/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "msgCore.h"  // precompiled header...
#include "nsCOMPtr.h"
#include "nsIMsgFolder.h"
#include "nsIFile.h"
#include "nsNetUtil.h"
#include "nsIMsgHdr.h"
#include "nsIChannel.h"
#include "nsIStreamListener.h"
#include "nsIMsgMessageService.h"
#include "nsMsgUtils.h"
#include "nsISeekableStream.h"
#include "nsIDBFolderInfo.h"
#include "nsIPrompt.h"
#include "nsIMsgLocalMailFolder.h"
#include "nsIMsgImapMailFolder.h"
#include "nsMailHeaders.h"
#include "nsMsgLocalFolderHdrs.h"
#include "nsIMsgDatabase.h"
#include "nsMsgMessageFlags.h"
#include "nsMsgFolderFlags.h"
#include "nsIMsgStatusFeedback.h"
#include "nsIMsgFolderNotificationService.h"
#include "nsMsgFolderCompactor.h"
#include "nsIOutputStream.h"
#include "nsIInputStream.h"
#include "nsPrintfCString.h"
#include "nsIStringBundle.h"
#include "nsICopyMessageStreamListener.h"
#include "nsIMsgWindow.h"
#include "nsIMsgPluggableStore.h"
#include "mozilla/Buffer.h"
#include "HeaderReader.h"
#include "LineReader.h"
#include "mozilla/Components.h"

static nsresult GetBaseStringBundle(nsIStringBundle** aBundle) {
  NS_ENSURE_ARG_POINTER(aBundle);
  nsCOMPtr<nsIStringBundleService> bundleService =
      mozilla::components::StringBundle::Service();
  NS_ENSURE_TRUE(bundleService, NS_ERROR_UNEXPECTED);
  nsCOMPtr<nsIStringBundle> bundle;
  return bundleService->CreateBundle(
      "chrome://messenger/locale/messenger.properties", aBundle);
}

#define COMPACTOR_READ_BUFF_SIZE 16384

/**
 * nsFolderCompactState is a helper class for nsFolderCompactor, which
 * handles compacting the mbox for a single local folder.
 *
 * This class also patches X-Mozilla-* headers where required. Usually
 * these headers are edited in-place without changing the overall size,
 * but sometimes there's not enough room. So as compaction involves
 * rewriting the whole file anyway, we take the opportunity to make some
 * more space and correct those headers.
 *
 * NOTE (for future cleanups):
 *
 * This base class calls nsIMsgMessageService.copyMessages() to iterate
 * through messages, passing itself in as a listener. Callbacks from
 * both nsICopyMessageStreamListener and nsIStreamListener are invoked.
 *
 * nsOfflineStoreCompactState uses a different mechanism - see separate
 * notes below.
 *
 * The way the service invokes the listener callbacks is pretty quirky
 * and probably needs a good sorting out, but for now I'll just document what
 * I've observed here:
 *
 * - The service calls OnStartRequest() at the start of the first message.
 * - StartMessage() is called at the start of subsequent messages.
 * - EndCopy() is called at the end of every message except the last one,
 *   where OnStopRequest() is invoked instead.
 * - OnDataAvailable() is called to pass the message body of each message
 *   (in multiple calls if the message is big enough).
 * - EndCopy() doesn't ever seem to be passed a failing error code from
 *   what I can see, and its own return code is ignored by upstream code.
 */
class nsFolderCompactState : public nsIStreamListener,
                             public nsICopyMessageStreamListener,
                             public nsIUrlListener {
 public:
  NS_DECL_ISUPPORTS
  NS_DECL_NSIREQUESTOBSERVER
  NS_DECL_NSISTREAMLISTENER
  NS_DECL_NSICOPYMESSAGESTREAMLISTENER
  NS_DECL_NSIURLLISTENER

  nsFolderCompactState(void);

  nsresult Compact(nsIMsgFolder* folder,
                   std::function<void(nsresult, uint64_t)> completionFn,
                   nsIMsgWindow* msgWindow);

 protected:
  virtual ~nsFolderCompactState(void);

  virtual nsresult InitDB(nsIMsgDatabase* db);
  virtual nsresult StartCompacting();
  virtual nsresult FinishCompact();
  void CloseOutputStream();
  void CleanupTempFilesAfterError();
  nsresult FlushBuffer();

  nsresult Init(nsIMsgFolder* aFolder, const char* aBaseMsgUri,
                nsIMsgDatabase* aDb, nsIFile* aPath, nsIMsgWindow* aMsgWindow);
  nsresult BuildMessageURI(const char* baseURI, nsMsgKey key, nsCString& uri);
  nsresult ShowStatusMsg(const nsString& aMsg);
  nsresult ReleaseFolderLock();
  void ShowCompactingStatusMsg();

  nsCString m_baseMessageUri;       // base message uri
  nsCString m_messageUri;           // current message uri being copy
  nsCOMPtr<nsIMsgFolder> m_folder;  // current folder being compact
  nsCOMPtr<nsIMsgDatabase> m_db;    // new database for the compact folder
  nsCOMPtr<nsIFile> m_file;         // new mailbox for the compact folder
  nsCOMPtr<nsIOutputStream> m_fileStream;  // output file stream for writing
  // All message keys that need to be copied over.
  nsTArray<nsMsgKey> m_keys;

  // Sum of the sizes of the messages, accumulated as we visit each msg.
  uint64_t m_totalMsgSize{0};
  // Number of bytes that can be expunged while compacting.
  uint64_t m_totalExpungedBytes{0};
  // Index of the current copied message key in key array.
  uint32_t m_curIndex{0};
  // Offset in mailbox of new message.
  uint64_t m_startOfNewMsg{0};
  mozilla::Buffer<char> m_buffer{COMPACTOR_READ_BUFF_SIZE};
  uint32_t m_bufferCount{0};

  // We'll use this if we need to output any EOLs - we try to preserve the
  // convention found in the input data.
  nsCString m_eolSeq{MSG_LINEBREAK};

  // The status of the copying operation.
  nsresult m_status{NS_OK};
  nsCOMPtr<nsIMsgMessageService> m_messageService;  // message service for
                                                    // copying
  nsCOMPtr<nsIMsgWindow> m_window;
  nsCOMPtr<nsIMsgDBHdr> m_curSrcHdr;
  // Flag set when we're waiting for local folder to complete parsing.
  bool m_parsingFolder;
  // Flag to indicate we're starting a new message, and that no data has
  // been written for it yet.
  bool m_startOfMsg;
  // Function which will be run when the folder compaction completes.
  // Takes a result code and the number of bytes which were expunged.
  std::function<void(nsresult, uint64_t)> m_completionFn;
  bool m_alreadyWarnedDiskSpace{false};
};

