1 files changed, 102 insertions, 0 deletions

diff --git a/lib/nes/app/input/input-manager.cc b/lib/nes/app/input/input-manager.cc
new file mode 100644
index 0000000..1c9db9e
--- /dev/null
+++ b/lib/nes/app/input/input-manager.cc
@@ -0,0 +1,102 @@
+#include "nes/app/input/input-manager.hh"
+
+namespace nes
+{
+	namespace
+	{
+		class input_device_dummy final : public input_device
+		{
+		public:
+			explicit input_device_dummy() = default;
+
+			static auto get_instance() -> input_device_dummy&
+			{
+				static auto res = input_device_dummy{};
+				return res;
+			}
+
+			auto read_key_up() -> bool override { return false; }
+			auto read_key_down() -> bool override { return false; }
+			auto read_key_left() -> bool override { return false; }
+			auto read_key_right() -> bool override { return false; }
+			auto read_key_a() -> bool override { return false; }
+			auto read_key_b() -> bool override { return false; }
+			auto read_key_select() -> bool override { return false; }
+			auto read_key_start() -> bool override { return false; }
+		};
+	} // namespace
+
+	input_manager::input_manager(input_device_keyboard& keyboard)
+		: keyboard_{ &keyboard }
+	{
+		fill_unassigned_inputs();
+	}
+
+	auto input_manager::add_controller(input_device_controller& controller) -> void
+	{
+		controllers_.append(controller);
+		if (controller.is_reliable())
+		{
+			auto const index = controller.get_index();
+			if (index != input_device_controller::index::unused)
+			{
+				// This controller was previously used and assigned an index -> replace the current device with this
+				// (known) controller.
+				auto const i = static_cast<std::size_t>(index);
+				if (inputs_[i].controller)
+				{
+					inputs_[i].controller->set_index(input_device_controller::index::unused);
+				}
+
+				inputs_[i].controller = &controller;
+				inputs_[i].device = &controller;
+			}
+
+			// There may be another free controller now.
+			fill_unassigned_inputs();
+		}
+	}
+
+	auto input_manager::remove_controller(input_device_controller& controller) -> void
+	{
+		controllers_.remove(controller);
+		fill_unassigned_inputs();
+	}
+
+	auto input_manager::fill_unassigned_inputs() -> void
+	{
+		auto it = controllers_.begin();
+		input_device* fallback = keyboard_;
+
+		for (auto i = std::size_t{ 0 }; i < input_count; ++i)
+		{
+			if (inputs_[i].controller != nullptr) { continue; }
+
+			// This input is not assigned -> use the next available controller if available.
+			while (it != controllers_.end())
+			{
+				auto controller = *it;
+				if (controller->is_reliable() && controller->get_index() == input_device_controller::index::unused)
+				{
+					break;
+				}
+				++it;
+			}
+
+			if (it != controllers_.end())
+			{
+				// We've found an unused controller -> assign it.
+				inputs_[i].controller = *it;
+				inputs_[i].controller->set_index(static_cast<input_device_controller::index>(i));
+				inputs_[i].device = *it;
+			}
+			else
+			{
+				// We're all out of controllers -> fall back to the keyboard (if this is the first missing controller)
+				// or nothing.
+				inputs_[i].device = fallback;
+				fallback = &input_device_dummy::get_instance(); // Only use the keyboard as a fallback once.
+			}
+		}
+	}
+} // namespace nes
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