perf(mail): fetch only headers for list/search (no body download)

list and search now fetch BODY.PEEK[HEADER] + BODYSTRUCTURE instead of the whole RFC822 message, so listing a large mailbox no longer downloads every message body and attachment. Header parsing reuses the same go-message path (RFC2047 decoding/formatting preserved); has_attachments is derived from the BODYSTRUCTURE tree. FetchFull keeps fetching the full message for get. Validated end-to-end against a live IMAP account: list/search/get output identical to the prior full-fetch behaviour, has_attachments correct. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-22 07:47:27 +01:00
parent a1440719ae
commit 8379fddbb2
4 changed files with 203 additions and 37 deletions
@@ -0,0 +1,79 @@
+package mail
+
+import (
+	"testing"
+
+	"github.com/emersion/go-imap"
+)
+
+func TestHasAttachment(t *testing.T) {
+	cases := []struct {
+		name string
+		bs   *imap.BodyStructure
+		want bool
+	}{
+		{"nil", nil, false},
+		{
+			"single inline text",
+			&imap.BodyStructure{MIMEType: "text", MIMESubType: "plain", Disposition: "inline"},
+			false,
+		},
+		{
+			"single attachment",
+			&imap.BodyStructure{MIMEType: "application", MIMESubType: "pdf", Disposition: "attachment"},
+			true,
+		},
+		{
+			"disposition case-insensitive",
+			&imap.BodyStructure{MIMEType: "image", MIMESubType: "png", Disposition: "ATTACHMENT"},
+			true,
+		},
+		{
+			"multipart with one attachment child",
+			&imap.BodyStructure{
+				MIMEType:    "multipart",
+				MIMESubType: "mixed",
+				Parts: []*imap.BodyStructure{
+					{MIMEType: "text", MIMESubType: "plain", Disposition: "inline"},
+					{MIMEType: "application", MIMESubType: "octet-stream", Disposition: "attachment"},
+				},
+			},
+			true,
+		},
+		{
+			"multipart all inline",
+			&imap.BodyStructure{
+				MIMEType:    "multipart",
+				MIMESubType: "alternative",
+				Parts: []*imap.BodyStructure{
+					{MIMEType: "text", MIMESubType: "plain", Disposition: "inline"},
+					{MIMEType: "text", MIMESubType: "html", Disposition: "inline"},
+				},
+			},
+			false,
+		},
+		{
+			"nested multipart with deep attachment",
+			&imap.BodyStructure{
+				MIMEType:    "multipart",
+				MIMESubType: "mixed",
+				Parts: []*imap.BodyStructure{
+					{
+						MIMEType:    "multipart",
+						MIMESubType: "alternative",
+						Parts: []*imap.BodyStructure{
+							{MIMEType: "text", MIMESubType: "plain", Disposition: "inline"},
+							{MIMEType: "application", MIMESubType: "pdf", Disposition: "attachment"},
+						},
+					},
+				},
+			},
+			true,
+		},
+	}
+	for _, c := range cases {
+		if got := hasAttachment(c.bs); got != c.want {
+			t.Errorf("%s: hasAttachment = %v, want %v", c.name, got, c.want)
+		}
+	}
+}