package main

import (
	"bufio"
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
)

func init() {
	if h, err := os.Hostname(); err != nil {
		log.Fatalf("error reading hostname: %s", err)
	} else {
		hostname = h
	}
}

func (s *applyState) populateLoadavg() {
	if s.loadavg != nil {
		return
	}

	if b, err := os.ReadFile("/proc/loadavg"); err != nil {
		log.Printf("error reading loadavg: %s", err)
	} else {
		res := strings.SplitN(string(b), " ", 4)
		if len(res) >= 3 {
			s.loadavg = (*[3]string)(res[:3])
			return
		}
		log.Printf("unexpected loadavg raw: %s", string(b))
	}

	s.loadavg = &[3]string{"?", "?", "?"}
}

func (s *applyState) populateMem() {
	if s.mem != nil {
		return
	}

	// failure defaults
	s.mem = &[2]int{-1, -1}

	if f, err := os.Open("/proc/meminfo"); err != nil {
		log.Printf("error reading meminfo: %s", err)
	} else {
		defer func() {
			if err = f.Close(); err != nil {
				log.Fatalf("error closing meminfo: %s", err)
			}
		}()

		p := bufio.NewScanner(f)
		for p.Scan() {
			res := strings.SplitN(strings.ReplaceAll(p.Text(), " ", ""), ":", 2)
			if len(res) != 2 {
				fmt.Printf("unexpected meminfo line: %s", p.Text())
				return
			}

			format := func(r string) int {
				var v int
				if v, err = strconv.Atoi(r[:len(r)-2]); err != nil {
					log.Printf("error parsing meminfo value: %s", err)
					v = -1
				}

				return v
			}

			switch res[0] {
			case "MemFree":
				s.mem[0] = format(res[1])
			case "MemTotal":
				s.mem[1] = format(res[1])
			}
		}
	}
}