// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab

#include "librbd/journal/DemoteRequest.h"
#include "common/dout.h"
#include "common/errno.h"
#include "common/WorkQueue.h"
#include "journal/Journaler.h"
#include "journal/Settings.h"
#include "librbd/ImageCtx.h"
#include "librbd/Journal.h"
#include "librbd/Utils.h"
#include "librbd/journal/OpenRequest.h"

#define dout_subsys ceph_subsys_rbd
#undef dout_prefix
#define dout_prefix *_dout << "librbd::journal::DemoteRequest: " << this \
                           << " " << __func__ << ": "

namespace librbd {
namespace journal {

using librbd::util::create_async_context_callback;
using librbd::util::create_context_callback;

template <typename I>
DemoteRequest<I>::DemoteRequest(I &image_ctx, Context *on_finish)
  : m_image_ctx(image_ctx), m_on_finish(on_finish),
    m_lock("DemoteRequest::m_lock") {
}

template <typename I>
DemoteRequest<I>::~DemoteRequest() {
  assert(m_journaler == nullptr);
}

template <typename I>
void DemoteRequest<I>::send() {
  open_journaler();
}

template <typename I>
void DemoteRequest<I>::open_journaler() {
  CephContext *cct = m_image_ctx.cct;
  ldout(cct, 20) << dendl;

  m_journaler = new Journaler(m_image_ctx.md_ctx, m_image_ctx.id,
                              Journal<>::IMAGE_CLIENT_ID, {});
  auto ctx = create_async_context_callback(
    m_image_ctx, create_context_callback<
      DemoteRequest<I>, &DemoteRequest<I>::handle_open_journaler>(this));
  auto req = OpenRequest<I>::create(&m_image_ctx, m_journaler, &m_lock,
                                    &m_client_meta, &m_tag_tid, &m_tag_data,
                                    ctx);
  req->send();
}

template <typename I>
void DemoteRequest<I>::handle_open_journaler(int r) {
  CephContext *cct = m_image_ctx.cct;
  ldout(cct, 20) << "r=" << r << dendl;

  if (r < 0) {
    m_ret_val = r;
    lderr(cct) << "failed to open journal: " << cpp_strerror(r) << dendl;
    shut_down_journaler();
    return;
  } else if (m_tag_data.mirror_uuid != Journal<>::LOCAL_MIRROR_UUID) {
    m_ret_val = -EINVAL;
    lderr(cct) << "image is not currently the primary" << dendl;
    shut_down_journaler();
    return;
  }

  allocate_tag();
}

template <typename I>
void DemoteRequest<I>::allocate_tag() {
  CephContext *cct = m_image_ctx.cct;
  ldout(cct, 20) << dendl;

  cls::journal::Client client;
  int r = m_journaler->get_cached_client(Journal<>::IMAGE_CLIENT_ID, &client);
  if (r < 0) {
    m_ret_val = r;
    lderr(cct) << "failed to retrieve client: " << cpp_strerror(r) << dendl;
    shut_down_journaler();
    return;
  }

  TagPredecessor predecessor;
  predecessor.mirror_uuid = Journal<>::LOCAL_MIRROR_UUID;
  if (!client.commit_position.object_positions.empty()) {
    auto position = client.commit_position.object_positions.front();
    predecessor.commit_valid = true;
    predecessor.tag_tid = position.tag_tid;
    predecessor.entry_tid = position.entry_tid;
  }

  TagData tag_data;
  tag_data.mirror_uuid = Journal<>::ORPHAN_MIRROR_UUID;
  tag_data.predecessor = std::move(predecessor);

  bufferlist tag_bl;
  ::encode(tag_data, tag_bl);

  auto ctx = create_context_callback<
    DemoteRequest<I>, &DemoteRequest<I>::handle_allocate_tag>(this);
  m_journaler->allocate_tag(m_client_meta.tag_class, tag_bl, &m_tag, ctx);
}

template <typename I>
void DemoteRequest<I>::handle_allocate_tag(int r) {
  CephContext *cct = m_image_ctx.cct;
  ldout(cct, 20) << "r=" << r << dendl;

  if (r < 0) {
    m_ret_val = r;
    lderr(cct) << "failed to allocate tag: " << cpp_strerror(r) << dendl;
    shut_down_journaler();
    return;
  }

  m_tag_tid = m_tag.tid;
  append_event();
}

template <typename I>
void DemoteRequest<I>::append_event() {
  CephContext *cct = m_image_ctx.cct;
  ldout(cct, 20) << dendl;

