/* -*- 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"
#include "nsMsgThreadedDBView.h"
#include "nsIMsgHdr.h"
#include "nsIMsgThread.h"
#include "nsIDBFolderInfo.h"
#include "nsIMsgSearchSession.h"
#include "nsMsgMessageFlags.h"

#define MSGHDR_CACHE_LOOK_AHEAD_SIZE  25    // Allocate this more to avoid reallocation on new mail.
#define MSGHDR_CACHE_MAX_SIZE         8192  // Max msghdr cache entries.
#define MSGHDR_CACHE_DEFAULT_SIZE     100

nsMsgThreadedDBView::nsMsgThreadedDBView()
{
  /* member initializers and constructor code */
  m_havePrevView = false;
}

nsMsgThreadedDBView::~nsMsgThreadedDBView()
{
  /* destructor code */
}

NS_IMETHODIMP nsMsgThreadedDBView::Open(nsIMsgFolder *folder, nsMsgViewSortTypeValue sortType, nsMsgViewSortOrderValue sortOrder, nsMsgViewFlagsTypeValue viewFlags, int32_t *pCount)
{
  nsresult rv = nsMsgDBView::Open(folder, sortType, sortOrder, viewFlags, pCount);
  NS_ENSURE_SUCCESS(rv, rv);

  if (!m_db)
    return NS_ERROR_NULL_POINTER;
  // Preset msg hdr cache size for performance reason.
  int32_t totalMessages, unreadMessages;
  nsCOMPtr <nsIDBFolderInfo> dbFolderInfo;
  PersistFolderInfo(getter_AddRefs(dbFolderInfo));
  NS_ENSURE_SUCCESS(rv, rv);
  // save off sort type and order, view type and flags
  dbFolderInfo->GetNumUnreadMessages(&unreadMessages);
  dbFolderInfo->GetNumMessages(&totalMessages);
  if (m_viewFlags & nsMsgViewFlagsType::kUnreadOnly)
  { 
    // Set unread msg size + extra entries to avoid reallocation on new mail.
    totalMessages = (uint32_t)unreadMessages+MSGHDR_CACHE_LOOK_AHEAD_SIZE;  
  }
  else
  {
    if (totalMessages > MSGHDR_CACHE_MAX_SIZE) 
      totalMessages = MSGHDR_CACHE_MAX_SIZE;        // use max default
    else if (totalMessages > 0)
      totalMessages += MSGHDR_CACHE_LOOK_AHEAD_SIZE;// allocate extra entries to avoid reallocation on new mail.
  }
  // if total messages is 0, then we probably don't have any idea how many headers are in the db
  // so we have no business setting the cache size.
  if (totalMessages > 0)
    m_db->SetMsgHdrCacheSize((uint32_t)totalMessages);
  
  if (pCount)
    *pCount = 0;
  rv = InitThreadedView(pCount);

  // this is a hack, but we're trying to find a way to correct
  // incorrect total and unread msg counts w/o paying a big
  // performance penalty. So, if we're not threaded, just add
  // up the total and unread messages in the view and see if that
  // matches what the db totals say. Except ignored threads are
  // going to throw us off...hmm. Unless we just look at the
  // unread counts which is what mostly tweaks people anyway...
  int32_t unreadMsgsInView = 0;
  if (!(m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay))
  {
    for (uint32_t i = m_flags.Length(); i > 0; )
    {
      if (!(m_flags[--i] & nsMsgMessageFlags::Read))
        ++unreadMsgsInView;
    }

    if (unreadMessages != unreadMsgsInView)
      m_db->SyncCounts();
  }
  m_db->SetMsgHdrCacheSize(MSGHDR_CACHE_DEFAULT_SIZE);

  return rv;
}

NS_IMETHODIMP nsMsgThreadedDBView::Close()
{
  return nsMsgDBView::Close();
}

nsresult nsMsgThreadedDBView::InitThreadedView(int32_t *pCount)
{
  nsresult rv;
  
  m_keys.Clear();
  m_flags.Clear();
  m_levels.Clear(); 
  m_prevKeys.Clear();
  m_prevFlags.Clear();
  m_prevLevels.Clear();
  m_havePrevView = false;
  nsresult getSortrv = NS_OK; // ### TODO m_db->GetSortInfo(&sortType, &sortOrder);
  
  // list all the ids into m_keys.
  nsMsgKey startMsg = 0; 
  do
  {
    const int32_t kIdChunkSize = 400;
    int32_t  numListed = 0;
    nsMsgKey idArray[kIdChunkSize];
    int32_t  flagArray[kIdChunkSize];
    char     levelArray[kIdChunkSize];

    rv = ListThreadIds(&startMsg, (m_viewFlags & nsMsgViewFlagsType::kUnreadOnly) != 0, idArray, flagArray, 
      levelArray, kIdChunkSize, &numListed, nullptr);
    if (NS_SUCCEEDED(rv))
    {
      int32_t numAdded = AddKeys(idArray, flagArray, levelArray, m_sortType, numListed);
      if (pCount)
        *pCount += numAdded;
    }
    
  } while (NS_SUCCEEDED(rv) && startMsg != nsMsgKey_None);
  
  if (NS_SUCCEEDED(getSortrv))
  {
    rv = InitSort(m_sortType, m_sortOrder);
    SaveSortInfo(m_sortType, m_sortOrder);

