package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"github.com/oz123/gupta"
	"log"
	"os"
	"time"
)

func readProcStatLine(r *os.File) string {
	buf := make([]byte, 80)
	r.ReadAt(buf, 0)
	idx := bytes.Index(buf, []byte("cpu0"))
	line := string(buf[:idx])
	r.Seek(0, 0)
	return line
}

var Usage = func() {
	fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])

	flag.PrintDefaults()
}

func main() {
	var interval int
	var partition, netInterface string
	var load, memory, cpu bool

	writer := os.Stdout
	enc := json.NewEncoder(writer)

	flag.IntVar(&interval, "i", 5, "polling inteval")
	flag.BoolVar(&memory, "m", false, "Poll memory")
	flag.BoolVar(&load, "l", false, "Poll load")
	flag.BoolVar(&cpu, "c", false, "poll CPU usage")
	flag.StringVar(&partition, "p", "", "Poll disk usage (partition)")
	flag.StringVar(&netInterface, "n", "", "Network usage (interface)")

	flag.Parse()

	if load == false && memory == false && cpu == false {
		Usage()
		os.Exit(1)
	}
	fmt.Println(gupta.Hello())
	r, _ := os.Open("/proc/stat")
	m, _ := os.Open("/proc/meminfo")
	defer r.Close()
	defer m.Close()

	for true {
		report := gupta.GuptaReport{Time: time.Now()}
		line := readProcStatLine(r)
		time.Sleep(time.Duration(interval) * time.Second)
		if cpu {
			lineNew := readProcStatLine(r)
			cpustat := gupta.NewCPUStat(line, lineNew)
			report.CPUUsage = &cpustat
		}
		if memory {
			mem := gupta.NewMemory(m)
			report.MemoryUsage = &mem
		}
		if err := enc.Encode(&report); err != nil {
			log.Println(err)
		}
		r.Seek(0, 0)
		m.Seek(0, 0)
	}
}