{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE NamedFieldPuns #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE StrictData #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE NoImplicitPrelude #-}
{-# OPTIONS_GHC -fno-warn-unused-binds #-}
{-# OPTIONS_GHC -fno-warn-unused-imports #-}
{-# OPTIONS_GHC -fno-warn-unused-matches #-}

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

-- |
-- Module      : Amazonka.IoTData.ListRetainedMessages
-- Copyright   : (c) 2013-2023 Brendan Hay
-- License     : Mozilla Public License, v. 2.0.
-- Maintainer  : Brendan Hay
-- Stability   : auto-generated
-- Portability : non-portable (GHC extensions)
--
-- Lists summary information about the retained messages stored for the
-- account.
--
-- This action returns only the topic names of the retained messages. It
-- doesn\'t return any message payloads. Although this action doesn\'t
-- return a message payload, it can still incur messaging costs.
--
-- To get the message payload of a retained message, call
-- <https://docs.aws.amazon.com/iot/latest/developerguide/API_iotdata_GetRetainedMessage.html GetRetainedMessage>
-- with the topic name of the retained message.
--
-- Requires permission to access the
-- <https://docs.aws.amazon.com/service-authorization/latest/reference/list_awsiotfleethubfordevicemanagement.html#awsiotfleethubfordevicemanagement-actions-as-permissions ListRetainedMessages>
-- action.
--
-- For more information about messaging costs, see
-- <http://aws.amazon.com/iot-core/pricing/#Messaging Amazon Web Services IoT Core pricing - Messaging>.
--
-- This operation returns paginated results.
module Amazonka.IoTData.ListRetainedMessages
  ( -- * Creating a Request
    ListRetainedMessages (..),
    newListRetainedMessages,

    -- * Request Lenses
    listRetainedMessages_maxResults,
    listRetainedMessages_nextToken,

    -- * Destructuring the Response
    ListRetainedMessagesResponse (..),
    newListRetainedMessagesResponse,

    -- * Response Lenses
    listRetainedMessagesResponse_nextToken,
    listRetainedMessagesResponse_retainedTopics,
    listRetainedMessagesResponse_httpStatus,
  )
where

import qualified Amazonka.Core as Core
import qualified Amazonka.Core.Lens.Internal as Lens
import qualified Amazonka.Data as Data
import Amazonka.IoTData.Types
import qualified Amazonka.Prelude as Prelude
import qualified Amazonka.Request as Request
import qualified Amazonka.Response as Response

-- | /See:/ 'newListRetainedMessages' smart constructor.
data ListRetainedMessages = ListRetainedMessages'
  { -- | The maximum number of results to return at one time.
    maxResults :: Prelude.Maybe Prelude.Natural,
    -- | To retrieve the next set of results, the @nextToken@ value from a
    -- previous response; otherwise __null__ to receive the first set of
    -- results.
    nextToken :: Prelude.Maybe Prelude.Text
  }
  deriving (Prelude.Eq, Prelude.Read, Prelude.Show, Prelude.Generic)

-- |
-- Create a value of 'ListRetainedMessages' with all optional fields omitted.
--
-- Use <https://hackage.haskell.org/package/generic-lens generic-lens> or <https://hackage.haskell.org/package/optics optics> to modify other optional fields.
--
-- The following record fields are available, with the corresponding lenses provided
-- for backwards compatibility:
--
-- 'maxResults', 'listRetainedMessages_maxResults' - The maximum number of results to return at one time.
--
-- 'nextToken', 'listRetainedMessages_nextToken' - To retrieve the next set of results, the @nextToken@ value from a
-- previous response; otherwise __null__ to receive the first set of
-- results.
newListRetainedMessages ::
  ListRetainedMessages
newListRetainedMessages =
  ListRetainedMessages'
    { maxResults = Prelude.Nothing,
      nextToken = Prelude.Nothing
    }

-- | The maximum number of results to return at one time.
listRetainedMessages_maxResults :: Lens.Lens' ListRetainedMessages (Prelude.Maybe Prelude.Natural)
listRetainedMessages_maxResults = Lens.lens (\ListRetainedMessages' {maxResults} -> maxResults) (\s@ListRetainedMessages' {} a -> s {maxResults = a} :: ListRetainedMessages)

-- | To retrieve the next set of results, the @nextToken@ value from a
-- previous response; otherwise __null__ to receive the first set of
-- results.
listRetainedMessages_nextToken :: Lens.Lens' ListRetainedMessages (Prelude.Maybe Prelude.Text)
listRetainedMessages_nextToken = Lens.lens (\ListRetainedMessages' {nextToken} -> nextToken) (\s@ListRetainedMessages' {} a -> s {nextToken = a} :: ListRetainedMessages)

instance Core.AWSPager ListRetainedMessages where
  page rq rs
    | Core.stop
        ( rs
            Lens.^? listRetainedMessagesResponse_nextToken
            Prelude.. Lens._Just
        ) =
        Prelude.Nothing
    | Core.stop
        ( rs
            Lens.^? listRetainedMessagesResponse_retainedTopics
            Prelude.. Lens._Just
        ) =
        Prelude.Nothing
    | Prelude.otherwise =
        Prelude.Just
          Prelude.$ rq
          Prelude.& listRetainedMessages_nextToken
          Lens..~ rs
          Lens.^? listRetainedMessagesResponse_nextToken
          Prelude.. Lens._Just

