implement gophernicus extensions for gophermaps

1 files changed, 220 insertions, 0 deletions

diff --git a/gopher/gophermap/extended.go b/gopher/gophermap/extended.go
new file mode 100644
index 0000000..d9fedd0
--- /dev/null
+++ b/gopher/gophermap/extended.go
@@ -0,0 +1,220 @@
+package gophermap
+
+import (
+	"bufio"
+	"errors"
+	"io"
+	"net/url"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"tildegit.org/tjp/sliderule/gopher"
+	"tildegit.org/tjp/sliderule/internal/types"
+)
+
+// ExtendedMapDocument is a gophermap doc with gophernicus's extensions
+//
+// These are documented at: gopher://gopher.gophernicus.org/0/docs/README.Gophermap
+type ExtendedMapDocument struct {
+	Lines    []gopher.MapItem
+	Location *url.URL
+}
+
+// ParseExtended parses a gophermap document including gophernicus extensions.
+func ParseExtended(input io.Reader, location *url.URL) (ExtendedMapDocument, error) {
+	rdr := bufio.NewReader(input)
+	doc := ExtendedMapDocument{Location: location}
+
+outer:
+	for num := 1; ; num += 1 {
+		line, err := rdr.ReadString('\n')
+		isEOF := errors.Is(err, io.EOF)
+		if err != nil && !isEOF {
+			return doc, err
+		}
+		line = strings.TrimRight(line, "\r\n")
+
+		if len(line) > 0 {
+			switch line[0] {
+
+			case '#':
+				doc.Lines = append(doc.Lines, gopher.MapItem{
+					Type:    CommentType,
+					Display: strings.TrimPrefix(line[1:], " "),
+				})
+				continue outer
+			case '!':
+				doc.Lines = append(doc.Lines, gopher.MapItem{
+					Type:    TitleType,
+					Display: line[1:],
+				})
+				continue outer
+			case '-':
+				doc.Lines = append(doc.Lines, gopher.MapItem{
+					Type:     HiddenType,
+					Selector: line[1:],
+				})
+				continue outer
+			case ':':
+				doc.Lines = append(doc.Lines, gopher.MapItem{
+					Type:    ExtensionType,
+					Display: line[1:],
+				})
+				continue outer
+			case '=':
+				doc.Lines = append(doc.Lines, gopher.MapItem{
+					Type:     InclusionType,
+					Selector: line[1:],
+				})
+				continue outer
+			}
+		}
+
+		switch line {
+		case "~":
+			doc.Lines = append(doc.Lines, gopher.MapItem{Type: UserListType})
+			continue outer
+		case "%":
+			doc.Lines = append(doc.Lines, gopher.MapItem{Type: VHostListType})
+			continue outer
+		case ".":
+			doc.Lines = append(doc.Lines, gopher.MapItem{Type: EndDocType})
+			break outer
+		case "*":
+			doc.Lines = append(doc.Lines, gopher.MapItem{Type: DirListType})
+			break outer
+		}
+
+		if !strings.Contains(line, "\t") {
+			doc.Lines = append(doc.Lines, gopher.MapItem{
+				Type:     gopher.InfoMessageType,
+				Display:  line,
+				Selector: location.Path,
+				Hostname: location.Hostname(),
+				Port:     location.Port(),
+			})
+			continue
+		}
+
+		item := gopher.MapItem{Type: types.Status(line[0])}
+
+		spl := strings.Split(line[1:], "\t")
+		if len(spl) != 4 {
+			return doc, InvalidLine(num)
+		}
+		item.Display = string(spl[0])
+		item.Selector = string(spl[1])
+		item.Hostname = string(spl[2])
+		item.Port = string(spl[3])
+		if _, err = strconv.Atoi(item.Port); err != nil {
+			return doc, InvalidLine(num)
+		}
+		doc.Lines = append(doc.Lines, item)
+
+		if isEOF {
+			break
+		}
+	}
+
+	return doc, nil
+}
+
+// Extensions to gopher types from Gophernicus.
+const (
+	// CommentType is omitted from generated compatible gophermaps.
+	CommentType types.Status = '#'
+
+	// TitleType defines the title of a gophermap document.
+	TitleType types.Status = '!'
+
+	// HiddenType hides a link from the generated compatible gophermap.
+	HiddenType types.Status = '-'
+
+	// ExtensionType defines the gopher type to use for files in the current directory with a given extension.
+	ExtensionType types.Status = ':'
+
+	// UserListType generates a list of users with valid ~/public_gopher directories.
+	UserListType types.Status = '~'
+
+	// VHostListType generates a listing of virtual hosts.
+	VHostListType types.Status = '%'
+
+	// InclusionType causes another gophermap to be included at this location.
+	InclusionType types.Status = '='
+
+	// DirListType stops parsing the current file and ends the generated gophermap with a listing of the current directory.
+	DirListType types.Status = '*'
+
+	// EndDocType ends the current gophermap file.
+	EndDocType types.Status = '.'
+)
+
+// Compatible builds a standards-compliant gophermap from the current extended menu.
+func (edoc ExtendedMapDocument) Compatible(cwd string) (gopher.MapDocument, string, error) {
+	doc := gopher.MapDocument{}
+
+	title := ""
+	hidden := map[string]struct{}{}
+	extensions := map[string]types.Status{}
+
+	for num, item := range edoc.Lines {
+		switch item.Type {
+		case CommentType:
+		case TitleType:
+			title = item.Display
+		case HiddenType:
+			hidden[item.Selector] = struct{}{}
+		case ExtensionType:
+			from, to, found := strings.Cut(item.Display, "=")
+			if !found {
+				return nil, "", InvalidLine(num)
+			}
+			extensions[from] = types.Status(to[0])
+		case UserListType: //TODO
+			return nil, "", errors.New("User listings '~' are not supported")
+		case VHostListType: //TODO
+			return nil, "", errors.New("Virtual host listings '%' are not supported")
+		case InclusionType:
+			location := filepath.Join(cwd, item.Selector)
+			subEdoc, err := openExtended(location, edoc.Location)
+			if err != nil {
+				return nil, "", err
+			}
+
+			lines, _, err := subEdoc.Compatible(filepath.Dir(location))
+			if err != nil {
+				return nil, "", err
+			}
+			doc = append(doc, lines...)
+		case DirListType:
+			dirlist, err := listDir(cwd, edoc.Location, hidden, extensions)
+			if err != nil {
+				return nil, "", err
+			}
+
+			doc = append(doc, dirlist...)
+
+			break
+		case EndDocType:
+			break
+		default:
+			doc = append(doc, item)
+		}
+	}
+
+	return doc, title, nil
+}
+
+func openExtended(path string, location *url.URL) (ExtendedMapDocument, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return ExtendedMapDocument{}, err
+	}
+	defer func() {
+		_ = file.Close()
+	}()
+
+	return ParseExtended(file, location)
+}