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#include <grpc++/completion_queue.h>

#include <memory>

#include <grpc/grpc.h>
#include <grpc/support/log.h>
#include <grpc/support/time.h>
#include "src/cpp/util/time.h"

namespace grpc {

CompletionQueue::CompletionQueue() { cq_ = grpc_completion_queue_create(); }

CompletionQueue::CompletionQueue(grpc_completion_queue* take) : cq_(take) {}

CompletionQueue::~CompletionQueue() { grpc_completion_queue_destroy(cq_); }

void CompletionQueue::Shutdown() { grpc_completion_queue_shutdown(cq_); }

// Helper class so we can declare a unique_ptr with grpc_event
class EventDeleter {
 public:
  void operator()(grpc_event* ev) {
    if (ev) grpc_event_finish(ev);
  }
};

bool CompletionQueue::Next(void** tag, bool* ok) {
  std::unique_ptr<grpc_event, EventDeleter> ev;

  for (;;) {
    ev.reset(grpc_completion_queue_next(cq_, gpr_inf_future));
    if (ev->type == GRPC_QUEUE_SHUTDOWN) {
      return false;
    }
    auto cq_tag = static_cast<CompletionQueueTag*>(ev->tag);
    *ok = ev->data.op_complete == GRPC_OP_OK;
    *tag = cq_tag;
    if (cq_tag->FinalizeResult(tag, ok)) {
      return true;
    }
  }
}

bool CompletionQueue::Pluck(CompletionQueueTag* tag) {
  std::unique_ptr<grpc_event, EventDeleter> ev;

  ev.reset(grpc_completion_queue_pluck(cq_, tag, gpr_inf_future));
  bool ok = ev->data.op_complete == GRPC_OP_OK;
  void* ignored = tag;
  GPR_ASSERT(tag->FinalizeResult(&ignored, &ok));
  GPR_ASSERT(ignored == tag);
  return ok;
}

void CompletionQueue::TryPluck(CompletionQueueTag* tag) {
  std::unique_ptr<grpc_event, EventDeleter> ev;

  ev.reset(grpc_completion_queue_pluck(cq_, tag, gpr_inf_past));
  if (!ev) return;
  bool ok = ev->data.op_complete == GRPC_OP_OK;
  void* ignored = tag;
  // the tag must be swallowed if using TryPluck
  GPR_ASSERT(!tag->FinalizeResult(&ignored, &ok));
}

}  // namespace grpc