threadbuilder: show siblings even when no parent found

Show all threading associations even when not all nodes are present.
Indicate if a thread is incomplete, i.e. misses a direct parent node.

Use the `msglist_thread_orphan.fg=red` styleobject in your stylesheet to
indicate whether a messsage has a missing parent.

Also use a different thread prefix ("┬─" instead of "├─") not to confuse
them with regular threads that have a visible parent.

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: Matěj Cepl <mcepl@cepl.eu>

8 files changed, 62 insertions, 32 deletions

diff --git a/app/msglist.go b/app/msglist.go
index 996ffa0c..24547b64 100644
--- a/app/msglist.go
+++ b/app/msglist.go
@@ -231,6 +231,9 @@ func addMessage(
 		if templateData.ThreadContext() {
 			params.styles = append(params.styles, config.STYLE_MSGLIST_THREAD_CONTEXT)
 		}
+		if templateData.ThreadOrphan() {
+			params.styles = append(params.styles, config.STYLE_MSGLIST_THREAD_ORPHAN)
+		}
 	}
 	// marked message
 	marked := store.Marker().IsMarked(msg.Uid)
@@ -482,16 +485,20 @@ func threadPrefix(t *types.Thread, reverse bool, msglist bool) string {
 
 	var hiddenOffspring bool = t.FirstChild != nil && t.FirstChild.Hidden > 0
 	var parentAndSiblings bool = t.Parent != nil && t.NextSibling != nil
+	var hasSiblings string = uiConfig.ThreadPrefixHasSiblings
+	if t.Parent != nil && t.Parent.Hidden > 0 && t.Hidden == 0 {
+		hasSiblings = dummy
+	}
 
 	switch {
 	case parentAndSiblings && hiddenOffspring:
-		prefix = uiConfig.ThreadPrefixHasSiblings +
+		prefix = hasSiblings +
 			uiConfig.ThreadPrefixFolded
 	case parentAndSiblings && t.FirstChild != nil:
-		prefix = uiConfig.ThreadPrefixHasSiblings +
+		prefix = hasSiblings +
 			firstChild + tip
 	case parentAndSiblings:
-		prefix = uiConfig.ThreadPrefixHasSiblings +
+		prefix = hasSiblings +
 			uiConfig.ThreadPrefixLimb +
 			uiConfig.ThreadPrefixUnfolded + tip
 	case t.Parent != nil && hiddenOffspring:
@@ -557,18 +564,19 @@ func newThreadView(store *lib.MessageStore) *threadView {
 }
 
 func (t *threadView) Update(data state.DataSetter, uid uint32) {
-	prefix, same, count, unread, folded, context := "", false, 0, 0, false, false
 	thread, err := t.store.Thread(uid)
+	info := state.ThreadInfo{}
 	if thread != nil && err == nil {
-		prefix = threadPrefix(thread, t.reverse, true)
+		info.Prefix = threadPrefix(thread, t.reverse, true)
 		subject := threadSubject(t.store, thread)
-		same = subject == t.prevSubj && sameParent(thread, t.prev) && !isParent(thread)
+		info.SameSubject = subject == t.prevSubj && sameParent(thread, t.prev) && !isParent(thread)
 		t.prev = thread
 		t.prevSubj = subject
-		count = countThreads(thread)
-		unread = unreadInThread(thread, t.store)
-		folded = thread.FirstChild != nil && thread.FirstChild.Hidden != 0
-		context = thread.Context
+		info.Count = countThreads(thread)
+		info.Unread = unreadInThread(thread, t.store)
+		info.Folded = thread.FirstChild != nil && thread.FirstChild.Hidden != 0
+		info.Context = thread.Context
+		info.Orphan = thread.Parent != nil && thread.Parent.Hidden > 0 && thread.Hidden == 0
 	}
-	data.SetThreading(prefix, same, count, unread, folded, context)
+	data.SetThreading(info)
 }
diff --git a/config/style.go b/config/style.go
index 95e60616..46c46378 100644
--- a/config/style.go
+++ b/config/style.go
@@ -42,6 +42,7 @@ const (
 	STYLE_MSGLIST_GUTTER
 	STYLE_MSGLIST_PILL
 	STYLE_MSGLIST_THREAD_CONTEXT
+	STYLE_MSGLIST_THREAD_ORPHAN
 
 	STYLE_DIRLIST_DEFAULT
 	STYLE_DIRLIST_UNREAD
@@ -92,6 +93,7 @@ var StyleNames = map[string]StyleObject{
 
 	"msglist_thread_folded":  STYLE_MSGLIST_THREAD_FOLDED,
 	"msglist_thread_context": STYLE_MSGLIST_THREAD_CONTEXT,
+	"msglist_thread_orphan":  STYLE_MSGLIST_THREAD_ORPHAN,
 
 	"dirlist_default": STYLE_DIRLIST_DEFAULT,
 	"dirlist_unread":  STYLE_DIRLIST_UNREAD,
diff --git a/config/templates.go b/config/templates.go
index 5a38cd61..4000b1fc 100644
--- a/config/templates.go
+++ b/config/templates.go
@@ -82,6 +82,7 @@ func (d *dummyData) ThreadCount() int                { return 0 }
 func (d *dummyData) ThreadUnread() int               { return 0 }
 func (d *dummyData) ThreadFolded() bool              { return false }
 func (d *dummyData) ThreadContext() bool             { return true }
+func (d *dummyData) ThreadOrphan() bool              { return true }
 func (d *dummyData) Subject() string                 { return "Re: [PATCH] hey" }
 func (d *dummyData) SubjectBase() string             { return "[PATCH] hey" }
 func (d *dummyData) Attach(string) string            { return "" }
diff --git a/doc/aerc-stylesets.7.scd b/doc/aerc-stylesets.7.scd
index bfe9dc05..d86d9f98 100644
--- a/doc/aerc-stylesets.7.scd
+++ b/doc/aerc-stylesets.7.scd
@@ -117,6 +117,8 @@ styling.
 :  Visible messages that have folded thread children.
 |  *msglist_thread_context*
 :  The messages not matching the mailbox / query, displayed for context.
+|  *msglist_thread_orphan*
+:  Threaded messages that have a missing parent message.
 |  *dirlist_default*
 :  The default style for directories in the directory list.
 |  *dirlist_unread*
@@ -287,6 +289,7 @@ The order that *msglist_\** styles are applied in is, from first to last:
 . *msglist_result*
 . *msglist_thread_folded*
 . *msglist_thread_context*
+. *msglist_thread_orphan*
 . *msglist_marked*
 
