#/bin/bash
#Copyright (c) [2019] Huawei Technologies Co., Ltd.
#generic-release is licensed under the Mulan PSL v2.
#You can use this software according to the terms and conditions of the Mulan PSL v2.
#You may obtain a copy of Mulan PSL v2 at:
#     http://license.coscl.org.cn/MulanPSL2
#THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND, EITHER EXPRESS OR
#IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT, MERCHANTABILITY OR FIT FOR A PARTICULAR
#PURPOSE.
#See the Mulan PSL v2 for more details.

# Welcome
welcome=$(uname -r)

#function
function get_mem_usage {
  differ=`expr $1 - $2 - $3 - $4 - $5`
  milli=`expr $differ \* 10000 / $1`
  percent=`expr $differ \* 1000 / $1`
  predominant=`expr $differ \* 100 / $1`

  round=`expr $milli % 10`
  if [[ ${round} -ge 5 ]];then
    mid=`expr $percent % 10`
    last=`expr $mid + 1`
  else
    last=`expr $percent % 10`
  fi
  echo "${predominant}.${last}%"
}

function get_swap_mem {
  swap_diff=`expr $1 - $2`
  swap_milli=`expr $swap_diff \* 10000 / $1`
  swap_percent=`expr $swap_diff \* 1000 / $1`
  swap_dominant=`expr $swap_diff \* 100 / $1`

  swap_round=`expr $swap_milli % 10`
  if [[ ${round} -ge 5 ]];then
    swap_mid=`expr $swap_percent % 10`
    swap_last=`expr $swap_mid + 1`
  else
    swap_last=`expr $swap_percent % 10`
  fi
  echo "${swap_dominant}.${swap_last}%"
}

# Memory
memory_total=$(cat /proc/meminfo | awk '/^MemTotal:/ {printf($2)}')
memory_free=$(cat /proc/meminfo | awk '/^MemFree:/ { printf($2)}')
buffers=$(cat /proc/meminfo | awk '/^Buffers:/ { printf($2)}')
cached=$(cat /proc/meminfo | awk '/^Cached:/ { printf($2)}')
sreclaimable=$(cat /proc/meminfo | awk '/^SReclaimable:/ { printf($2)}')
swap_total=$(cat /proc/meminfo | awk '/^SwapTotal:/ { printf($2)}')
swap_free=$(cat /proc/meminfo | awk '/^SwapFree:/ { printf($2)}')

if [[ $memory_total -gt 0 ]]
then
    memory_usage=`get_mem_usage $memory_total $memory_free $buffers $cached $sreclaimable`
else
    memory_usage=0.0%
fi

# Swap memory
if [[ $swap_total -gt 0 ]]
then
    swap_mem=`get_swap_mem $swap_total $swap_free`
else
    swap_mem=0.0%
fi

# Usage
usageof=$(df -h / | awk '/\// {print $(NF-1)}')

# System load
load_average=$(awk '{print $1}' /proc/loadavg)

# WHO I AM
whoiam=$(whoami)

# Time
time_cur=$(date)

# Processes
processes=$(ps aux | wc -l)

# Users
user_num=$(users | wc -w)

# Ip address
ip_pre=""
if [ -x "/sbin/ip" ]
then
	    ip_pre=$(/sbin/ip a | grep inet | grep -v "127.0.0.1" | grep -v inet6 | awk '{print $2}')
fi

echo -e "\n"
echo -e "Welcome to $welcome\n"
echo -e "System information as of time: \t$time_cur\n"
echo -e "System load: \t\033[0;33;40m$load_average\033[0m"
echo -e "Processes: \t$processes"
echo -e "Memory used: \t$memory_usage"
echo -e "Swap used: \t$swap_mem"
echo -e "Usage On: \t$usageof"
for line in $ip_pre
do
	    ip_address=${line%/*}
	    echo -e "IP address: \t$ip_address"
done
echo -e "Users online: \t$user_num"
if [ "$whoiam" == "root" ]
then
	echo -e "\n"
else
	echo -e "To run a command as administrator(user \"root\"),use \"sudo <command>\"."
fi