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>

8 files changed, 439 insertions, 13 deletions

diff --git a/worker/imap/open.go b/worker/imap/open.go
index 4b4e943..2849573 100644
--- a/worker/imap/open.go
+++ b/worker/imap/open.go
@@ -1,6 +1,8 @@
 package imap
 
 import (
+	"sort"
+
 	"github.com/emersion/go-imap"
 	sortthread "github.com/emersion/go-imap-sortthread"
 
@@ -92,3 +94,64 @@ func translateSortCriterions(
 	}
 	return result
 }
+
+func (imapw *IMAPWorker) handleDirectoryThreaded(
+	msg *types.FetchDirectoryThreaded) {
+	imapw.worker.Logger.Printf("Fetching threaded UID list")
+
+	seqSet := &imap.SeqSet{}
+	seqSet.AddRange(1, imapw.selected.Messages)
+	threads, err := imapw.client.thread.UidThread(sortthread.References,
+		&imap.SearchCriteria{SeqNum: seqSet})
+	if err != nil {
+		imapw.worker.PostMessage(&types.Error{
+			Message: types.RespondTo(msg),
+			Error:   err,
+		}, nil)
+	} else {
+		aercThreads, count := convertThreads(threads, nil)
+		sort.Sort(types.ByUID(aercThreads))
+		imapw.worker.Logger.Printf("Found %d threaded messages", count)
+		imapw.seqMap = make([]uint32, count)
+		imapw.worker.PostMessage(&types.DirectoryThreaded{
+			Message: types.RespondTo(msg),
+			Threads: aercThreads,
+		}, nil)
+		imapw.worker.PostMessage(&types.Done{types.RespondTo(msg)}, nil)
+	}
+}
+
+func convertThreads(threads []*sortthread.Thread, parent *types.Thread) ([]*types.Thread, int) {
+	if threads == nil {
+		return nil, 0
+	}
+	conv := make([]*types.Thread, len(threads))
+	count := 0
+
+	for i := 0; i < len(threads); i++ {
+		t := threads[i]
+		conv[i] = &types.Thread{
+			Uid: t.Id,
+		}
+
+		// Set the first child node
+		children, childCount := convertThreads(t.Children, conv[i])
+		if len(children) > 0 {
+			conv[i].FirstChild = children[0]
+		}
+
+		// Set the parent node
+		if parent != nil {
+			conv[i].Parent = parent
+
+			// elements of threads are siblings
+			if i > 0 {
+				conv[i].PrevSibling = conv[i-1]
+				conv[i-1].NextSibling = conv[i]
+			}
+		}
+
+		count += childCount + 1
+	}
+	return conv, count
+}
diff --git a/worker/imap/worker.go b/worker/imap/worker.go
index cd52536..2c0e6a6 100644
--- a/worker/imap/worker.go
+++ b/worker/imap/worker.go
@@ -26,7 +26,8 @@ var errUnsupported = fmt.Errorf("unsupported command")
 
 type imapClient struct {
 	*client.Client
-	sort *sortthread.SortClient
+	thread *sortthread.ThreadClient
+	sort   *sortthread.SortClient
 }
 
 type IMAPWorker struct {
@@ -158,7 +159,7 @@ func (w *IMAPWorker) handleMessage(msg types.WorkerMessage) error {
 		}
 
 		c.Updates = w.updates
-		w.client = &imapClient{c, sortthread.NewSortClient(c)}
+		w.client = &imapClient{c, sortthread.NewThreadClient(c), sortthread.NewSortClient(c)}
 		w.worker.PostMessage(&types.Done{types.RespondTo(msg)}, nil)
 	case *types.Disconnect:
 		if w.client == nil {
@@ -175,6 +176,8 @@ func (w *IMAPWorker) handleMessage(msg types.WorkerMessage) error {
 		w.handleOpenDirectory(msg)
 	case *types.FetchDirectoryContents:
 		w.handleFetchDirectoryContents(msg)
+	case *types.FetchDirectoryThreaded:
+		w.handleDirectoryThreaded(msg)
 	case *types.CreateDirectory:
 		w.handleCreateDirectory(msg)
 	case *types.RemoveDirectory:
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()
diff --git a/worker/types/messages.go b/worker/types/messages.go
index 599e870..fb701bd 100644
--- a/worker/types/messages.go
+++ b/worker/types/messages.go
@@ -81,11 +81,21 @@ type FetchDirectoryContents struct {
 	SortCriteria []*SortCriterion
 }
 
+type FetchDirectoryThreaded struct {
+	Message
+	SortCriteria []*SortCriterion
+}
+
 type SearchDirectory struct {
 	Message
 	Argv []string
 }
 
