fix: component flattener not popping styles in correct order

Closes #1254

Author: diogotcorreia

api/src/main/java/net/kyori/adventure/text/flattener/ComponentFlattenerImpl.java

@@ -79,10 +79,12 @@ final class ComponentFlattenerImpl implements ComponentFlattener {
   private static final class StackEntry {
     final Component component;
     final int depth;
+    final int stylesToPop;
 
-    StackEntry(final Component component, final int depth) {
+    StackEntry(final Component component, final int depth, final int stylesToPop) {
       this.component = component;
       this.depth = depth;
+      this.stylesToPop = stylesToPop;
     }
   }
 
@@ -104,7 +106,7 @@ private void flatten0(final @NotNull Component input, final @NotNull FlattenerLi
     final Deque<Style> styleStack = new ArrayDeque<>();
 
     // Push the starting component.
-    componentStack.push(new StackEntry(input, depth));
+    componentStack.push(new StackEntry(input, depth, 1));
 
     while (!componentStack.isEmpty()) {
       final StackEntry entry = componentStack.pop();
@@ -130,12 +132,19 @@ private void flatten0(final @NotNull Component input, final @NotNull FlattenerLi
         // Push any children onto the stack in reverse order so they are popped in the right order.
         final List<Component> children = component.children();
         for (int i = children.size() - 1; i >= 0; i--) {
-          componentStack.push(new StackEntry(children.get(i), currentDepth + 1));
+          if (i == children.size() - 1) {
+            // The last child is responsible for popping all the parents' styles.
+            componentStack.push(new StackEntry(children.get(i), currentDepth + 1, entry.stylesToPop + 1));
+          } else {
+            componentStack.push(new StackEntry(children.get(i), currentDepth + 1, 1));
+          }
         }
       } else {
-        // If there are no children, we pop the latest style to go back "up" the tree.
-        final Style style = styleStack.pop();
-        listener.popStyle(style);
+        // If there are no children, we pop the latest N styles to go back "up" the tree.
+        for (int i = entry.stylesToPop; i > 0; i--) {
+          final Style style = styleStack.pop();
+          listener.popStyle(style);
+        }
       }
     }
 

api/src/test/java/net/kyori/adventure/text/flattener/ComponentFlattenerTest.java

@@ -34,6 +34,7 @@
 import net.kyori.adventure.text.NBTComponent;
 import net.kyori.adventure.text.TranslatableComponent;
 import net.kyori.adventure.text.TranslationArgument;
+import net.kyori.adventure.text.event.ClickEvent;
 import net.kyori.adventure.text.format.NamedTextColor;
 import net.kyori.adventure.text.format.Style;
 import net.kyori.adventure.text.format.TextDecoration;
@@ -52,6 +53,7 @@ static class TrackingFlattener implements FlattenerListener {
     int pushCount;
     int popCount;
     final List<Style> pushedStyles = new ArrayList<>();
+    final List<Style> poppedStyles = new ArrayList<>();
     final List<String> strings = new ArrayList<>();
 
     @Override
@@ -68,6 +70,7 @@ public void component(final @NotNull String text) {
     @Override
     public void popStyle(final @NotNull Style style) {
       this.popCount++;
+      this.poppedStyles.add(style);
     }
 
     public TrackingFlattener assertBalanced() {
@@ -90,6 +93,11 @@ public TrackingFlattener assertStyles(final Style... styles) {
       assertIterableEquals(Arrays.asList(styles), this.pushedStyles);
       return this;
     }
+
+    public TrackingFlattener assertPoppedStyles(final Style... styles) {
+      assertIterableEquals(Arrays.asList(styles), this.poppedStyles);
+      return this;
+    }
   }
 
   static class CancellingFlattener extends TrackingFlattener {
@@ -154,6 +162,40 @@ void testComplex() {
       .assertContents("Hi there my", " blue ", "friend");
   }
 
+  @Test
+  void testComplexNested() {
+    final Component input = Component.text()
+      .content("Hi there my")
+      .append(Component.text(" clickable ")
+        .clickEvent(ClickEvent.copyToClipboard("some text"))
+        .append(
+          Component.text("and bold ")
+            .decorate(TextDecoration.BOLD)
+            .append(Component.text("red ", NamedTextColor.RED)))
+        .append(
+          Component.text("and blue ", NamedTextColor.BLUE)))
+      .append(Component.text("friend"))
+      .build();
+
+    this.testFlatten(ComponentFlattener.basic(), input).assertBalanced()
+      .assertPushesAndPops(6)
+      .assertStyles(
+        Style.empty(),
+        Style.style(ClickEvent.copyToClipboard("some text")),
+        Style.style(TextDecoration.BOLD),
+        Style.style(NamedTextColor.RED),
+        Style.style(NamedTextColor.BLUE),
+        Style.empty())
+      .assertPoppedStyles(
+        Style.style(NamedTextColor.RED),
+        Style.style(TextDecoration.BOLD),
+        Style.style(NamedTextColor.BLUE),
+        Style.style(ClickEvent.copyToClipboard("some text")),
+        Style.empty(),
+        Style.empty())
+      .assertContents("Hi there my", " clickable ", "and bold ", "red ", "and blue ", "friend");
+  }
+
   @Test
   void testTranslatable() {
     this.testFlatten(ComponentFlattener.basic(), Component.translatable("adventure.test.key"))