  }
  return rv;
}

nsresult nsMsgThreadedDBView::SortThreads(nsMsgViewSortTypeValue sortType, nsMsgViewSortOrderValue sortOrder)
{
  NS_PRECONDITION(m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay, "trying to sort unthreaded threads");

  uint32_t numThreads = 0;
  // the idea here is that copy the current view,  then build up an m_keys and m_flags array of just the top level
  // messages in the view, and then call nsMsgDBView::Sort(sortType, sortOrder).
  // Then, we expand the threads in the result array that were expanded in the original view (perhaps by copying
  // from the original view, but more likely just be calling expand).
  for (uint32_t i = 0; i < m_keys.Length(); i++)
  {
    if (m_flags[i] & MSG_VIEW_FLAG_ISTHREAD)
    {
      if (numThreads < i)
      {
        m_keys[numThreads] = m_keys[i];
        m_flags[numThreads] = m_flags[i];
      }
      m_levels[numThreads] = 0;
      numThreads++;
    }
  }
  m_keys.SetLength(numThreads);
  m_flags.SetLength(numThreads);
  m_levels.SetLength(numThreads);
  //m_viewFlags &= ~nsMsgViewFlagsType::kThreadedDisplay;
  m_sortType = nsMsgViewSortType::byNone; // sort from scratch
  nsMsgDBView::Sort(sortType, sortOrder);
  m_viewFlags |= nsMsgViewFlagsType::kThreadedDisplay;
  SetSuppressChangeNotifications(true);
  // Loop through the original array, for each thread that's expanded, find it in the new array
  // and expand the thread. We have to update MSG_VIEW_FLAG_HAS_CHILDREN because
  // we may be going from a flat sort, which doesn't maintain that flag,
  // to a threaded sort, which requires that flag.
  for (uint32_t j = 0; j < m_keys.Length(); j++)
  {
    uint32_t flags = m_flags[j];
    if ((flags & (MSG_VIEW_FLAG_HASCHILDREN | nsMsgMessageFlags::Elided)) == MSG_VIEW_FLAG_HASCHILDREN)
    {
      uint32_t numExpanded;
      m_flags[j] = flags | nsMsgMessageFlags::Elided;
      ExpandByIndex(j, &numExpanded);
      j += numExpanded;
      if (numExpanded > 0)
        m_flags[j - numExpanded] = flags | MSG_VIEW_FLAG_HASCHILDREN;
    }
    else if (flags & MSG_VIEW_FLAG_ISTHREAD && ! (flags & MSG_VIEW_FLAG_HASCHILDREN))
    {
      nsCOMPtr <nsIMsgDBHdr> msgHdr;
      nsCOMPtr <nsIMsgThread> pThread;
      m_db->GetMsgHdrForKey(m_keys[j], getter_AddRefs(msgHdr));
      if (msgHdr)
      {
        m_db->GetThreadContainingMsgHdr(msgHdr, getter_AddRefs(pThread));
        if (pThread)
        {
          uint32_t numChildren;
          pThread->GetNumChildren(&numChildren);
          if (numChildren > 1)
            m_flags[j] = flags | MSG_VIEW_FLAG_HASCHILDREN | nsMsgMessageFlags::Elided;
        }
      }
    }
  }
  SetSuppressChangeNotifications(false);

  return NS_OK;
}

int32_t nsMsgThreadedDBView::AddKeys(nsMsgKey *pKeys, int32_t *pFlags, const char *pLevels, nsMsgViewSortTypeValue sortType, int32_t numKeysToAdd)

{
  int32_t	numAdded = 0;
  // Allocate enough space first to avoid memory allocation/deallocation.
  m_keys.SetCapacity(m_keys.Length() + numKeysToAdd);
  m_flags.SetCapacity(m_flags.Length() + numKeysToAdd);
  m_levels.SetCapacity(m_levels.Length() + numKeysToAdd);
  for (int32_t i = 0; i < numKeysToAdd; i++)
  {
    int32_t threadFlag = pFlags[i];
    int32_t flag = threadFlag;
    
    // skip ignored threads.
    if ((threadFlag & nsMsgMessageFlags::Ignored) && !(m_viewFlags & nsMsgViewFlagsType::kShowIgnored))
      continue;
    
    // skip ignored subthreads
    nsCOMPtr <nsIMsgDBHdr> msgHdr;
    m_db->GetMsgHdrForKey(pKeys[i], getter_AddRefs(msgHdr));
    if (!(m_viewFlags & nsMsgViewFlagsType::kShowIgnored))
    {
      bool killed;
      msgHdr->GetIsKilled(&killed);
      if (killed)
        continue;
    }

    // by default, make threads collapsed, unless we're in only viewing new msgs
    
    if (flag & MSG_VIEW_FLAG_HASCHILDREN)
      flag |= nsMsgMessageFlags::Elided;
    // should this be persistent? Doesn't seem to need to be.
    flag |= MSG_VIEW_FLAG_ISTHREAD;
    m_keys.AppendElement(pKeys[i]);
    m_flags.AppendElement(flag);
    m_levels.AppendElement(pLevels[i]);
    numAdded++;
    // we expand as we build the view, which allows us to insert at the end of the key array,
    // instead of the middle, and is much faster.
    if ((!(m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) || m_viewFlags & nsMsgViewFlagsType::kExpandAll) && flag & nsMsgMessageFlags::Elided)
       ExpandByIndex(m_keys.Length() - 1, NULL);
  }
  return numAdded;
}

