messages: allow displaying email threads

Display threads in the message list. For now, only supported by the
notmuch backend and on IMAP when the server supports the THREAD
extension.

Setting threading-enable=true is global and will cause the message list
to be empty with maildir:// accounts.

Co-authored-by: Kevin Kuehler <keur@xcf.berkeley.edu>
Co-authored-by: Reto Brunner <reto@labrat.space>
Signed-off-by: Robin Jarry <robin@jarry.cc>

3 files changed, 154 insertions, 11 deletions

diff --git a/worker/notmuch/lib/database.go b/worker/notmuch/lib/database.go
index 683ace5..ad670c5 100644
--- a/worker/notmuch/lib/database.go
+++ b/worker/notmuch/lib/database.go
@@ -7,6 +7,8 @@ import (
 	"log"
 	"time"
 
+	"git.sr.ht/~rjarry/aerc/lib/uidstore"
+	"git.sr.ht/~rjarry/aerc/worker/types"
 	notmuch "github.com/zenhack/go.notmuch"
 )
 
@@ -18,6 +20,7 @@ type DB struct {
 	logger       *log.Logger
 	lastOpenTime time.Time
 	db           *notmuch.DB
+	uidStore     *uidstore.Store
 }
 
 func NewDB(path string, excludedTags []string,
@@ -26,6 +29,7 @@ func NewDB(path string, excludedTags []string,
 		path:         path,
 		excludedTags: excludedTags,
 		logger:       logger,
+		uidStore:     uidstore.NewStore(),
 	}
 	return db
 }
@@ -106,7 +110,7 @@ func (db *DB) ListTags() ([]string, error) {
 //It also configures the query as specified on the worker
 func (db *DB) newQuery(ndb *notmuch.DB, query string) (*notmuch.Query, error) {
 	q := ndb.NewQuery(query)
-	q.SetExcludeScheme(notmuch.EXCLUDE_TRUE)
+	q.SetExcludeScheme(notmuch.EXCLUDE_ALL)
 	q.SetSortScheme(notmuch.SORT_OLDEST_FIRST)
 	for _, t := range db.excludedTags {
 		err := q.AddTagExclude(t)
@@ -125,18 +129,37 @@ func (db *DB) MsgIDsFromQuery(q string) ([]string, error) {
 			return err
 		}
 		defer query.Close()
-		msgs, err := query.Messages()
+		msgIDs, err = msgIdsFromQuery(query)
+		return err
+	})
+	return msgIDs, err
+}
+
+func (db *DB) ThreadsFromQuery(q string) ([]*types.Thread, error) {
+	var res []*types.Thread
+	err := db.withConnection(false, func(ndb *notmuch.DB) error {
+		query, err := db.newQuery(ndb, q)
 		if err != nil {
 			return err
 		}
-		defer msgs.Close()
-		var msg *notmuch.Message
-		for msgs.Next(&msg) {
-			msgIDs = append(msgIDs, msg.ID())
+		defer query.Close()
+		qMsgIDs, err := msgIdsFromQuery(query)
+		if err != nil {
+			return err
 		}
-		return nil
+		valid := make(map[string]struct{})
+		for _, id := range qMsgIDs {
+			valid[id] = struct{}{}
+		}
+		threads, err := query.Threads()
+		if err != nil {
+			return err
+		}
+		defer threads.Close()
+		res, err = db.enumerateThread(threads, valid)
+		return err
 	})
-	return msgIDs, err
+	return res, err
 }
 
