refactor: project structure

internal/attachments/attachments.go

@@ -0,0 +1,42 @@
+package attachments
+
+import (
+	"bytes"
+	"encoding/base64"
+	"fmt"
+	"io"
+)
+
+const delimeter = "**=myohmy689407924327"
+
+type EmailAttachment struct {
+	File  io.Reader
+	Title string
+}
+
+func (e EmailAttachment) ReadContent() ([]byte, error) {
+	bts, err := io.ReadAll(e.File)
+	if err != nil {
+		return nil, fmt.Errorf("error loading attachment: %s", err)
+	}
+	return bts, nil
+}
+
+func AttachmentsToBytes(body string, attachments []EmailAttachment) ([]byte, error) {
+	var message bytes.Buffer
+	message.WriteString("Content-Type: text/html; charset=\"UTF-8\"\r\n\r\n")
+	message.WriteString(body + "\r\n\r\n")
+	for _, attachment := range attachments {
+		attachmentRawFile, err := attachment.ReadContent()
+		if err != nil {
+			return nil, err
+		}
+		message.WriteString("--" + delimeter + "\r\n")
+		message.WriteString("Content-Disposition: attachment; filename=\"" + attachment.Title + "\"\r\n")
+		message.WriteString("Content-Type: application/octet-stream\r\n")
+		message.WriteString("Content-Transfer-Encoding: base64\r\n\r\n")
+		message.WriteString(base64.StdEncoding.EncodeToString(attachmentRawFile) + "\r\n")
+	}
+	message.WriteString("--" + delimeter + "--") // End the message
+	return message.Bytes(), nil
+}