instance Core.AWSRequest ListRetainedMessages where
  type
    AWSResponse ListRetainedMessages =
      ListRetainedMessagesResponse
  request overrides =
    Request.get (overrides defaultService)
  response =
    Response.receiveJSON
      ( \s h x ->
          ListRetainedMessagesResponse'
            Prelude.<$> (x Data..?> "nextToken")
            Prelude.<*> (x Data..?> "retainedTopics" Core..!@ Prelude.mempty)
            Prelude.<*> (Prelude.pure (Prelude.fromEnum s))
      )

instance Prelude.Hashable ListRetainedMessages where
  hashWithSalt _salt ListRetainedMessages' {..} =
    _salt
      `Prelude.hashWithSalt` maxResults
      `Prelude.hashWithSalt` nextToken

instance Prelude.NFData ListRetainedMessages where
  rnf ListRetainedMessages' {..} =
    Prelude.rnf maxResults
      `Prelude.seq` Prelude.rnf nextToken

instance Data.ToHeaders ListRetainedMessages where
  toHeaders = Prelude.const Prelude.mempty

instance Data.ToPath ListRetainedMessages where
  toPath = Prelude.const "/retainedMessage"

instance Data.ToQuery ListRetainedMessages where
  toQuery ListRetainedMessages' {..} =
    Prelude.mconcat
      [ "maxResults" Data.=: maxResults,
        "nextToken" Data.=: nextToken
      ]

-- | /See:/ 'newListRetainedMessagesResponse' smart constructor.
data ListRetainedMessagesResponse = ListRetainedMessagesResponse'
  { -- | The token for the next set of results, or null if there are no
    -- additional results.
    nextToken :: Prelude.Maybe Prelude.Text,
    -- | A summary list the account\'s retained messages. The information
    -- returned doesn\'t include the message payloads of the retained messages.
    retainedTopics :: Prelude.Maybe [RetainedMessageSummary],
    -- | The response's http status code.
    httpStatus :: Prelude.Int
  }
  deriving (Prelude.Eq, Prelude.Read, Prelude.Show, Prelude.Generic)

-- |
-- Create a value of 'ListRetainedMessagesResponse' with all optional fields omitted.
--
-- Use <https://hackage.haskell.org/package/generic-lens generic-lens> or <https://hackage.haskell.org/package/optics optics> to modify other optional fields.
--
-- The following record fields are available, with the corresponding lenses provided
-- for backwards compatibility:
--
-- 'nextToken', 'listRetainedMessagesResponse_nextToken' - The token for the next set of results, or null if there are no
-- additional results.
--
-- 'retainedTopics', 'listRetainedMessagesResponse_retainedTopics' - A summary list the account\'s retained messages. The information
-- returned doesn\'t include the message payloads of the retained messages.
--
-- 'httpStatus', 'listRetainedMessagesResponse_httpStatus' - The response's http status code.
newListRetainedMessagesResponse ::
  -- | 'httpStatus'
  Prelude.Int ->
  ListRetainedMessagesResponse
newListRetainedMessagesResponse pHttpStatus_ =
  ListRetainedMessagesResponse'
    { nextToken =
        Prelude.Nothing,
      retainedTopics = Prelude.Nothing,
      httpStatus = pHttpStatus_
    }

-- | The token for the next set of results, or null if there are no
-- additional results.
listRetainedMessagesResponse_nextToken :: Lens.Lens' ListRetainedMessagesResponse (Prelude.Maybe Prelude.Text)
listRetainedMessagesResponse_nextToken = Lens.lens (\ListRetainedMessagesResponse' {nextToken} -> nextToken) (\s@ListRetainedMessagesResponse' {} a -> s {nextToken = a} :: ListRetainedMessagesResponse)

-- | A summary list the account\'s retained messages. The information
-- returned doesn\'t include the message payloads of the retained messages.
listRetainedMessagesResponse_retainedTopics :: Lens.Lens' ListRetainedMessagesResponse (Prelude.Maybe [RetainedMessageSummary])
listRetainedMessagesResponse_retainedTopics = Lens.lens (\ListRetainedMessagesResponse' {retainedTopics} -> retainedTopics) (\s@ListRetainedMessagesResponse' {} a -> s {retainedTopics = a} :: ListRetainedMessagesResponse) Prelude.. Lens.mapping Lens.coerced

-- | The response's http status code.
listRetainedMessagesResponse_httpStatus :: Lens.Lens' ListRetainedMessagesResponse Prelude.Int
listRetainedMessagesResponse_httpStatus = Lens.lens (\ListRetainedMessagesResponse' {httpStatus} -> httpStatus) (\s@ListRetainedMessagesResponse' {} a -> s {httpStatus = a} :: ListRetainedMessagesResponse)

instance Prelude.NFData ListRetainedMessagesResponse where
  rnf ListRetainedMessagesResponse' {..} =
    Prelude.rnf nextToken
      `Prelude.seq` Prelude.rnf retainedTopics
      `Prelude.seq` Prelude.rnf httpStatus