package main

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

type Memory struct {
	MemTotal     int
	MemFree      int
	MemAvailable int
}

func GetMemoryInfo() *Memory {
	toInt := func(raw string) int {
		if raw == "" {
			return 0
		}
		res, err := strconv.Atoi(raw)
		if err != nil {
			panic(err)
		}
		return res
	}

	parseLine := func(raw string) (key string, value int) {
		text := strings.ReplaceAll(raw[:len(raw)-2], " ", "")
		keyValue := strings.Split(text, ":")
		return keyValue[0], toInt(keyValue[1])
	}

	if _, err := os.Stat("/proc/meminfo"); err != nil {
		return nil
	}
	file, err := os.Open("/proc/meminfo")
	if err != nil {
		panic(err)
	}
	defer file.Close()
	bufio.NewScanner(file)
	scanner := bufio.NewScanner(file)
	res := Memory{}
	for scanner.Scan() {
		key, value := parseLine(scanner.Text())
		switch key {
		case "MemTotal":
			res.MemTotal = value / 1024
		case "MemFree":
			res.MemFree = value / 1024
		case "MemAvailable":
			res.MemAvailable = value / 1024
		}
	}
	return &res
}