widgets: add list box with filter/scrollbar

Implement a scrollable text box that displays a list of strings which
can be filtered. The widget is closed by pressing ESC or ENTER. If ENTER
is pressed and an entry has been selected, this text will be passed to
the closing callback.

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

widgets/listbox.go

@@ -0,0 +1,239 @@
+package widgets
+
+import (
+	"math"
+	"strings"
+	"sync"
+
+	"git.sr.ht/~rjarry/aerc/config"
+	"git.sr.ht/~rjarry/aerc/lib/ui"
+	"git.sr.ht/~rjarry/aerc/logging"
+	"github.com/gdamore/tcell/v2"
+)
+
+type ListBox struct {
+	Scrollable
+	ui.Invalidatable
+	title       string
+	lines       []string
+	selected    string
+	cursorPos   int
+	jump        int
+	showCursor  bool
+	showFilter  bool
+	filterMutex sync.Mutex
+	filter      *ui.TextInput
+	uiConfig    *config.UIConfig
+	cb          func(string)
+}
+
+func NewListBox(title string, lines []string, uiConfig *config.UIConfig, cb func(string)) *ListBox {
+	lb := &ListBox{
+		title:     title,
+		lines:     lines,
+		cursorPos: -1,
+		jump:      -1,
+		uiConfig:  uiConfig,
+		cb:        cb,
+		filter:    ui.NewTextInput("", uiConfig),
+	}
+	lb.filter.OnChange(func(ti *ui.TextInput) {
+		var show bool
+		if ti.String() == "" {
+			show = false
+		} else {
+			show = true
+		}
+		lb.setShowFilterField(show)
+		lb.filter.Focus(show)
+		lb.Invalidate()
+	})
+	lb.dedup()
+	return lb
+}
+
+func (lb *ListBox) dedup() {
+	dedupped := make([]string, 0, len(lb.lines))
+	dedup := make(map[string]struct{})
+	for _, line := range lb.lines {
+		if _, dup := dedup[line]; dup {
+			logging.Warnf("ignore duplicate: %s", line)
+			continue
+		}
+		dedup[line] = struct{}{}
+		dedupped = append(dedupped, line)
+	}
+	lb.lines = dedupped
+}
+
+func (lb *ListBox) setShowFilterField(b bool) {
+	lb.filterMutex.Lock()
+	defer lb.filterMutex.Unlock()
+	lb.showFilter = b
+}
+
+func (lb *ListBox) showFilterField() bool {
+	lb.filterMutex.Lock()
+	defer lb.filterMutex.Unlock()
+	return lb.showFilter
+}
+
+func (lb *ListBox) Draw(ctx *ui.Context) {
+	defaultStyle := lb.uiConfig.GetStyle(config.STYLE_DEFAULT)
+	titleStyle := lb.uiConfig.GetStyle(config.STYLE_TITLE)
+	w, h := ctx.Width(), ctx.Height()
+	ctx.Fill(0, 0, w, h, ' ', defaultStyle)
+	ctx.Fill(0, 0, w, 1, ' ', titleStyle)
+	ctx.Printf(0, 0, titleStyle, "%s", lb.title)
+
+	y := 0
+	if lb.showFilterField() {
+		y = 1
+		x := ctx.Printf(0, y, defaultStyle, "Filter: ")
+		lb.filter.Draw(ctx.Subcontext(x, y, w-x, 1))
+	}
+
+	lb.drawBox(ctx.Subcontext(0, y+1, w, h-(y+1)))
+}
+
+func (lb *ListBox) moveCursor(delta int) {
+	list := lb.filtered()
+	if len(list) == 0 {
+		return
+	}
+	lb.cursorPos += delta
+	if lb.cursorPos < 0 {
+		lb.cursorPos = 0
+	}
+	if lb.cursorPos >= len(list) {
