openstack/storage/v1/objects/results.go

package objects

import (
	"fmt"
	"io/ioutil"
	"net/http"
	"strings"

	"github.com/rackspace/gophercloud/pagination"
)

// Object is a structure that holds information related to a storage object.
type Object map[string]interface{}

// ListResult is a single page of objects that is returned from a call to the List function.
type ObjectPage struct {
	pagination.MarkerPageBase
}

// IsEmpty returns true if a ListResult contains no object names.
func (r ObjectPage) IsEmpty() (bool, error) {
	names, err := ExtractNames(r)
	if err != nil {
		return true, err
	}
	return len(names) == 0, nil
}

// LastMarker returns the last object name in a ListResult.
func (r ObjectPage) LastMarker() (string, error) {
	names, err := ExtractNames(r)
	if err != nil {
		return "", err
	}
	if len(names) == 0 {
		return "", nil
	}
	return names[len(names)-1], nil
}

// DownloadResult is a *http.Response that is returned from a call to the Download function.
type DownloadResult struct {
	Resp *http.Response
	Err  error
}

// GetResult is a *http.Response that is returned from a call to the Get function.
type GetResult struct {
	Resp *http.Response
	Err  error
}

// ExtractInfo is a function that takes a page of objects and returns their full information.
func ExtractInfo(page pagination.Page) ([]Object, error) {
	untyped := page.(ObjectPage).Body.([]interface{})
	results := make([]Object, len(untyped))
	for index, each := range untyped {
		results[index] = Object(each.(map[string]interface{}))
	}
	return results, nil
}

// ExtractNames is a function that takes a page of objects and returns only their names.
func ExtractNames(page pagination.Page) ([]string, error) {
	casted := page.(ObjectPage)
	ct := casted.Header.Get("Content-Type")

	switch {
	case strings.HasPrefix(ct, "application/json"):
		parsed, err := ExtractInfo(page)
		if err != nil {
			return nil, err
		}

		names := make([]string, 0, len(parsed))
		for _, object := range parsed {
			names = append(names, object["name"].(string))
		}
		return names, nil
	case strings.HasPrefix(ct, "text/plain"):
		names := make([]string, 0, 50)

		body := string(page.(ObjectPage).Body.([]uint8))
		for _, name := range strings.Split(body, "\n") {
			if len(name) > 0 {
				names = append(names, name)
			}
		}

		return names, nil
	default:
		return nil, fmt.Errorf("Cannot extract names from response with content-type: [%s]", ct)
	}
}

// ExtractContent is a function that takes a DownloadResult (of type *http.Response)
// and returns the object's content.
func (dr DownloadResult) ExtractContent() ([]byte, error) {
	if dr.Err != nil {
		return nil, nil
	}
	var body []byte
	defer dr.Resp.Body.Close()
	body, err := ioutil.ReadAll(dr.Resp.Body)
	if err != nil {
		return body, fmt.Errorf("Error trying to read DownloadResult body: %v", err)
	}
	return body, nil
}

// ExtractMetadata is a function that takes a GetResult (of type *http.Response)
// and returns the custom metadata associated with the object.
func (gr GetResult) ExtractMetadata() (map[string]string, error) {
	if gr.Err != nil {
		return nil, gr.Err
	}
	metadata := make(map[string]string)
	for k, v := range gr.Resp.Header {
		if strings.HasPrefix(k, "X-Object-Meta-") {
			key := strings.TrimPrefix(k, "X-Object-Meta-")
			metadata[key] = v[0]
		}
	}
	return metadata, nil
}