commands: Added File interface and implementations

commands/file.go

+package commands
+
+import (
+	"errors"
+	"io"
+	"mime"
+	"mime/multipart"
+	"net/http"
+)
+
+const (
+	multipartFormdataType = "multipart/form-data"
+	multipartMixedType    = "multipart/mixed"
+
+	contentTypeHeader = "Content-Type"
+)
+
+var (
+	ErrNotDirectory = errors.New("Couln't call NextFile(), this isn't a directory")
+	ErrNotReader    = errors.New("This file is a directory, can't use Reader functions")
+)
+
+type File interface {
+	io.ReadCloser
+	FileName() string
+	IsDirectory() bool
+	NextFile() (File, error)
+}
+
+type MultipartFile struct {
+	File
+
+	Part      *multipart.Part
+	Reader    *multipart.Reader
+	Mediatype string
+}
+
+func NewFileFromPart(part *multipart.Part) (File, error) {
+	f := &MultipartFile{
+		Part: part,
+	}
+
+	contentType := part.Header.Get(contentTypeHeader)
+
+	var params map[string]string
+	var err error
+	f.Mediatype, params, err = mime.ParseMediaType(contentType)
+	if err != nil {
+		return nil, err
+	}
+
+	if f.IsDirectory() {
+		boundary, found := params["boundary"]
+		if !found {
+			return nil, http.ErrMissingBoundary
+		}
+
+		f.Reader = multipart.NewReader(part, boundary)
+	}
+
+	return f, nil
+}
+
+func (f *MultipartFile) IsDirectory() bool {
+	return f.Mediatype == multipartFormdataType || f.Mediatype == multipartMixedType
+}
+
+func (f *MultipartFile) NextFile() (File, error) {
+	if !f.IsDirectory() {
+		return nil, ErrNotDirectory
+	}
+
+	part, err := f.Reader.NextPart()
+	if err != nil {
+		return nil, err
+	}
+
+	return NewFileFromPart(part)
+}
+
+func (f *MultipartFile) FileName() string {
+	return f.Part.FileName()
+}
+
+func (f *MultipartFile) Read(p []byte) (int, error) {
+	if f.IsDirectory() {
+		return 0, ErrNotReader
+	}
+	return f.Part.Read(p)
+}
+
+func (f *MultipartFile) Close() error {
+	if f.IsDirectory() {
+		return ErrNotReader
+	}
+	return f.Part.Close()
+}
+
+type SliceFile struct {
+	Filename string
+	Files    []File
+}
+
+func (f *SliceFile) IsDirectory() bool {
+	return true
+}
+
+func (f *SliceFile) NextFile() (File, error) {
+	if len(f.Files) == 0 {
+		return nil, io.EOF
+	}
+	file := f.Files[0]
+	f.Files = f.Files[1:]
+	return file, nil
+}
+
+func (f *SliceFile) FileName() string {
+	return f.Filename
+}
+
+func (f *SliceFile) Read(p []byte) (int, error) {
+	return 0, ErrNotReader
+}
+
+func (f *SliceFile) Close() error {
+	return ErrNotReader
+}
+
+type ReaderFile struct {
+	Filename string
+	Reader   io.Reader
+}
+
+func (f *ReaderFile) IsDirectory() bool {
+	return false
+}
+
+func (f *ReaderFile) NextFile() (File, error) {
+	return nil, ErrNotDirectory
+}
+
+func (f *ReaderFile) FileName() string {
+	return f.Filename
+}
+
+func (f *ReaderFile) Read(p []byte) (int, error) {
+	return f.Reader.Read(p)
+}
+
+func (f *ReaderFile) Close() error {
+	closer, ok := f.Reader.(io.Closer)
+	if !ok {
+		return nil
+	}
+	return closer.Close()
+}