NS_IMPL_ISUPPORTS(nsFolderCompactState, nsIRequestObserver, nsIStreamListener,
                  nsICopyMessageStreamListener, nsIUrlListener)

nsFolderCompactState::nsFolderCompactState() {
  m_parsingFolder = false;
  m_startOfMsg = true;
}

nsFolderCompactState::~nsFolderCompactState() {
  CloseOutputStream();
  if (NS_FAILED(m_status)) {
    CleanupTempFilesAfterError();
    // if for some reason we failed remove the temp folder and database
  }
}

void nsFolderCompactState::CloseOutputStream() {
  if (m_fileStream) {
    m_fileStream->Close();
    m_fileStream = nullptr;
  }
}

void nsFolderCompactState::CleanupTempFilesAfterError() {
  CloseOutputStream();
  if (m_db) m_db->ForceClosed();
  nsCOMPtr<nsIFile> summaryFile;
  GetSummaryFileLocation(m_file, getter_AddRefs(summaryFile));
  m_file->Remove(false);
  summaryFile->Remove(false);
}

nsresult nsFolderCompactState::BuildMessageURI(const char* baseURI,
                                               nsMsgKey key, nsCString& uri) {
  uri.Append(baseURI);
  uri.Append('#');
  uri.AppendInt(key);

  return NS_OK;
}

nsresult nsFolderCompactState::InitDB(nsIMsgDatabase* db) {
  nsCOMPtr<nsIMsgDatabase> mailDBFactory;
  nsresult rv = db->ListAllKeys(m_keys);
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIMsgDBService> msgDBService =
      do_GetService("@mozilla.org/msgDatabase/msgDBService;1", &rv);
  NS_ENSURE_SUCCESS(rv, rv);
  rv = msgDBService->OpenMailDBFromFile(m_file, m_folder, true, false,
                                        getter_AddRefs(m_db));

  if (rv == NS_MSG_ERROR_FOLDER_SUMMARY_OUT_OF_DATE ||
      rv == NS_MSG_ERROR_FOLDER_SUMMARY_MISSING)
    // if it's out of date then reopen with upgrade.
    return msgDBService->OpenMailDBFromFile(m_file, m_folder, true, true,
                                            getter_AddRefs(m_db));
  return rv;
}

nsresult nsFolderCompactState::Compact(
    nsIMsgFolder* folder, std::function<void(nsresult, uint64_t)> completionFn,
    nsIMsgWindow* msgWindow) {
  NS_ENSURE_ARG_POINTER(folder);
  m_completionFn = completionFn;
  m_window = msgWindow;
  nsresult rv;
  nsCOMPtr<nsIMsgDatabase> db;
  nsCOMPtr<nsIFile> path;
  nsCString baseMessageURI;

  nsCOMPtr<nsIMsgLocalMailFolder> localFolder = do_QueryInterface(folder, &rv);
  if (NS_SUCCEEDED(rv) && localFolder) {
    rv = localFolder->GetDatabaseWOReparse(getter_AddRefs(db));
    if (NS_FAILED(rv) || !db) {
      if (rv == NS_MSG_ERROR_FOLDER_SUMMARY_MISSING ||
          rv == NS_MSG_ERROR_FOLDER_SUMMARY_OUT_OF_DATE) {
        m_folder = folder;  // will be used to compact
        m_parsingFolder = true;
        rv = localFolder->ParseFolder(m_window, this);
      }
      return rv;
    } else {
      bool valid;
      rv = db->GetSummaryValid(&valid);
      if (!valid)  // we are probably parsing the folder because we selected it.
      {
        folder->NotifyCompactCompleted();
        if (m_completionFn) {
          m_completionFn(NS_OK, m_totalExpungedBytes);
        }
        return NS_OK;
      }
    }
  } else {
    rv = folder->GetMsgDatabase(getter_AddRefs(db));
    NS_ENSURE_SUCCESS(rv, rv);
  }

  rv = folder->GetFilePath(getter_AddRefs(path));
  NS_ENSURE_SUCCESS(rv, rv);

  do {
    bool exists = false;
    rv = path->Exists(&exists);
    if (!exists) {
      // No need to compact if the local file does not exist.
      // Can happen e.g. on IMAP when the folder is not marked for offline use.
      break;
    }

    int64_t expunged = 0;
    folder->GetExpungedBytes(&expunged);
    if (expunged == 0) {
      // No need to compact if nothing would be expunged.
      break;
    }

    int64_t diskSize;
    rv = folder->GetSizeOnDisk(&diskSize);
    NS_ENSURE_SUCCESS(rv, rv);

    int64_t diskFree;
    rv = path->GetDiskSpaceAvailable(&diskFree);
    if (NS_FAILED(rv)) {
      // If GetDiskSpaceAvailable() failed, better bail out fast.
      if (rv != NS_ERROR_NOT_IMPLEMENTED) return rv;
      // Some platforms do not have GetDiskSpaceAvailable implemented.
      // In that case skip the preventive free space analysis and let it
      // fail in compact later if space actually wasn't available.
    } else {
      // Let's try to not even start compact if there is really low free space.
      // It may still fail later as we do not know how big exactly the folder DB
      // will end up being. The DB already doesn't contain references to
      // messages that are already deleted. So theoretically it shouldn't shrink
      // with compact. But in practice, the automatic shrinking of the DB may
      // still have not yet happened. So we cap the final size at 1KB per
      // message.
      db->Commit(nsMsgDBCommitType::kCompressCommit);

      int64_t dbSize;
      rv = db->GetDatabaseSize(&dbSize);
      NS_ENSURE_SUCCESS(rv, rv);

      int32_t totalMsgs;
      rv = folder->GetTotalMessages(false, &totalMsgs);
      NS_ENSURE_SUCCESS(rv, rv);
      int64_t expectedDBSize =
          std::min<int64_t>(dbSize, ((int64_t)totalMsgs) * 1024);
      if (diskFree < diskSize - expunged + expectedDBSize) {
        if (!m_alreadyWarnedDiskSpace) {
          folder->ThrowAlertMsg("compactFolderInsufficientSpace", m_window);
          m_alreadyWarnedDiskSpace = true;
        }
        break;
      }
    }

    rv = folder->GetBaseMessageURI(baseMessageURI);
    NS_ENSURE_SUCCESS(rv, rv);

    rv = Init(folder, baseMessageURI.get(), db, path, m_window);
    NS_ENSURE_SUCCESS(rv, rv);

    bool isLocked = true;
    m_folder->GetLocked(&isLocked);
    if (isLocked) {
      CleanupTempFilesAfterError();
      m_folder->ThrowAlertMsg("compactFolderDeniedLock", m_window);
      break;
    }

    // If we got here start the real compacting.
    nsCOMPtr<nsISupports> supports;
    QueryInterface(NS_GET_IID(nsISupports), getter_AddRefs(supports));
    m_folder->AcquireSemaphore(supports);
    m_totalExpungedBytes += expunged;
    return StartCompacting();

  } while (false);  // block for easy skipping the compaction using 'break'

