binds: display active keybinds in a dialog box

Show contextual keybinds in a textbox when using the ':help keys'
command. This command is bound to '?' by default.

Fixes: https://todo.sr.ht/~rjarry/aerc/42
Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

commands/help.go

@@ -19,6 +19,7 @@ var pages = []string{
 	"stylesets",
 	"templates",
 	"tutorial",
+	"keys",
 }
 
 func init() {
@@ -40,5 +41,29 @@ func (Help) Execute(aerc *widgets.Aerc, args []string) error {
 	} else if len(args) > 2 {
 		return errors.New("Usage: help [topic]")
 	}
+
+	if page == "aerc-keys" {
+		aerc.AddDialog(widgets.NewDialog(
+			widgets.NewListBox(
+				"Bindings: Press <Esc> or <Enter> to close. "+
+					"Start typing to filter bindings.",
+				aerc.HumanReadableBindings(),
+				aerc.SelectedAccountUiConfig(),
+				func(_ string) {
+					helpClose(aerc)
+					aerc.CloseDialog()
+				},
+			),
+			func(h int) int { return h / 4 },
+			func(h int) int { return h / 2 },
+		))
+	}
+
 	return TermCore(aerc, []string{"term", "man", page})
 }
+
+func helpClose(aerc *widgets.Aerc) {
+	if content, ok := aerc.SelectedTabContent().(*widgets.MessageViewer); ok {
+		content.UpdateScreen()
+	}
+}

config/bindings.go

@@ -22,7 +22,7 @@ type Binding struct {
 }
 
 type KeyBindings struct {
-	bindings []*Binding
+	Bindings []*Binding
 
 	// If false, disable global keybindings in this context
 	Globals bool
@@ -48,7 +48,7 @@ func NewKeyBindings() *KeyBindings {
 func MergeBindings(bindings ...*KeyBindings) *KeyBindings {
 	merged := NewKeyBindings()
 	for _, b := range bindings {
-		merged.bindings = append(merged.bindings, b.bindings...)
+		merged.Bindings = append(merged.Bindings, b.Bindings...)
 	}
 	merged.ExKey = bindings[0].ExKey
 	merged.Globals = bindings[0].Globals
@@ -79,7 +79,7 @@ func (config AercConfig) MergeContextualBinds(baseBinds *KeyBindings,
 
 func (bindings *KeyBindings) Add(binding *Binding) {
 	// TODO: Search for conflicts?
-	bindings.bindings = append(bindings.bindings, binding)
+	bindings.Bindings = append(bindings.Bindings, binding)
 }
 
 func (bindings *KeyBindings) GetBinding(
@@ -88,7 +88,7 @@ func (bindings *KeyBindings) GetBinding(
 	incomplete := false
 	// TODO: This could probably be a sorted list to speed things up
 	// TODO: Deal with bindings that share a prefix
-	for _, binding := range bindings.bindings {
+	for _, binding := range bindings.Bindings {
 		if len(binding.Input) < len(input) {
 			continue
 		}
@@ -121,7 +121,7 @@ func (bindings *KeyBindings) GetBinding(
 func (bindings *KeyBindings) GetReverseBindings(output []KeyStroke) [][]KeyStroke {
 	var inputs [][]KeyStroke
 
-	for _, binding := range bindings.bindings {
+	for _, binding := range bindings.Bindings {
 		if len(binding.Output) != len(output) {
 			continue
 		}

config/binds.conf

@@ -4,6 +4,7 @@
 <C-p> = :prev-tab<Enter>
 <C-n> = :next-tab<Enter>
 <C-t> = :term<Enter>
+? = :help keys<Enter>
 
 [messages]
 q = :quit<Enter>

widgets/aerc.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"net/url"
+	"sort"
 	"strings"
 	"time"
 
@@ -199,6 +200,40 @@ func (aerc *Aerc) Draw(ctx *ui.Context) {
 	}
 }
 
+func (aerc *Aerc) HumanReadableBindings() []string {
+	var result []string
+	binds := aerc.getBindings()
+	format := func(s string) string {
+		s = strings.ReplaceAll(s, "<space>", " ")
+		return strings.ReplaceAll(s, "%", "%%")
+	}
+	fmtStr := "%10s %s"
+	for _, bind := range binds.Bindings {
+		result = append(result, fmt.Sprintf(fmtStr,
+			format(config.FormatKeyStrokes(bind.Input)),
+			format(config.FormatKeyStrokes(bind.Output)),
+		))
+	}
+	if binds.Globals && aerc.conf.Bindings.Global != nil {
+		for _, bind := range aerc.conf.Bindings.Global.Bindings {
+			result = append(result, fmt.Sprintf(fmtStr+" (Globals)",
+				format(config.FormatKeyStrokes(bind.Input)),
+				format(config.FormatKeyStrokes(bind.Output)),
+			))
+		}
+	}
+	result = append(result, fmt.Sprintf(fmtStr,
+		"$ex",
+		fmt.Sprintf("'%c'", binds.ExKey.Rune),
+	))
+	result = append(result, fmt.Sprintf(fmtStr,
+		"Globals",
+		fmt.Sprintf("%v", binds.Globals),
+	))
+	sort.Strings(result)
+	return result
+}
+
 func (aerc *Aerc) getBindings() *config.KeyBindings {
 	selectedAccountName := ""
 	if aerc.SelectedAccount() != nil {

widgets/msgviewer.go

@@ -392,6 +392,22 @@ func (mv *MessageViewer) Close() error {
 	return nil
 }
 
+func (mv *MessageViewer) UpdateScreen() {
+	if mv.switcher == nil {
+		return
+	}
+	parts := mv.switcher.parts
+	selected := mv.switcher.selected
+	if selected < 0 {
+		return
+	}
+	if len(parts) > 0 && selected < len(parts) {
+		if part := parts[selected]; part != nil {
+			part.UpdateScreen()
+		}
+	}
+}
+
 func (ps *PartSwitcher) Invalidate() {
 	ps.DoInvalidate(ps)
 }
@@ -628,6 +644,12 @@ func (pv *PartViewer) SetSource(reader io.Reader) {
 	pv.attemptCopy()
 }
 
+func (pv *PartViewer) UpdateScreen() {
+	if pv.term != nil {
+		pv.term.Invalidate()
+	}
+}
+
 func (pv *PartViewer) attemptCopy() {
 	if pv.source == nil || pv.pager == nil || pv.pager.Process == nil {
 		return