Create abtract scrollable widget

This cleans up a bunch of boilerplate for scrollable items and standardizes their usage

wtf/scrollable.go

@@ -0,0 +1,79 @@
+package wtf
+
+import (
+	"strconv"
+
+	"github.com/rivo/tview"
+	"github.com/wtfutil/wtf/cfg"
+)
+
+type ScrollableWidget struct {
+	TextWidget
+
+	selected       int
+	maxItems       int
+	RenderFunction func()
+}
+
+func NewScrollableWidget(app *tview.Application, commonSettings *cfg.Common, focusable bool) ScrollableWidget {
+
+	widget := ScrollableWidget{
+		TextWidget: NewTextWidget(app, commonSettings, focusable),
+	}
+
+	widget.Unselect()
+	widget.View.SetScrollable(true)
+	widget.View.SetRegions(true)
+	return widget
+}
+
+func (widget *ScrollableWidget) SetRenderFunction(displayFunc func()) {
+	widget.RenderFunction = displayFunc
+}
+
+func (widget *ScrollableWidget) SetItemCount(items int) {
+	widget.maxItems = items
+}
+
+func (widget *ScrollableWidget) GetSelected() int {
+	return widget.selected
+}
+
+func (widget *ScrollableWidget) RowColor(idx int) string {
+	if widget.View.HasFocus() && (idx == widget.selected) {
+		widget.CommonSettings.DefaultFocussedRowColor()
+	}
+
+	return widget.CommonSettings.RowColor(idx)
+}
+
+func (widget *ScrollableWidget) Next() {
+	widget.selected++
+	if widget.selected >= widget.maxItems {
+		widget.selected = 0
+	}
+	widget.RenderFunction()
+}
+
+func (widget *ScrollableWidget) Prev() {
+	widget.selected--
+	if widget.selected < 0 {
+		widget.selected = widget.maxItems - 1
+	}
+	widget.RenderFunction()
+}
+
+func (widget *ScrollableWidget) Unselect() {
+	widget.selected = -1
+	if widget.RenderFunction != nil {
+		widget.RenderFunction()
+	}
+}
+
+func (widget *ScrollableWidget) Redraw(title, content string, wrap bool) {
+
+	widget.TextWidget.Redraw(title, content, wrap)
+	widget.app.QueueUpdateDraw(func() {
+		widget.View.Highlight(strconv.Itoa(widget.selected)).ScrollToHighlight()
+	})
+}