{-# 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.DynamoDB.DescribeLimits
-- 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)
--
-- Returns the current provisioned-capacity limits for your AWS account in
-- a region, both for the region as a whole and for any one DynamoDB table
-- that you create there.
--
-- When you establish an AWS account, the account has initial limits on the
-- maximum read capacity units and write capacity units that you can
-- provision across all of your DynamoDB tables in a given region. Also,
-- there are per-table limits that apply when you create a table there. For
-- more information, see
-- <http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Limits.html Limits>
-- page in the /Amazon DynamoDB Developer Guide/.
--
-- Although you can increase these limits by filing a case at
-- <https://console.aws.amazon.com/support/home#/ AWS Support Center>,
-- obtaining the increase is not instantaneous. The /DescribeLimits/ API
-- lets you write code to compare the capacity you are currently using to
-- those limits imposed by your account so that you have enough time to
-- apply for an increase before you hit a limit.
--
-- For example, you could use one of the AWS SDKs to do the following:
--
-- 1.  Call /DescribeLimits/ for a particular region to obtain your current
--     account limits on provisioned capacity there.
-- 2.  Create a variable to hold the aggregate read capacity units
--     provisioned for all your tables in that region, and one to hold the
--     aggregate write capacity units. Zero them both.
-- 3.  Call /ListTables/ to obtain a list of all your DynamoDB tables.
-- 4.  For each table name listed by /ListTables/, do the following:
--
--     -   Call /DescribeTable/ with the table name.
--     -   Use the data returned by /DescribeTable/ to add the read
--         capacity units and write capacity units provisioned for the
--         table itself to your variables.
--     -   If the table has one or more global secondary indexes (GSIs),
--         loop over these GSIs and add their provisioned capacity values
--         to your variables as well.
--
-- 5.  Report the account limits for that region returned by
--     /DescribeLimits/, along with the total current provisioned capacity
--     levels you have calculated.
--
-- This will let you see whether you are getting close to your
-- account-level limits.
--
-- The per-table limits apply only when you are creating a new table. They
-- restrict the sum of the provisioned capacity of the new table itself and
-- all its global secondary indexes.
--
-- For existing tables and their GSIs, DynamoDB will not let you increase
-- provisioned capacity extremely rapidly, but the only upper limit that
-- applies is that the aggregate provisioned capacity over all your tables
-- and GSIs cannot exceed either of the per-account limits.
--
-- /DescribeLimits/ should only be called periodically. You can expect
-- throttling errors if you call it more than once in a minute.
--
-- The /DescribeLimits/ Request element has no content.
module Network.AWS.DynamoDB.DescribeLimits
    (
    -- * Creating a Request
      describeLimits
    , DescribeLimits

    -- * Destructuring the Response
    , describeLimitsResponse
    , DescribeLimitsResponse
    -- * Response Lenses
    , dlrsTableMaxWriteCapacityUnits
    , dlrsTableMaxReadCapacityUnits
    , dlrsAccountMaxWriteCapacityUnits
    , dlrsAccountMaxReadCapacityUnits
    , dlrsResponseStatus
    ) where

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

-- | Represents the input of a /DescribeLimits/ operation. Has no content.
--
-- /See:/ 'describeLimits' smart constructor.
data DescribeLimits =
    DescribeLimits'
    deriving (Eq,Read,Show,Data,Typeable,Generic)

-- | Creates a value of 'DescribeLimits' with the minimum fields required to make a request.
--
describeLimits
    :: DescribeLimits
describeLimits = DescribeLimits'

instance AWSRequest DescribeLimits where
        type Rs DescribeLimits = DescribeLimitsResponse
        request = postJSON dynamoDB
        response
          = receiveJSON
              (\ s h x ->
                 DescribeLimitsResponse' <$>
                   (x .?> "TableMaxWriteCapacityUnits") <*>
                     (x .?> "TableMaxReadCapacityUnits")
                     <*> (x .?> "AccountMaxWriteCapacityUnits")
                     <*> (x .?> "AccountMaxReadCapacityUnits")
                     <*> (pure (fromEnum s)))