  // Skipped folder, for whatever reason.
  folder->NotifyCompactCompleted();
  if (m_completionFn) {
    m_completionFn(NS_OK, m_totalExpungedBytes);
  }
  return NS_OK;
}

nsresult nsFolderCompactState::ShowStatusMsg(const nsString& aMsg) {
  if (!m_window || aMsg.IsEmpty()) return NS_OK;

  nsCOMPtr<nsIMsgStatusFeedback> statusFeedback;
  nsresult rv = m_window->GetStatusFeedback(getter_AddRefs(statusFeedback));
  if (NS_FAILED(rv) || !statusFeedback) return NS_OK;

  // Try to prepend account name to the message.
  nsString statusMessage;
  do {
    nsCOMPtr<nsIMsgIncomingServer> server;
    rv = m_folder->GetServer(getter_AddRefs(server));
    if (NS_FAILED(rv)) break;
    nsAutoString accountName;
    rv = server->GetPrettyName(accountName);
    if (NS_FAILED(rv)) break;
    nsCOMPtr<nsIStringBundle> bundle;
    rv = GetBaseStringBundle(getter_AddRefs(bundle));
    if (NS_FAILED(rv)) break;
    AutoTArray<nsString, 2> params = {accountName, aMsg};
    rv = bundle->FormatStringFromName("statusMessage", params, statusMessage);
  } while (false);

  // If fetching any of the needed info failed, just show the original message.
  if (NS_FAILED(rv)) statusMessage.Assign(aMsg);
  return statusFeedback->SetStatusString(statusMessage);
}

nsresult nsFolderCompactState::Init(nsIMsgFolder* folder,
                                    const char* baseMsgUri, nsIMsgDatabase* db,
                                    nsIFile* path, nsIMsgWindow* aMsgWindow) {
  nsresult rv;

  m_folder = folder;
  m_baseMessageUri = baseMsgUri;
  m_file = do_CreateInstance(NS_LOCAL_FILE_CONTRACTID, &rv);
  NS_ENSURE_SUCCESS(rv, rv);
  m_file->InitWithFile(path);

  m_file->SetNativeLeafName("nstmp"_ns);
  // Make sure we are not crunching existing nstmp file.
  rv = m_file->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 00600);
  NS_ENSURE_SUCCESS(rv, rv);

  m_window = aMsgWindow;
  m_totalMsgSize = 0;
  rv = InitDB(db);
  if (NS_FAILED(rv)) {
    CleanupTempFilesAfterError();
    return rv;
  }

  m_curIndex = 0;

  rv = MsgNewBufferedFileOutputStream(getter_AddRefs(m_fileStream), m_file, -1,
                                      00600);
  if (NS_FAILED(rv))
    m_folder->ThrowAlertMsg("compactFolderWriteFailed", m_window);
  else
    rv = GetMessageServiceFromURI(nsDependentCString(baseMsgUri),
                                  getter_AddRefs(m_messageService));
  if (NS_FAILED(rv)) {
    m_status = rv;
  }
  return rv;
}

void nsFolderCompactState::ShowCompactingStatusMsg() {
  nsString statusString;
  nsresult rv = m_folder->GetStringWithFolderNameFromBundle("compactingFolder",
                                                            statusString);
  if (!statusString.IsEmpty() && NS_SUCCEEDED(rv)) ShowStatusMsg(statusString);
}

NS_IMETHODIMP nsFolderCompactState::OnStartRunningUrl(nsIURI* url) {
  return NS_OK;
}

// If we had to kick off a folder parse, this will be called when it
// completes.
NS_IMETHODIMP nsFolderCompactState::OnStopRunningUrl(nsIURI* url,
                                                     nsresult status) {
  if (m_parsingFolder) {
    m_parsingFolder = false;
    if (NS_SUCCEEDED(status)) {
      // Folder reparse succeeded. Start compacting it.
      status = Compact(m_folder, m_completionFn, m_window);
      if (NS_SUCCEEDED(status)) {
        return NS_OK;
      }
    }
  }

  // This is from bug 249754. The aim is to close the DB file to avoid
  // running out of filehandles when large numbers of folders are compacted.
  // But it seems like filehandle management would be better off being
  // handled by the DB class itself (it might be already, but it's hard to
  // tell)...
  m_folder->SetMsgDatabase(nullptr);

  if (m_completionFn) {
    m_completionFn(status, m_totalExpungedBytes);
  }
  return NS_OK;
}

nsresult nsFolderCompactState::StartCompacting() {
  nsresult rv = NS_OK;
  // Notify that compaction is beginning.  We do this even if there are no
  // messages to be copied because the summary database still gets blown away
  // which is still pretty interesting.  (And we like consistency.)
  nsCOMPtr<nsIMsgFolderNotificationService> notifier(
      do_GetService("@mozilla.org/messenger/msgnotificationservice;1"));
  if (notifier) {
    notifier->NotifyFolderCompactStart(m_folder);
  }

  // TODO: test whether sorting the messages (m_keys) by messageOffset
  // would improve performance on large files (less seeks).
  // The m_keys array is in the order as stored in DB and on IMAP or News
  // the messages stored on the mbox file are not necessarily in the same order.
  if (m_keys.Length() > 0) {
    nsCOMPtr<nsIURI> notUsed;
    ShowCompactingStatusMsg();
    NS_ADDREF_THIS();
    rv = m_messageService->CopyMessages(m_keys, m_folder, this, false, nullptr,
                                        m_window, getter_AddRefs(notUsed));
  } else {  // no messages to copy with
    FinishCompact();
  }
  return rv;
}

nsresult nsFolderCompactState::FinishCompact() {
  NS_ENSURE_TRUE(m_folder, NS_ERROR_NOT_INITIALIZED);
  NS_ENSURE_TRUE(m_file, NS_ERROR_NOT_INITIALIZED);

  // All okay time to finish up the compact process
  nsCOMPtr<nsIFile> path;
  nsCOMPtr<nsIDBFolderInfo> folderInfo;

  // get leaf name and database name of the folder
  nsresult rv = m_folder->GetFilePath(getter_AddRefs(path));
  nsCOMPtr<nsIFile> folderPath =
      do_CreateInstance(NS_LOCAL_FILE_CONTRACTID, &rv);
  NS_ENSURE_SUCCESS(rv, rv);
  rv = folderPath->InitWithFile(path);
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIFile> oldSummaryFile;
  rv = GetSummaryFileLocation(folderPath, getter_AddRefs(oldSummaryFile));
  NS_ENSURE_SUCCESS(rv, rv);
  nsAutoCString dbName;
  oldSummaryFile->GetNativeLeafName(dbName);
  nsAutoCString folderName;
  path->GetNativeLeafName(folderName);

  // close down the temp file stream; preparing for deleting the old folder
  // and its database; then rename the temp folder and database
  if (m_fileStream) {
    m_fileStream->Flush();
    m_fileStream->Close();
    m_fileStream = nullptr;
  }

  // make sure the new database is valid.
  // Close it so we can rename the .msf file.
  if (m_db) {
    m_db->ForceClosed();
    m_db = nullptr;
  }

  nsCOMPtr<nsIFile> newSummaryFile;
  rv = GetSummaryFileLocation(m_file, getter_AddRefs(newSummaryFile));
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIDBFolderInfo> transferInfo;
  m_folder->GetDBTransferInfo(getter_AddRefs(transferInfo));

