Support attachment base64 and custom filename.

src/client/attachment.go

@@ -0,0 +1,92 @@
+package client
+
+import (
+	"reflect"
+	"strings"
+)
+
+type AttachmentEntry struct {
+	MimeInfo string
+	FileName string
+	Base64   string
+	FilePath string
+}
+
+func NewAttachmentEntry(attachmentData string) *AttachmentEntry {
+	attachmentEntry := AttachmentEntry{
+		MimeInfo: "",
+		FileName: "",
+		Base64:   "",
+		FilePath: "",
+	}
+
+	attachmentEntry.extractMetaData(attachmentData)
+
+	return &attachmentEntry
+}
+
+func (attachmentEntry *AttachmentEntry) extractMetaData(attachmentData string) {
+	base64FlagIndex := strings.LastIndex(attachmentData, "base64,")
+
+	if !strings.Contains(attachmentData, "data:") && base64FlagIndex == -1 {
+		attachmentEntry.Base64 = attachmentData
+		return
+	}
+
+	attachmentEntry.Base64 = attachmentData[base64FlagIndex+len("base64,"):]
+	metaDataKeys := map[string]string{
+		"data:":     "MimeInfo",
+		"filename=": "FileName",
+	}
+
+	for _, metaDataLineItem := range strings.Split(attachmentData[:base64FlagIndex-1], ";") {
+		for metaDataKey, metaDataFieldName := range metaDataKeys {
+			flagIndex := strings.Index(metaDataLineItem, metaDataKey)
+
+			if flagIndex != 0 {
+				continue
+			}
+
+			attachmentEntry.setFieldValueByName(metaDataFieldName, metaDataLineItem[len(metaDataKey):])
+		}
+	}
+}
+
+func (attachmentEntry *AttachmentEntry) setFieldValueByName(fieldName string, fieldValue string) {
+	reflectPointer := reflect.ValueOf(attachmentEntry)
+	reflectStructure := reflectPointer.Elem()
+
+	if reflectStructure.Kind() != reflect.Struct {
+		return
+	}
+
+	field := reflectStructure.FieldByName(fieldName)
+	if !field.IsValid() {
+		return
+	}
+
+	if !field.CanSet() || field.Kind() != reflect.String {
+		return
+	}
+
+	field.SetString(fieldValue)
+}
+
+func (attachmentEntry *AttachmentEntry) isWithMetaData() bool {
+	return len(attachmentEntry.MimeInfo) > 0 && len(attachmentEntry.Base64) > 0
+}
+
+func (attachmentEntry *AttachmentEntry) toDataForSignal() string {
+	result := ""
+	if !attachmentEntry.isWithMetaData() && len(attachmentEntry.FilePath) > 0 {
+		return attachmentEntry.FilePath
+	}
+
+	result = "data:" + attachmentEntry.MimeInfo
+
+	if len(attachmentEntry.FileName) > 0 {
+		result = result + ";filename=" + attachmentEntry.FileName
+	}
+
+	return result + ";base64," + attachmentEntry.Base64
+}