status code.
grrsResponseStatus :: Lens' GetRecordsResponse Int
grrsResponseStatus = lens _grrsResponseStatus (\ s a -> s{_grrsResponseStatus = a});