/*  PCSX2 - PS2 Emulator for PCs
 *  Copyright (C) 2002-2021  PCSX2 Dev Team
 *
 *  PCSX2 is free software: you can redistribute it and/or modify it under the terms
 *  of the GNU Lesser General Public License as published by the Free Software Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  PCSX2 is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 *  PURPOSE.  See the GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along with PCSX2.
 *  If not, see <http://www.gnu.org/licenses/>.
 */

#include "common/GL/ContextWGL.h"
#include "common/Assertions.h"
#include "common/Console.h"
#include "common/ScopedGuard.h"

static void* GetProcAddressCallback(const char* name)
{
	void* addr = wglGetProcAddress(name);
	if (addr)
		return addr;

	// try opengl32.dll
	return ::GetProcAddress(GetModuleHandleA("opengl32.dll"), name);
}

namespace GL
{
	ContextWGL::ContextWGL(const WindowInfo& wi)
		: Context(wi)
	{
	}

	ContextWGL::~ContextWGL()
	{
		if (wglGetCurrentContext() == m_rc)
			wglMakeCurrent(m_dc, nullptr);

		if (m_rc)
			wglDeleteContext(m_rc);

		ReleaseDC();
	}

	std::unique_ptr<Context> ContextWGL::Create(const WindowInfo& wi, gsl::span<const Version> versions_to_try)
	{
		std::unique_ptr<ContextWGL> context = std::make_unique<ContextWGL>(wi);
		if (!context->Initialize(versions_to_try))
			return nullptr;

		return context;
	}

	bool ContextWGL::Initialize(gsl::span<const Version> versions_to_try)
	{
		if (m_wi.type == WindowInfo::Type::Win32)
		{
			if (!InitializeDC())
				return false;
		}
		else
		{
			Console.Error("ContextWGL must always start with a valid surface.");
			return false;
		}

		// Everything including core/ES requires a dummy profile to load the WGL extensions.
		if (!CreateAnyContext(nullptr, true))
			return false;

		for (const Version& cv : versions_to_try)
		{
			if (cv.profile == Profile::NoProfile)
			{
				// we already have the dummy context, so just use that
				m_version = cv;
				return true;
			}
			else if (CreateVersionContext(cv, nullptr, true))
			{
				m_version = cv;
				return true;
			}
		}

		return false;
	}

	void* ContextWGL::GetProcAddress(const char* name)
	{
		return GetProcAddressCallback(name);
	}

	bool ContextWGL::ChangeSurface(const WindowInfo& new_wi)
	{
		const bool was_current = (wglGetCurrentContext() == m_rc);

		ReleaseDC();

		m_wi = new_wi;
		if (!InitializeDC())
			return false;

		if (was_current && !wglMakeCurrent(m_dc, m_rc))
		{
			Console.Error("Failed to make context current again after surface change: 0x%08X", GetLastError());
			return false;
		}

		return true;
	}

	void ContextWGL::ResizeSurface(u32 new_surface_width /*= 0*/, u32 new_surface_height /*= 0*/)
	{
		RECT client_rc = {};
		GetClientRect(GetHWND(), &client_rc);
		m_wi.surface_width = static_cast<u32>(client_rc.right - client_rc.left);
		m_wi.surface_height = static_cast<u32>(client_rc.bottom - client_rc.top);
	}

	bool ContextWGL::SwapBuffers()
	{
		return ::SwapBuffers(m_dc);
	}

	bool ContextWGL::MakeCurrent()
	{
		if (!wglMakeCurrent(m_dc, m_rc))
		{
			Console.Error("wglMakeCurrent() failed: 0x%08X", GetLastError());
			return false;
		}

		return true;
	}

	bool ContextWGL::DoneCurrent()
	{
		return wglMakeCurrent(m_dc, nullptr);
	}

	bool ContextWGL::SetSwapInterval(s32 interval)
	{
		if (!GLAD_WGL_EXT_swap_control)
			return false;

		return wglSwapIntervalEXT(interval);
	}

	std::unique_ptr<Context> ContextWGL::CreateSharedContext(const WindowInfo& wi)
	{
		std::unique_ptr<ContextWGL> context = std::make_unique<ContextWGL>(wi);
		if (wi.type == WindowInfo::Type::Win32)
		{
			if (!context->InitializeDC())
				return nullptr;
		}
		else
		{
			Console.Error("PBuffer not implemented");
			return nullptr;
		}

