From 201c9d7c775da90763f562e0ed3d414a7d3eaf9e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?kleines=20Filmr=C3=B6llchen?= <filmroellchen@serenityos.org>
Date: Wed, 14 Dec 2022 17:53:41 +0100
Subject: [PATCH] Help+LibManual: Open sibling page for subsections

Clicking on a subsection now displays the sibling page, which is
intended to be the main page for that section.
---
 Userland/Applications/Help/ManualModel.cpp    |  4 ++--
 Userland/Libraries/LibManual/Node.h           |  1 +
 Userland/Libraries/LibManual/PageNode.h       |  1 +
 Userland/Libraries/LibManual/SectionNode.h    |  1 +
 .../Libraries/LibManual/SubsectionNode.cpp    | 20 +++++++++++++++++++
 Userland/Libraries/LibManual/SubsectionNode.h |  1 +
 6 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/Userland/Applications/Help/ManualModel.cpp b/Userland/Applications/Help/ManualModel.cpp
index 7809a0dd12..9f22293539 100644
--- a/Userland/Applications/Help/ManualModel.cpp
+++ b/Userland/Applications/Help/ManualModel.cpp
@@ -58,9 +58,9 @@ Optional<String> ManualModel::page_path(const GUI::ModelIndex& index) const
     if (!index.is_valid())
         return {};
     auto* node = static_cast<Manual::Node const*>(index.internal_data());
-    if (!node->is_page())
+    auto page = node->document();
+    if (!page)
         return {};
-    auto* page = static_cast<Manual::PageNode const*>(node);
     auto path = page->path();
     if (path.is_error())
         return {};
diff --git a/Userland/Libraries/LibManual/Node.h b/Userland/Libraries/LibManual/Node.h
index aceca11084..9e1c2aeda1 100644
--- a/Userland/Libraries/LibManual/Node.h
+++ b/Userland/Libraries/LibManual/Node.h
@@ -26,6 +26,7 @@ public:
     virtual bool is_page() const { return false; }
     virtual bool is_open() const { return false; }
     virtual ErrorOr<String> path() const = 0;
+    virtual PageNode const* document() const = 0;
 
     // Backend for the command-line argument format that Help and man accept. Handles:
     // [/path/to/documentation.md] (no second argument)
diff --git a/Userland/Libraries/LibManual/PageNode.h b/Userland/Libraries/LibManual/PageNode.h
index 3dc33d9a67..7c48a7dc8d 100644
--- a/Userland/Libraries/LibManual/PageNode.h
+++ b/Userland/Libraries/LibManual/PageNode.h
@@ -27,6 +27,7 @@ public:
     virtual Node const* parent() const override;
     virtual ErrorOr<String> name() const override { return m_page; };
     virtual bool is_page() const override { return true; }
+    virtual PageNode const* document() const override { return this; };
 
     virtual ErrorOr<String> path() const override;
 
diff --git a/Userland/Libraries/LibManual/SectionNode.h b/Userland/Libraries/LibManual/SectionNode.h
index d0d4476eaa..4e228799f9 100644
--- a/Userland/Libraries/LibManual/SectionNode.h
+++ b/Userland/Libraries/LibManual/SectionNode.h
@@ -33,6 +33,7 @@ public:
     virtual ErrorOr<String> name() const override;
     String const& section_name() const { return m_section; }
     virtual ErrorOr<String> path() const override;
+    virtual PageNode const* document() const override { return nullptr; }
 
     virtual bool is_open() const override { return m_open; }
     void set_open(bool open);
diff --git a/Userland/Libraries/LibManual/SubsectionNode.cpp b/Userland/Libraries/LibManual/SubsectionNode.cpp
index 1d166b9282..18f81d54fe 100644
--- a/Userland/Libraries/LibManual/SubsectionNode.cpp
+++ b/Userland/Libraries/LibManual/SubsectionNode.cpp
@@ -5,6 +5,8 @@
  */
 
 #include "SubsectionNode.h"
+#include "PageNode.h"
+#include <AK/TypeCasts.h>
 
 namespace Manual {
 
@@ -16,6 +18,24 @@ SubsectionNode::SubsectionNode(NonnullRefPtr<SectionNode> parent, StringView nam
 
 Node const* SubsectionNode::parent() const { return m_parent; }
 
+PageNode const* SubsectionNode::document() const
+{
+    auto maybe_siblings = parent()->children();
+    if (maybe_siblings.is_error())
+        return nullptr;
+    auto siblings = maybe_siblings.release_value();
+    for (auto const& sibling : siblings) {
+        if (&*sibling == this)
+            continue;
+        auto sibling_name = sibling->name();
+        if (sibling_name.is_error())
+            continue;
+        if (sibling_name.value() == m_name && is<PageNode>(*sibling))
+            return static_cast<PageNode*>(&*sibling);
+    }
+    return nullptr;
+}
+
 ErrorOr<String> SubsectionNode::name() const { return m_name; }
 
 ErrorOr<String> SubsectionNode::path() const
diff --git a/Userland/Libraries/LibManual/SubsectionNode.h b/Userland/Libraries/LibManual/SubsectionNode.h
index c2f8461bd8..fec53604dc 100644
--- a/Userland/Libraries/LibManual/SubsectionNode.h
+++ b/Userland/Libraries/LibManual/SubsectionNode.h
@@ -19,6 +19,7 @@ public:
     virtual Node const* parent() const override;
     virtual ErrorOr<String> path() const override;
     virtual ErrorOr<String> name() const override;
+    virtual PageNode const* document() const override;
 
 protected:
     NonnullRefPtr<SectionNode> m_parent;