// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
	// vim: ts=8 sw=2 smarttab
	
	#include "EventPreprocessor.h"
	#include "common/debug.h"
	#include "common/dout.h"
	#include "common/errno.h"
	#include "common/WorkQueue.h"
	#include "journal/Journaler.h"
	#include "librbd/ImageCtx.h"
	#include "librbd/ImageState.h"
	#include "librbd/Utils.h"
	#include "librbd/journal/Types.h"
	#include <boost/variant.hpp>
	
	#define dout_context g_ceph_context
	#define dout_subsys ceph_subsys_rbd_mirror
	
	#undef dout_prefix
	#define dout_prefix *_dout << "rbd::mirror::image_replayer::EventPreprocessor: " \
	                           << this << " " << __func__
	
	namespace rbd {
	namespace mirror {
	namespace image_replayer {
	
	using librbd::util::create_context_callback;
	
	template <typename I>
	EventPreprocessor<I>::EventPreprocessor(I &local_image_ctx,
	                                        Journaler &remote_journaler,
	                                        const std::string &local_mirror_uuid,
	                                        MirrorPeerClientMeta *client_meta,
	                                        ContextWQ *work_queue)
	  : m_local_image_ctx(local_image_ctx), m_remote_journaler(remote_journaler),
	    m_local_mirror_uuid(local_mirror_uuid), m_client_meta(client_meta),
	    m_work_queue(work_queue) {
	}
	
	template <typename I>

	EventPreprocessor<I>::~EventPreprocessor() {

	  ceph_assert(!m_in_progress);
	}
	
	template <typename I>
	bool EventPreprocessor<I>::is_required(const EventEntry &event_entry) {
	  SnapSeqs snap_seqs(m_client_meta->snap_seqs);
	  return (prune_snap_map(&snap_seqs) ||
	          event_entry.get_event_type() ==
	            librbd::journal::EVENT_TYPE_SNAP_RENAME);
	}
	
	template <typename I>
	void EventPreprocessor<I>::preprocess(EventEntry *event_entry,
	                                      Context *on_finish) {
	  ceph_assert(!m_in_progress);
	  m_in_progress = true;
	  m_event_entry = event_entry;
	  m_on_finish = on_finish;
	
	  refresh_image();
	}
	
	template <typename I>
	void EventPreprocessor<I>::refresh_image() {
	  dout(20) << dendl;
	
	  Context *ctx = create_context_callback<
	    EventPreprocessor<I>, &EventPreprocessor<I>::handle_refresh_image>(this);
	  m_local_image_ctx.state->refresh(ctx);
	}
	
	template <typename I>
	void EventPreprocessor<I>::handle_refresh_image(int r) {
	  dout(20) << ": r=" << r << dendl;
	
	  if (r < 0) {
	    derr << "error encountered during image refresh: " << cpp_strerror(r)
	         << dendl;
	    finish(r);
	    return;
	  }
	
	  preprocess_event();
	}
	
	template <typename I>
	void EventPreprocessor<I>::preprocess_event() {
	  dout(20) << dendl;
	
	  m_snap_seqs = m_client_meta->snap_seqs;
	  m_snap_seqs_updated = prune_snap_map(&m_snap_seqs);
	
	  int r = boost::apply_visitor(PreprocessEventVisitor(this),
	                               m_event_entry->event);
	  if (r < 0) {
	    finish(r);
	    return;
	  }
	
	  update_client();
	}
	
	template <typename I>
	int EventPreprocessor<I>::preprocess_snap_rename(
	    librbd::journal::SnapRenameEvent &event) {
	  dout(20) << ": "
	           << "remote_snap_id=" << event.snap_id << ", "
	           << "src_snap_name=" << event.src_snap_name << ", "
	           << "dest_snap_name=" << event.dst_snap_name << dendl;
	
	  auto snap_seq_it = m_snap_seqs.find(event.snap_id);
	  if (snap_seq_it != m_snap_seqs.end()) {
	    dout(20) << ": remapping remote snap id " << snap_seq_it->first << " "
	             << "to local snap id " << snap_seq_it->second << dendl;
	    event.snap_id = snap_seq_it->second;
	    return 0;
	  }
	
	  auto snap_id_it = m_local_image_ctx.snap_ids.find({cls::rbd::UserSnapshotNamespace(),
							     event.src_snap_name});
	  if (snap_id_it == m_local_image_ctx.snap_ids.end()) {
	    dout(20) << ": cannot map remote snapshot '" << event.src_snap_name << "' "
	             << "to local snapshot" << dendl;
	    event.snap_id = CEPH_NOSNAP;
	    return -ENOENT;
	  }
	
	  dout(20) << ": mapping remote snap id " << event.snap_id << " "
	           << "to local snap id " << snap_id_it->second << dendl;
	  m_snap_seqs_updated = true;
	  m_snap_seqs[event.snap_id] = snap_id_it->second;
	  event.snap_id = snap_id_it->second;
	  return 0;
	}
	
	template <typename I>
	void EventPreprocessor<I>::update_client() {
	  if (!m_snap_seqs_updated) {
	    finish(0);
	    return;
	  }
	
	  dout(20) << dendl;
	  librbd::journal::MirrorPeerClientMeta client_meta(*m_client_meta);
	  client_meta.snap_seqs = m_snap_seqs;
	
	  librbd::journal::ClientData client_data(client_meta);
	  bufferlist data_bl;
	  encode(client_data, data_bl);
	
	  Context *ctx = create_context_callback<
	    EventPreprocessor<I>, &EventPreprocessor<I>::handle_update_client>(
	      this);
	  m_remote_journaler.update_client(data_bl, ctx);
	}
	
	template <typename I>
	void EventPreprocessor<I>::handle_update_client(int r) {
	  dout(20) << ": r=" << r << dendl;
	
	  if (r < 0) {
	    derr << "failed to update mirror peer journal client: "
	         << cpp_strerror(r) << dendl;
	    finish(r);
	    return;
	  }
	
	  m_client_meta->snap_seqs = m_snap_seqs;
	  finish(0);
	}
	
	template <typename I>
	bool EventPreprocessor<I>::prune_snap_map(SnapSeqs *snap_seqs) {
	  bool pruned = false;
	
	  std::shared_lock image_locker{m_local_image_ctx.image_lock};
	  for (auto it = snap_seqs->begin(); it != snap_seqs->end(); ) {
	    auto current_it(it++);
	    if (m_local_image_ctx.snap_info.count(current_it->second) == 0) {
	      snap_seqs->erase(current_it);
	      pruned = true;
	    }
	  }
	  return pruned;
	}
	
	template <typename I>
	void EventPreprocessor<I>::finish(int r) {
	  dout(20) << ": r=" << r << dendl;
	
	  Context *on_finish = m_on_finish;
	  m_on_finish = nullptr;
	  m_event_entry = nullptr;
	  m_in_progress = false;
	  m_snap_seqs_updated = false;
	  m_work_queue->queue(on_finish, r);
	}
	
	} // namespace image_replayer
	} // namespace mirror
	} // namespace rbd
	
	template class rbd::mirror::image_replayer::EventPreprocessor<librbd::ImageCtx>;