templates: add ThreadCount and ThreadFolded

Add the number of threads and a flag to indicated folded threads to the
template data. Use {{.ThreadCount}} and {{.ThreadFolded}} in template
expression for the message list.

column-subject = {{.ThreadPrefix}}{{if .ThreadFolded}}[{{.ThreadCount}}] {{end}}{{.Subject}}

Update default configuration accordingly.

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: inwit <inwit@sindominio.net>

9 files changed, 67 insertions, 14 deletions

diff --git a/commands/commands_test.go b/commands/commands_test.go
index 7c3ec84f..c01019d0 100644
--- a/commands/commands_test.go
+++ b/commands/commands_test.go
@@ -75,6 +75,8 @@ func (d *dummyData) Date() time.Time                           { return time.Now
 func (d *dummyData) DateAutoFormat(time.Time) string           { return "" }
 func (d *dummyData) Header(string) string                      { return "" }
 func (d *dummyData) ThreadPrefix() string                      { return "└─>" }
+func (d *dummyData) ThreadCount() int                          { return 0 }
+func (d *dummyData) ThreadFolded() bool                        { return false }
 func (d *dummyData) Subject() string                           { return "Re: [PATCH] hey" }
 func (d *dummyData) SubjectBase() string                       { return "[PATCH] hey" }
 func (d *dummyData) Number() int                               { return 0 }
diff --git a/config/aerc.conf b/config/aerc.conf
index c6cd29d5..d6ffa389 100644
--- a/config/aerc.conf
+++ b/config/aerc.conf
@@ -73,7 +73,7 @@
 #column-date={{.DateAutoFormat .Date.Local}}
 #column-name={{index (.From | names) 0}}
 #column-flags={{.Flags | join ""}}
-#column-subject={{.ThreadPrefix}}{{.Subject}}
+#column-subject={{.ThreadPrefix}}{{if .ThreadFolded}}{{printf "{%d}" .ThreadCount}}{{end}}{{.Subject}}
 
