package gupta

import (
	"bytes"
	"io"
	"strconv"
	"strings"
)

type Memory struct {
	total uint64
	free  uint64
}

func (m *Memory) Free() uint64 {
	return m.free
}

func (m *Memory) Total() uint64 {
	return m.total
}

func (m *Memory) Used() uint64 {
	return m.total - m.free
}

func NewMemory(r io.ReaderAt) Memory {
	m := Memory{}
	buf := make([]byte, 80)
	r.ReadAt(buf, 0)
	idx := bytes.Index(buf, []byte("MemAvailable"))
	line := string(buf[:idx])
	elements := strings.Fields(line)
	m.total, _ = strconv.ParseUint(elements[1], 10, 64)
	m.free, _ = strconv.ParseUint(elements[4], 10, 64)
	return m
}