Add Matrix content URI parsing

contenturi.go

@@ -0,0 +1,47 @@
+package mautrix
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+)
+
+var InvalidContentURI = errors.New("invalid Matrix content URI")
+
+type ContentURI struct {
+	Homeserver string
+	FileID     string
+}
+
+func ParseContentURI(uri string) (parsed ContentURI, err error) {
+	if !strings.HasPrefix(uri, "mxc://") {
+		err = InvalidContentURI
+	} else if index := strings.IndexRune(uri[6:], '/'); index == -1 || index == len(uri)-7 {
+		err = InvalidContentURI
+	} else {
+		parsed.Homeserver = uri[6 : 6+index]
+		parsed.FileID = uri[6+index+1:]
+	}
+	return
+}
+
+func (uri *ContentURI) UnmarshalJSON(raw []byte) (err error) {
+	parsed, err := ParseContentURI(string(raw))
+	if err != nil {
+		return err
+	}
+	*uri = parsed
+	return nil
+}
+
+func (uri *ContentURI) MarshalJSON() ([]byte, error) {
+	return []byte(uri.String()), nil
+}
+
+func (uri *ContentURI) String() string {
+	return fmt.Sprintf("mxc://%s/%s", uri.Homeserver, uri.FileID)
+}
+
+func (uri *ContentURI) IsEmpty() bool {
+	return len(uri.Homeserver) == 0 || len(uri.FileID) == 0
+}