init push

internal/service/email_raw_mime.go

@@ -0,0 +1,138 @@
+package service
+
+import (
+	"bytes"
+	"encoding/base64"
+	"fmt"
+	"mime/quotedprintable"
+	"strings"
+
+	sestypes "github.com/aws/aws-sdk-go-v2/service/sesv2/types"
+
+	"wucher/internal/queue"
+	"wucher/internal/shared/pkg/uuidv7"
+)
+
+func buildSESRawContent(from string, to, cc, replyTo []string, job queue.EmailJob) (*sestypes.EmailContent, error) {
+	mixedBoundary := randomMIMEBoundary("mixed")
+	relatedBoundary := randomMIMEBoundary("related")
+	alternativeBoundary := randomMIMEBoundary("alt")
+
+	var buf bytes.Buffer
+	writeMIMEHeader(&buf, "From", from)
+	if len(to) > 0 {
+		writeMIMEHeader(&buf, "To", strings.Join(to, ", "))
+	}
+	if len(cc) > 0 {
+		writeMIMEHeader(&buf, "Cc", strings.Join(cc, ", "))
+	}
+	if len(replyTo) > 0 {
+		writeMIMEHeader(&buf, "Reply-To", strings.Join(replyTo, ", "))
+	}
+	writeMIMEHeader(&buf, "Subject", sanitizeSubject(job.Subject))
+	writeMIMEHeader(&buf, "MIME-Version", "1.0")
+	writeMIMEHeader(&buf, "Content-Type", fmt.Sprintf(`multipart/mixed; boundary="%s"`, mixedBoundary))
+	buf.WriteString("\r\n")
+
+	writeBoundary(&buf, mixedBoundary)
+	writeMIMEHeader(&buf, "Content-Type", fmt.Sprintf(`multipart/related; boundary="%s"`, relatedBoundary))
+	buf.WriteString("\r\n")
+
+	writeBoundary(&buf, relatedBoundary)
+	writeMIMEHeader(&buf, "Content-Type", fmt.Sprintf(`multipart/alternative; boundary="%s"`, alternativeBoundary))
+	buf.WriteString("\r\n")
+
+	if textBody := strings.TrimSpace(job.TextBodyValue()); textBody != "" {
+		writeBoundary(&buf, alternativeBoundary)
+		writeTextPart(&buf, "text/plain", textBody)
+	}
+	if htmlBody := strings.TrimSpace(job.HTMLBody); htmlBody != "" {
+		writeBoundary(&buf, alternativeBoundary)
+		writeTextPart(&buf, "text/html", htmlBody)
+	}
+	writeClosingBoundary(&buf, alternativeBoundary)
+
+	for i := range job.Attachments {
+		writeBoundary(&buf, relatedBoundary)
+		writeAttachmentPart(&buf, job.Attachments[i])
+	}
+	writeClosingBoundary(&buf, relatedBoundary)
+	writeClosingBoundary(&buf, mixedBoundary)
+
+	return &sestypes.EmailContent{
+		Raw: &sestypes.RawMessage{Data: buf.Bytes()},
+	}, nil
+}
+
+func writeTextPart(buf *bytes.Buffer, contentType, body string) {
+	writeMIMEHeader(buf, "Content-Type", contentType+`; charset="UTF-8"`)
+	writeMIMEHeader(buf, "Content-Transfer-Encoding", "quoted-printable")
+	buf.WriteString("\r\n")
+	qp := quotedprintable.NewWriter(buf)
+	_, _ = qp.Write([]byte(body))
+	_ = qp.Close()
+	buf.WriteString("\r\n")
+}
+
+func writeAttachmentPart(buf *bytes.Buffer, attachment queue.EmailAttachment) {
+	filename := attachment.Filename
+	if filename == "" {
+		filename = "attachment"
+	}
+	writeMIMEHeader(buf, "Content-Type", fmt.Sprintf(`%s; name="%s"`, attachment.ContentType, escapeMIMEHeaderValue(filename)))
+	writeMIMEHeader(buf, "Content-Transfer-Encoding", "base64")
+	disposition := "attachment"
+	if attachment.Inline {
+		disposition = "inline"
+	}
+	writeMIMEHeader(buf, "Content-Disposition", fmt.Sprintf(`%s; filename="%s"`, disposition, escapeMIMEHeaderValue(filename)))
+	if attachment.Inline && strings.TrimSpace(attachment.ContentID) != "" {
+		writeMIMEHeader(buf, "Content-ID", "<"+strings.TrimSpace(attachment.ContentID)+">")
+	}
+	buf.WriteString("\r\n")
+	writeBase64Lines(buf, attachment.Content)
+}
+
+func writeBase64Lines(buf *bytes.Buffer, payload []byte) {
+	encoded := base64.StdEncoding.EncodeToString(payload)
+	for len(encoded) > 76 {
+		buf.WriteString(encoded[:76])
+		buf.WriteString("\r\n")
+		encoded = encoded[76:]
+	}
+	if encoded != "" {
+		buf.WriteString(encoded)
+		buf.WriteString("\r\n")
+	}
+}
+
+func writeMIMEHeader(buf *bytes.Buffer, key, value string) {
+	buf.WriteString(key)
+	buf.WriteString(": ")
+	buf.WriteString(value)
+	buf.WriteString("\r\n")
+}
+
+func writeBoundary(buf *bytes.Buffer, boundary string) {
+	buf.WriteString("--")
+	buf.WriteString(boundary)
+	buf.WriteString("\r\n")
+}
+
+func writeClosingBoundary(buf *bytes.Buffer, boundary string) {
+	buf.WriteString("--")
+	buf.WriteString(boundary)
+	buf.WriteString("--\r\n")
+}
+
+func randomMIMEBoundary(prefix string) string {
+	id, err := uuidv7.String(uuidv7.MustNew())
+	if err != nil {
+		return prefix + "_fallback"
+	}
+	return prefix + "_" + strings.ReplaceAll(id, "-", "")
+}
+
+func escapeMIMEHeaderValue(value string) string {
+	return strings.ReplaceAll(strings.TrimSpace(value), `"`, `'`)
+}