flamegraph: variable leaf bar heights for height metric (uo)

3 files changed, 128 insertions, 14 deletions

diff --git a/internal/tui/flamegraph/model.go b/internal/tui/flamegraph/model.go
index b1f3f1e..fe9b73b 100644
--- a/internal/tui/flamegraph/model.go
+++ b/internal/tui/flamegraph/model.go
@@ -510,7 +510,7 @@ func (m Model) renderViewContent() string {
 		renderHeight = 3
 	}
 
-	content := RenderTerminalView(m.frames, m.width, renderHeight, m.selectedIdx, m.subtreeSet, m.matchIndices, m.filterVisible, m.globalTotal, m.countFieldLabel(), m.isDark, m.searchActive, m.searchQuery)
+	content := RenderTerminalView(m.frames, m.width, renderHeight, m.selectedIdx, m.subtreeSet, m.matchIndices, m.filterVisible, m.globalTotal, m.countFieldLabel(), strings.TrimSpace(m.heightField) != "", m.isDark, m.searchActive, m.searchQuery)
 	content = replaceHeaderLine(content, m.toolbarLine())
 	if m.searchActive {
 		content = replaceFooterLine(content, m.searchFooter())
diff --git a/internal/tui/flamegraph/renderer.go b/internal/tui/flamegraph/renderer.go
index 3a35de9..e5bbae2 100644
--- a/internal/tui/flamegraph/renderer.go
+++ b/internal/tui/flamegraph/renderer.go
@@ -227,6 +227,7 @@ type renderViewParams struct {
 	rowOffset     int
 	maxRow        int
 	barHeight     int
+	leafBarHeight int
 	availableRows int
 	visibleFrames int
 	truncated     bool
@@ -234,12 +235,17 @@ type renderViewParams struct {
 
 // computeRenderParams derives the row-layout parameters for a given frame set
 // and viewport height.
-func computeRenderParams(frames []tuiFrame, height int) renderViewParams {
+func computeRenderParams(frames []tuiFrame, height int, heightMetricActive bool) renderViewParams {
 	availableRows := height - 2 // toolbar + frame-status line
 	maxRow := maxFrameRowForSet(frames, nil)
 	totalDepthRows := maxRow + 1
 	barHeight := computeBarHeight(availableRows, totalDepthRows, maxBarVisualHeight)
+	leafBarHeight := barHeight
 	visibleDepthRows := availableRows / barHeight
+	if heightMetricActive {
+		barHeight = 1
+		visibleDepthRows = availableRows
+	}
 	if visibleDepthRows < 1 {
 		visibleDepthRows = 1
 	}
@@ -249,10 +255,18 @@ func computeRenderParams(frames []tuiFrame, height int) renderViewParams {
 		rowOffset = maxRow + 1 - visibleDepthRows
 		truncated = true
 	}
+	if heightMetricActive {
+		visibleNonLeafRows := max(0, maxRow-rowOffset)
+		leafBarHeight = availableRows - visibleNonLeafRows
+		if leafBarHeight < 1 {
+			leafBarHeight = 1
+		}
+	}
 	return renderViewParams{
 		rowOffset:     rowOffset,
 		maxRow:        maxRow,
 		barHeight:     barHeight,
+		leafBarHeight: leafBarHeight,
 		availableRows: availableRows,
 		visibleFrames: countVisibleFrames(frames, nil),
 		truncated:     truncated,
@@ -313,7 +327,7 @@ func buildNormalStatus(selected tuiFrame, metricLabel string, globalTotal uint64
 // RenderTerminalView renders a terminal flamegraph viewport from laid out frames.
 // The function is split into helpers (computeRenderParams, buildToolbar,
 // buildFilteredStatus, buildNormalStatus) to keep each piece under 50 lines.
-func RenderTerminalView(frames []tuiFrame, width, height, selectedIdx int, subtreeSet, matchSet, filterSet map[int]bool, globalTotal uint64, metricLabel string, isDark, searchActive bool, searchQuery string) string {
+func RenderTerminalView(frames []tuiFrame, width, height, selectedIdx int, subtreeSet, matchSet, filterSet map[int]bool, globalTotal uint64, metricLabel string, heightMetricActive, isDark, searchActive bool, searchQuery string) string {
 	if width < minFlameWidth {
 		return common.PanelStyle.Render("Flame: terminal too narrow (need >= 60 columns)")
 	}
@@ -342,7 +356,7 @@ func RenderTerminalView(frames []tuiFrame, width, height, selectedIdx int, subtr
 	if subtreeSet == nil {
 		subtreeSet = computeSubtreeSet(frames, selectedIdx)
 	}
-	params := computeRenderParams(frames, height)
+	params := computeRenderParams(frames, height, heightMetricActive)
 	toolbar := buildToolbar(frames, width, params)
 	var status string
 	if filterIsActive {
@@ -350,11 +364,11 @@ func RenderTerminalView(frames []tuiFrame, width, height, selectedIdx int, subtr
 	} else {
 		status = buildNormalStatus(selected, metricLabel, globalTotal)
 	}
-	return renderViewRows(toolbar, status, rowsForRender(frames, width, params.rowOffset, params.maxRow, params.barHeight, params.availableRows, selected.Path, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterIsActive), width)
+	return renderViewRows(toolbar, status, rowsForRender(frames, width, params.rowOffset, params.maxRow, params.barHeight, params.leafBarHeight, params.availableRows, selected.Path, subtreeSet, matchSet, selectedIdx, heightMetricActive, isDark, searchActive, filterIsActive), width)
 }
 
