1 files changed, 162 insertions, 0 deletions
diff --git a/gopher/response.go b/gopher/response.go
new file mode 100644
index 0000000..c600b10
--- /dev/null
+++ b/gopher/response.go
@@ -0,0 +1,162 @@
+package gopher
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"sync"
+
+	"tildegit.org/tjp/gus"
+)
+
+// The Canonical gopher item types.
+const (
+	TextFileType      gus.Status = '0'
+	MenuType          gus.Status = '1'
+	CSOPhoneBookType  gus.Status = '2'
+	ErrorType         gus.Status = '3'
+	MacBinHexType     gus.Status = '4'
+	DosBinType        gus.Status = '5'
+	UuencodedType     gus.Status = '6'
+	SearchType        gus.Status = '7'
+	TelnetSessionType gus.Status = '8'
+	BinaryFileType    gus.Status = '9'
+	MirrorServerType  gus.Status = '+'
+	GifFileType       gus.Status = 'g'
+	ImageFileType     gus.Status = 'I'
+	Telnet3270Type    gus.Status = 'T'
+)
+
+// The gopher+ types.
+const (
+	BitmapType    gus.Status = ':'
+	MovieFileType gus.Status = ';'
+	SoundFileType gus.Status = '<'
+)
+
+// The various non-canonical gopher types.
+const (
+	DocumentType     gus.Status = 'd'
+	HTMLType         gus.Status = 'h'
+	InfoMessageType  gus.Status = 'i'
+	PngImageFileType gus.Status = 'p'
+	RtfDocumentType  gus.Status = 'r'
+	WavSoundFileType gus.Status = 's'
+	PdfDocumentType  gus.Status = 'P'
+	XmlDocumentType  gus.Status = 'X'
+)
+
+// MapItem is a single item in a gophermap.
+type MapItem struct {
+	Type     gus.Status
+	Display  string
+	Selector string
+	Hostname string
+	Port     string
+}
+
+// String serializes the item into a gophermap CRLF-terminated text line.
+func (mi MapItem) String() string {
+	return fmt.Sprintf(
+		"%s%s\t%s\t%s\t%s\r\n",
+		[]byte{byte(mi.Type)},
+		mi.Display,
+		mi.Selector,
+		mi.Hostname,
+		mi.Port,
+	)
+}
+
+// Response builds a response which contains just this single MapItem.
+//
+// Meta in the response will be a pointer to the MapItem.
+func (mi *MapItem) Response() *gus.Response {
+	return &gus.Response{
+		Status: mi.Type,
+		Meta:   &mi,
+		Body:   bytes.NewBufferString(mi.String() + ".\r\n"),
+	}
+}
+
+// MapDocument is a list of map items which can print out a full gophermap document.
+type MapDocument []MapItem
+
+// String serializes the document into gophermap format.
+func (md MapDocument) String() string {
+	return md.serialize().String()
+}
+
+// Response builds a gopher response containing the gophermap.
+//
+// Meta will be the MapDocument itself.
+func (md MapDocument) Response() *gus.Response {
+	return &gus.Response{
+		Status: DocumentType,
+		Meta:   md,
+		Body:   md.serialize(),
+	}
+}
+
+func (md MapDocument) serialize() *bytes.Buffer {
+	buf := &bytes.Buffer{}
+	for _, mi := range md {
+		_, _ = buf.WriteString(mi.String())
+	}
+	_, _ = buf.WriteString(".\r\n")
+	return buf
+}
+
+// Error builds an error message MapItem.
+func Error(err error) *MapItem {
+	return &MapItem{
+		Type:     ErrorType,
+		Display:  err.Error(),
+		Hostname: "none",
+		Port:     "0",
+	}
+}
+
+// File builds a minimal response delivering a file's contents.
+//
+// Meta is nil and Status is 0 in this response.
+func File(status gus.Status, contents io.Reader) *gus.Response {
+	return &gus.Response{Status: status, Body: contents}
+}
+
+// NewResponseReader produces a reader which supports reading gopher protocol responses.
+func NewResponseReader(response *gus.Response) gus.ResponseReader {
+	return &responseReader{
+		Response: response,
+		once:     &sync.Once{},
+	}
+}
+
+type responseReader struct {
+	*gus.Response
+	reader io.Reader
+	once   *sync.Once
+}
+
+func (rdr *responseReader) Read(b []byte) (int, error) {
+	rdr.ensureReader()
+	return rdr.reader.Read(b)
+}
+
+func (rdr *responseReader) WriteTo(dst io.Writer) (int64, error) {
+	rdr.ensureReader()
+	return rdr.reader.(io.WriterTo).WriteTo(dst)
+}
+
+func (rdr *responseReader) ensureReader() {
+	rdr.once.Do(func() {
+		if _, ok := rdr.Body.(io.WriterTo); ok {
+			rdr.reader = rdr.Body
+			return
+		}
+
+		// rdr.reader needs to implement WriterTo, so in this case
+		// we borrow an implementation in terms of io.Reader from
+		// io.MultiReader.
+		rdr.reader = io.MultiReader(rdr.Body)
+	})
+}