#!/usr/bin/env python3

import time
import sys

def read_file(filename):
    with open(filename) as f:
        return f.read()

def read_cpu_idle_jiffys(procstat):
    line = procstat.split("\n")[0]
    fields = line.split()
    return int(fields[4])

def count_cpus(procstat):
    count = -1
    for line in procstat.split("\n"):
        if line.startswith("cpu"):
            count += 1
    return count

def read_cpu_percent():
    procstat = read_file("/proc/stat")
    num_cpus = count_cpus(procstat)

    tstart = time.time()
    idle_jiffy1 = read_cpu_idle_jiffys(procstat)
    time.sleep(0.1)
    idle_jiffy2 = read_cpu_idle_jiffys(read_file("/proc/stat"))
    tend = time.time()

    duration = tend - tstart
    idle_jiffys_per_second = (idle_jiffy2 - idle_jiffy1) / duration

    idle_jiffys_per_cpu_second = idle_jiffys_per_second / num_cpus

    # One jiffy is 10ms, so we can get the percentage very easily!
    return 100 - idle_jiffys_per_cpu_second

def read_mem_percent():
    meminfo = read_file("/proc/meminfo")

    d = {}
    for line in meminfo.strip().split("\n"):
        key, value = line.split()[:2]
        d[key] = int(value)

    mem_total = d["MemTotal:"]
    mem_free = d["MemAvailable:"]
    mem_used = mem_total - mem_free

    return mem_used / mem_total * 100

def write(s):
    sys.stdout.write(s)

def print_percent(name, units, value, red_threshold):
    if value > red_threshold:
        color = "red"
    else:
        color = "black"

    write(
        "%s <span color='%s'>%s</span>%s  " %
        (name, color, value, units)
    )

def main():
    write("<txt>")

    print_percent(
        "cpu", "%",
        round(read_cpu_percent()),
        red_threshold=50,
    )

    print_percent(
        "mem", "%",
        round(read_mem_percent()),
        red_threshold=70,
    )

    write("</txt>")

if __name__ == "__main__":
    main()