1 files changed, 44 insertions, 0 deletions
diff --git a/worker/imap/extensions/xgmext/search.go b/worker/imap/extensions/xgmext/search.go
new file mode 100644
index 00000000..49b3448e
--- /dev/null
+++ b/worker/imap/extensions/xgmext/search.go
@@ -0,0 +1,44 @@
+package xgmext
+
+import "github.com/emersion/go-imap"
+
+type threadIDSearch struct {
+	Charset   string
+	ThreadIDs []string
+}
+
+// NewThreadIDSearch return an imap.Command to search UIDs for the provided
+// thread IDs using the X-GM-EXT-1 (Gmail extension)
+func NewThreadIDSearch(threadIDs []string) *threadIDSearch {
+	return &threadIDSearch{
+		Charset:   "UTF-8",
+		ThreadIDs: threadIDs,
+	}
+}
+
+func (cmd *threadIDSearch) Command() *imap.Command {
+	const threadSearchKey = "X-GM-THRID"
+
+	var args []interface{}
+	if cmd.Charset != "" {
+		args = append(args, imap.RawString("CHARSET"))
+		args = append(args, imap.RawString(cmd.Charset))
+	}
+
+	// we want to produce a search query that looks like this:
+	// SEARCH CHARSET UTF-8 OR OR X-GM-THRID 1771431779961568536 \
+	// X-GM-THRID 1765355745646219617 X-GM-THRID 1771500774375286796
+	for i := 0; i < len(cmd.ThreadIDs)-1; i++ {
+		args = append(args, imap.RawString("OR"))
+	}
+
+	for _, thrid := range cmd.ThreadIDs {
+		args = append(args, imap.RawString(threadSearchKey))
+		args = append(args, imap.RawString(thrid))
+	}
+
+	return &imap.Command{
+		Name:      "SEARCH",
+		Arguments: args,
+	}
+}