/* vim: tabstop=2 shiftwidth=2 expandtab textwidth=80 linebreak wrap
 *
 * Copyright 2012 Matthew McCormick
 * Copyright 2015 Pawel 'l0ner' Soltys
 *
 * 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.
 */

#include <sstream>
#include <string>

// Ugly fix to compilation on OpenBSD 5.6
// these need to be before include sys/mount.h
// and be in this exact order. Otherwise compiling on
// OpenBSD 5.6 will fail with missing NGROUPS define
// or missing gid_t typedefs
#ifdef OPENBSD_WORKAROUND
#include <sys/types.h> // typedefs
#include <sys/param.h> // missing NGROUPS
#include <sys/ucred.h>
#else
#include <sys/types.h>
#endif

#include <sys/mount.h> // VFS_* which we use to get cache
#include <sys/sysctl.h>
#include <sys/vmmeter.h> // vmtotal struct

#include "error.h"
#include "memory.h"
#include "luts.h"
#include "conversions.h"

static int pageshift;

#define pagesh(size) ((size) << pageshift)

std::string mem_string( bool use_colors = false )
{
  std::ostringstream oss;

  // These values are in bytes
  int64_t total_mem = 0;
  int64_t used_mem = 0;
  int32_t free_mem = 0;
  size_t size;

  // get page size
  static int hw_pagesize[] = { CTL_HW, HW_PAGESIZE };
  int page_size = 0;
  size = sizeof( page_size );
  if( sysctl( hw_pagesize, 2, &page_size, &size, NULL, 0) < 0)
  {
    error("memory: error getting page size");
    exit(23);
  }

  // calculate how far we must shift the variables
  pageshift = 0;
  while( page_size > 1 )
  {
    pageshift++;
    page_size >>= 1;
  }

  // get vm memory stats
  static int vm_totalmem[] = { CTL_VM, VM_METER };
  struct vmtotal vm_total;
  size = sizeof( vm_total );
  if( sysctl( vm_totalmem, 2, &vm_total, &size, NULL, 0 ) < 0 )
  {
    error("memory: error getting vm memory stats");
    exit(23);
  }

  // In case we need it, this gets the cached memory (bcstats.numbufpages)
  static int vm_bcstats[] = { CTL_VFS, VFS_GENERIC, VFS_BCACHESTAT };
  struct bcachestats bcstats;
  size = sizeof( bcstats );
  if( sysctl( vm_bcstats, 3, &bcstats, &size, NULL, 0 ) < 0 )
  {
    error( "memory: error getting cached memory size" );
    exit( 23 );
  }

  // calculations based on conky openbsd port
  used_mem = pagesh( vm_total.t_rm );
  free_mem = pagesh( vm_total.t_free );

  // from nagios-memory plugin
  used_mem -= pagesh( bcstats.numbufpages );
  free_mem += pagesh( bcstats.numbufpages );

  // calculate total memory
  total_mem = used_mem + free_mem;

  if( use_colors )
  {
    oss << mem_lut[( 100 * used_mem ) / total_mem];
  }

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

  if( use_colors )
  {
    oss << "#[fg=default,bg=default]";
  }

  return oss.str();
}