 #
 # String separator inserted between columns. When the column width specifier is
diff --git a/config/templates.go b/config/templates.go
index 97ba89b8..ef304ae2 100644
--- a/config/templates.go
+++ b/config/templates.go
@@ -76,6 +76,8 @@ func (d *dummyData) Date() time.Time                 { return time.Now() }
 func (d *dummyData) DateAutoFormat(time.Time) string { return "" }
 func (d *dummyData) Header(string) string            { return "" }
 func (d *dummyData) ThreadPrefix() string            { return "└─>" }
+func (d *dummyData) ThreadCount() int                { return 0 }
+func (d *dummyData) ThreadFolded() bool              { return false }
 func (d *dummyData) Subject() string                 { return "Re: [PATCH] hey" }
 func (d *dummyData) SubjectBase() string             { return "[PATCH] hey" }
 func (d *dummyData) Number() int                     { return 0 }
diff --git a/config/ui.go b/config/ui.go
index dfd66224..ff6fbccf 100644
--- a/config/ui.go
+++ b/config/ui.go
@@ -303,7 +303,8 @@ func (*UIConfig) ParseIndexColumns(section *ini.Section, key *ini.Key) ([]*Colum
 		_, _ = section.NewKey("column-flags", `{{.Flags | join ""}}`)
 	}
 	if !section.HasKey("column-subject") {
-		_, _ = section.NewKey("column-subject", `{{.ThreadPrefix}}{{.Subject}}`)
+		_, _ = section.NewKey("column-subject",
+			`{{.ThreadPrefix}}{{if .ThreadFolded}}{{printf "{%d}" .ThreadCount}}{{end}}{{.Subject}}`)
 	}
 	return ParseColumnDefs(key, section)
 }
diff --git a/doc/aerc-config.5.scd b/doc/aerc-config.5.scd
index 06f7c0b0..573ae557 100644
--- a/doc/aerc-config.5.scd
+++ b/doc/aerc-config.5.scd
@@ -116,7 +116,7 @@ These options are configured in the *[ui]* section of _aerc.conf_.
 	column-date = {{.DateAutoFormat .Date.Local}}
 	column-name = {{index (.From | names) 0}}
 	column-flags = {{.Flags | join ""}}
-	column-subject = {{.Subject}}
+	column-subject = {{.ThreadPrefix}}{{if .ThreadFolded}}{{printf "{%d}" .ThreadCount}}{{end}}{{.Subject}}
 	```
 
 	See *aerc-templates*(7) for all available symbols and functions.
diff --git a/doc/aerc-templates.7.scd b/doc/aerc-templates.7.scd
index ce0b9a7c..19a7bd36 100644
--- a/doc/aerc-templates.7.scd
+++ b/doc/aerc-templates.7.scd
@@ -80,7 +80,7 @@ available always.
 	is enabled).
 
 	```
-	{{.ThreadPrefix}}{{.Subject}}
+	{{.ThreadPrefix}}{{if .ThreadFolded}}{{printf "{%d}" .ThreadCount}}{{end}}{{.Subject}}
 	```
 
 	The subject of the email stripped of any _Re:_ and _Fwd:_ prefixes.
@@ -88,6 +88,21 @@ available always.
 	```
 	{{.SubjectBase}}
 	```
+*Threading*
+	When threading is enabled, these attributes are available in the message
+	list:
+
+	_ThreadPrefix_
+		If the message is part of a thread, this will contain arrows
+		that represent the message tree based on _In-Reply-To_ and
+		_References_ headers.
+
+	_ThreadFolded_
+		Will be _true_ if the message has thread children which are
+		hidden by *:fold*.
+
+	_ThreadCount_
+		The number of thread children.
 
 *Flags*
 	List of message flags, not available when composing, replying nor
diff --git a/lib/state/templates.go b/lib/state/templates.go
index 36f7b725..7b877c76 100644
--- a/lib/state/templates.go
+++ b/lib/state/templates.go
@@ -16,7 +16,7 @@ type DataSetter interface {
 	Data() models.TemplateData
 	SetHeaders(*mail.Header, *models.OriginalMail)
 	SetInfo(*models.MessageInfo, int, bool)
-	SetThreading(string, bool)
+	SetThreading(string, bool, int, bool)
 	SetAccount(*config.AccountConfig)
 	SetFolder(*models.Directory)
 	SetRUE([]string, func(string) (int, int, int))
@@ -24,6 +24,13 @@ type DataSetter interface {
 	SetPendingKeys([]config.KeyStroke)
 }
 
+type ThreadInfo struct {
+	SameSubject bool
+	Prefix      string
+	Count       int
+	Folded      bool
+}
+
 type templateData struct {
 	// only available when composing/replying/forwarding
 	headers *mail.Header
@@ -35,8 +42,7 @@ type templateData struct {
 	msgNum int
 
 	// message list threading
-	threadSameSubject bool
-	threadPrefix      string
+	threadInfo ThreadInfo
 
 	// selected account
 	account     *config.AccountConfig
@@ -72,9 +78,13 @@ func (d *templateData) SetInfo(info *models.MessageInfo, num int, marked bool,
 	d.marked = marked
 }
 
-func (d *templateData) SetThreading(prefix string, same bool) {
-	d.threadPrefix = prefix
-	d.threadSameSubject = same
+func (d *templateData) SetThreading(prefix string, same bool, count int,
+	folded bool,
+) {
+	d.threadInfo.Prefix = prefix
+	d.threadInfo.SameSubject = same
+	d.threadInfo.Count = count
+	d.threadInfo.Folded = folded
 }
 
 func (d *templateData) SetAccount(acct *config.AccountConfig) {
@@ -260,7 +270,15 @@ func (d *templateData) Header(name string) string {
 }
 
 func (d *templateData) ThreadPrefix() string {
-	return d.threadPrefix
+	return d.threadInfo.Prefix
+}
+
+func (d *templateData) ThreadCount() int {
+	return d.threadInfo.Count
+}
+
+func (d *templateData) ThreadFolded() bool {
+	return d.threadInfo.Folded
 }
 
 func (d *templateData) Subject() string {
@@ -271,7 +289,7 @@ func (d *templateData) Subject() string {
 	case d.headers != nil:
 		subject = d.Header("subject")
 	}
-	if d.threadSameSubject {
+	if d.threadInfo.SameSubject {
 		subject = ""
 	}
 	return subject
diff --git a/models/templates.go b/models/templates.go
index eb696ccc..686687cc 100644
--- a/models/templates.go
+++ b/models/templates.go
@@ -20,6 +20,8 @@ type TemplateData interface {
 	DateAutoFormat(date time.Time) string
 	Header(name string) string
 	ThreadPrefix() string
+	ThreadCount() int
+	ThreadFolded() bool
 	Subject() string
 	SubjectBase() string
 	Number() int
diff --git a/widgets/msglist.go b/widgets/msglist.go
index 548735d3..9ce60756 100644
--- a/widgets/msglist.go
+++ b/widgets/msglist.go
@@ -384,6 +384,17 @@ func (ml *MessageList) drawEmptyMessage(ctx *ui.Context) {
 		uiConfig.GetStyle(config.STYLE_MSGLIST_DEFAULT), "%s", msg)
 }
 
+func countThreads(thread *types.Thread) (ctr int) {
+	if thread == nil {
+		return
+	}
+	_ = thread.Walk(func(t *types.Thread, _ int, _ error) error {
+		ctr++
+		return nil
+	})
+	return
+}
+
 func threadPrefix(t *types.Thread, reverse bool, point bool) string {
 	var arrow string
 	if t.Parent != nil {
@@ -457,7 +468,7 @@ func newThreadView(store *lib.MessageStore) *threadView {
 }
 
 func (t *threadView) Update(data state.DataSetter, uid uint32) {
-	prefix, same := "", false
+	prefix, same, count, folded := "", false, 0, false
 	thread, err := t.store.Thread(uid)
 	if thread != nil && err == nil {
 		prefix = threadPrefix(thread, t.reverse, true)
@@ -465,6 +476,8 @@ func (t *threadView) Update(data state.DataSetter, uid uint32) {
 		same = subject == t.prevSubj && sameParent(thread, t.prev) && !isParent(thread)
 		t.prev = thread
 		t.prevSubj = subject
+		count = countThreads(thread)
+		folded = thread.FirstChild != nil && thread.FirstChild.Hidden
 	}
-	data.SetThreading(prefix, same)
+	data.SetThreading(prefix, same, count, folded)
 }