-func rowsForRender(frames []tuiFrame, width, rowOffset, maxRow, barHeight, availableRows int, selectedPath string, subtreeSet, matchSet map[int]bool, selectedIdx int, isDark, searchActive, filterActive bool) []string {
-	return buildRenderRows(frames, width, rowOffset, maxRow, barHeight, availableRows, selectedPath, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterActive)
+func rowsForRender(frames []tuiFrame, width, rowOffset, maxRow, barHeight, leafBarHeight, availableRows int, selectedPath string, subtreeSet, matchSet map[int]bool, selectedIdx int, heightMetricActive, isDark, searchActive, filterActive bool) []string {
+	return buildRenderRows(frames, width, rowOffset, maxRow, barHeight, leafBarHeight, availableRows, selectedPath, subtreeSet, matchSet, selectedIdx, heightMetricActive, isDark, searchActive, filterActive)
 }
 
 func renderViewRows(toolbar, status string, rows []string, width int) string {
@@ -376,7 +390,7 @@ type indexedFrame struct {
 	frame tuiFrame
 }
 
-func buildRenderRows(frames []tuiFrame, width, rowOffset, maxRow, barHeight, availableRows int, selectedPath string, subtreeSet, matchSet map[int]bool, selectedIdx int, isDark, searchActive, filterActive bool) []string {
+func buildRenderRows(frames []tuiFrame, width, rowOffset, maxRow, barHeight, leafBarHeight, availableRows int, selectedPath string, subtreeSet, matchSet map[int]bool, selectedIdx int, heightMetricActive, isDark, searchActive, filterActive bool) []string {
 	rowsByDepth := make(map[int][]indexedFrame)
 	for idx, frame := range frames {
 		if frame.Row < rowOffset || frame.Row > maxRow {
@@ -395,6 +409,14 @@ func buildRenderRows(frames []tuiFrame, width, rowOffset, maxRow, barHeight, ava
 		slices.SortFunc(framesAtRow, func(a, b indexedFrame) int {
 			return cmp.Compare(a.frame.Col, b.frame.Col)
 		})
+		if heightMetricActive && row == maxRow {
+			frameHeights := leafFrameHeights(framesAtRow, leafBarHeight)
+			for h := leafBarHeight - 1; h >= 0; h-- {
+				showLabels := h == 0
+				rows = append(rows, renderLeafRowBand(framesAtRow, frameHeights, h, width, selectedPath, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterActive, showLabels))
+			}
+			continue
+		}
 		for repeat := 0; repeat < barHeight; repeat++ {
 			showLabels := repeat == barHeight/2
 			rows = append(rows, renderRow(framesAtRow, width, selectedPath, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterActive, showLabels))
@@ -418,6 +440,40 @@ func buildRenderRows(frames []tuiFrame, width, rowOffset, maxRow, barHeight, ava
 	return rows
 }
 