  // close down database of the original folder
  m_folder->ForceDBClosed();

  nsCOMPtr<nsIFile> cloneFile;
  int64_t fileSize = 0;
  rv = m_file->Clone(getter_AddRefs(cloneFile));
  if (NS_SUCCEEDED(rv)) rv = cloneFile->GetFileSize(&fileSize);
  bool tempFileRightSize = ((uint64_t)fileSize == m_totalMsgSize);
  NS_WARNING_ASSERTION(tempFileRightSize,
                       "temp file not of expected size in compact");

  bool folderRenameSucceeded = false;
  bool msfRenameSucceeded = false;
  if (NS_SUCCEEDED(rv) && tempFileRightSize) {
    // First we're going to try and move the old summary file out the way.
    // We don't delete it yet, as we want to keep the files in sync.
    nsCOMPtr<nsIFile> tempSummaryFile;
    rv = oldSummaryFile->Clone(getter_AddRefs(tempSummaryFile));
    if (NS_SUCCEEDED(rv))
      rv = tempSummaryFile->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0600);

    nsAutoCString tempSummaryFileName;
    if (NS_SUCCEEDED(rv))
      rv = tempSummaryFile->GetNativeLeafName(tempSummaryFileName);

    if (NS_SUCCEEDED(rv))
      rv = oldSummaryFile->MoveToNative((nsIFile*)nullptr, tempSummaryFileName);

    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
                         "error moving compacted folder's db out of the way");
    if (NS_SUCCEEDED(rv)) {
      // Now we've successfully moved the summary file out the way, try moving
      // the newly compacted message file over the old one.
      rv = m_file->MoveToNative((nsIFile*)nullptr, folderName);
      folderRenameSucceeded = NS_SUCCEEDED(rv);
      NS_WARNING_ASSERTION(folderRenameSucceeded,
                           "error renaming compacted folder");
      if (folderRenameSucceeded) {
        // That worked, so land the new summary file in the right place.
        nsCOMPtr<nsIFile> renamedCompactedSummaryFile;
        newSummaryFile->Clone(getter_AddRefs(renamedCompactedSummaryFile));
        if (renamedCompactedSummaryFile) {
          rv = renamedCompactedSummaryFile->MoveToNative((nsIFile*)nullptr,
                                                         dbName);
          msfRenameSucceeded = NS_SUCCEEDED(rv);
        }
        NS_WARNING_ASSERTION(msfRenameSucceeded,
                             "error renaming compacted folder's db");
      }

      if (!msfRenameSucceeded) {
        // Do our best to put the summary file back to where it was
        rv = tempSummaryFile->MoveToNative((nsIFile*)nullptr, dbName);
        if (NS_SUCCEEDED(rv)) {
          // Flagging that a renamed db no longer exists.
          tempSummaryFile = nullptr;
        } else {
          NS_WARNING("error restoring uncompacted folder's db");
        }
      }
    }
    // We don't want any temporarily renamed summary file to lie around
    if (tempSummaryFile) tempSummaryFile->Remove(false);
  }

  NS_WARNING_ASSERTION(msfRenameSucceeded, "compact failed");
  nsresult rvReleaseFolderLock = ReleaseFolderLock();
  NS_WARNING_ASSERTION(NS_SUCCEEDED(rvReleaseFolderLock),
                       "folder lock not released successfully");
  rv = NS_FAILED(rv) ? rv : rvReleaseFolderLock;

  // Cleanup of nstmp-named compacted files if failure
  if (!folderRenameSucceeded) {
    // remove the abandoned compacted version with the wrong name
    m_file->Remove(false);
  }
  if (!msfRenameSucceeded) {
    // remove the abandoned compacted summary file
    newSummaryFile->Remove(false);
  }

  if (msfRenameSucceeded) {
    // Transfer local db information from transferInfo
    nsCOMPtr<nsIMsgDBService> msgDBService =
        do_GetService("@mozilla.org/msgDatabase/msgDBService;1", &rv);
    NS_ENSURE_SUCCESS(rv, rv);
    rv = msgDBService->OpenFolderDB(m_folder, true, getter_AddRefs(m_db));
    NS_ENSURE_TRUE(m_db, NS_FAILED(rv) ? rv : NS_ERROR_FAILURE);
    // These errors are expected.
    rv = (rv == NS_MSG_ERROR_FOLDER_SUMMARY_MISSING ||
          rv == NS_MSG_ERROR_FOLDER_SUMMARY_OUT_OF_DATE)
             ? NS_OK
             : rv;
    m_db->SetSummaryValid(true);
    if (transferInfo) m_folder->SetDBTransferInfo(transferInfo);

    // since we're transferring info from the old db, we need to reset the
    // expunged bytes
    nsCOMPtr<nsIDBFolderInfo> dbFolderInfo;
    m_db->GetDBFolderInfo(getter_AddRefs(dbFolderInfo));
    if (dbFolderInfo) dbFolderInfo->SetExpungedBytes(0);
  }
  if (m_db) m_db->Close(true);
  m_db = nullptr;

  // Notify that compaction of the folder is completed.
  nsCOMPtr<nsIMsgFolderNotificationService> notifier(
      do_GetService("@mozilla.org/messenger/msgnotificationservice;1"));
  if (notifier) {
    notifier->NotifyFolderCompactFinish(m_folder);
  }

  m_folder->NotifyCompactCompleted();
  if (m_completionFn) {
    m_completionFn(rv, m_totalExpungedBytes);
  }

  return NS_OK;
}

nsresult nsFolderCompactState::ReleaseFolderLock() {
  nsresult result = NS_OK;
  if (!m_folder) return result;
  bool haveSemaphore;
  nsCOMPtr<nsISupports> supports;
  QueryInterface(NS_GET_IID(nsISupports), getter_AddRefs(supports));
  result = m_folder->TestSemaphore(supports, &haveSemaphore);
  if (NS_SUCCEEDED(result) && haveSemaphore)
    result = m_folder->ReleaseSemaphore(supports);
  return result;
}

NS_IMETHODIMP
nsFolderCompactState::OnStartRequest(nsIRequest* request) {
  return StartMessage();
}

NS_IMETHODIMP
nsFolderCompactState::OnStopRequest(nsIRequest* request, nsresult status) {
  nsCOMPtr<nsIMsgDBHdr> msgHdr;
  if (NS_FAILED(status)) {
    // Set m_status to status so the destructor can remove the temp folder and
    // database.
    m_status = status;
    CleanupTempFilesAfterError();
    m_folder->NotifyCompactCompleted();
    ReleaseFolderLock();
    m_folder->ThrowAlertMsg("compactFolderWriteFailed", m_window);
  } else {
    // XXX TODO: Error checking and handling missing here.
    EndCopy(nullptr, status);
    if (m_curIndex >= m_keys.Length()) {
      msgHdr = nullptr;
      // no more to copy finish it up
      FinishCompact();
    } else {
      // in case we're not getting an error, we still need to pretend we did get
      // an error, because the compact did not successfully complete.
      m_folder->NotifyCompactCompleted();
      CleanupTempFilesAfterError();
      ReleaseFolderLock();
    }
  }
  NS_RELEASE_THIS();  // kill self
  return status;
}