 type MessageCount struct {
@@ -236,3 +259,85 @@ func (db *DB) MsgModifyTags(key string, add, remove []string) error {
 	})
 	return err
 }
+
+func msgIdsFromQuery(query *notmuch.Query) ([]string, error) {
+	var msgIDs []string
+	msgs, err := query.Messages()
+	if err != nil {
+		return nil, err
+	}
+	defer msgs.Close()
+	var msg *notmuch.Message
+	for msgs.Next(&msg) {
+		msgIDs = append(msgIDs, msg.ID())
+	}
+	return msgIDs, nil
+}
+
+func (db *DB) UidFromKey(key string) uint32 {
+	return db.uidStore.GetOrInsert(key)
+}
+
+func (db *DB) KeyFromUid(uid uint32) (string, bool) {
+	return db.uidStore.GetKey(uid)
+}
+
+func (db *DB) enumerateThread(nt *notmuch.Threads,
+	valid map[string]struct{}) ([]*types.Thread, error) {
+	var res []*types.Thread
+	var thread *notmuch.Thread
+	for nt.Next(&thread) {
+		root := db.makeThread(nil, thread.TopLevelMessages(), valid)
+		res = append(res, root)
+	}
+	return res, nil
+}
+
+func (db *DB) makeThread(parent *types.Thread, msgs *notmuch.Messages,
+	valid map[string]struct{}) *types.Thread {
+	var lastSibling *types.Thread
+	var msg *notmuch.Message
+	for msgs.Next(&msg) {
+		msgID := msg.ID()
+		_, inQuery := valid[msgID]
+		node := &types.Thread{
+			Uid:    db.uidStore.GetOrInsert(msgID),
+			Parent: parent,
+			Hidden: !inQuery,
+		}
+		if parent != nil && parent.FirstChild == nil {
+			parent.FirstChild = node
+		}
+		if lastSibling != nil {
+			if lastSibling.NextSibling != nil {
+				panic(fmt.Sprintf(
+					"%v already had a NextSibling, tried setting it",
+					lastSibling))
+			}
+			lastSibling.NextSibling = node
+		}
+		lastSibling = node
+		replies, err := msg.Replies()
+		if err != nil {
+			// if there are no replies it will return an error
+			continue
+		}
+		defer replies.Close()
+		db.makeThread(node, replies, valid)
+	}
+
+	// We want to return the root node
+	var root *types.Thread
+	if parent != nil {
+		root = parent
+	} else if lastSibling != nil {
+		root = lastSibling // first iteration has no parent
+	} else {
+		return nil // we don't have any messages at all
+	}
+
+	for ; root.Parent != nil; root = root.Parent {
+		// move to the root
+	}
+	return root
+}
diff --git a/worker/notmuch/lib/thread.go b/worker/notmuch/lib/thread.go
new file mode 100644
index 0000000..297260d
--- /dev/null
+++ b/worker/notmuch/lib/thread.go
@@ -0,0 +1,14 @@
+//+build notmuch
+
+package lib
+
+type ThreadNode struct {
+	Uid     string
+	From    string
+	Subject string
+	InQuery bool // is the msg included in the query
+
+	Parent      *ThreadNode
+	NextSibling *ThreadNode
+	FirstChild  *ThreadNode
+}
diff --git a/worker/notmuch/worker.go b/worker/notmuch/worker.go
index f8f8b11..dc362af 100644
--- a/worker/notmuch/worker.go
+++ b/worker/notmuch/worker.go
@@ -107,6 +107,8 @@ func (w *worker) handleMessage(msg types.WorkerMessage) error {
 		return w.handleOpenDirectory(msg)
 	case *types.FetchDirectoryContents:
 		return w.handleFetchDirectoryContents(msg)
+	case *types.FetchDirectoryThreaded:
+		return w.handleFetchDirectoryThreaded(msg)
 	case *types.FetchMessageHeaders:
 		return w.handleFetchMessageHeaders(msg)
 	case *types.FetchMessageBodyPart:
@@ -157,7 +159,6 @@ func (w *worker) handleConfigure(msg *types.Configure) error {
 		return fmt.Errorf("could not resolve home directory: %v", err)
 	}
 	pathToDB := filepath.Join(home, u.Path)
-	w.uidStore = uidstore.NewStore()
 	err = w.loadQueryMap(msg.Config)
 	if err != nil {
 		return fmt.Errorf("could not load query map configuration: %v", err)
@@ -267,6 +268,17 @@ func (w *worker) handleFetchDirectoryContents(
 	return nil
 }
 
+func (w *worker) handleFetchDirectoryThreaded(
+	msg *types.FetchDirectoryThreaded) error {
+	// w.currentSortCriteria = msg.SortCriteria
+	err := w.emitDirectoryThreaded(msg)
+	if err != nil {
+		return err
+	}
+	w.done(msg)
+	return nil
+}
+
 func (w *worker) handleFetchMessageHeaders(
 	msg *types.FetchMessageHeaders) error {
 	for _, uid := range msg.Uids {
@@ -294,7 +306,7 @@ func (w *worker) uidsFromQuery(query string) ([]uint32, error) {
 	}
 	var uids []uint32
 	for _, id := range msgIDs {
-		uid := w.uidStore.GetOrInsert(id)
+		uid := w.db.UidFromKey(id)
 		uids = append(uids, uid)
 
 	}
@@ -302,7 +314,7 @@ func (w *worker) uidsFromQuery(query string) ([]uint32, error) {
 }
 
 func (w *worker) msgFromUid(uid uint32) (*Message, error) {
-	key, ok := w.uidStore.GetKey(uid)
+	key, ok := w.db.KeyFromUid(uid)
 	if !ok {
 		return nil, fmt.Errorf("Invalid uid: %v", uid)
 	}
@@ -528,6 +540,18 @@ func (w *worker) emitDirectoryContents(parent types.WorkerMessage) error {
 	return nil
 }
 
+func (w *worker) emitDirectoryThreaded(parent types.WorkerMessage) error {
+	threads, err := w.db.ThreadsFromQuery(w.query)
+	if err != nil {
+		return err
+	}
+	w.w.PostMessage(&types.DirectoryThreaded{
+		Message: types.RespondTo(parent),
+		Threads: threads,
+	}, nil)
+	return nil
+}
+
 func (w *worker) emitMessageInfo(m *Message,
 	parent types.WorkerMessage) error {
 	info, err := m.MessageInfo()