+type DirectoryThreaded struct {
+	Message
+	Threads []*Thread
+}
+
 type CreateDirectory struct {
 	Message
 	Directory string
diff --git a/worker/types/thread.go b/worker/types/thread.go
new file mode 100644
index 0000000..09f9dbb
--- /dev/null
+++ b/worker/types/thread.go
@@ -0,0 +1,99 @@
+package types
+
+import (
+	"errors"
+	"fmt"
+)
+
+type Thread struct {
+	Uid         uint32
+	Parent      *Thread
+	PrevSibling *Thread
+	NextSibling *Thread
+	FirstChild  *Thread
+
+	Hidden  bool // if this flag is set the message isn't rendered in the UI
+	Deleted bool // if this flag is set the message was deleted
+}
+
+func (t *Thread) Walk(walkFn NewThreadWalkFn) error {
+	err := newWalk(t, walkFn, 0, nil)
+	if err == ErrSkipThread {
+		return nil
+	}
+	return err
+}
+
+func (t *Thread) String() string {
+	if t == nil {
+		return "<nil>"
+	}
+	parent := -1
+	if t.Parent != nil {
+		parent = int(t.Parent.Uid)
+	}
+	next := -1
+	if t.NextSibling != nil {
+		next = int(t.NextSibling.Uid)
+	}
+	child := -1
+	if t.FirstChild != nil {
+		child = int(t.FirstChild.Uid)
+	}
+	return fmt.Sprintf(
+		"[%d] (parent:%v, next:%v, child:%v)",
+		t.Uid, parent, next, child,
+	)
+}
+
+func newWalk(node *Thread, walkFn NewThreadWalkFn, lvl int, ce error) error {
+	if node == nil {
+		return nil
+	}
+	err := walkFn(node, lvl, ce)
+	if err != nil {
+		return err
+	}
+	for child := node.FirstChild; child != nil; child = child.NextSibling {
+		err = newWalk(child, walkFn, lvl+1, err)
+		if err == ErrSkipThread {
+			err = nil
+			continue
+		} else if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+var ErrSkipThread = errors.New("skip this Thread")
+
+type NewThreadWalkFn func(t *Thread, level int, currentErr error) error
+
+//Implement interface to be able to sort threads by newest (max UID)
+type ByUID []*Thread
+
+func getMaxUID(thread *Thread) uint32 {
+	// TODO: should we make this part of the Thread type to avoid recomputation?
+	var Uid uint32
+
+	thread.Walk(func(t *Thread, _ int, currentErr error) error {
+		if t.Uid > Uid {
+			Uid = t.Uid
+		}
+		return nil
+	})
+	return Uid
+}
+
+func (s ByUID) Len() int {
+	return len(s)
+}
+func (s ByUID) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+func (s ByUID) Less(i, j int) bool {
+	maxUID_i := getMaxUID(s[i])
+	maxUID_j := getMaxUID(s[j])
+	return maxUID_i < maxUID_j
+}
diff --git a/worker/types/thread_test.go b/worker/types/thread_test.go
new file mode 100644
index 0000000..e79dddd
--- /dev/null
+++ b/worker/types/thread_test.go
@@ -0,0 +1,108 @@
+package types
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+)
+
+func genFakeTree() *Thread {
+	tree := &Thread{
+		Uid: 0,
+	}
+	var prevChild *Thread
+	for i := 1; i < 3; i++ {
+		child := &Thread{
+			Uid:         uint32(i * 10),
+			Parent:      tree,
+			PrevSibling: prevChild,
+		}
+		if prevChild != nil {
+			prevChild.NextSibling = child
+		} else if tree.FirstChild == nil {
+			tree.FirstChild = child
+		} else {
+			panic("unreachable")
+		}
+		prevChild = child
+		var prevSecond *Thread
+		for j := 1; j < 3; j++ {
+			second := &Thread{
+				Uid:         child.Uid + uint32(j),
+				Parent:      child,
+				PrevSibling: prevSecond,
+			}
+			if prevSecond != nil {
+				prevSecond.NextSibling = second
+			} else if child.FirstChild == nil {
+				child.FirstChild = second
+			} else {
+				panic("unreachable")
+			}
+			prevSecond = second
+			var prevThird *Thread
+			limit := 3
+			if j == 2 {
+				limit = 8
+			}
+			for k := 1; k < limit; k++ {
+				third := &Thread{
+					Uid:         second.Uid*10 + uint32(k),
+					Parent:      second,
+					PrevSibling: prevThird,
+				}
+				if prevThird != nil {
+					prevThird.NextSibling = third
+				} else if second.FirstChild == nil {
+					second.FirstChild = third
+				} else {
+					panic("unreachable")
+				}
+				prevThird = third
+			}
+		}
+	}
+	return tree
+}
+
+func TestNewWalk(t *testing.T) {
+	tree := genFakeTree()
+	var prefix []string
+	lastLevel := 0
+	tree.Walk(func(t *Thread, lvl int, e error) error {
+		// if t.Uid%2 != 0 {
+		// 	return ErrSkipThread
+		// }
+		if e != nil {
+			fmt.Printf("ERROR: %v\n", e)
+		}
+		if lvl > lastLevel && lvl > 1 {
+			// we actually just descended... so figure out what connector we need
+			// level 1 is flush to the root, so we avoid the indentation there
+			if t.Parent.NextSibling != nil {
+				prefix = append(prefix, "│  ")
+			} else {
+				prefix = append(prefix, "   ")
+			}
+		} else if lvl < lastLevel {
+			//ascended, need to trim the prefix layers
+			diff := lastLevel - lvl
+			prefix = prefix[:len(prefix)-diff]
+		}
+
+		var arrow string
+		if t.Parent != nil {
+			if t.NextSibling != nil {
+				arrow = "├─>"
+			} else {
+				arrow = "└─>"
+			}
+		}
+
+		// format
+		fmt.Printf("%s%s%s\n", strings.Join(prefix, ""), arrow, t)
+
+		lastLevel = lvl
+		return nil
+	})
+}