NS_IMETHODIMP nsMsgThreadedDBView::Sort(nsMsgViewSortTypeValue sortType, nsMsgViewSortOrderValue sortOrder)
{
  nsresult rv;

  int32_t rowCountBeforeSort = GetSize();

  if (!rowCountBeforeSort) 
  {
    // still need to setup our flags even when no articles - bug 98183.
    m_sortType = sortType;
    if (sortType == nsMsgViewSortType::byThread && ! (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay))
      SetViewFlags(m_viewFlags | nsMsgViewFlagsType::kThreadedDisplay);
    SaveSortInfo(sortType, sortOrder);
    return NS_OK;
  }

  if (!m_checkedCustomColumns && CustomColumnsInSortAndNotRegistered())
    return NS_OK;

  // sort threads by sort order
  bool sortThreads = m_viewFlags & (nsMsgViewFlagsType::kThreadedDisplay | nsMsgViewFlagsType::kGroupBySort);
  
  // if sort type is by thread, and we're already threaded, change sort type to byId
  if (sortType == nsMsgViewSortType::byThread && (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) != 0)
    sortType = nsMsgViewSortType::byId;

  nsMsgKey preservedKey;
  AutoTArray<nsMsgKey, 1> preservedSelection;
  SaveAndClearSelection(&preservedKey, preservedSelection);
  // if the client wants us to forget our cached id arrays, they
  // should build a new view. If this isn't good enough, we
  // need a method to do that.
  if (sortType != m_sortType || !m_sortValid || sortThreads)
  {
    SaveSortInfo(sortType, sortOrder);
    if (sortType == nsMsgViewSortType::byThread)  
    {
      m_sortType = sortType;
      m_viewFlags |= nsMsgViewFlagsType::kThreadedDisplay;
      m_viewFlags &= ~nsMsgViewFlagsType::kGroupBySort;
      if ( m_havePrevView)
      {
        // restore saved id array and flags array
        m_keys = m_prevKeys;
        m_flags = m_prevFlags;
        m_levels = m_prevLevels;
        m_sortValid = true;
        
        // the sort may have changed the number of rows
        // before we restore the selection, tell the tree
        // do this before we call restore selection
        // this is safe when there is no selection.
        rv = AdjustRowCount(rowCountBeforeSort, GetSize());
        
        RestoreSelection(preservedKey, preservedSelection);
        if (mTree) mTree->Invalidate();
        return NS_OK;
      }
      else
      {
        // set sort info in anticipation of what Init will do.
        InitThreadedView(nullptr);	// build up thread list.
        if (sortOrder != nsMsgViewSortOrder::ascending)
          Sort(sortType, sortOrder);
        
        // the sort may have changed the number of rows
        // before we update the selection, tell the tree
        // do this before we call restore selection
        // this is safe when there is no selection.
        rv = AdjustRowCount(rowCountBeforeSort, GetSize());
        
        RestoreSelection(preservedKey, preservedSelection);
        if (mTree) mTree->Invalidate();
        return NS_OK;
      }
    }
    else if (sortType  != nsMsgViewSortType::byThread && (m_sortType == nsMsgViewSortType::byThread  || sortThreads)/* && !m_havePrevView*/)
    {
      if (sortThreads)
      {
        SortThreads(sortType, sortOrder);
        sortType = nsMsgViewSortType::byThread; // hack so base class won't do anything
      }
      else
      {
        // going from SortByThread to non-thread sort - must build new key, level,and flags arrays 
        m_prevKeys = m_keys;
        m_prevFlags = m_flags;
        m_prevLevels = m_levels;
        // do this before we sort, so that we'll use the cheap method
        // of expanding.
        m_viewFlags &= ~(nsMsgViewFlagsType::kThreadedDisplay | nsMsgViewFlagsType::kGroupBySort);
        ExpandAll();
        //			m_idArray.RemoveAll();
        //			m_flags.Clear();
        m_havePrevView = true;
      }
    }
  }
  else if (m_sortOrder != sortOrder)// check for toggling the sort
  {
    nsMsgDBView::Sort(sortType, sortOrder);
  }
  if (!sortThreads)
  {
    // call the base class in case we're not sorting by thread
    rv = nsMsgDBView::Sort(sortType, sortOrder);
    SaveSortInfo(sortType, sortOrder);
  }
  // the sort may have changed the number of rows
  // before we restore the selection, tell the tree
  // do this before we call restore selection
  // this is safe when there is no selection.
  rv = AdjustRowCount(rowCountBeforeSort, GetSize());

  RestoreSelection(preservedKey, preservedSelection);
  if (mTree) mTree->Invalidate();
  NS_ENSURE_SUCCESS(rv,rv);
  return NS_OK;
}

