1 files changed, 46 insertions, 0 deletions
diff --git a/worker/maildir/container.go b/worker/maildir/container.go
index 85e892a..a7acfb7 100644
--- a/worker/maildir/container.go
+++ b/worker/maildir/container.go
@@ -10,6 +10,7 @@ import (
 	"github.com/emersion/go-maildir"
 
 	"git.sr.ht/~sircmpwn/aerc/lib/uidstore"
+	"git.sr.ht/~sircmpwn/aerc/worker/types"
 )
 
 // A Container is a directory which contains other directories which adhere to
@@ -123,3 +124,48 @@ func (c *Container) copyMessage(
 	_, err := src.Copy(dest, key)
 	return err
 }
+
+func (c *Container) ScanThreads(d maildir.Dir) ([]*types.Thread, error) {
+	uids, err := c.UIDs(d)
+	if err != nil {
+		return nil, err
+	}
+
+	// a map from message-id to the Thread that represents it
+	threads := make(map[string]*types.Thread)
+
+	for _, uid := range uids {
+		m, err := c.Message(d, uid)
+		if err != nil {
+			return nil, err
+		}
+		hs, err := m.Headers()
+		if err != nil {
+			return nil, err
+		}
+		msgID, err := hs.Text("message-id")
+		if err != nil {
+			return nil, err
+		}
+		irt, err := hs.Text("in-reply-to")
+		if err != nil {
+			return nil, err
+		}
+
+		t := &types.Thread{Uid: uid}
+		threads[msgID] = t
+
+		if p, ok := threads[irt]; ok {
+			p.Children = append(p.Children, t)
+			t.Parent = p
+		}
+	}
+
+	var threadSlice []*types.Thread
+	for _, t := range threads {
+		if t.Parent == nil {
+			threadSlice = append(threadSlice, t)
+		}
+	}
+	return threadSlice, nil
+}