prompt 4

internal/mailer/sink.go

@@ -0,0 +1,64 @@
+package mailer
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"time"
+)
+
+var sinkFileSafe = regexp.MustCompile(`[^a-zA-Z0-9@._-]+`)
+
+type SinkMailer struct {
+	dir string
+}
+
+func NewSinkMailer(dir string) (*SinkMailer, error) {
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		return nil, fmt.Errorf("create sink dir: %w", err)
+	}
+
+	return &SinkMailer{dir: dir}, nil
+}
+
+func (m *SinkMailer) Send(ctx context.Context, to, subject, htmlBody, textBody string) error {
+	if ctx != nil {
+		if err := ctx.Err(); err != nil {
+			return err
+		}
+	}
+
+	ts := time.Now().UTC().Format("20060102T150405.000000000Z")
+	safeTo := sanitizeRecipient(to)
+	base := fmt.Sprintf("%s__email__%s", ts, safeTo)
+
+	emlPath := filepath.Join(m.dir, base+".eml")
+	textPath := filepath.Join(m.dir, base+".txt")
+	htmlPath := filepath.Join(m.dir, base+".html")
+
+	emlContent := fmt.Sprintf("Subject: %s\nTo: %s\nDate: %s\n\nTEXT:\n%s\n\nHTML:\n%s\n", subject, to, time.Now().UTC().Format(time.RFC3339), textBody, htmlBody)
+	if err := os.WriteFile(emlPath, []byte(emlContent), 0o644); err != nil {
+		return fmt.Errorf("write sink eml: %w", err)
+	}
+
+	if err := os.WriteFile(textPath, []byte(textBody), 0o644); err != nil {
+		return fmt.Errorf("write sink text: %w", err)
+	}
+
+	if err := os.WriteFile(htmlPath, []byte(htmlBody), 0o644); err != nil {
+		return fmt.Errorf("write sink html: %w", err)
+	}
+
+	return nil
+}
+
+func sanitizeRecipient(to string) string {
+	clean := strings.TrimSpace(to)
+	if clean == "" {
+		return "unknown"
+	}
+	return sinkFileSafe.ReplaceAllString(clean, "_")
+}