instance Hashable DescribeLimits

instance ToHeaders DescribeLimits where
        toHeaders
          = const
              (mconcat
                 ["X-Amz-Target" =#
                    ("DynamoDB_20120810.DescribeLimits" :: ByteString),
                  "Content-Type" =#
                    ("application/x-amz-json-1.0" :: ByteString)])

instance ToJSON DescribeLimits where
        toJSON = const (Object mempty)

instance ToPath DescribeLimits where
        toPath = const "/"

instance ToQuery DescribeLimits where
        toQuery = const mempty

-- | Represents the output of a /DescribeLimits/ operation.
--
-- /See:/ 'describeLimitsResponse' smart constructor.
data DescribeLimitsResponse = DescribeLimitsResponse'
    { _dlrsTableMaxWriteCapacityUnits   :: !(Maybe Nat)
    , _dlrsTableMaxReadCapacityUnits    :: !(Maybe Nat)
    , _dlrsAccountMaxWriteCapacityUnits :: !(Maybe Nat)
    , _dlrsAccountMaxReadCapacityUnits  :: !(Maybe Nat)
    , _dlrsResponseStatus               :: !Int
    } deriving (Eq,Read,Show,Data,Typeable,Generic)

-- | Creates a value of 'DescribeLimitsResponse' with the minimum fields required to make a request.
--
-- Use one of the following lenses to modify other fields as desired:
--
-- * 'dlrsTableMaxWriteCapacityUnits'
--
-- * 'dlrsTableMaxReadCapacityUnits'
--
-- * 'dlrsAccountMaxWriteCapacityUnits'
--
-- * 'dlrsAccountMaxReadCapacityUnits'
--
-- * 'dlrsResponseStatus'
describeLimitsResponse
    :: Int -- ^ 'dlrsResponseStatus'
    -> DescribeLimitsResponse
describeLimitsResponse pResponseStatus_ =
    DescribeLimitsResponse'
    { _dlrsTableMaxWriteCapacityUnits = Nothing
    , _dlrsTableMaxReadCapacityUnits = Nothing
    , _dlrsAccountMaxWriteCapacityUnits = Nothing
    , _dlrsAccountMaxReadCapacityUnits = Nothing
    , _dlrsResponseStatus = pResponseStatus_
    }

-- | The maximum write capacity units that your account allows you to
-- provision for a new table that you are creating in this region,
-- including the write capacity units provisioned for its global secondary
-- indexes (GSIs).
dlrsTableMaxWriteCapacityUnits :: Lens' DescribeLimitsResponse (Maybe Natural)
dlrsTableMaxWriteCapacityUnits = lens _dlrsTableMaxWriteCapacityUnits (\ s a -> s{_dlrsTableMaxWriteCapacityUnits = a}) . mapping _Nat;

-- | The maximum read capacity units that your account allows you to
-- provision for a new table that you are creating in this region,
-- including the read capacity units provisioned for its global secondary
-- indexes (GSIs).
dlrsTableMaxReadCapacityUnits :: Lens' DescribeLimitsResponse (Maybe Natural)
dlrsTableMaxReadCapacityUnits = lens _dlrsTableMaxReadCapacityUnits (\ s a -> s{_dlrsTableMaxReadCapacityUnits = a}) . mapping _Nat;

-- | The maximum total write capacity units that your account allows you to
-- provision across all of your tables in this region.
dlrsAccountMaxWriteCapacityUnits :: Lens' DescribeLimitsResponse (Maybe Natural)
dlrsAccountMaxWriteCapacityUnits = lens _dlrsAccountMaxWriteCapacityUnits (\ s a -> s{_dlrsAccountMaxWriteCapacityUnits = a}) . mapping _Nat;

-- | The maximum total read capacity units that your account allows you to
-- provision across all of your tables in this region.
dlrsAccountMaxReadCapacityUnits :: Lens' DescribeLimitsResponse (Maybe Natural)
dlrsAccountMaxReadCapacityUnits = lens _dlrsAccountMaxReadCapacityUnits (\ s a -> s{_dlrsAccountMaxReadCapacityUnits = a}) . mapping _Nat;

-- | The response status code.
dlrsResponseStatus :: Lens' DescribeLimitsResponse Int
dlrsResponseStatus = lens _dlrsResponseStatus (\ s a -> s{_dlrsResponseStatus = a});