		if (m_version.profile == Profile::NoProfile)
		{
			if (!context->CreateAnyContext(m_rc, false))
				return nullptr;
		}
		else
		{
			if (!context->CreateVersionContext(m_version, m_rc, false))
				return nullptr;
		}

		context->m_version = m_version;
		return context;
	}

	HDC ContextWGL::GetDCAndSetPixelFormat(HWND hwnd)
	{
		PIXELFORMATDESCRIPTOR pfd = {};
		pfd.nSize = sizeof(pfd);
		pfd.nVersion = 1;
		pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;
		pfd.iPixelType = PFD_TYPE_RGBA;
		pfd.dwLayerMask = PFD_MAIN_PLANE;
		pfd.cRedBits = 8;
		pfd.cGreenBits = 8;
		pfd.cBlueBits = 8;
		pfd.cColorBits = 24;

		HDC hDC = ::GetDC(hwnd);
		if (!hDC)
		{
			Console.Error("GetDC() failed: 0x%08X", GetLastError());
			return false;
		}

		if (!m_pixel_format.has_value())
		{
			const int pf = ChoosePixelFormat(hDC, &pfd);
			if (pf == 0)
			{
				Console.Error("ChoosePixelFormat() failed: 0x%08X", GetLastError());
				::ReleaseDC(hwnd, hDC);
				return false;
			}

			m_pixel_format = pf;
		}

		if (!SetPixelFormat(hDC, m_pixel_format.value(), &pfd))
		{
			Console.Error("SetPixelFormat() failed: 0x%08X", GetLastError());
			::ReleaseDC(hwnd, hDC);
			return {};
		}

		return hDC;
	}

	bool ContextWGL::InitializeDC()
	{
		if (m_wi.type == WindowInfo::Type::Win32)
		{
			m_dc = GetDCAndSetPixelFormat(GetHWND());
			if (!m_dc)
			{
				Console.Error("Failed to get DC for window");
				return false;
			}

			return true;
		}
		else if (m_wi.type == WindowInfo::Type::Surfaceless)
		{
			return CreatePBuffer();
		}
		else
		{
			Console.Error("Unknown window info type %u", static_cast<unsigned>(m_wi.type));
			return false;
		}
	}

	void ContextWGL::ReleaseDC()
	{
		if (m_pbuffer)
		{
			wglReleasePbufferDCARB(m_pbuffer, m_dc);
			m_dc = {};

			wglDestroyPbufferARB(m_pbuffer);
			m_pbuffer = {};

			::ReleaseDC(m_dummy_window, m_dummy_dc);
			m_dummy_dc = {};

			DestroyWindow(m_dummy_window);
			m_dummy_window = {};
		}
		else if (m_dc)
		{
			::ReleaseDC(GetHWND(), m_dc);
			m_dc = {};
		}
	}

	bool ContextWGL::CreatePBuffer()
	{
		static bool window_class_registered = false;
		static const wchar_t* window_class_name = L"ContextWGLPBuffer";

		if (!window_class_registered)
		{
			WNDCLASSEXW wc = {};
			wc.cbSize = sizeof(WNDCLASSEXW);
			wc.style = 0;
			wc.lpfnWndProc = DefWindowProcW;
			wc.cbClsExtra = 0;
			wc.cbWndExtra = 0;
			wc.hInstance = GetModuleHandle(nullptr);
			wc.hIcon = NULL;
			wc.hCursor = LoadCursor(NULL, IDC_ARROW);
			wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
			wc.lpszMenuName = NULL;
			wc.lpszClassName = window_class_name;
			wc.hIconSm = NULL;

			if (!RegisterClassExW(&wc))
			{
				Console.Error("(ContextWGL::CreatePBuffer) RegisterClassExW() failed");
				return false;
			}

			window_class_registered = true;
		}

		HWND hwnd = CreateWindowExW(0, window_class_name, window_class_name, 0, 0, 0, 0, 0, NULL, NULL, NULL, NULL);
		if (!hwnd)
		{
			Console.Error("(ContextWGL::CreatePBuffer) CreateWindowEx() failed");
			return false;
		}

		ScopedGuard hwnd_guard([hwnd]() { DestroyWindow(hwnd); });

		HDC hdc = GetDCAndSetPixelFormat(hwnd);
		if (!hdc)
			return false;

		ScopedGuard hdc_guard([hdc, hwnd]() { ::ReleaseDC(hwnd, hdc); });

		static constexpr const int pb_attribs[] = {0, 0};

		pxAssertRel(m_pixel_format.has_value(), "Has pixel format for pbuffer");
		HPBUFFERARB pbuffer = wglCreatePbufferARB(hdc, m_pixel_format.value(), 1, 1, pb_attribs);
		if (!pbuffer)
		{
			Console.Error("(ContextWGL::CreatePBuffer) wglCreatePbufferARB() failed");
			return false;
		}

