/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */

#include <node.h>
#include <nan.h>

#include "grpc/grpc.h"
#include "grpc/support/log.h"
#include "grpc/support/time.h"
#include "completion_queue_async_worker.h"
#include "call.h"

namespace grpc {
namespace node {

const int max_queue_threads = 2;

using v8::Function;
using v8::Local;
using v8::Object;
using v8::Value;

grpc_completion_queue *CompletionQueueAsyncWorker::queue;

// Invariants: current_threads <= max_queue_threads
// (current_threads == max_queue_threads) || (waiting_next_calls == 0)

int CompletionQueueAsyncWorker::current_threads;
int CompletionQueueAsyncWorker::waiting_next_calls;

CompletionQueueAsyncWorker::CompletionQueueAsyncWorker()
    : Nan::AsyncWorker(NULL) {}

CompletionQueueAsyncWorker::~CompletionQueueAsyncWorker() {}

void CompletionQueueAsyncWorker::Execute() {
  result =
      grpc_completion_queue_next(queue, gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
  if (!result.success) {
    SetErrorMessage("The async function encountered an error");
  }
}

grpc_completion_queue *CompletionQueueAsyncWorker::GetQueue() { return queue; }

void CompletionQueueAsyncWorker::Next() {
  Nan::HandleScope scope;
  if (current_threads < max_queue_threads) {
    current_threads += 1;
    CompletionQueueAsyncWorker *worker = new CompletionQueueAsyncWorker();
    Nan::AsyncQueueWorker(worker);
  } else {
    waiting_next_calls += 1;
  }
  GPR_ASSERT(current_threads <= max_queue_threads);
  GPR_ASSERT((current_threads == max_queue_threads) ||
             (waiting_next_calls == 0));
}

void CompletionQueueAsyncWorker::Init(Local<Object> exports) {
  Nan::HandleScope scope;
  current_threads = 0;
  waiting_next_calls = 0;
  queue = grpc_completion_queue_create(NULL);
}

void CompletionQueueAsyncWorker::HandleOKCallback() {
  Nan::HandleScope scope;
  if (waiting_next_calls > 0) {
    waiting_next_calls -= 1;
    // Old worker removed, new worker added. current_threads += 0
    CompletionQueueAsyncWorker *worker = new CompletionQueueAsyncWorker();
    Nan::AsyncQueueWorker(worker);
  } else {
    current_threads -= 1;
  }
  GPR_ASSERT(current_threads <= max_queue_threads);
  GPR_ASSERT((current_threads == max_queue_threads) ||
             (waiting_next_calls == 0));
  Nan::Callback *callback = GetTagCallback(result.tag);
  Local<Value> argv[] = {Nan::Null(), GetTagNodeValue(result.tag)};
  callback->Call(2, argv);

  DestroyTag(result.tag);
}

void CompletionQueueAsyncWorker::HandleErrorCallback() {
  if (waiting_next_calls > 0) {
    waiting_next_calls -= 1;
    // Old worker removed, new worker added. current_threads += 0
    CompletionQueueAsyncWorker *worker = new CompletionQueueAsyncWorker();
    Nan::AsyncQueueWorker(worker);
  } else {
    current_threads -= 1;
  }
  GPR_ASSERT(current_threads <= max_queue_threads);
  GPR_ASSERT((current_threads == max_queue_threads) ||
             (waiting_next_calls == 0));
  Nan::HandleScope scope;
  Nan::Callback *callback = GetTagCallback(result.tag);
  Local<Value> argv[] = {Nan::Error(ErrorMessage())};

  callback->Call(1, argv);

  DestroyTag(result.tag);
}

}  // namespace node
}  // namespace grpc