package fs

import (
	"bufio"
	"fmt"
	"os"
	"path/filepath"

	"github.com/dotcloud/docker/pkg/cgroups"
)

type blkioGroup struct {
}

func (s *blkioGroup) Set(d *data) error {
	// we just want to join this group even though we don't set anything
	if _, err := d.join("blkio"); err != nil && err != cgroups.ErrNotFound {
		return err
	}
	return nil
}

func (s *blkioGroup) Remove(d *data) error {
	return removePath(d.path("blkio"))
}

/*
examples:

    blkio.sectors
    8:0 6792

    blkio.io_service_bytes
    8:0 Read 1282048
    8:0 Write 2195456
    8:0 Sync 2195456
    8:0 Async 1282048
    8:0 Total 3477504
    Total 3477504

    blkio.io_serviced
    8:0 Read 124
    8:0 Write 104
    8:0 Sync 104
    8:0 Async 124
    8:0 Total 228
    Total 228

    blkio.io_queued
    8:0 Read 0
    8:0 Write 0
    8:0 Sync 0
    8:0 Async 0
    8:0 Total 0
    Total 0
*/
func (s *blkioGroup) Stats(d *data) (map[string]float64, error) {
	var (
		paramData = make(map[string]float64)
		params    = []string{
			"sectors",
			"io_service_bytes",
			"io_serviced",
			"io_queued",
		}
	)

	path, err := d.path("blkio")
	if err != nil {
		return nil, err
	}

	for _, param := range params {
		f, err := os.Open(filepath.Join(path, fmt.Sprintf("blkio.%s", param)))
		if err != nil {
			return nil, err
		}
		defer f.Close()

		sc := bufio.NewScanner(f)
		for sc.Scan() {
			_, v, err := getCgroupParamKeyValue(sc.Text())
			if err != nil {
				return nil, err
			}
			paramData[param] = v
		}
	}
	return paramData, nil
}