+func leafFrameHeights(frames []indexedFrame, leafBarHeight int) map[int]int {
+	heights := make(map[int]int, len(frames))
+	if leafBarHeight < 1 {
+		leafBarHeight = 1
+	}
+	maxHeightTotal := uint64(0)
+	for _, item := range frames {
+		if item.frame.HeightTotal > maxHeightTotal {
+			maxHeightTotal = item.frame.HeightTotal
+		}
+	}
+	for _, item := range frames {
+		frameHeight := 1
+		if maxHeightTotal > 0 {
+			scaled := math.Round(float64(leafBarHeight) * (float64(item.frame.HeightTotal) / float64(maxHeightTotal)))
+			frameHeight = int(scaled)
+		}
+		frameHeight = max(1, frameHeight)
+		frameHeight = min(leafBarHeight, frameHeight)
+		heights[item.idx] = frameHeight
+	}
+	return heights
+}
+
+func renderLeafRowBand(frames []indexedFrame, frameHeights map[int]int, band, width int, selectedPath string, subtreeSet, matchSet map[int]bool, selectedIdx int, isDark, searchActive, filterActive, showLabels bool) string {
+	visible := make([]indexedFrame, 0, len(frames))
+	for _, item := range frames {
+		if frameHeights[item.idx] > band {
+			visible = append(visible, item)
+		}
+	}
+	return renderRow(visible, width, selectedPath, subtreeSet, matchSet, selectedIdx, isDark, searchActive, filterActive, showLabels)
+}
+
 func renderRow(frames []indexedFrame, width int, selectedPath string, subtreeSet, matchSet map[int]bool, selectedIdx int, isDark, searchActive, filterActive, showLabels bool) string {
 	if len(frames) == 0 {
 		return strings.Repeat(" ", width)
diff --git a/internal/tui/flamegraph/renderer_test.go b/internal/tui/flamegraph/renderer_test.go
index 354b40a..f34d23d 100644
--- a/internal/tui/flamegraph/renderer_test.go
+++ b/internal/tui/flamegraph/renderer_test.go
@@ -152,7 +152,7 @@ func TestTerminalFrameColorSemanticPalette(t *testing.T) {
 }
 
 func TestRenderTerminalViewShowsNarrowMessage(t *testing.T) {
-	out := RenderTerminalView(nil, 50, 10, 0, nil, nil, nil, 0, "events", true, false, "")
+	out := RenderTerminalView(nil, 50, 10, 0, nil, nil, nil, 0, "events", false, true, false, "")
 	if !strings.Contains(out, "terminal too narrow") {
 		t.Fatalf("expected narrow terminal warning, got %q", out)
 	}
@@ -177,7 +177,7 @@ func TestRenderTerminalViewIncludesToolbarAndStatus(t *testing.T) {
 	}
 	frames := BuildTerminalLayout(snapshot, 80, 6)
 
-	out := RenderTerminalView(frames, 80, 6, 1, nil, nil, nil, 0, "events", true, false, "")
+	out := RenderTerminalView(frames, 80, 6, 1, nil, nil, nil, 0, "events", false, true, false, "")
 	if !strings.Contains(out, "Flame | view:root | frames:2") {
 		t.Fatalf("expected toolbar to include frame count, got %q", out)
 	}
@@ -196,7 +196,7 @@ func TestRenderTerminalViewFillsAvailableHeightForShallowTree(t *testing.T) {
 	}
 	frames := BuildTerminalLayout(snapshot, 100, 20)
 
-	out := RenderTerminalView(frames, 100, 20, 1, nil, nil, nil, 0, "events", true, false, "")
+	out := RenderTerminalView(frames, 100, 20, 1, nil, nil, nil, 0, "events", false, true, false, "")
 	lines := strings.Split(out, "\n")
 	if got, want := len(lines), 20; got != want {
 		t.Fatalf("expected render to fill viewport height (%d lines), got %d", want, got)
@@ -245,7 +245,7 @@ func TestRenderTerminalViewShowsPersistentFilterContext(t *testing.T) {
 	frames := BuildTerminalLayout(snapshot, 80, 6)
 	matchSet := map[int]bool{1: true}
 
-	out := RenderTerminalView(frames, 140, 6, 1, nil, matchSet, nil, 0, "events", true, false, "child")
+	out := RenderTerminalView(frames, 140, 6, 1, nil, matchSet, nil, 0, "events", false, true, false, "child")
 	if !strings.Contains(out, `Filter "child"`) {
 		t.Fatalf("expected filter context in status line, got %q", out)
 	}
@@ -279,7 +279,7 @@ func TestRenderTerminalViewFilterKeepsNonMatchingBranchesVisible(t *testing.T) {
 	}
 	matchSet := map[int]bool{needleIdx: true}
 
