From 8c0ea49169b47321b40749a978073c7a5b6b8572 Mon Sep 17 00:00:00 2001
From: Celtic Minstrel <celtic.minstrel.ca@some.place>
Date: Mon, 10 Apr 2017 14:08:09 -0400
Subject: [PATCH] Help Browser: Implement history

---
 src/gui/dialogs/help_browser.cpp | 26 ++++++++++++++++++++++++++
 src/gui/dialogs/help_browser.hpp | 11 +++++++++--
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/src/gui/dialogs/help_browser.cpp b/src/gui/dialogs/help_browser.cpp
index c3c505337d4f..9ab9f219cb8f 100644
--- a/src/gui/dialogs/help_browser.cpp
+++ b/src/gui/dialogs/help_browser.cpp
@@ -56,6 +56,12 @@ help_browser::help_browser()
 void help_browser::pre_show(window& window)
 {
 	tree_view& topic_tree = find_widget<tree_view>(&window, "topic_tree", false);
+	button& back_button = find_widget<button>(&window, "back", false);
+	button& next_button = find_widget<button>(&window, "next", false);
+	next_button.set_visible(widget::visibility::hidden);
+	back_button.set_visible(widget::visibility::hidden);
+	connect_signal_mouse_left_click(back_button, std::bind(&help_browser::on_history_navigate, this, std::ref(window), true));
+	connect_signal_mouse_left_click(next_button, std::bind(&help_browser::on_history_navigate, this, std::ref(window), false));
 
 	topic_tree.set_selection_change_callback(std::bind(&help_browser::on_topic_select, this, std::ref(window)));
 
@@ -218,9 +224,29 @@ void help_browser::on_topic_select(window& window)
 		window.invalidate_layout();
 	}
 
+	if(!history_.empty()) {
+		history_.erase(std::next(history_pos_), history_.end());
+	}
+	history_.push_back(topic_id);
+	history_pos_ = std::prev(history_.end());
+	find_widget<button>(&window, "back", false).set_visible(widget::visibility::visible);
+	find_widget<button>(&window, "next", false).set_visible(widget::visibility::hidden);
+
 	const unsigned topic_i = parsed_pages_.at(topic_id);
 	topic_pages.select_page(topic_i);
 }
 
+void help_browser::on_history_navigate(window& window, bool backwards) {
+	if(backwards) {
+		history_pos_--;
+	} else {
+		history_pos_++;
+	}
+	find_widget<button>(&window, "back", false).set_visible(history_pos_ == history_.begin() ? widget::visibility::hidden : widget::visibility::visible);
+	find_widget<button>(&window, "next", false).set_visible(history_pos_ == std::prev(history_.end()) ? widget::visibility::hidden : widget::visibility::visible);
+	const unsigned topic_i = parsed_pages_.at(*history_pos_);
+	find_widget<multi_page>(&window, "topic_text_pages", false).select_page(topic_i);
+}
+
 } // namespace dialogs
 } // namespace gui2
diff --git a/src/gui/dialogs/help_browser.hpp b/src/gui/dialogs/help_browser.hpp
index 124eaf6e848a..b1425c73a152 100644
--- a/src/gui/dialogs/help_browser.hpp
+++ b/src/gui/dialogs/help_browser.hpp
@@ -17,13 +17,16 @@
 
 #include "gui/dialogs/modal_dialog.hpp"
 
-#include "help/help_impl.hpp"
-
 #include <map>
+#include <list>
 
 class config;
 class CVideo;
 
+namespace help {
+	struct section;
+}
+
 namespace gui2
 {
 class tree_view_node;
@@ -47,6 +50,9 @@ class help_browser : public modal_dialog
 
 	std::map<std::string, int> parsed_pages_;
 
+	std::list<std::string> history_;
+	std::list<std::string>::const_iterator history_pos_;
+
 	/** Inherited from modal_dialog, implemented by REGISTER_DIALOG. */
 	virtual const std::string& window_id() const;
 
@@ -54,6 +60,7 @@ class help_browser : public modal_dialog
 	void pre_show(window& window);
 
 	void on_topic_select(window& window);
+	void on_history_navigate(window& window, bool backwards);
 
 	void add_topics_for_section(const help::section& parent_section, tree_view_node& parent_node);
 	tree_view_node& add_topic(const std::string& topic_id, const std::string& topic_title,