fix: scrolling on suggestions

suggestions.go

@@ -2,10 +2,15 @@ package main
 
 import (
 	"strings"
+	"sync"
 
 	"github.com/charmbracelet/x/ansi"
 )
 
+const suggestionRenderCacheLimit = 256
+
+var renderedSuggestions = newSuggestionRenderCache(suggestionRenderCacheLimit)
+
 type parsedCommentBody struct {
 	Prose       string
 	Suggestions []string
@@ -16,6 +21,98 @@ type codeRange struct {
 	End   int
 }
 
+type suggestionRenderCacheKey struct {
+	path         string
+	removed      string
+	removedLines int
+	replacement  string
+	width        int
+}
+
+type suggestionRenderCacheEntry struct {
+	removed []detailLine
+	added   []detailLine
+}
+
+type suggestionRenderCache struct {
+	mu      sync.Mutex
+	limit   int
+	entries map[suggestionRenderCacheKey]suggestionRenderCacheEntry
+	order   []suggestionRenderCacheKey
+}
+
+func newSuggestionRenderCache(limit int) *suggestionRenderCache {
+	return &suggestionRenderCache{
+		limit: limit, entries: make(map[suggestionRenderCacheKey]suggestionRenderCacheEntry),
+	}
+}
+
+func (c *suggestionRenderCache) get(
+	key suggestionRenderCacheKey,
+) (suggestionRenderCacheEntry, bool) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	entry, ok := c.entries[key]
+	return cloneSuggestionRenderEntry(entry), ok
+}
+
+func (c *suggestionRenderCache) put(
+	key suggestionRenderCacheKey, entry suggestionRenderCacheEntry,
+) suggestionRenderCacheEntry {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if cached, ok := c.entries[key]; ok {
+		return cloneSuggestionRenderEntry(cached)
+	}
+	if len(c.entries) >= c.limit {
+		delete(c.entries, c.order[0])
+		c.order = c.order[1:]
+	}
+	c.entries[key] = cloneSuggestionRenderEntry(entry)
+	c.order = append(c.order, key)
+	return cloneSuggestionRenderEntry(entry)
+}
+
+func (c *suggestionRenderCache) clear() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.entries = make(map[suggestionRenderCacheKey]suggestionRenderCacheEntry)
+	c.order = nil
+}
+
+func cloneSuggestionRenderEntry(entry suggestionRenderCacheEntry) suggestionRenderCacheEntry {
+	return suggestionRenderCacheEntry{
+		removed: append([]detailLine(nil), entry.removed...),
+		added:   append([]detailLine(nil), entry.added...),
+	}
+}
+
+func renderSuggestion(
+	path string, reviewed []string, replacement string, width int,
+) suggestionRenderCacheEntry {
+	key := suggestionRenderCacheKey{
+		path: path, removed: strings.Join(reviewed, "\n"), removedLines: len(reviewed),
+		replacement: replacement, width: width,
+	}
+	if cached, ok := renderedSuggestions.get(key); ok {
+		return cached
+	}
+	removed, added := normalizeSuggestion(reviewed, replacement)
+	removedRanges, addedRanges := suggestionChangedRanges(removed, added)
+	entry := suggestionRenderCacheEntry{}
+	for index, source := range removed {
+		entry.removed = append(entry.removed, wrapSuggestionLine(
+			path, source, '-', removedRanges[index], width,
+		)...)
+	}
+	for index, source := range added {
+		entry.added = append(entry.added, wrapSuggestionLine(
+			path, source, '+', addedRanges[index], width,
+		)...)
+	}
+	return renderedSuggestions.put(key, entry)
+}
+
 func parseCommentBody(body string) parsedCommentBody {
 	var (
 		result       parsedCommentBody

suggestions_test.go

@@ -85,6 +85,27 @@ func TestDetailRendersSuggestionAsRemovalAndAddition(t *testing.T) {
 	}
 }
 
+func TestRenderedSuggestionsAreCachedWithoutSharingMutableLines(t *testing.T) {
+	renderedSuggestions.clear()
+	reviewed := []string{"old_value = compute()", "return old_value"}
+	first := renderSuggestion(
+		"example.py", reviewed, "new_value = compute()\nreturn new_value", 50,
+	)
+	if len(renderedSuggestions.entries) != 1 {
+		t.Fatalf("suggestion cache entries = %d, want 1", len(renderedSuggestions.entries))
+	}
+	first.removed[0].rail = "mutated"
+	second := renderSuggestion(
+		"example.py", reviewed, "new_value = compute()\nreturn new_value", 50,
+	)
+	if second.removed[0].rail != "" {
+		t.Fatal("caller mutation changed cached suggestion lines")
+	}
+	if len(renderedSuggestions.entries) != 1 {
+		t.Fatalf("cache miss for unchanged suggestion: %d entries", len(renderedSuggestions.entries))
+	}
+}
+
 func TestSuggestionBackgroundIsDirectionalWithoutTextUnderline(t *testing.T) {
 	removed := suggestionHighlight("  - ", "old", 12, '-')
 	added := suggestionHighlight("  + ", "new", 12, '+')

theme.go

@@ -102,6 +102,7 @@ func applyTheme(name string, custom ...CustomThemeConfig) error {
 	currentThemeName = name
 	commentMarkdownRenderers.Clear()
 	commentMarkdownLines.clear()
+	renderedSuggestions.clear()
 	return nil
 }
 

tui.go

@@ -3766,27 +3766,16 @@ func (m App) detailLines(width int) []detailLine {
 				}
 			}
 			for suggestionIndex, suggestion := range content.Suggestions {
-				removed, added := normalizeSuggestion(reviewedSourceLines(thread, comment), suggestion)
-				removedRanges, addedRanges := suggestionChangedRanges(removed, added)
 				label := "suggested change"
 				if len(content.Suggestions) > 1 {
 					label = fmt.Sprintf("suggested change %d/%d", suggestionIndex+1, len(content.Suggestions))
 				}
 				lines = append(lines, detailLine{rail: rail}, detailLine{rail: rail, text: dimStyle.Render(label)})
-				for sourceIndex, source := range removed {
-					lines = append(lines, addCommentRail(
-						wrapSuggestionLine(
-							thread.Path, source, '-', removedRanges[sourceIndex], max(1, width-4),
-						), rail,
-					)...)
-				}
-				for sourceIndex, source := range added {
-					lines = append(lines, addCommentRail(
-						wrapSuggestionLine(
-							thread.Path, source, '+', addedRanges[sourceIndex], max(1, width-4),
-						), rail,
-					)...)
-				}
+				rendered := renderSuggestion(
+					thread.Path, reviewedSourceLines(thread, comment), suggestion, max(1, width-4),
+				)
+				lines = append(lines, addCommentRail(rendered.removed, rail)...)
+				lines = append(lines, addCommentRail(rendered.added, rail)...)
 			}
 			for reactionIndex, reactionLine := range renderReactionSummary(
 				comment.Reactions, max(1, width-4),

version.go

@@ -1,3 +1,3 @@
 package main
 
-const dipleVersion = "0.3.1"
+const dipleVersion = "0.3.2"