feat: pull out most things as attachments

pkg/message/parser/handler.go

@@ -0,0 +1,40 @@
+package parser
+
+import "regexp"
+
+type HandlerFunc func(*Part) error
+
+type handler struct {
+	typeRegExp, dispRegExp string
+	fn                     HandlerFunc
+}
+
+func (h *handler) matchPart(p *Part) bool {
+	return h.matchType(p) || h.matchDisp(p)
+}
+
+func (h *handler) matchType(p *Part) bool {
+	if h.typeRegExp == "" {
+		return false
+	}
+
+	t, _, err := p.Header.ContentType()
+	if err != nil {
+		t = ""
+	}
+
+	return regexp.MustCompile(h.typeRegExp).MatchString(t)
+}
+
+func (h *handler) matchDisp(p *Part) bool {
+	if h.dispRegExp == "" {
+		return false
+	}
+
+	disp, _, err := p.Header.ContentDisposition()
+	if err != nil {
+		disp = ""
+	}
+
+	return regexp.MustCompile(h.dispRegExp).MatchString(disp)
+}