// Handle the message data.
// (NOTE: nsOfflineStoreCompactState overrides this)
NS_IMETHODIMP
nsFolderCompactState::OnDataAvailable(nsIRequest* request,
                                      nsIInputStream* inStr,
                                      uint64_t sourceOffset, uint32_t count) {
  MOZ_ASSERT(m_fileStream);
  MOZ_ASSERT(inStr);

  nsresult rv = NS_OK;

  // TODO: This block should be moved in to the callback that indicates the
  // start of a new message, but it's complicated because of the derived
  // nsOfflineStoreCompactState and also the odd message copy listener
  // orderings. Leaving it here for now, but it's ripe for tidying up in
  // future.
  if (m_startOfMsg) {
    m_messageUri.Truncate();  // clear the previous message uri
    if (NS_SUCCEEDED(BuildMessageURI(m_baseMessageUri.get(), m_keys[m_curIndex],
                                     m_messageUri))) {
      rv = m_messageService->MessageURIToMsgHdr(m_messageUri,
                                                getter_AddRefs(m_curSrcHdr));
      NS_ENSURE_SUCCESS(rv, rv);
    }
  }

  while (count > 0) {
    uint32_t maxReadCount =
        std::min((uint32_t)m_buffer.Length() - m_bufferCount, count);
    uint32_t readCount;
    rv = inStr->Read(m_buffer.Elements() + m_bufferCount, maxReadCount,
                     &readCount);
    NS_ENSURE_SUCCESS(rv, rv);

    count -= readCount;
    m_bufferCount += readCount;
    if (m_bufferCount == m_buffer.Length()) {
      rv = FlushBuffer();
      NS_ENSURE_SUCCESS(rv, rv);
    }
  }
  if (m_bufferCount > 0) {
    rv = FlushBuffer();
    NS_ENSURE_SUCCESS(rv, rv);
  }
  return NS_OK;
}

// Helper to write data to an outputstream, until complete or error.
static nsresult WriteSpan(nsIOutputStream* writeable,
                          mozilla::Span<const char> data) {
  while (!data.IsEmpty()) {
    uint32_t n;
    nsresult rv = writeable->Write(data.Elements(), data.Length(), &n);
    NS_ENSURE_SUCCESS(rv, rv);
    data = data.Last(data.Length() - n);
  }
  return NS_OK;
}

// Flush contents of m_buffer to the output file.
// (NOTE: not used by nsOfflineStoreCompactState)
// More complicated than it should be because we need to fiddle with
// some of the X-Mozilla-* headers on the fly.
nsresult nsFolderCompactState::FlushBuffer() {
  MOZ_ASSERT(m_fileStream);
  nsresult rv;
  auto buf = m_buffer.AsSpan().First(m_bufferCount);
  if (!m_startOfMsg) {
    // We only do header twiddling for the first chunk. So from now on we
    // just copy data verbatim.
    rv = WriteSpan(m_fileStream, buf);
    NS_ENSURE_SUCCESS(rv, rv);
    m_bufferCount = 0;
    return NS_OK;
  }

  // This is the first chunk of a new message. We'll update the
  // X-Mozilla-(Status|Status2|Keys) headers as we go.
  m_startOfMsg = false;

  // Sniff the data to see if we can spot any CRs.
  // If so, we'll use CRLFs instead of platform-native EOLs.
  auto sniffChunk = buf.First(std::min<size_t>(buf.Length(), 512));
  auto cr = std::find(sniffChunk.cbegin(), sniffChunk.cend(), '\r');
  if (cr != sniffChunk.cend()) {
    m_eolSeq.Assign("\r\n"_ns);
  }

  // Add a "From " line if missing.
  // NOTE: Ultimately we should never see "From " lines in this data - it's an
  // mbox detail the message streaming should filter out. But for now we'll
  // handle it optionally.
  nsAutoCString fromLine;
  auto l = FirstLine(buf);
  if (l.Length() > 5 &&
      nsDependentCSubstring(l.Elements(), 5).EqualsLiteral("From ")) {
    fromLine = nsDependentCSubstring(l);
    buf = buf.From(l.Length());
  } else {
    fromLine = "From "_ns + m_eolSeq;
  }
  rv = WriteSpan(m_fileStream, fromLine);
  NS_ENSURE_SUCCESS(rv, rv);

  // Read as many headers as we can. We might not have the complete header
  // block our in buffer, but that's OK - the X-Mozilla-* ones should be
  // right at the start).
  nsTArray<HeaderReader::Hdr> headers;
  HeaderReader rdr;
  auto leftover = rdr.Parse(buf, [&](auto const& hdr) -> bool {
    auto const& name = hdr.Name(buf);
    if (!name.EqualsLiteral(HEADER_X_MOZILLA_STATUS) &&
        !name.EqualsLiteral(HEADER_X_MOZILLA_STATUS2) &&
        !name.EqualsLiteral(HEADER_X_MOZILLA_KEYWORDS)) {
      headers.AppendElement(hdr);
    }
    return true;
  });

  // Write out X-Mozilla-* headers first - we'll create these from scratch.
  uint32_t msgFlags = 0;
  nsAutoCString keywords;
  if (m_curSrcHdr) {
    m_curSrcHdr->GetFlags(&msgFlags);
    m_curSrcHdr->GetStringProperty("keywords", keywords);
    // growKeywords is set if msgStore didn't have enough room to edit
    // X-Mozilla-* headers in situ. We'll rewrite all those headers
    // regardless but we still want to clear it.
    uint32_t grow;
    m_curSrcHdr->GetUint32Property("growKeywords", &grow);
    if (grow) {
      m_curSrcHdr->SetUint32Property("growKeywords", 0);
    }
  }

  auto out =
      nsPrintfCString(HEADER_X_MOZILLA_STATUS ": %4.4x", msgFlags & 0xFFFF);
  out.Append(m_eolSeq);
  rv = WriteSpan(m_fileStream, out);
  NS_ENSURE_SUCCESS(rv, rv);

  out = nsPrintfCString(HEADER_X_MOZILLA_STATUS2 ": %8.8x",
                        msgFlags & 0xFFFF0000);
  out.Append(m_eolSeq);
  rv = WriteSpan(m_fileStream, out);
  NS_ENSURE_SUCCESS(rv, rv);

  // Try to leave room for future in-place keyword edits.
  while (keywords.Length() < X_MOZILLA_KEYWORDS_BLANK_LEN) {
    keywords.Append(' ');
  }
  out = nsPrintfCString(HEADER_X_MOZILLA_KEYWORDS ": %s", keywords.get());
  out.Append(m_eolSeq);
  rv = WriteSpan(m_fileStream, out);
  NS_ENSURE_SUCCESS(rv, rv);

