// Copyright 2019 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include "VideoBackends/D3DCommon/SwapChain.h"

#include <algorithm>
#include <cstdint>

#include "Common/Assert.h"
#include "Common/CommonFuncs.h"
#include "Common/Logging/Log.h"
#include "Common/MsgHandler.h"
#include "VideoCommon/VideoConfig.h"

static bool IsTearingSupported(IDXGIFactory2* dxgi_factory)
{
  Microsoft::WRL::ComPtr<IDXGIFactory5> factory5;
  if (FAILED(dxgi_factory->QueryInterface(IID_PPV_ARGS(&factory5))))
    return false;

  UINT allow_tearing = 0;
  return SUCCEEDED(factory5->CheckFeatureSupport(DXGI_FEATURE_PRESENT_ALLOW_TEARING, &allow_tearing,
                                                 sizeof(allow_tearing))) &&
         allow_tearing != 0;
}

static bool GetFullscreenState(IDXGISwapChain1* swap_chain)
{
  BOOL fs = FALSE;
  return SUCCEEDED(swap_chain->GetFullscreenState(&fs, nullptr)) && fs;
}

namespace D3DCommon
{
SwapChain::SwapChain(const WindowSystemInfo& wsi, IDXGIFactory2* dxgi_factory, IUnknown* d3d_device)
    : m_wsi(wsi), m_dxgi_factory(dxgi_factory), m_d3d_device(d3d_device),
      m_allow_tearing_supported(IsTearingSupported(dxgi_factory))
{
}

SwapChain::~SwapChain()
{
  // Can't destroy swap chain while it's fullscreen.
  if (m_swap_chain && GetFullscreenState(m_swap_chain.Get()))
    m_swap_chain->SetFullscreenState(FALSE, nullptr);
}

bool SwapChain::WantsStereo()
{
  return g_ActiveConfig.stereo_mode == StereoMode::QuadBuffer;
}

u32 SwapChain::GetSwapChainFlags() const
{
  // This flag is necessary if we want to use a flip-model swapchain without locking the framerate
  return m_allow_tearing_supported ? DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING : 0;
}

bool SwapChain::CreateSwapChain(bool stereo)
{
  RECT client_rc;
  if (GetClientRect(static_cast<HWND>(m_wsi.render_surface), &client_rc))
  {
    m_width = client_rc.right - client_rc.left;
    m_height = client_rc.bottom - client_rc.top;
  }

  DXGI_SWAP_CHAIN_DESC1 swap_chain_desc = {};
  swap_chain_desc.Width = m_width;
  swap_chain_desc.Height = m_height;
  swap_chain_desc.BufferCount = SWAP_CHAIN_BUFFER_COUNT;
  swap_chain_desc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
  swap_chain_desc.SampleDesc.Count = 1;
  swap_chain_desc.SampleDesc.Quality = 0;
  swap_chain_desc.Format = GetDXGIFormatForAbstractFormat(m_texture_format, false);
  swap_chain_desc.Scaling = DXGI_SCALING_STRETCH;
  swap_chain_desc.SwapEffect = DXGI_SWAP_EFFECT_FLIP_DISCARD;
  swap_chain_desc.Stereo = stereo;
  swap_chain_desc.Flags = GetSwapChainFlags();

  HRESULT hr = m_dxgi_factory->CreateSwapChainForHwnd(
      m_d3d_device.Get(), static_cast<HWND>(m_wsi.render_surface), &swap_chain_desc, nullptr,
      nullptr, &m_swap_chain);
  if (FAILED(hr))
  {
    // Flip-model discard swapchains aren't supported on Windows 8, so here we fall back to
    // a sequential swapchain
    swap_chain_desc.SwapEffect = DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL;
    hr = m_dxgi_factory->CreateSwapChainForHwnd(m_d3d_device.Get(),
                                                static_cast<HWND>(m_wsi.render_surface),
                                                &swap_chain_desc, nullptr, nullptr, &m_swap_chain);
  }

  if (FAILED(hr))
  {
    // Flip-model swapchains aren't supported on Windows 7, so here we fall back to a legacy
    // BitBlt-model swapchain
    swap_chain_desc.SwapEffect = DXGI_SWAP_EFFECT_DISCARD;
    hr = m_dxgi_factory->CreateSwapChainForHwnd(m_d3d_device.Get(),
                                                static_cast<HWND>(m_wsi.render_surface),
                                                &swap_chain_desc, nullptr, nullptr, &m_swap_chain);
  }

  if (FAILED(hr))
  {
    PanicAlert("Failed to create swap chain with HRESULT %08X", hr);
    return false;
  }