-	out := RenderTerminalView(frames, 180, 8, needleIdx, nil, matchSet, nil, 100, "bytes", true, false, "needle")
+	out := RenderTerminalView(frames, 180, 8, needleIdx, nil, matchSet, nil, 100, "bytes", false, true, false, "needle")
 	if !strings.Contains(out, `Filter "needle": 60.0% bytes`) {
 		t.Fatalf("expected filter status to report 60.0%% bytes share, got %q", out)
 	}
@@ -368,7 +368,7 @@ func TestRenderTerminalViewShowsDeepLevelTruncationHint(t *testing.T) {
 		},
 	}
 	frames := BuildTerminalLayout(snapshot, 80, 10)
-	out := RenderTerminalView(frames, 80, 4, 0, nil, nil, nil, 0, "events", true, false, "")
+	out := RenderTerminalView(frames, 80, 4, 0, nil, nil, nil, 0, "events", false, true, false, "")
 	if !strings.Contains(out, "showing deepest levels") {
 		t.Fatalf("expected truncation hint in toolbar, got %q", out)
 	}
@@ -391,6 +391,64 @@ func TestComputeSubtreeSetIncludesAncestorsAndDescendants(t *testing.T) {
 	}
 }
 
+func TestComputeRenderParamsHeightMetricExpandsLeafBand(t *testing.T) {
+	frames := []tuiFrame{
+		{Name: "root", Row: 0, Col: 0, Width: 20, Path: "root"},
+		{Name: "leaf", Row: 1, Col: 0, Width: 20, Path: "root" + pathSeparator + "leaf", HeightTotal: 100},
+	}
+
+	params := computeRenderParams(frames, 8, true) // availableRows=6
+	if got, want := params.barHeight, 1; got != want {
+		t.Fatalf("height metric active: barHeight=%d want=%d", got, want)
+	}
+	if got, want := params.leafBarHeight, 5; got != want {
+		t.Fatalf("height metric active: leafBarHeight=%d want=%d", got, want)
+	}
+}
+
+func TestLeafFrameHeightsScaledByHeightTotal(t *testing.T) {
+	frames := []indexedFrame{
+		{idx: 10, frame: tuiFrame{Name: "A", HeightTotal: 100}},
+		{idx: 11, frame: tuiFrame{Name: "B", HeightTotal: 50}},
+		{idx: 12, frame: tuiFrame{Name: "C", HeightTotal: 0}},
+	}
+
+	heights := leafFrameHeights(frames, 5)
+	if got, want := heights[10], 5; got != want {
+		t.Fatalf("A height=%d want=%d", got, want)
+	}
+	if got, want := heights[11], 3; got != want {
+		t.Fatalf("B height=%d want=%d", got, want)
+	}
+	if got, want := heights[12], 1; got != want {
+		t.Fatalf("C height=%d want=%d", got, want)
+	}
+}
+
+func TestRenderLeafRowBandFiltersFramesByBand(t *testing.T) {
+	frames := []indexedFrame{
+		{idx: 0, frame: tuiFrame{Name: "A", Col: 0, Width: 5, Path: "root" + pathSeparator + "A", Fill: color.RGBA{R: 150, G: 80, B: 80, A: 255}}},
+		{idx: 1, frame: tuiFrame{Name: "B", Col: 5, Width: 5, Path: "root" + pathSeparator + "B", Fill: color.RGBA{R: 80, G: 120, B: 180, A: 255}}},
+	}
+	heights := map[int]int{
+		0: 5,
+		1: 2,
+	}
+
+	topBand := renderLeafRowBand(frames, heights, 3, 10, "root"+pathSeparator+"A", nil, nil, 0, true, false, false, true)
+	if !strings.Contains(topBand, "A") {
+		t.Fatalf("expected top band to render taller frame A, got %q", topBand)
+	}
+	if strings.Contains(topBand, "B") {
+		t.Fatalf("expected top band to hide shorter frame B, got %q", topBand)
+	}
+
+	lowerBand := renderLeafRowBand(frames, heights, 1, 10, "root"+pathSeparator+"A", nil, nil, 0, true, false, false, true)
+	if !strings.Contains(lowerBand, "A") || !strings.Contains(lowerBand, "B") {
+		t.Fatalf("expected lower band to render both frames, got %q", lowerBand)
+	}
+}
+
 func mustFindFrame(t *testing.T, frames []tuiFrame, path string) tuiFrame {
 	t.Helper()
 	for _, frame := range frames {