// list the ids of the top-level thread ids starting at id == startMsg. This actually returns
// the ids of the first message in each thread.
nsresult nsMsgThreadedDBView::ListThreadIds(nsMsgKey *startMsg, bool unreadOnly, nsMsgKey *pOutput, int32_t *pFlags, char *pLevels, 
									 int32_t numToList, int32_t *pNumListed, int32_t *pTotalHeaders)
{
  nsresult rv = NS_OK;
  // N.B..don't ret before assigning numListed to *pNumListed
  int32_t	numListed = 0;
  
  if (*startMsg > 0)
  {
    NS_ASSERTION(m_threadEnumerator != nullptr, "where's our iterator?");	// for now, we'll just have to rely on the caller leaving
    // the iterator in the right place.
  }
  else
  {
    NS_ASSERTION(m_db, "no db");
    if (!m_db) return NS_ERROR_UNEXPECTED;
    rv = m_db->EnumerateThreads(getter_AddRefs(m_threadEnumerator));
    NS_ENSURE_SUCCESS(rv, rv);
  }
  
  bool hasMore = false;
  
  nsCOMPtr <nsIMsgThread> threadHdr ;
  int32_t	threadsRemoved = 0;
  while (numListed < numToList &&
         NS_SUCCEEDED(rv = m_threadEnumerator->HasMoreElements(&hasMore)) &&
         hasMore)
  {
    nsCOMPtr <nsISupports> supports;
    rv = m_threadEnumerator->GetNext(getter_AddRefs(supports));
    if (NS_FAILED(rv))
    {
      threadHdr = nullptr;
      break;
    }
    threadHdr = do_QueryInterface(supports);
    if (!threadHdr)
      break;
    nsCOMPtr <nsIMsgDBHdr> msgHdr;
    uint32_t numChildren;
    if (unreadOnly)
      threadHdr->GetNumUnreadChildren(&numChildren);
    else
      threadHdr->GetNumChildren(&numChildren);
    uint32_t threadFlags;
    threadHdr->GetFlags(&threadFlags);
    if (numChildren != 0)	// not empty thread
    {
      int32_t unusedRootIndex;
      if (pTotalHeaders)
        *pTotalHeaders += numChildren;
      if (unreadOnly)
        rv = threadHdr->GetFirstUnreadChild(getter_AddRefs(msgHdr));
      else
        rv = threadHdr->GetRootHdr(&unusedRootIndex, getter_AddRefs(msgHdr));
      if (NS_SUCCEEDED(rv) && msgHdr != nullptr && WantsThisThread(threadHdr))
      {
        uint32_t msgFlags;
        uint32_t newMsgFlags;
        nsMsgKey msgKey;
        msgHdr->GetMessageKey(&msgKey);
        msgHdr->GetFlags(&msgFlags);
        // turn off high byte of msg flags - used for view flags.
        msgFlags &= ~MSG_VIEW_FLAGS;
        pOutput[numListed] = msgKey;
        pLevels[numListed] = 0;
        // turn off these flags on msg hdr - they belong in thread
        msgHdr->AndFlags(~(nsMsgMessageFlags::Watched), &newMsgFlags);
        AdjustReadFlag(msgHdr, &msgFlags);
        // try adding in MSG_VIEW_FLAG_ISTHREAD flag for unreadonly view.
        pFlags[numListed] = msgFlags | MSG_VIEW_FLAG_ISTHREAD | threadFlags;
        if (numChildren > 1)
          pFlags[numListed] |= MSG_VIEW_FLAG_HASCHILDREN;
        
        numListed++;
      }
      else
        NS_ASSERTION(NS_SUCCEEDED(rv) && msgHdr, "couldn't get header for some reason");
    }
    else if (threadsRemoved < 10 && !(threadFlags & (nsMsgMessageFlags::Watched | nsMsgMessageFlags::Ignored)))
    {
      // ### remove thread.
      threadsRemoved++;	// don't want to remove all empty threads first time
      // around as it will choke preformance for upgrade.
#ifdef DEBUG_bienvenu
      printf("removing empty non-ignored non-watched thread\n");
#endif
    }
  }
  
  if (hasMore && threadHdr)
  {
    threadHdr->GetThreadKey(startMsg);
  }
  else
  {
    *startMsg = nsMsgKey_None;
    nsCOMPtr <nsIDBChangeListener> dbListener = do_QueryInterface(m_threadEnumerator);
    // this is needed to make the thread enumerator release its reference to the db.
    if (dbListener)
      dbListener->OnAnnouncerGoingAway(nullptr);
    m_threadEnumerator = nullptr;
  }
  *pNumListed = numListed;
  return rv;
}