  EventEntry event_entry{DemotePromoteEvent{}, {}};
  bufferlist event_entry_bl;
  ::encode(event_entry, event_entry_bl);

  m_journaler->start_append(0, 0, 0);
  m_future = m_journaler->append(m_tag_tid, event_entry_bl);

  auto ctx = create_context_callback<
    DemoteRequest<I>, &DemoteRequest<I>::handle_append_event>(this);
  m_future.flush(ctx);

}

template <typename I>
void DemoteRequest<I>::handle_append_event(int r) {
  CephContext *cct = m_image_ctx.cct;
  ldout(cct, 20) << "r=" << r << dendl;

  if (r < 0) {
    m_ret_val = r;
    lderr(cct) << "failed to append demotion journal event: " << cpp_strerror(r)
               << dendl;
    stop_append();
    return;
  }

  commit_event();
}

template <typename I>
void DemoteRequest<I>::commit_event() {
  CephContext *cct = m_image_ctx.cct;
  ldout(cct, 20) << dendl;

  m_journaler->committed(m_future);

  auto ctx = create_context_callback<
    DemoteRequest<I>, &DemoteRequest<I>::handle_commit_event>(this);
  m_journaler->flush_commit_position(ctx);
}

template <typename I>
void DemoteRequest<I>::handle_commit_event(int r) {
  CephContext *cct = m_image_ctx.cct;
  ldout(cct, 20) << "r=" << r << dendl;

  if (r < 0) {
    m_ret_val = r;
    lderr(cct) << "failed to flush demotion commit position: "
               << cpp_strerror(r) << dendl;
  }

  stop_append();
}

template <typename I>
void DemoteRequest<I>::stop_append() {
  CephContext *cct = m_image_ctx.cct;
  ldout(cct, 20) << dendl;

  auto ctx = create_context_callback<
    DemoteRequest<I>, &DemoteRequest<I>::handle_stop_append>(this);
  m_journaler->stop_append(ctx);
}

template <typename I>
void DemoteRequest<I>::handle_stop_append(int r) {
  CephContext *cct = m_image_ctx.cct;
  ldout(cct, 20) << "r=" << r << dendl;

  if (r < 0) {
    if (m_ret_val == 0) {
      m_ret_val = r;
    }
    lderr(cct) << "failed to stop journal append: " << cpp_strerror(r) << dendl;
  }

  shut_down_journaler();
}

template <typename I>
void DemoteRequest<I>::shut_down_journaler() {
  CephContext *cct = m_image_ctx.cct;
  ldout(cct, 20) << dendl;

  Context *ctx = create_async_context_callback(
    m_image_ctx, create_context_callback<
      DemoteRequest<I>, &DemoteRequest<I>::handle_shut_down_journaler>(this));
  m_journaler->shut_down(ctx);
}

template <typename I>
void DemoteRequest<I>::handle_shut_down_journaler(int r) {
  CephContext *cct = m_image_ctx.cct;
  ldout(cct, 20) << "r=" << r << dendl;

  if (r < 0) {
    lderr(cct) << "failed to shut down journal: " << cpp_strerror(r) << dendl;
  }

  delete m_journaler;
  m_journaler = nullptr;
  finish(r);
}

template <typename I>
void DemoteRequest<I>::finish(int r) {
  if (m_ret_val < 0) {
    r = m_ret_val;
  }

  CephContext *cct = m_image_ctx.cct;
  ldout(cct, 20) << "r=" << r << dendl;

  m_on_finish->complete(r);
  delete this;
}

} // namespace journal
} // namespace librbd

template class librbd::journal::DemoteRequest<librbd::ImageCtx>;