		ScopedGuard pbuffer_guard([pbuffer]() { wglDestroyPbufferARB(pbuffer); });

		m_dc = wglGetPbufferDCARB(pbuffer);
		if (!m_dc)
		{
			Console.Error("(ContextWGL::CreatePbuffer) wglGetPbufferDCARB() failed");
			return false;
		}

		m_dummy_window = hwnd;
		m_dummy_dc = hdc;
		m_pbuffer = pbuffer;

		pbuffer_guard.Cancel();
		hdc_guard.Cancel();
		hwnd_guard.Cancel();
		return true;
	}

	bool ContextWGL::CreateAnyContext(HGLRC share_context, bool make_current)
	{
		m_rc = wglCreateContext(m_dc);
		if (!m_rc)
		{
			Console.Error("wglCreateContext() failed: 0x%08X", GetLastError());
			return false;
		}

		if (make_current)
		{
			if (!wglMakeCurrent(m_dc, m_rc))
			{
				Console.Error("wglMakeCurrent() failed: 0x%08X", GetLastError());
				return false;
			}

			// re-init glad-wgl
			if (!gladLoadWGLLoader([](const char* name) -> void* { return wglGetProcAddress(name); }, m_dc))
			{
				Console.Error("Loading GLAD WGL functions failed");
				return false;
			}
		}

		if (share_context && !wglShareLists(share_context, m_rc))
		{
			Console.Error("wglShareLists() failed: 0x%08X", GetLastError());
			return false;
		}

		return true;
	}

	bool ContextWGL::CreateVersionContext(const Version& version, HGLRC share_context, bool make_current)
	{
		// we need create context attribs
		if (!GLAD_WGL_ARB_create_context)
		{
			Console.Error("Missing GLAD_WGL_ARB_create_context.");
			return false;
		}

		HGLRC new_rc;
		if (version.profile == Profile::Core)
		{
			const int attribs[] = {
				WGL_CONTEXT_PROFILE_MASK_ARB, WGL_CONTEXT_CORE_PROFILE_BIT_ARB,
				WGL_CONTEXT_MAJOR_VERSION_ARB, version.major_version,
				WGL_CONTEXT_MINOR_VERSION_ARB, version.minor_version,
#ifdef _DEBUG
				WGL_CONTEXT_FLAGS_ARB, WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB | WGL_CONTEXT_DEBUG_BIT_ARB,
#else
				WGL_CONTEXT_FLAGS_ARB, WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB,
#endif
				0, 0};

			new_rc = wglCreateContextAttribsARB(m_dc, share_context, attribs);
		}
		else if (version.profile == Profile::ES)
		{
			if ((version.major_version >= 2 && !GLAD_WGL_EXT_create_context_es2_profile) ||
				(version.major_version < 2 && !GLAD_WGL_EXT_create_context_es_profile))
			{
				Console.Error("WGL_EXT_create_context_es_profile not supported");
				return false;
			}

			const int attribs[] = {
				WGL_CONTEXT_PROFILE_MASK_ARB, ((version.major_version >= 2) ? WGL_CONTEXT_ES2_PROFILE_BIT_EXT : WGL_CONTEXT_ES_PROFILE_BIT_EXT),
				WGL_CONTEXT_MAJOR_VERSION_ARB, version.major_version,
				WGL_CONTEXT_MINOR_VERSION_ARB, version.minor_version,
				0, 0};

			new_rc = wglCreateContextAttribsARB(m_dc, share_context, attribs);
		}
		else
		{
			Console.Error("Unknown profile");
			return false;
		}

		if (!new_rc)
			return false;

		// destroy and swap contexts
		if (m_rc)
		{
			if (!wglMakeCurrent(m_dc, make_current ? new_rc : nullptr))
			{
				Console.Error("wglMakeCurrent() failed: 0x%08X", GetLastError());
				wglDeleteContext(new_rc);
				return false;
			}

			// re-init glad-wgl
			if (make_current && !gladLoadWGLLoader([](const char* name) -> void* { return wglGetProcAddress(name); }, m_dc))
			{
				Console.Error("Loading GLAD WGL functions failed");
				return false;
			}

			wglDeleteContext(m_rc);
		}

		m_rc = new_rc;
		return true;
	}
} // namespace GL