void	nsMsgThreadedDBView::OnExtraFlagChanged(nsMsgViewIndex index, uint32_t extraFlag)
{
  if (IsValidIndex(index))
  {
    if (m_havePrevView)
    {
      nsMsgKey keyChanged = m_keys[index];
      nsMsgViewIndex prevViewIndex = m_prevKeys.IndexOf(keyChanged);
      if (prevViewIndex != nsMsgViewIndex_None)
      {
        uint32_t prevFlag = m_prevFlags[prevViewIndex];
        // don't want to change the elided bit, or has children or is thread
        if (prevFlag & nsMsgMessageFlags::Elided)
          extraFlag |= nsMsgMessageFlags::Elided;
        else
          extraFlag &= ~nsMsgMessageFlags::Elided;
        if (prevFlag & MSG_VIEW_FLAG_ISTHREAD)
          extraFlag |= MSG_VIEW_FLAG_ISTHREAD;
        else
          extraFlag &= ~MSG_VIEW_FLAG_ISTHREAD;
        if (prevFlag & MSG_VIEW_FLAG_HASCHILDREN)
          extraFlag |= MSG_VIEW_FLAG_HASCHILDREN;
        else
          extraFlag &= ~MSG_VIEW_FLAG_HASCHILDREN;
        m_prevFlags[prevViewIndex] = extraFlag; // will this be right?
      }
    }
  }
  // we don't really know what's changed, but to be on the safe side, set the sort invalid
  // so that reverse sort will pick it up.
  if (m_sortType == nsMsgViewSortType::byStatus || m_sortType == nsMsgViewSortType::byFlagged || 
    m_sortType == nsMsgViewSortType::byUnread || m_sortType == nsMsgViewSortType::byPriority)
    m_sortValid = false;
}

void nsMsgThreadedDBView::OnHeaderAddedOrDeleted()
{
  ClearPrevIdArray();
}

void nsMsgThreadedDBView::ClearPrevIdArray()
{
  m_prevKeys.Clear();
  m_prevLevels.Clear();
  m_prevFlags.Clear();
  m_havePrevView = false;
}

nsresult nsMsgThreadedDBView::InitSort(nsMsgViewSortTypeValue sortType, nsMsgViewSortOrderValue sortOrder)
{
  if (m_viewFlags & nsMsgViewFlagsType::kGroupBySort)
    return NS_OK; // nothing to do.

  if (sortType == nsMsgViewSortType::byThread)
  {
    nsMsgDBView::Sort(nsMsgViewSortType::byId, sortOrder); // sort top level threads by id.
    m_sortType = nsMsgViewSortType::byThread;
    m_viewFlags |= nsMsgViewFlagsType::kThreadedDisplay;
    m_viewFlags &= ~nsMsgViewFlagsType::kGroupBySort;
    SetViewFlags(m_viewFlags); // persist the view flags.
    //		m_db->SetSortInfo(m_sortType, sortOrder);
  }
//  else
//    m_viewFlags &= ~nsMsgViewFlagsType::kThreadedDisplay;
  
  // by default, the unread only view should have all threads expanded.
  if ((m_viewFlags & (nsMsgViewFlagsType::kUnreadOnly|nsMsgViewFlagsType::kExpandAll)) 
      && (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay))
    ExpandAll();
  if (! (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay))
    ExpandAll(); // for now, expand all and do a flat sort.
  
  Sort(sortType, sortOrder);
  if (sortType != nsMsgViewSortType::byThread)	// forget prev view, since it has everything expanded.
    ClearPrevIdArray();
  return NS_OK;
}

nsresult nsMsgThreadedDBView::OnNewHeader(nsIMsgDBHdr *newHdr, nsMsgKey aParentKey, bool ensureListed)
{
  if (m_viewFlags & nsMsgViewFlagsType::kGroupBySort)
    return nsMsgGroupView::OnNewHeader(newHdr, aParentKey, ensureListed);

  NS_ENSURE_TRUE(newHdr, NS_MSG_MESSAGE_NOT_FOUND);

  nsMsgKey newKey;
  newHdr->GetMessageKey(&newKey);

  // views can override this behaviour, which is to append to view.
  // This is the mail behaviour, but threaded views want
  // to insert in order...
  uint32_t msgFlags;
  newHdr->GetFlags(&msgFlags);
  if ((m_viewFlags & nsMsgViewFlagsType::kUnreadOnly) && !ensureListed &&
      (msgFlags & nsMsgMessageFlags::Read))
    return NS_OK;
  // Currently, we only add the header in a threaded view if it's a thread.
  // We used to check if this was the first header in the thread, but that's
  // a bit harder in the unreadOnly view. But we'll catch it below.

  // if not threaded display just add it to the view.
  if (!(m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay))
    return AddHdr(newHdr);

  // need to find the thread we added this to so we can change the hasnew flag
  // added message to existing thread, but not to view
  // Fix flags on thread header.
  int32_t threadCount;
  uint32_t threadFlags;
  bool moveThread = false;
  nsMsgViewIndex threadIndex = ThreadIndexOfMsg(newKey, nsMsgViewIndex_None, &threadCount, &threadFlags);
  bool threadRootIsDisplayed = false;

  nsCOMPtr <nsIMsgThread> threadHdr;
  m_db->GetThreadContainingMsgHdr(newHdr, getter_AddRefs(threadHdr));
  if (threadHdr && m_sortType == nsMsgViewSortType::byDate)
  {
    uint32_t newestMsgInThread = 0, msgDate = 0;
    threadHdr->GetNewestMsgDate(&newestMsgInThread);
    newHdr->GetDateInSeconds(&msgDate);
    moveThread = (msgDate == newestMsgInThread);
  }