  // Write out the rest of the headers.
  for (auto const& hdr : headers) {
    rv = WriteSpan(m_fileStream, buf.Subspan(hdr.pos, hdr.len));
    NS_ENSURE_SUCCESS(rv, rv);
  }

  // The header parser consumes the blank line, If we've completed parsing
  // we need to output it now.
  // If we haven't parsed all the headers yet then the blank line will be
  // safely copied verbatim as part of the remaining data.
  if (rdr.IsComplete()) {
    rv = WriteSpan(m_fileStream, m_eolSeq);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  // Write out everything else in the buffer verbatim.
  if (leftover.Length() > 0) {
    rv = WriteSpan(m_fileStream, leftover);
    NS_ENSURE_SUCCESS(rv, rv);
  }
  m_bufferCount = 0;
  return NS_OK;
}

/**
 * nsOfflineStoreCompactState is a helper class for nsFolderCompactor which
 * handles compacting the mbox for a single offline IMAP folder.
 *
 * nsOfflineStoreCompactState does *not* do any special X-Mozilla-* header
 * handling, unlike the base class.
 *
 * NOTE (for future cleanups):
 * This class uses a different mechanism to iterate through messages. It uses
 * nsIMsgMessageService.streamMessage() to stream each message in turn,
 * passing itself in as an nsIStreamListener. The nsICopyMessageStreamListener
 * callbacks implemented in the base class are _not_ used here.
 * For each message, the standard OnStartRequest(), OnDataAvailable()...,
 * OnStopRequest() sequence is seen.
 * Nothing too fancy, but it's not always clear where code from the base class
 * is being used and when it is not, so it can be complicated to pick through.
 *
 */
class nsOfflineStoreCompactState : public nsFolderCompactState {
 public:
  nsOfflineStoreCompactState(void);
  virtual ~nsOfflineStoreCompactState(void);
  NS_IMETHOD OnStopRequest(nsIRequest* request, nsresult status) override;
  NS_IMETHODIMP OnDataAvailable(nsIRequest* request, nsIInputStream* inStr,
                                uint64_t sourceOffset, uint32_t count) override;

 protected:
  nsresult CopyNextMessage(bool& done);
  virtual nsresult InitDB(nsIMsgDatabase* db) override;
  virtual nsresult StartCompacting() override;
  virtual nsresult FinishCompact() override;

  char m_dataBuffer[COMPACTOR_READ_BUFF_SIZE + 1];  // temp data buffer for
                                                    // copying message
  uint32_t m_offlineMsgSize;
};

nsOfflineStoreCompactState::nsOfflineStoreCompactState()
    : m_offlineMsgSize(0) {}

nsOfflineStoreCompactState::~nsOfflineStoreCompactState() {}

nsresult nsOfflineStoreCompactState::InitDB(nsIMsgDatabase* db) {
  // Start with the list of messages we have offline as the possible
  // message to keep when compacting the offline store.
  db->ListAllOfflineMsgs(m_keys);
  m_db = db;
  return NS_OK;
}

/**
 * This will copy one message to the offline store, but if it fails to
 * copy the next message, it will keep trying messages until it finds one
 * it can copy, or it runs out of messages.
 */
nsresult nsOfflineStoreCompactState::CopyNextMessage(bool& done) {
  while (m_curIndex < m_keys.Length()) {
    // Filter out msgs that have the "pendingRemoval" attribute set.
    nsCOMPtr<nsIMsgDBHdr> hdr;
    nsCString pendingRemoval;
    nsresult rv =
        m_db->GetMsgHdrForKey(m_keys[m_curIndex], getter_AddRefs(hdr));
    NS_ENSURE_SUCCESS(rv, rv);
    hdr->GetStringProperty("pendingRemoval", pendingRemoval);
    if (!pendingRemoval.IsEmpty()) {
      m_curIndex++;
      // Turn off offline flag for message, since after the compact is
      // completed; we won't have the message in the offline store.
      uint32_t resultFlags;
      hdr->AndFlags(~nsMsgMessageFlags::Offline, &resultFlags);
      // We need to clear this in case the user changes the offline retention
      // settings.
      hdr->SetStringProperty("pendingRemoval", ""_ns);
      continue;
    }
    m_messageUri.Truncate();  // clear the previous message uri
    rv = BuildMessageURI(m_baseMessageUri.get(), m_keys[m_curIndex],
                         m_messageUri);
    NS_ENSURE_SUCCESS(rv, rv);
    m_startOfMsg = true;
    nsCOMPtr<nsISupports> thisSupports;
    QueryInterface(NS_GET_IID(nsISupports), getter_AddRefs(thisSupports));
    nsCOMPtr<nsIURI> dummyNull;
    rv = m_messageService->StreamMessage(m_messageUri, thisSupports, m_window,
                                         nullptr, false, EmptyCString(), true,
                                         getter_AddRefs(dummyNull));
    // if copy fails, we clear the offline flag on the source message.
    if (NS_FAILED(rv)) {
      nsCOMPtr<nsIMsgDBHdr> hdr;
      m_messageService->MessageURIToMsgHdr(m_messageUri, getter_AddRefs(hdr));
      if (hdr) {
        uint32_t resultFlags;
        hdr->AndFlags(~nsMsgMessageFlags::Offline, &resultFlags);
      }
      m_curIndex++;
      continue;
    } else
      break;
  }
  done = m_curIndex >= m_keys.Length();
  // In theory, we might be able to stream the next message, so
  // return NS_OK, not rv.
  return NS_OK;
}

NS_IMETHODIMP
nsOfflineStoreCompactState::OnStopRequest(nsIRequest* request,
                                          nsresult status) {
  nsresult rv = status;
  nsCOMPtr<nsIURI> uri;
  nsCOMPtr<nsIMsgDBHdr> msgHdr;
  nsCOMPtr<nsIMsgStatusFeedback> statusFeedback;
  nsCOMPtr<nsIChannel> channel;
  bool done = false;

  // The NS_MSG_ERROR_MSG_NOT_OFFLINE error should allow us to continue, so we
  // check for it specifically and don't terminate the compaction.
  if (NS_FAILED(rv) && rv != NS_MSG_ERROR_MSG_NOT_OFFLINE) goto done;

  // We know the request is an nsIChannel we can get a URI from, but this is
  // probably bad form. See Bug 1528662.
  channel = do_QueryInterface(request, &rv);
  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
                       "error QI nsIRequest to nsIChannel failed");
  if (NS_FAILED(rv)) goto done;
  rv = channel->GetURI(getter_AddRefs(uri));
  if (NS_FAILED(rv)) goto done;
  rv = m_messageService->MessageURIToMsgHdr(m_messageUri,
                                            getter_AddRefs(msgHdr));
  if (NS_FAILED(rv)) goto done;