+		lb.cursorPos = len(list) - 1
+	}
+	lb.selected = list[lb.cursorPos]
+	lb.showCursor = true
+}
+
+func (lb *ListBox) filtered() []string {
+	list := []string{}
+	filterTerm := lb.filter.String()
+	for _, line := range lb.lines {
+		if strings.Contains(line, filterTerm) {
+			list = append(list, line)
+		}
+	}
+	return list
+}
+
+func (lb *ListBox) drawBox(ctx *ui.Context) {
+	defaultStyle := lb.uiConfig.GetStyle(config.STYLE_DEFAULT)
+	selectedStyle := lb.uiConfig.GetComposedStyleSelected(config.STYLE_MSGLIST_DEFAULT, nil)
+
+	w, h := ctx.Width(), ctx.Height()
+	lb.jump = h
+	list := lb.filtered()
+
+	lb.UpdateScroller(ctx.Height(), len(list))
+	scroll := 0
+	lb.cursorPos = -1
+	for i := 0; i < len(list); i++ {
+		if lb.selected == list[i] {
+			scroll = i
+			lb.cursorPos = i
+			break
+		}
+	}
+	lb.EnsureScroll(scroll)
+
+	needScrollbar := lb.NeedScrollbar()
+	if needScrollbar {
+		w -= 1
+		if w < 0 {
+			w = 0
+		}
+	}
+
+	if lb.lines == nil || len(list) == 0 {
+		return
+	}
+
+	y := 0
+	for i := lb.Scroll(); i < len(list) && y < h; i++ {
+		style := defaultStyle
+		if lb.selected == list[i] && lb.showCursor {
+			style = selectedStyle
+		}
+		ctx.Printf(1, y, style, list[i])
+		y += 1
+	}
+
+	if needScrollbar {
+		scrollBarCtx := ctx.Subcontext(w, 0, 1, ctx.Height())
+		lb.drawScrollbar(scrollBarCtx)
+	}
+}
+
+func (lb *ListBox) drawScrollbar(ctx *ui.Context) {
+	gutterStyle := tcell.StyleDefault
+	pillStyle := tcell.StyleDefault.Reverse(true)
+
+	// gutter
+	h := ctx.Height()
+	ctx.Fill(0, 0, 1, h, ' ', gutterStyle)
+
+	// pill
+	pillSize := int(math.Ceil(float64(h) * lb.PercentVisible()))
+	pillOffset := int(math.Floor(float64(h) * lb.PercentScrolled()))
+	ctx.Fill(0, pillOffset, 1, pillSize, ' ', pillStyle)
+}
+
+func (lb *ListBox) Invalidate() {
+	lb.DoInvalidate(lb)
+}
+
+func (lb *ListBox) Event(event tcell.Event) bool {
+	if event, ok := event.(*tcell.EventKey); ok {
+		switch event.Key() {
+		case tcell.KeyCtrlP, tcell.KeyUp:
+			lb.moveCursor(-1)
+			lb.Invalidate()
+			return true
+		case tcell.KeyCtrlN, tcell.KeyDown:
+			lb.moveCursor(+1)
+			lb.Invalidate()
+			return true
+		case tcell.KeyPgUp:
+			if lb.jump >= 0 {
+				lb.moveCursor(-lb.jump)
+				lb.Invalidate()
+			}
+			return true
+		case tcell.KeyPgDn:
+			if lb.jump >= 0 {
+				lb.moveCursor(+lb.jump)
+				lb.Invalidate()
+			}
+			return true
+		case tcell.KeyEnter:
+			return lb.quit(lb.selected)
+		case tcell.KeyEsc:
+			return lb.quit("")
+		}
+	}
+	if lb.filter != nil {
+		handled := lb.filter.Event(event)
+		lb.Invalidate()
+		return handled
+	}
+	return false
+}
+
+func (lb *ListBox) quit(s string) bool {
+	lb.filter.Focus(false)
+	if lb.cb != nil {
+		lb.cb(s)
+	}
+	return true
+}
+
+func (lb *ListBox) Focus(f bool) {
+	lb.filter.Focus(f)
+}