  if (threadIndex != nsMsgViewIndex_None)
  {
    threadRootIsDisplayed = (m_currentlyDisplayedViewIndex == threadIndex);
    uint32_t flags = m_flags[threadIndex];
    if (!(flags & MSG_VIEW_FLAG_HASCHILDREN))
    {
      flags |= MSG_VIEW_FLAG_HASCHILDREN | MSG_VIEW_FLAG_ISTHREAD;
      if (!(m_viewFlags & nsMsgViewFlagsType::kUnreadOnly))
        flags |= nsMsgMessageFlags::Elided;
      m_flags[threadIndex] = flags;
    }

    if (!(flags & nsMsgMessageFlags::Elided))
    { // thread is expanded
      // insert child into thread
      // levels of other hdrs may have changed!
      uint32_t newFlags = msgFlags;
      int32_t level = 0;
      nsMsgViewIndex insertIndex = threadIndex;
      if (aParentKey == nsMsgKey_None)
      {
        newFlags |= MSG_VIEW_FLAG_ISTHREAD | MSG_VIEW_FLAG_HASCHILDREN;
      }
      else
      {
        nsMsgViewIndex parentIndex = FindParentInThread(aParentKey, threadIndex);
        level = m_levels[parentIndex] + 1;
        insertIndex = GetInsertInfoForNewHdr(newHdr, parentIndex, level);
      }
      InsertMsgHdrAt(insertIndex, newHdr, newKey, newFlags, level);
      // the call to NoteChange() has to happen after we add the key
      // as NoteChange() will call RowCountChanged() which will call our GetRowCount()
      NoteChange(insertIndex, 1, nsMsgViewNotificationCode::insertOrDelete);

      if (aParentKey == nsMsgKey_None)
      {
        // this header is the new king! try collapsing the existing thread,
        // removing it, installing this header as king, and expanding it.
        CollapseByIndex(threadIndex, nullptr);
        // call base class, so child won't get promoted.
        // nsMsgDBView::RemoveByIndex(threadIndex);
        ExpandByIndex(threadIndex, nullptr);
      }
    }
    else if (aParentKey == nsMsgKey_None)
    {
      // if we have a collapsed thread which just got a new
      // top of thread, change the keys array.
      m_keys[threadIndex] = newKey;
    }

    // If this message is new, the thread is collapsed, it is the
    // root and it was displayed, expand it so that the user does
    // not find that their message has magically turned into a summary.
    if (msgFlags & nsMsgMessageFlags::New &&
        m_flags[threadIndex] & nsMsgMessageFlags::Elided &&
        threadRootIsDisplayed)
      ExpandByIndex(threadIndex, nullptr);

    if (moveThread)
      MoveThreadAt(threadIndex);
    else
      // note change, to update the parent thread's unread and total counts
      NoteChange(threadIndex, 1, nsMsgViewNotificationCode::changed);
  }
  else if (threadHdr)
    // adding msg to thread that's not in view.
    AddMsgToThreadNotInView(threadHdr, newHdr, ensureListed);

  return NS_OK;
}


NS_IMETHODIMP nsMsgThreadedDBView::OnParentChanged (nsMsgKey aKeyChanged, nsMsgKey oldParent, nsMsgKey newParent, nsIDBChangeListener *aInstigator)
{
  // we need to adjust the level of the hdr whose parent changed, and invalidate that row,
  // iff we're in threaded mode.
#if 0
  // This code never runs due to the if (false) and Clang complains about it
  // so it is ifdefed out for now.
  if (false && m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay)
  {
    nsMsgViewIndex childIndex = FindViewIndex(aKeyChanged);
    if (childIndex != nsMsgViewIndex_None)
    {
      nsMsgViewIndex parentIndex = FindViewIndex(newParent);
      int32_t newParentLevel = (parentIndex == nsMsgViewIndex_None) ? -1 : m_levels[parentIndex];
      nsMsgViewIndex oldParentIndex = FindViewIndex(oldParent);
      int32_t oldParentLevel = (oldParentIndex != nsMsgViewIndex_None || newParent == nsMsgKey_None) 
        ? m_levels[oldParentIndex] : -1 ;
      int32_t levelChanged = m_levels[childIndex];
      int32_t parentDelta = oldParentLevel - newParentLevel;
      m_levels[childIndex] = (newParent == nsMsgKey_None) ? 0 : newParentLevel + 1;
      if (parentDelta > 0)
      {
        for (nsMsgViewIndex viewIndex = childIndex + 1; viewIndex < GetSize() && m_levels[viewIndex] > levelChanged;  viewIndex++)
        {
          m_levels[viewIndex] = m_levels[viewIndex] - parentDelta;
          NoteChange(viewIndex, 1, nsMsgViewNotificationCode::changed);
        }
      }
      NoteChange(childIndex, 1, nsMsgViewNotificationCode::changed);
    }
  }
#endif
  return NS_OK;
}


nsMsgViewIndex nsMsgThreadedDBView::GetInsertInfoForNewHdr(nsIMsgDBHdr *newHdr, nsMsgViewIndex parentIndex, int32_t targetLevel)
{
  uint32_t viewSize = GetSize();
  while (++parentIndex < viewSize)
  {
    // loop until we find a message at a level less than or equal to the parent level
    if (m_levels[parentIndex] < targetLevel)
      break;
  }
  return parentIndex;
}