 So, the marked style will override all other msglist styles.
diff --git a/lib/state/templates.go b/lib/state/templates.go
index e5206cf0..868f9184 100644
--- a/lib/state/templates.go
+++ b/lib/state/templates.go
@@ -28,7 +28,7 @@ type DataSetter interface {
 	SetHeaders(*mail.Header, *models.OriginalMail)
 	SetInfo(*models.MessageInfo, int, bool)
 	SetVisual(bool)
-	SetThreading(string, bool, int, int, bool, bool)
+	SetThreading(ThreadInfo)
 	SetComposer(Composer)
 	SetAccount(*config.AccountConfig)
 	SetFolder(*models.Directory)
@@ -44,6 +44,7 @@ type ThreadInfo struct {
 	Unread      int
 	Folded      bool
 	Context     bool
+	Orphan      bool
 }
 
 type templateData struct {
@@ -100,15 +101,8 @@ func (d *templateData) SetVisual(visual bool) {
 	d.visual = visual
 }
 
-func (d *templateData) SetThreading(prefix string, same bool, count int,
-	unread int, folded bool, context bool,
-) {
-	d.threadInfo.Prefix = prefix
-	d.threadInfo.SameSubject = same
-	d.threadInfo.Count = count
-	d.threadInfo.Unread = unread
-	d.threadInfo.Folded = folded
-	d.threadInfo.Context = context
+func (d *templateData) SetThreading(info ThreadInfo) {
+	d.threadInfo = info
 }
 
 func (d *templateData) SetAccount(acct *config.AccountConfig) {
@@ -334,6 +328,10 @@ func (d *templateData) ThreadContext() bool {
 	return d.threadInfo.Context
 }
 
+func (d *templateData) ThreadOrphan() bool {
+	return d.threadInfo.Orphan
+}
+
 func (d *templateData) Subject() string {
 	var subject string
 	switch {
diff --git a/lib/threadbuilder.go b/lib/threadbuilder.go
index c18ab3d0..b7dae431 100644
--- a/lib/threadbuilder.go
+++ b/lib/threadbuilder.go
@@ -165,23 +165,30 @@ func (builder *ThreadBuilder) buildTree(c jwz.Threadable, parent *types.Thread,
 		return
 	}
 	for node := c; node != nil; node = node.GetNext() {
-		thread := parent
-		if !node.IsDummy() {
-			thread = builder.newThread(node, parent)
-			if rootLevel {
-				thread.NextSibling = parent.FirstChild
-				parent.FirstChild = thread
-			} else {
-				parent.InsertCmp(thread, bigger)
-			}
+		thread := builder.newThread(node, parent, node.IsDummy())
+		if rootLevel {
+			thread.NextSibling = parent.FirstChild
+			parent.FirstChild = thread
+		} else {
+			parent.InsertCmp(thread, bigger)
 		}
 		builder.buildTree(node.GetChild(), thread, bigger, node.IsDummy())
 	}
 }
 
-func (builder *ThreadBuilder) newThread(c jwz.Threadable, parent *types.Thread) *types.Thread {
+func (builder *ThreadBuilder) newThread(c jwz.Threadable, parent *types.Thread,
+	hidden bool,
+) *types.Thread {
+	hide := 0
+	if hidden {
+		hide += 1
+	}
 	if threadable, ok := c.(*threadable); ok {
-		return &types.Thread{Uid: threadable.MsgInfo.Uid, Parent: parent}
+		return &types.Thread{
+			Uid:    threadable.UID(),
+			Parent: parent,
+			Hidden: hide,
+		}
 	}
 	return nil
 }
@@ -297,6 +304,13 @@ func cleanRefs(m, irp string, refs []string) []string {
 	return cleanRefs
 }
 
+func (t *threadable) UID() uint32 {
+	if t.MsgInfo == nil {
+		return 0
+	}
+	return t.MsgInfo.Uid
+}
+
 func (t *threadable) Subject() string {
 	// deactivate threading by subject for now
 	return ""
diff --git a/models/templates.go b/models/templates.go
index c9b5d5b3..757e934a 100644
--- a/models/templates.go
+++ b/models/templates.go
@@ -25,6 +25,7 @@ type TemplateData interface {
 	ThreadUnread() int
 	ThreadFolded() bool
 	ThreadContext() bool
+	ThreadOrphan() bool
 	Subject() string
 	SubjectBase() string
 	Number() int
diff --git a/worker/types/thread.go b/worker/types/thread.go
index a79a0b2d..42565964 100644
--- a/worker/types/thread.go
+++ b/worker/types/thread.go
@@ -146,6 +146,9 @@ func getMaxUID(thread *Thread) uint32 {
 	var Uid uint32
 
 	_ = thread.Walk(func(t *Thread, _ int, currentErr error) error {
+		if t.Deleted || t.Hidden > 0 {
+			return nil
+		}
 		if t.Uid > Uid {
 			Uid = t.Uid
 		}