/*
 * Copyright 2012 Matthew McCormick
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * */
// This file was Authored by Justin Crawford <Justasic@gmail.com>
// Based on: https://github.com/freebsd/freebsd/blob/master/usr.bin/top/machine.c
// Based on: Apple.cpp for load_string/mem_string and apple's documentation


#include <sstream>
#include <string>
#include <sys/types.h>

#include "common.h"
#include "memory.h"

std::string mem_string() {
  // These values are in bytes
  int64_t total_mem = 0;
  int64_t used_mem = 0;
  int64_t unused_mem = 0;
  int32_t inactive_mem = 0;
  int32_t active_mem = 0;
  int32_t free_mem = 0;
  int32_t wired_mem = 0;
  int32_t page_size = 0;
  int32_t cache_mem = 0;
  std::ostringstream oss;

  // Get total physical memory, page size, and some other needed info
  GETSYSCTL("hw.realmem", total_mem);
  GETSYSCTL("hw.pagesize", page_size);

  GETSYSCTL("vm.stats.vm.v_free_count", free_mem);
  GETSYSCTL("vm.stats.vm.v_inactive_count", inactive_mem);
  GETSYSCTL("vm.stats.vm.v_cache_count", cache_mem);
  GETSYSCTL("vm.stats.vm.v_wire_count", wired_mem);
  GETSYSCTL("vm.stats.vm.v_active_count", active_mem);

  // Get all memory which can be allocated
  //unused_mem = (cache_mem + free_mem) * page_size;
  used_mem = (
	  static_cast<int64_t>(active_mem) + static_cast<int64_t>(inactive_mem) +
	  static_cast<int64_t>(wired_mem)) * static_cast<int64_t>(page_size);

  oss << MEGABYTES(used_mem) << '/' << MEGABYTES(total_mem) << "MB";

  return oss.str();
}