#include "d3d11_window.hpp"

#include <imgui_impl_win32.h>

// Forward declared in the ImGui Win32 backend; lets ImGui consume input first.
extern IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam);

using Microsoft::WRL::ComPtr;

namespace coop
{

namespace
{
constexpr wchar_t kWindowClass[] = L"CoopAllTheThingsWindow";
}

D3D11Window::~D3D11Window()
{
	release_render_target();
	if (hwnd_ != nullptr)
	{
		DestroyWindow(hwnd_);
		hwnd_ = nullptr;
	}
	UnregisterClassW(kWindowClass, GetModuleHandleW(nullptr));
}

bool D3D11Window::create(const wchar_t* title)
{
	const HINSTANCE instance = GetModuleHandleW(nullptr);

	WNDCLASSEXW wc = {};
	wc.cbSize = sizeof(wc);
	wc.style = CS_HREDRAW | CS_VREDRAW;
	wc.lpfnWndProc = &D3D11Window::wnd_proc;
	wc.hInstance = instance;
	wc.hCursor = LoadCursorW(nullptr, IDC_ARROW);
	wc.lpszClassName = kWindowClass;
	if (RegisterClassExW(&wc) == 0)
	{
		return false;
	}

	// Borderless popup covering the primary monitor. Steam RPT only streams the
	// focused window, and exclusive-fullscreen swap chains can't be captured, so
	// a plain WS_POPUP is exactly what we want.
	const int width = GetSystemMetrics(SM_CXSCREEN);
	const int height = GetSystemMetrics(SM_CYSCREEN);

	hwnd_ = CreateWindowExW(0, kWindowClass, title, WS_POPUP, 0, 0, width, height, nullptr, nullptr, instance, this);
	if (hwnd_ == nullptr)
	{
		return false;
	}

	if (!create_device())
	{
		return false;
	}

	ShowWindow(hwnd_, SW_SHOW);
	UpdateWindow(hwnd_);
	SetForegroundWindow(hwnd_);
	return true;
}

bool D3D11Window::create_device()
{
	DXGI_SWAP_CHAIN_DESC1 desc = {};
	desc.Width = 0; // derive from the window client area
	desc.Height = 0;
	desc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
	desc.SampleDesc.Count = 1;
	desc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
	desc.BufferCount = 2;
	desc.Scaling = DXGI_SCALING_STRETCH;
	desc.SwapEffect = DXGI_SWAP_EFFECT_FLIP_DISCARD;
	desc.AlphaMode = DXGI_ALPHA_MODE_IGNORE;

	UINT flags = 0;
#ifdef _DEBUG
	flags |= D3D11_CREATE_DEVICE_DEBUG;
#endif
	const D3D_FEATURE_LEVEL levels[] = {D3D_FEATURE_LEVEL_11_1, D3D_FEATURE_LEVEL_11_0};

	if (FAILED(D3D11CreateDevice(nullptr, D3D_DRIVER_TYPE_HARDWARE, nullptr, flags, levels, _countof(levels),
	                             D3D11_SDK_VERSION, device_.GetAddressOf(), nullptr, context_.GetAddressOf())))
	{
		return false;
	}

	ComPtr<IDXGIDevice> dxgi_device;
	if (FAILED(device_.As(&dxgi_device)))
	{
		return false;
	}
	ComPtr<IDXGIAdapter> adapter;
	if (FAILED(dxgi_device->GetAdapter(adapter.GetAddressOf())))
	{
		return false;
	}
	ComPtr<IDXGIFactory2> factory;
	if (FAILED(adapter->GetParent(IID_PPV_ARGS(factory.GetAddressOf()))))
	{
		return false;
	}

	if (FAILED(factory->CreateSwapChainForHwnd(device_.Get(), hwnd_, &desc, nullptr, nullptr,
	                                           swap_chain_.GetAddressOf())))
	{
		return false;
	}
	// Don't let DXGI swallow Alt+Enter into an exclusive-fullscreen transition.
	factory->MakeWindowAssociation(hwnd_, DXGI_MWA_NO_ALT_ENTER);

	create_render_target();
	return true;
}

void D3D11Window::create_render_target()
{
	ComPtr<ID3D11Texture2D> back_buffer;
	if (SUCCEEDED(swap_chain_->GetBuffer(0, IID_PPV_ARGS(back_buffer.GetAddressOf()))))
	{
		device_->CreateRenderTargetView(back_buffer.Get(), nullptr, rtv_.ReleaseAndGetAddressOf());
	}
}

void D3D11Window::release_render_target()
{
	rtv_.Reset();
}

void D3D11Window::handle_resize(UINT width, UINT height)
{
	if (swap_chain_ == nullptr || width == 0 || height == 0)
	{
		return;
	}
	release_render_target();
	swap_chain_->ResizeBuffers(0, width, height, DXGI_FORMAT_UNKNOWN, 0);
	create_render_target();
}

bool D3D11Window::pump_messages()
{
	MSG msg;
	while (PeekMessageW(&msg, nullptr, 0, 0, PM_REMOVE))
	{
		if (msg.message == WM_QUIT)
		{
			return false;
		}
		TranslateMessage(&msg);
		DispatchMessageW(&msg);
	}
	if (resize_pending_)
	{
		handle_resize(resize_width_, resize_height_);
		resize_pending_ = false;
	}
	return true;
}

void D3D11Window::render_frame(const RenderCallback& render)
{
	const float clear[4] = {0.06f, 0.06f, 0.08f, 1.0f};
	context_->OMSetRenderTargets(1, rtv_.GetAddressOf(), nullptr);
	context_->ClearRenderTargetView(rtv_.Get(), clear);

	if (render)
	{
		render();
	}

	// vsync on: matches the captured stream cadence and avoids a busy spin.
	swap_chain_->Present(1, 0);
}

LRESULT CALLBACK D3D11Window::wnd_proc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
{
	if (msg == WM_NCCREATE)
	{
		auto* create = reinterpret_cast<CREATESTRUCTW*>(lparam);
		SetWindowLongPtrW(hwnd, GWLP_USERDATA, reinterpret_cast<LONG_PTR>(create->lpCreateParams));
	}

	if (ImGui_ImplWin32_WndProcHandler(hwnd, msg, wparam, lparam))
	{
		return true;
	}

	auto* self = reinterpret_cast<D3D11Window*>(GetWindowLongPtrW(hwnd, GWLP_USERDATA));

	switch (msg)
	{
	case WM_SIZE:
		if (self != nullptr && wparam != SIZE_MINIMIZED)
		{
			self->resize_pending_ = true;
			self->resize_width_ = LOWORD(lparam);
			self->resize_height_ = HIWORD(lparam);
		}
		return 0;
	case WM_KEYDOWN:
		// Spike convenience: Esc quits so we aren't stuck in a borderless window.
		if (wparam == VK_ESCAPE)
		{
			PostQuitMessage(0);
		}
		return 0;
	case WM_DESTROY:
		PostQuitMessage(0);
		return 0;
	default:
		break;
	}
	return DefWindowProcW(hwnd, msg, wparam, lparam);
}

} // namespace coop