  // This is however an unexpected condition, so let's print a warning.
  if (rv == NS_MSG_ERROR_MSG_NOT_OFFLINE) {
    nsAutoCString spec;
    uri->GetSpec(spec);
    nsPrintfCString msg("Message expectedly not available offline: %s",
                        spec.get());
    NS_WARNING(msg.get());
  }

  if (msgHdr) {
    if (NS_SUCCEEDED(status)) {
      msgHdr->SetMessageOffset(m_startOfNewMsg);
      nsCString storeToken = nsPrintfCString("%" PRIu64, m_startOfNewMsg);
      msgHdr->SetStringProperty("storeToken", storeToken);
      msgHdr->SetOfflineMessageSize(m_offlineMsgSize);
    } else {
      uint32_t resultFlags;
      msgHdr->AndFlags(~nsMsgMessageFlags::Offline, &resultFlags);
    }
  }

  if (m_window) {
    m_window->GetStatusFeedback(getter_AddRefs(statusFeedback));
    if (statusFeedback)
      statusFeedback->ShowProgress(100 * m_curIndex / m_keys.Length());
  }
  // advance to next message
  m_curIndex++;
  rv = CopyNextMessage(done);
  if (done) {
    m_db->Commit(nsMsgDBCommitType::kCompressCommit);
    msgHdr = nullptr;
    // no more to copy finish it up
    ReleaseFolderLock();
    FinishCompact();
    NS_RELEASE_THIS();  // kill self
  }

done:
  if (NS_FAILED(rv)) {
    m_status = rv;  // set the status to rv so the destructor can remove the
                    // temp folder and database
    ReleaseFolderLock();
    NS_RELEASE_THIS();  // kill self

    if (m_completionFn) {
      m_completionFn(m_status, m_totalExpungedBytes);
    }
    return rv;
  }
  return rv;
}

nsresult nsOfflineStoreCompactState::FinishCompact() {
  // All okay time to finish up the compact process
  nsCOMPtr<nsIFile> path;
  uint32_t flags;

  // get leaf name and database name of the folder
  m_folder->GetFlags(&flags);
  nsresult rv = m_folder->GetFilePath(getter_AddRefs(path));

  nsCString leafName;
  path->GetNativeLeafName(leafName);

  if (m_fileStream) {
    // close down the temp file stream; preparing for deleting the old folder
    // and its database; then rename the temp folder and database
    m_fileStream->Flush();
    m_fileStream->Close();
    m_fileStream = nullptr;
  }

  // make sure the new database is valid
  nsCOMPtr<nsIDBFolderInfo> dbFolderInfo;
  m_db->GetDBFolderInfo(getter_AddRefs(dbFolderInfo));
  if (dbFolderInfo) dbFolderInfo->SetExpungedBytes(0);
  // this forces the m_folder to update mExpungedBytes from the db folder info.
  int64_t expungedBytes;
  m_folder->GetExpungedBytes(&expungedBytes);
  m_folder->UpdateSummaryTotals(true);
  m_db->SetSummaryValid(true);

  // remove the old folder
  path->Remove(false);

  // rename the copied folder to be the original folder
  m_file->MoveToNative((nsIFile*)nullptr, leafName);

  ShowStatusMsg(EmptyString());
  m_folder->NotifyCompactCompleted();
  if (m_completionFn) {
    m_completionFn(NS_OK, m_totalExpungedBytes);
  }
  return rv;
}

NS_IMETHODIMP
nsFolderCompactState::Init(nsICopyMessageListener* destination) {
  return NS_OK;
}

NS_IMETHODIMP
nsFolderCompactState::StartMessage() {
  nsresult rv = NS_ERROR_FAILURE;
  NS_ASSERTION(m_fileStream, "Fatal, null m_fileStream...");
  if (m_fileStream) {
    nsCOMPtr<nsISeekableStream> seekableStream =
        do_QueryInterface(m_fileStream, &rv);
    NS_ENSURE_SUCCESS(rv, rv);
    // this will force an internal flush, but not a sync. Tell should really do
    // an internal flush, but it doesn't, and I'm afraid to change that
    // nsIFileStream.cpp code anymore.
    seekableStream->Seek(nsISeekableStream::NS_SEEK_CUR, 0);
    // record the new message key for the message
    int64_t curStreamPos;
    seekableStream->Tell(&curStreamPos);
    m_startOfNewMsg = curStreamPos;
    rv = NS_OK;
  }
  return rv;
}

NS_IMETHODIMP
nsFolderCompactState::EndMessage(nsMsgKey key) { return NS_OK; }

// XXX TODO: This function is sadly lacking all status checking, it always
// returns NS_OK and moves onto the next message.
NS_IMETHODIMP
nsFolderCompactState::EndCopy(nsIURI* uri, nsresult status) {
  nsCOMPtr<nsIMsgDBHdr> msgHdr;
  nsCOMPtr<nsIMsgDBHdr> newMsgHdr;

  if (m_curIndex >= m_keys.Length()) {
    NS_ASSERTION(false, "m_curIndex out of bounds");
    return NS_OK;
  }

  // Take note of the end offset of the message (without the trailing blank
  // line).
  nsCOMPtr<nsITellableStream> tellable(do_QueryInterface(m_fileStream));
  MOZ_ASSERT(tellable);
  int64_t endOfMsg;
  nsresult rv = tellable->Tell(&endOfMsg);
  NS_ENSURE_SUCCESS(rv, rv);

  /* Messages need to have trailing blank lines */
  rv = WriteSpan(m_fileStream, m_eolSeq);
  NS_ENSURE_SUCCESS(rv, rv);

  /*
   * Done with the current message; copying the existing message header
   * to the new database.
   */
  if (m_curSrcHdr) {
    nsMsgKey key;
    m_curSrcHdr->GetMessageKey(&key);
    m_db->CopyHdrFromExistingHdr(key, m_curSrcHdr, true,
                                 getter_AddRefs(newMsgHdr));
  }
  m_curSrcHdr = nullptr;
  if (newMsgHdr) {
    nsCString storeToken = nsPrintfCString("%" PRIu64, m_startOfNewMsg);
    newMsgHdr->SetStringProperty("storeToken", storeToken);
    newMsgHdr->SetMessageOffset(m_startOfNewMsg);
    uint64_t msgSize = endOfMsg - m_startOfNewMsg;
    newMsgHdr->SetMessageSize(msgSize);

    m_totalMsgSize += msgSize + m_eolSeq.Length();
  }

  //  m_db->Commit(nsMsgDBCommitType::kLargeCommit);  // no sense committing
  //  until the end
  // advance to next message
  m_curIndex++;
  m_startOfMsg = true;
  nsCOMPtr<nsIMsgStatusFeedback> statusFeedback;
  if (m_window) {
    m_window->GetStatusFeedback(getter_AddRefs(statusFeedback));
    if (statusFeedback)
      statusFeedback->ShowProgress(100 * m_curIndex / m_keys.Length());
  }
  return NS_OK;
}

nsresult nsOfflineStoreCompactState::StartCompacting() {
  nsresult rv = NS_OK;
  if (m_keys.Length() > 0 && m_curIndex == 0) {
    NS_ADDREF_THIS();  // we own ourselves, until we're done, anyway.
    ShowCompactingStatusMsg();
    bool done = false;
    rv = CopyNextMessage(done);
    if (!done) return rv;
  }
  ReleaseFolderLock();
  FinishCompact();
  return rv;
}