// This method removes the thread at threadIndex from the view 
// and puts it back in its new position, determined by the sort order.
// And, if the selection is affected, save and restore the selection.
void nsMsgThreadedDBView::MoveThreadAt(nsMsgViewIndex threadIndex)
{
  // we need to check if the thread is collapsed or not...
  // We want to turn off tree notifications so that we don't
  // reload the current message.
  // We also need to invalidate the range between where the thread was
  // and where it ended up.
  bool changesDisabled = mSuppressChangeNotification;
  if (!changesDisabled)
    SetSuppressChangeNotifications(true);

  nsCOMPtr <nsIMsgDBHdr> threadHdr;

  GetMsgHdrForViewIndex(threadIndex, getter_AddRefs(threadHdr));
  int32_t childCount = 0;

  nsMsgKey preservedKey;
  AutoTArray<nsMsgKey, 1> preservedSelection;
  int32_t selectionCount;
  int32_t currentIndex;
  bool hasSelection = mTree && mTreeSelection &&
                        ((NS_SUCCEEDED(mTreeSelection->GetCurrentIndex(&currentIndex)) &&
                         currentIndex >= 0 && (uint32_t)currentIndex < GetSize()) ||
                         (NS_SUCCEEDED(mTreeSelection->GetRangeCount(&selectionCount)) &&
                          selectionCount > 0));
  if (hasSelection)
    SaveAndClearSelection(&preservedKey, preservedSelection);
  uint32_t saveFlags = m_flags[threadIndex];
  bool threadIsExpanded = !(saveFlags & nsMsgMessageFlags::Elided);

  if (threadIsExpanded)
  {
    ExpansionDelta(threadIndex, &childCount);
    childCount = -childCount;
  }
  nsTArray<nsMsgKey> threadKeys;
  nsTArray<uint32_t> threadFlags;
  nsTArray<uint8_t> threadLevels;

  if (threadIsExpanded)
  {
    threadKeys.SetCapacity(childCount);
    threadFlags.SetCapacity(childCount);
    threadLevels.SetCapacity(childCount);
    for (nsMsgViewIndex index = threadIndex + 1; 
        index < GetSize() && m_levels[index]; index++)
    {
      threadKeys.AppendElement(m_keys[index]);
      threadFlags.AppendElement(m_flags[index]);
      threadLevels.AppendElement(m_levels[index]);
    }
    uint32_t collapseCount;
    CollapseByIndex(threadIndex, &collapseCount);
  }
  nsMsgDBView::RemoveByIndex(threadIndex);
  nsMsgViewIndex newIndex = nsMsgViewIndex_None;
  AddHdr(threadHdr, &newIndex);

  // AddHdr doesn't always set newIndex, and getting it to do so
  // is going to require some refactoring.
  if (newIndex == nsMsgViewIndex_None)
    newIndex = FindHdr(threadHdr);

  if (threadIsExpanded)
  {
    m_keys.InsertElementsAt(newIndex + 1, threadKeys);
    m_flags.InsertElementsAt(newIndex + 1, threadFlags);
    m_levels.InsertElementsAt(newIndex + 1, threadLevels);
  }
  if (newIndex == nsMsgViewIndex_None)
  {
     NS_WARNING("newIndex=-1 in MoveThreadAt");
     newIndex = 0;
  }
  m_flags[newIndex] = saveFlags;
  // unfreeze selection.
  if (hasSelection)
    RestoreSelection(preservedKey, preservedSelection);

  if (!changesDisabled)
    SetSuppressChangeNotifications(false);
  nsMsgViewIndex lowIndex = threadIndex < newIndex ? threadIndex : newIndex;
  nsMsgViewIndex highIndex = lowIndex == threadIndex ? newIndex : threadIndex;
  NoteChange(lowIndex, highIndex - lowIndex + childCount + 1,
             nsMsgViewNotificationCode::changed);
}
nsresult nsMsgThreadedDBView::AddMsgToThreadNotInView(nsIMsgThread *threadHdr, nsIMsgDBHdr *msgHdr, bool ensureListed)
{
  nsresult rv = NS_OK;
  uint32_t threadFlags;
  threadHdr->GetFlags(&threadFlags);
  if (!(threadFlags & nsMsgMessageFlags::Ignored))
  {
    bool msgKilled;
    msgHdr->GetIsKilled(&msgKilled);
    if (!msgKilled)
      rv = nsMsgDBView::AddHdr(msgHdr);
  }
  return rv;
}

// This method just removes the specified line from the view. It does
// NOT delete it from the database.
nsresult nsMsgThreadedDBView::RemoveByIndex(nsMsgViewIndex index)
{
  nsresult rv = NS_OK;
  int32_t flags;

  if (!IsValidIndex(index))
    return NS_MSG_INVALID_DBVIEW_INDEX;
  
  OnHeaderAddedOrDeleted();

  flags = m_flags[index];

  if (! (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay)) 
    return nsMsgDBView::RemoveByIndex(index);

  nsCOMPtr<nsIMsgThread> threadHdr; 
  GetThreadContainingIndex(index, getter_AddRefs(threadHdr));
  NS_ENSURE_SUCCESS(rv, rv);
  uint32_t numThreadChildren = 0;
  // If we can't get a thread, it's already deleted and thus has 0 children.
  if (threadHdr)
    threadHdr->GetNumChildren(&numThreadChildren);

