feat(debugger): Make header of sequence diagram always be shown

The boxes above each line for the reactor is now always on top so that it is
easier to track what reactor is sending to whom.

src/debugger/cmd/detsys-debug/main.go

@@ -33,6 +33,11 @@ var diagram = tview.NewTextView().
 	Highlight("focused")
 var w2 = tview.ANSIWriter(diagram)
 
+var diagramHeader = tview.NewTextView().
+	SetWrap(false).
+	SetDynamicColors(true)
+var wDiagramHeader = tview.ANSIWriter(diagramHeader)
+
 var reactorsWidget = tview.NewList()
 
 var messageView = tview.NewTextView().
@@ -78,12 +83,14 @@ func (da *DebugApplication) setRow(row int) {
 func (da *DebugApplication) redraw() {
 	textView.Clear()
 	diagram.Clear()
+	diagramHeader.Clear()
 	messageView.Clear()
 	logView.Clear()
 	row := da.activeRow
 	{
 		fmt.Fprintf(w2, "%s", da.diagrams.At(row-1))
 		diagram.ScrollToHighlight()
+		fmt.Fprintf(wDiagramHeader, "%s", da.diagrams.Header())
 	}
 	reactor := da.reactors[da.activeReactor]
 	old := da.heaps[row-1][reactor]
@@ -166,9 +173,16 @@ func main() {
 	da := MakeDebugApplication(lib.TestId{testId}, lib.RunId{runId})
 
 	messageView.SetBorderPadding(1, 1, 2, 0).SetBorder(true).SetTitle("Current Message")
-	diagram.SetBorderPadding(1, 1, 2, 0).SetBorder(true).SetTitle("Sequence Diagram")
 	logView.SetBorderPadding(1, 1, 2, 0).SetBorder(true).SetTitle("Reactor Log")
 
+	diagramWidget := tview.NewFlex().
+		SetDirection(tview.FlexRow).
+		AddItem(diagramHeader, 3, 0, false).
+		AddItem(diagram, 0, 1, false)
+	diagramWidget.
+		SetBorder(true).
+		SetTitle("Sequence Diagram")
+
 	da.redraw()
 
 	table := tview.NewTable().
@@ -245,7 +259,7 @@ func main() {
 				SetDirection(tview.FlexRow).
 				AddItem(stateWidget, 0, 1, false).
 				AddItem(table, 20, 1, false), 0, 1, false).
-			AddItem(diagram, 0, 1, false), 0, 20, false).
+			AddItem(diagramWidget, 0, 1, false), 0, 20, false).
 		AddItem(messageView, 5, 1, false).
 		AddItem(logView, 10, 1, false)
 

src/debugger/internal/debugger.go

@@ -196,8 +196,9 @@ func colon(s string) string {
 }
 
 type SequenceDiagrams struct {
-	inner map[int][]byte
-	net   []NetworkEvent
+	inner  map[int][]byte
+	header []byte
+	net    []NetworkEvent
 }
 
 func NewSequenceDiagrams(testId lib.TestId, runId lib.RunId) *SequenceDiagrams {
@@ -224,15 +225,23 @@ func (s *SequenceDiagrams) At(at int) []byte {
 			Dropped: event.Dropped,
 		})
 	}
-	gen := DrawDiagram(arrows, DrawSettings{
+	header, gen := DrawDiagram(arrows, DrawSettings{
 		MarkerSize: 3,
 		MarkAt:     at,
 	})
 
+	if s.header == nil {
+		s.header = header
+	}
+
 	s.inner[at] = gen
 	return gen
 }
 
+func (s *SequenceDiagrams) Header() []byte {
+	return s.header
+}
+
 func GetLogMessages(testId lib.TestId, runId lib.RunId, reactor string, at int) [][]byte {
 	db := lib.OpenDB()
 	defer db.Close()

src/debugger/internal/sequence.go

@@ -133,7 +133,6 @@ func appendBoxes(isTop bool, output *strings.Builder, names []string, gaps []int
 			WriteRepeat(output, hLine, halfPoint)
 			output.WriteString("╯")
 		}
-		output.WriteString("\n")
 	}
 }
 
@@ -271,13 +270,14 @@ func appendArrows(output *strings.Builder, names []string, arrows []arrowInterna
 	}
 }
 
-func drawDiagram(names []string, arrows []arrowInternal, gaps []int, nrLoops int) []byte {
+func drawDiagram(names []string, arrows []arrowInternal, gaps []int, nrLoops int) ([]byte, []byte) {
 	if len(names) < 1 {
 		panic("We need at least one box")
 	}
 
 	boxSize := boxSize(names)
 
+	var header strings.Builder
 	var output strings.Builder
 	var expectedSize int
 	{
@@ -291,12 +291,13 @@ func drawDiagram(names []string, arrows []arrowInternal, gaps []int, nrLoops int
 	}
 	output.Grow(expectedSize)
 
-	appendBoxes(true, &output, names, gaps)
+	appendBoxes(true, &header, names, gaps)
+
 	appendArrows(&output, names, arrows, gaps, boxSize)
 	appendBoxes(false, &output, names, gaps)
 
 	// remove last newline
-	return []byte(output.String()[:output.Len()-1])
+	return []byte(header.String()), []byte(output.String())
 }
 
 func index(haystack []string, needle string) int {
@@ -313,7 +314,7 @@ type DrawSettings struct {
 	MarkAt     int
 }
 
-func DrawDiagram(arrows []Arrow, settings DrawSettings) []byte {
+func DrawDiagram(arrows []Arrow, settings DrawSettings) ([]byte, []byte) {
 	var names []string
 	{
 		for _, arr := range arrows {

src/debugger/internal/sequence_test.go

@@ -9,10 +9,12 @@ import (
 
 func goldenTest(t *testing.T, settings DrawSettings, arrows []Arrow, outcome string) {
 	shouldBe := strings.TrimSpace(outcome)
-	boxes := string(DrawDiagram(arrows, settings))
+	header, boxes := DrawDiagram(arrows, settings)
+
+	whole := strings.Join([]string{string(header), string(boxes)}, "\n")
 
 	//sanitize, boxes might have some extra spaces at the end..
-	boxesLines := strings.Split(boxes, "\n")
+	boxesLines := strings.Split(whole, "\n")
 	for i, s := range boxesLines {
 		boxesLines[i] = strings.TrimRight(s, " ")
 	}
@@ -110,7 +112,7 @@ func benchmarkSequence(many int, b *testing.B) {
 	// away
 	var r []byte
 	for i := 0; i < b.N; i++ {
-		r = DrawDiagram(arrows, settings)
+		_, r = DrawDiagram(arrows, settings)
 	}
 	result = r
 }