#include "ImGuiLayer.hh"

#include "ImGuiCpp.hh"
#include "ImGuiManager.hh"

#include "Keyboard.hh"
#include "MSXMotherBoard.hh"
#include "Reactor.hh"

#include <imgui.h>
#include <imgui_impl_opengl3.h>
#include <imgui_impl_sdl2.h>
#include <imgui_internal.h>

#include <SDL.h>

namespace openmsx {

ImGuiLayer::ImGuiLayer(ImGuiManager& manager_)
	: Layer(Layer::Coverage::PARTIAL, Layer::ZIndex::IMGUI)
	, manager(manager_)
{
}

void ImGuiLayer::paint(OutputSurface& /*surface*/)
{
	manager.preNewFrame();

	// Start the Dear ImGui frame
	ImGui_ImplOpenGL3_NewFrame();
	ImGui_ImplSDL2_NewFrame();
	ImGui::NewFrame();

	// Allow docking in main window
	auto* mainViewport = ImGui::GetMainViewport();
	auto dockspaceId = 0;
	im::StyleVar(ImGuiStyleVar_Alpha, /*transparent*/0.0f, [&]{
		dockspaceId = ImGui::DockSpaceOverViewport(0, mainViewport,
			ImGuiDockNodeFlags_NoDockingOverCentralNode |
			ImGuiDockNodeFlags_PassthruCentralNode |
			ImGuiDockNodeFlags_AutoHideTabBar);
	});

	// Main content window: focus target for the MSX display area.  Docked
	// into central node so it receives clicks there.  When focused, we
	// override WantCapture so input goes to the application (see
	// ImGuiManager).
	ImGui::SetNextWindowPos(mainViewport->Pos);
	ImGui::SetNextWindowSize(mainViewport->Size);
	auto flags = ImGuiWindowFlags_NoTitleBar |
			ImGuiWindowFlags_NoBackground |
			ImGuiWindowFlags_NoResize |
			ImGuiWindowFlags_NoMove |
			ImGuiWindowFlags_NoScrollbar |
			ImGuiWindowFlags_NoCollapse |
			ImGuiWindowFlags_NoBringToFrontOnFocus;
	bool focus = false;
	im::Window("MSX Display Area", nullptr, flags, [&]{
		// Ensure this window has focus on startup (after other windows are loaded)
		if (ImGui::GetFrameCount() == 1) {
			ImGui::SetWindowFocus();
		}
		// If no other window currently has focus, then take it ourselves.
		if (ImGui::GetCurrentContext()->NavWindow == nullptr) {
			ImGui::SetWindowFocus();
		}

		focus = ImGui::IsWindowFocused(ImGuiFocusedFlags_RootWindow);
		if (focus) {
			ImGui::SetNextFrameWantCaptureMouse(false);
			ImGui::SetNextFrameWantCaptureKeyboard(false);
		}
		if (auto* motherBoard = manager.getReactor().getMotherBoard()) {
			if (auto* keyb = motherBoard->getKeyboard()) {
				auto time = motherBoard->getCurrentTime();
				keyb->setFocus(focus, time);
			}
		}
	});

	manager.paintImGui(focus);

	// Rendering
	const ImGuiIO& io = ImGui::GetIO();
	ImGui::Render();
	ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

	// Update and Render additional Platform Windows
	// (Platform functions may change the current OpenGL context, so we
	// save/restore it to make it easier to paste this code elsewhere.
	if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) {
		SDL_Window* backup_current_window = SDL_GL_GetCurrentWindow();
		SDL_GLContext backup_current_context = SDL_GL_GetCurrentContext();
		ImGui::UpdatePlatformWindows();
		ImGui::RenderPlatformWindowsDefault();
		SDL_GL_MakeCurrent(backup_current_window, backup_current_context);

#ifdef __APPLE__
		if (ImGui::GetFrameCount() == 1) {
			// On startup, bring main openMSX window to front, which it doesn't
			// do it by itself due to creation of platform windows for viewports.
			SDL_RaiseWindow(SDL_GetWindowFromID(WindowEvent::getMainWindowId()));
		}
#endif
	}
}

} // namespace openmsx