//go:build linux

package uptime

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

func getLinuxUptime() (UptimeInformation, error) {
	uptimeFile, err := os.Open("/proc/uptime")
	if err != nil {
		return UptimeInformation{}, fmt.Errorf("Could not find /proc/uptime. Are you sure you are on linux?")
	}
	defer uptimeFile.Close()

	fileReader := bufio.NewScanner(uptimeFile)

	var busyTime float64

	fileReader.Scan()
	if fileReader.Err() != nil {
		return UptimeInformation{}, fmt.Errorf("Could not read /proc/uptime.")
	}

	data := fileReader.Text()

	/*
	 * fields[0] Time spent busy/suspended
	 * fields[1] Time spent idling, it's combined from all CPU cores
	 */
	fields := strings.Split(data, " ")

	busyTime, _ = strconv.ParseFloat(fields[0], 64)

	return UptimeInformation{
		uptime: busyTime,
	}, nil
}

func GetUptimeInformation() (UptimeInformation, error) {
	info, err := getLinuxUptime()
	if err != nil {
		return UptimeInformation{}, fmt.Errorf("Could not read uptime info. Error: %v", err)
	}
	return info, nil
}