  // We handle fullscreen ourselves.
  hr = m_dxgi_factory->MakeWindowAssociation(static_cast<HWND>(m_wsi.render_surface),
                                             DXGI_MWA_NO_WINDOW_CHANGES | DXGI_MWA_NO_ALT_ENTER);
  if (FAILED(hr))
    WARN_LOG(VIDEO, "MakeWindowAssociation() failed with HRESULT %08X", hr);

  m_stereo = stereo;
  if (!CreateSwapChainBuffers())
  {
    PanicAlert("Failed to create swap chain buffers");
    DestroySwapChainBuffers();
    m_swap_chain.Reset();
    return false;
  }

  return true;
}

void SwapChain::DestroySwapChain()
{
  DestroySwapChainBuffers();

  // Can't destroy swap chain while it's fullscreen.
  if (m_swap_chain && GetFullscreenState(m_swap_chain.Get()))
    m_swap_chain->SetFullscreenState(FALSE, nullptr);

  m_swap_chain.Reset();
}

bool SwapChain::ResizeSwapChain()
{
  DestroySwapChainBuffers();

  HRESULT hr = m_swap_chain->ResizeBuffers(SWAP_CHAIN_BUFFER_COUNT, 0, 0,
                                           GetDXGIFormatForAbstractFormat(m_texture_format, false),
                                           GetSwapChainFlags());
  if (FAILED(hr))
    WARN_LOG(VIDEO, "ResizeBuffers() failed with HRESULT %08X", hr);

  DXGI_SWAP_CHAIN_DESC1 desc;
  if (SUCCEEDED(m_swap_chain->GetDesc1(&desc)))
  {
    m_width = desc.Width;
    m_height = desc.Height;
  }

  return CreateSwapChainBuffers();
}

void SwapChain::SetStereo(bool stereo)
{
  if (m_stereo == stereo)
    return;

  DestroySwapChain();
  if (!CreateSwapChain(stereo))
  {
    PanicAlert("Failed to switch swap chain stereo mode");
    CreateSwapChain(false);
  }
}

bool SwapChain::GetFullscreen() const
{
  return GetFullscreenState(m_swap_chain.Get());
}

void SwapChain::SetFullscreen(bool request)
{
  m_swap_chain->SetFullscreenState(request, nullptr);
}

bool SwapChain::CheckForFullscreenChange()
{
  if (m_fullscreen_request != m_has_fullscreen)
  {
    HRESULT hr = m_swap_chain->SetFullscreenState(m_fullscreen_request, nullptr);
    if (SUCCEEDED(hr))
    {
      m_has_fullscreen = m_fullscreen_request;
      return true;
    }
  }

  const bool new_fullscreen_state = GetFullscreenState(m_swap_chain.Get());
  if (new_fullscreen_state != m_has_fullscreen)
  {
    m_has_fullscreen = new_fullscreen_state;
    m_fullscreen_request = new_fullscreen_state;
    return true;
  }

  return false;
}

bool SwapChain::Present()
{
  // When using sync interval 0, it is recommended to always pass the tearing flag when it is
  // supported, even when presenting in windowed mode. However, this flag cannot be used if the app
  // is in fullscreen mode as a result of calling SetFullscreenState.
  UINT present_flags = 0;
  if (m_allow_tearing_supported && !g_ActiveConfig.bVSyncActive && !m_has_fullscreen)
    present_flags |= DXGI_PRESENT_ALLOW_TEARING;

  HRESULT hr = m_swap_chain->Present(static_cast<UINT>(g_ActiveConfig.bVSyncActive), present_flags);
  if (FAILED(hr))
  {
    WARN_LOG(VIDEO, "Swap chain present failed with HRESULT %08X", hr);
    return false;
  }

  return true;
}

bool SwapChain::ChangeSurface(void* native_handle)
{
  DestroySwapChain();
  m_wsi.render_surface = native_handle;
  return CreateSwapChain(m_stereo);
}

}  // namespace D3DCommon