NS_IMETHODIMP
nsOfflineStoreCompactState::OnDataAvailable(nsIRequest* request,
                                            nsIInputStream* inStr,
                                            uint64_t sourceOffset,
                                            uint32_t count) {
  if (!m_fileStream || !inStr) return NS_ERROR_FAILURE;

  nsresult rv = NS_OK;

  if (m_startOfMsg) {
    m_offlineMsgSize = 0;
    m_messageUri.Truncate();  // clear the previous message uri
    if (NS_SUCCEEDED(BuildMessageURI(m_baseMessageUri.get(), m_keys[m_curIndex],
                                     m_messageUri))) {
      rv = m_messageService->MessageURIToMsgHdr(m_messageUri,
                                                getter_AddRefs(m_curSrcHdr));
      NS_ENSURE_SUCCESS(rv, rv);
    }
  }
  uint32_t maxReadCount, readCount, writeCount;
  uint32_t bytesWritten;

  while (NS_SUCCEEDED(rv) && (int32_t)count > 0) {
    maxReadCount =
        count > sizeof(m_dataBuffer) - 1 ? sizeof(m_dataBuffer) - 1 : count;
    writeCount = 0;
    rv = inStr->Read(m_dataBuffer, maxReadCount, &readCount);

    if (NS_SUCCEEDED(rv)) {
      if (m_startOfMsg) {
        m_startOfMsg = false;
        // check if there's an envelope header; if not, write one.
        if (strncmp(m_dataBuffer, "From ", 5)) {
          m_fileStream->Write("From " CRLF, 7, &bytesWritten);
          m_offlineMsgSize += bytesWritten;
        }
      }
      m_fileStream->Write(m_dataBuffer, readCount, &bytesWritten);
      m_offlineMsgSize += bytesWritten;
      writeCount += bytesWritten;
      count -= readCount;
      if (writeCount != readCount) {
        m_folder->ThrowAlertMsg("compactFolderWriteFailed", m_window);
        return NS_MSG_ERROR_WRITING_MAIL_FOLDER;
      }
    }
  }
  return rv;
}

//////////////////////////////////////////////////////////////////////////////
// nsMsgFolderCompactor implementation
//////////////////////////////////////////////////////////////////////////////

NS_IMPL_ISUPPORTS(nsMsgFolderCompactor, nsIMsgFolderCompactor)

nsMsgFolderCompactor::nsMsgFolderCompactor() {}

nsMsgFolderCompactor::~nsMsgFolderCompactor() {}

NS_IMETHODIMP nsMsgFolderCompactor::CompactFolders(
    const nsTArray<RefPtr<nsIMsgFolder>>& folders, nsIUrlListener* listener,
    nsIMsgWindow* window) {
  MOZ_ASSERT(mQueue.IsEmpty());
  mWindow = window;
  mListener = listener;
  mTotalBytesGained = 0;
  mQueue = folders.Clone();
  mQueue.Reverse();

  // Can't guarantee that anyone will keep us in scope until we're done, so...
  MOZ_ASSERT(!mKungFuDeathGrip);
  mKungFuDeathGrip = this;

  // nsIMsgFolderCompactor idl states this isn't called...
  // but maybe it should be?
  //  if (mListener) {
  //    mListener->OnStartRunningUrl(nullptr);
  //  }

  NextFolder();

  return NS_OK;
}

void nsMsgFolderCompactor::NextFolder() {
  while (!mQueue.IsEmpty()) {
    // Should only ever have one compactor running.
    MOZ_ASSERT(mCompactor == nullptr);

    nsCOMPtr<nsIMsgFolder> folder = mQueue.PopLastElement();

    // Sanity check - should we be compacting this folder?
    nsCOMPtr<nsIMsgPluggableStore> msgStore;
    nsresult rv = folder->GetMsgStore(getter_AddRefs(msgStore));
    if (NS_FAILED(rv)) {
      NS_WARNING("Skipping folder with no msgStore");
      continue;
    }
    bool storeSupportsCompaction;
    msgStore->GetSupportsCompaction(&storeSupportsCompaction);
    if (!storeSupportsCompaction) {
      NS_WARNING("Trying to compact a non-mbox folder");
      continue;  // just skip it.
    }

    nsCOMPtr<nsIMsgImapMailFolder> imapFolder(do_QueryInterface(folder));
    if (imapFolder) {
      uint32_t flags;
      folder->GetFlags(&flags);
      if (flags & nsMsgFolderFlags::Offline) {
        mCompactor = new nsOfflineStoreCompactState();
      }
    } else {
      mCompactor = new nsFolderCompactState();
    }
    if (!mCompactor) {
      NS_WARNING("skipping compact of non-offline folder");
      continue;
    }
    nsCString uri;
    folder->GetURI(uri);

    // Callback for when a folder compaction completes.
    auto completionFn = [self = RefPtr<nsMsgFolderCompactor>(this),
                         compactState = mCompactor](nsresult status,
                                                    uint64_t expungedBytes) {
      if (NS_SUCCEEDED(status)) {
        self->mTotalBytesGained += expungedBytes;
      } else {
        // Failed. We want to keep going with the next folder, but make sure
        // we return a failing code upon overall completion.
        self->mOverallStatus = status;
        NS_WARNING("folder compact failed.");
      }

      // Release our lock on the compactor - it's done.
      self->mCompactor = nullptr;
      self->NextFolder();
    };

    rv = mCompactor->Compact(folder, completionFn, mWindow);
    if (NS_SUCCEEDED(rv)) {
      // Now wait for the compactor to let us know it's finished,
      // via the completion callback fn.
      return;
    }
    mOverallStatus = rv;
    mCompactor = nullptr;
    NS_WARNING("folder compact failed - skipping folder");
  }

  // Done. No more folders to compact.

  if (mListener) {
    // If there were multiple failures, this will communicate only the
    // last one, but that's OK. Main thing is to indicate that _something_
    // went wrong.
    mListener->OnStopRunningUrl(nullptr, mOverallStatus);
  }
  ShowDoneStatus();

  // We're not needed any more.
  mKungFuDeathGrip = nullptr;
  return;
}

void nsMsgFolderCompactor::ShowDoneStatus() {
  if (!mWindow) {
    return;
  }
  nsCOMPtr<nsIStringBundle> bundle;
  nsresult rv = GetBaseStringBundle(getter_AddRefs(bundle));
  NS_ENSURE_SUCCESS_VOID(rv);
  nsAutoString expungedAmount;
  FormatFileSize(mTotalBytesGained, true, expungedAmount);
  AutoTArray<nsString, 1> params = {expungedAmount};
  nsString msg;
  rv = bundle->FormatStringFromName("compactingDone", params, msg);
  NS_ENSURE_SUCCESS_VOID(rv);

  nsCOMPtr<nsIMsgStatusFeedback> statusFeedback;
  mWindow->GetStatusFeedback(getter_AddRefs(statusFeedback));
  if (statusFeedback) {
    statusFeedback->SetStatusString(msg);
  }
}