From 4fe67b36e3bbe6ea5505ed7233c245be9374f0ce Mon Sep 17 00:00:00 2001
From: Hannes Schulze <haschu0103@outlook.de>
Date: Sun, 2 Feb 2025 20:59:36 +0100
Subject: refactor selection

---
 lib/nes/app/ui/selection.hh | 125 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 lib/nes/app/ui/selection.hh

(limited to 'lib/nes/app/ui/selection.hh')

diff --git a/lib/nes/app/ui/selection.hh b/lib/nes/app/ui/selection.hh
new file mode 100644
index 0000000..fafa4a6
--- /dev/null
+++ b/lib/nes/app/ui/selection.hh
@@ -0,0 +1,125 @@
+#pragma once
+
+#include "nes/common/types.hh"
+#include "nes/app/graphics/renderer.hh"
+#include "nes/app/graphics/color.hh"
+
+namespace nes::app
+{
+	/// A selection menu managing a fixed number of items and pagination.
+	template<typename Item, u32 PageSize>
+	class selection
+	{
+		Item items_[PageSize];
+		u32 count_{ 0 };
+		u32 page_count_{ 0 };
+		i32 x_{};
+		i32 y_{};
+		u32 width_{};
+		i32 selected_{ -1 };
+		i32 current_page_{ -1 };
+
+	public:
+		explicit selection(i32 const x, i32 const y, u32 const width)
+			: x_{ x }
+			, y_{ y }
+			, width_{ width }
+		{
+		}
+
+		virtual ~selection() = default;
+
+		selection(selection const&) = delete;
+		selection(selection&&) = delete;
+		auto operator=(selection const&) -> selection& = delete;
+		auto operator=(selection&&) -> selection& = delete;
+
+		auto set_page_count(u32 const page_count) -> void
+		{
+			page_count_ = page_count;
+			set_page(page_count_ > 0 ? 0 : -1);
+		}
+
+		auto get_page_count() const -> u32 { return page_count_; }
+		auto get_current_page() const -> i32 { return current_page_; }
+		auto get_selected() const -> Item const* { return selected_ >= 0 ? &items_[selected_] : nullptr; }
+
+		auto render(renderer& renderer) const -> void
+		{
+			for (auto i = u32{ 0 }; i < count_; ++i)
+			{
+				auto const y = y_ + static_cast<i32>(3 * i);
+				auto const is_selected = static_cast<i32>(i) == selected_;
+				auto const color = is_selected ? color::accent_primary : color::foreground_primary;
+				if (is_selected)
+				{
+					renderer.render_text(x_, y, ">", color);
+				}
+
+				render_item(renderer, items_[i], x_ + 2, y, width_ - 2, color);
+			}
+		}
+
+		auto go_next() -> void
+		{
+			if (selected_ < 0) { return; }
+
+			selected_ += 1;
+			if (selected_ == static_cast<i32>(count_)) { selected_ = 0; }
+		}
+
+		auto go_up() -> void
+		{
+			if (selected_ <= 0)
+			{
+				if (current_page_ <= 0) { return; }
+
+				set_page(current_page_ - 1, true);
+				return;
+			}
+			selected_ -= 1;
+		}
+
+		auto go_down() -> void
+		{
+			if (selected_ < 0 || selected_ + 1 == static_cast<i32>(count_))
+			{
+				if (current_page_ < 0 || current_page_ + 1 == static_cast<i32>(page_count_)) { return; }
+
+				set_page(current_page_ + 1, false);
+				return;
+			}
+			selected_ += 1;
+		}
+
+	protected:
+		/// Render an item's caption at the given position and width.
+		virtual auto render_item(renderer&, Item const&, i32 x, i32 y, u32 width, color) const -> void = 0;
+
+		/// Load the items for a page (max. PageSize items) and return the number of loaded items.
+		virtual auto load_page(Item(&)[PageSize], u32 page) -> u32 = 0;
+
+	private:
+		auto set_page(i32 const page, bool const select_last = false) -> void
+		{
+			if (page < 0)
+			{
+				current_page_ = -1;
+				count_ = 0;
+				selected_ = -1;
+				return;
+			}
+
+			current_page_ = page;
+			count_ = load_page(items_, static_cast<u32>(page));
+			if (count_ > 0)
+			{
+				selected_ = select_last ? static_cast<i32>(count_) - 1 : 0;
+			}
+			else
+			{
+				selected_ = -1;
+			}
+		}
+	};
+} // namespace nes::app
\ No newline at end of file
-- 
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