package stat

import (
	"io"
	"bufio"
	"strings"
	"fmt"
)

type DiskIOStat struct {
	device,
	readCompleted,
	readMerged,
	sectorRead,
	timeSpentReading,
	writesCompleted,
	writesMerged,
	sectorsWritten,
	timeSpentWriting,
	ioInProg,
	timeSpentIO,
	weightedTimeSpentIO string
}

func (diskio DiskIOStat) Command() string {
	return "cat /proc/diskstats"
}

func (diskio DiskIOStat) Parse(r io.Reader) ([]DiskIOStat, error) {
	var (
		DiskIOStats = []DiskIOStat{}
		scanner   = bufio.NewScanner(r)
	)

	for scanner.Scan() {
		parts := strings.Fields(scanner.Text())
		if len(parts) < 4 {
			return nil, fmt.Errorf("invalid line in %s: %s", "/proc/diskstats", scanner.Text())
		}
		deviceName := parts[2]
		if !strings.HasPrefix(deviceName, "sd") {
			continue
		}
		DiskIOStats = append(DiskIOStats, DiskIOStat{
			device:              deviceName,
			readCompleted:       parts[3],
			readMerged:          parts[4],
			sectorRead:          parts[5],
			timeSpentReading:    parts[6],
			writesCompleted:     parts[7],
			writesMerged:        parts[8],
			sectorsWritten:      parts[9],
			timeSpentWriting:    parts[10],
			ioInProg:            parts[11],
			timeSpentIO:         parts[12],
			weightedTimeSpentIO: parts[13],
		})

	}

	return DiskIOStats, scanner.Err()
}