  // Check if we're the top level msg in the thread, and we're not collapsed.
  if ((flags & MSG_VIEW_FLAG_ISTHREAD) &&
      !(flags & nsMsgMessageFlags::Elided) &&
      (flags & MSG_VIEW_FLAG_HASCHILDREN))
  {
    // Fix flags on thread header - newly promoted message should have
    // flags set correctly.
    if (threadHdr)
    {
      nsMsgDBView::RemoveByIndex(index);
      nsCOMPtr<nsIMsgThread> nextThreadHdr;
      // Above RemoveByIndex may now make index out of bounds.
      if (IsValidIndex(index) && numThreadChildren > 0)
      {
        // unreadOnly
        nsCOMPtr<nsIMsgDBHdr> msgHdr;
        rv = threadHdr->GetChildHdrAt(0, getter_AddRefs(msgHdr));
        if (msgHdr != nullptr)
        {
          uint32_t flag = 0;
          msgHdr->GetFlags(&flag);
          if (numThreadChildren > 1)
            flag |= MSG_VIEW_FLAG_ISTHREAD | MSG_VIEW_FLAG_HASCHILDREN;

          m_flags[index] = flag;
          m_levels[index] = 0;
        }
      }
    }
    return rv;
  }
  else if (!(flags & MSG_VIEW_FLAG_ISTHREAD))
  {
    // We're not deleting the top level msg, but top level msg might be the
    // only msg in thread now.
    if (threadHdr && numThreadChildren == 1) 
    {
      nsMsgKey msgKey;
      rv = threadHdr->GetChildKeyAt(0, &msgKey);
      if (NS_SUCCEEDED(rv))
      {
        nsMsgViewIndex threadIndex = FindViewIndex(msgKey);
        if (IsValidIndex(threadIndex))
        {
          uint32_t flags = m_flags[threadIndex];
          flags &= ~(MSG_VIEW_FLAG_ISTHREAD |
                     nsMsgMessageFlags::Elided |
                     MSG_VIEW_FLAG_HASCHILDREN);
          m_flags[threadIndex] = flags;
          NoteChange(threadIndex, 1, nsMsgViewNotificationCode::changed);
        }
      }
      
    }
    return nsMsgDBView::RemoveByIndex(index);
  }
  // Deleting collapsed thread header is special case. Child will be promoted,
  // so just tell FE that line changed, not that it was deleted.
  // Header has aleady been deleted from thread.
  if (threadHdr && numThreadChildren > 0)
  {
    // change the id array and flags array to reflect the child header.
    // If we're not deleting the header, we want the second header,
    // Otherwise, the first one (which just got promoted).
    nsCOMPtr<nsIMsgDBHdr> msgHdr;
    rv = threadHdr->GetChildHdrAt(0, getter_AddRefs(msgHdr));
    if (msgHdr != nullptr)
    {
      msgHdr->GetMessageKey(&m_keys[index]);

      uint32_t flag = 0;
      msgHdr->GetFlags(&flag);
      flag |= MSG_VIEW_FLAG_ISTHREAD;

      // if only hdr in thread (with one about to be deleted)
      if (numThreadChildren == 1)
      {
        // adjust flags.
        flag &=  ~MSG_VIEW_FLAG_HASCHILDREN;
        flag &= ~nsMsgMessageFlags::Elided;
        // tell FE that thread header needs to be repainted.
        NoteChange(index, 1, nsMsgViewNotificationCode::changed);
      }
      else
      {
        flag |= MSG_VIEW_FLAG_HASCHILDREN;
        flag |= nsMsgMessageFlags::Elided;
      }
      m_flags[index] = flag;
      mIndicesToNoteChange.RemoveElement(index);
    }
    else
      NS_ASSERTION(false, "couldn't find thread child");	

    NoteChange(index, 1, nsMsgViewNotificationCode::changed);	
  }
  else
  {
    // we may have deleted a whole, collapsed thread - if so,
    // ensure that the current index will be noted as changed.
    if (!mIndicesToNoteChange.Contains(index))
      mIndicesToNoteChange.AppendElement(index);

    rv = nsMsgDBView::RemoveByIndex(index);
  }
  return rv;
}

NS_IMETHODIMP nsMsgThreadedDBView::GetViewType(nsMsgViewTypeValue *aViewType)
{
    NS_ENSURE_ARG_POINTER(aViewType);
    *aViewType = nsMsgViewType::eShowAllThreads; 
    return NS_OK;
}

NS_IMETHODIMP
nsMsgThreadedDBView::CloneDBView(nsIMessenger *aMessengerInstance, nsIMsgWindow *aMsgWindow, nsIMsgDBViewCommandUpdater *aCmdUpdater, nsIMsgDBView **_retval)
{
  nsMsgThreadedDBView* newMsgDBView = new nsMsgThreadedDBView();

  if (!newMsgDBView)
    return NS_ERROR_OUT_OF_MEMORY;

  nsresult rv = CopyDBView(newMsgDBView, aMessengerInstance, aMsgWindow, aCmdUpdater);
  NS_ENSURE_SUCCESS(rv,rv);

  NS_IF_ADDREF(*_retval = newMsgDBView);
  return NS_OK;
}
