// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "third_party/blink/renderer/modules/xr/xr_webgl_layer.h"

#include <algorithm>
#include <utility>

#include "base/numerics/safe_conversions.h"
#include "base/trace_event/trace_event.h"
#include "third_party/blink/renderer/core/frame/web_feature.h"
#include "third_party/blink/renderer/core/imagebitmap/image_bitmap.h"
#include "third_party/blink/renderer/core/inspector/console_message.h"
#include "third_party/blink/renderer/modules/webgl/webgl_framebuffer.h"
#include "third_party/blink/renderer/modules/webgl/webgl_rendering_context_base.h"
#include "third_party/blink/renderer/modules/xr/xr_frame_provider.h"
#include "third_party/blink/renderer/modules/xr/xr_session.h"
#include "third_party/blink/renderer/modules/xr/xr_system.h"
#include "third_party/blink/renderer/modules/xr/xr_utils.h"
#include "third_party/blink/renderer/modules/xr/xr_view.h"
#include "third_party/blink/renderer/modules/xr/xr_viewport.h"
#include "third_party/blink/renderer/modules/xr/xr_webgl_frame_transport_context_impl.h"
#include "third_party/blink/renderer/platform/bindings/exception_state.h"
#include "ui/gfx/geometry/point_f.h"
#include "ui/gfx/geometry/size.h"
#include "ui/gfx/geometry/size_conversions.h"
#include "ui/gfx/geometry/size_f.h"

namespace blink {

namespace {

const double kFramebufferMinScale = 0.2;
const uint32_t kCleanFrameWarningLimit = 5;

const char kCleanFrameWarning[] =
    "Note: The XRSession has completed multiple animation frames without "
    "drawing anything to the baseLayer's framebuffer, resulting in no visible "
    "output.";

}  // namespace

XRWebGLLayer* XRWebGLLayer::Create(XRSession* session,
                                   const V8XRWebGLRenderingContext* context,
                                   const XRWebGLLayerInit* initializer,
                                   ExceptionState& exception_state) {
  if (session->ended()) {
    exception_state.ThrowDOMException(DOMExceptionCode::kInvalidStateError,
                                      "Cannot create an XRWebGLLayer for an "
                                      "XRSession which has already ended.");
    return nullptr;
  }

  WebGLRenderingContextBase* webgl_context =
      webglRenderingContextBaseFromUnion(context);

  if (webgl_context->isContextLost()) {
    exception_state.ThrowDOMException(DOMExceptionCode::kInvalidStateError,
                                      "Cannot create an XRWebGLLayer with a "
                                      "lost WebGL context.");
    return nullptr;
  }

  if (session->immersive() && !webgl_context->IsXRCompatible()) {
    exception_state.ThrowDOMException(
        DOMExceptionCode::kInvalidStateError,
        "WebGL context must be marked as XR compatible in order to "
        "use with an immersive XRSession");
    return nullptr;
  }

  if (session->GraphicsApi() != XRGraphicsBinding::Api::kWebGL) {
    exception_state.ThrowDOMException(DOMExceptionCode::kInvalidStateError,
                                      "Cannot create an XRWebGLLayer with a "
                                      "WebGPU-based XRSession.");
    return nullptr;
  }

  // TODO(crbug.com/941753): In the future this should be communicated by the
  // drawing buffer and indicate whether the depth buffers are being supplied to
  // the XR compositor.
  bool compositor_supports_depth_values = false;
  bool want_ignore_depth_values = initializer->ignoreDepthValues();

  if (want_ignore_depth_values) {
    UseCounter::Count(session->GetExecutionContext(),
                      WebFeature::kWebXrIgnoreDepthValues);
  }

  // The ignoreDepthValues attribute of XRWebGLLayer may only be set to false if
  // the compositor is actually making use of the depth values and the user did
  // not set ignoreDepthValues to true explicitly.
  bool ignore_depth_values =
      !compositor_supports_depth_values || want_ignore_depth_values;

  double framebuffer_scale = 1.0;

  // Inline sessions don't go through the XR compositor, so they don't need to
  // allocate a separate drawing buffer or expose a framebuffer.
  if (!session->immersive()) {
    return MakeGarbageCollected<XRWebGLLayer>(session, webgl_context, nullptr,
                                              nullptr, framebuffer_scale,
                                              ignore_depth_values);
  }

  const bool want_antialiasing =
      initializer->antialias() && session->CanEnableAntiAliasing();
  const bool want_depth_buffer = initializer->depth();
  const bool want_stencil_buffer = initializer->stencil();
  const bool want_alpha_channel = initializer->alpha();

  // Allocate a drawing buffer to back the framebuffer if needed.
  if (initializer->hasFramebufferScaleFactor()) {
    UseCounter::Count(session->GetExecutionContext(),
                      WebFeature::kWebXrFramebufferScale);

    // The max size will be either the native resolution or the default
    // if that happens to be larger than the native res. (That can happen on
    // desktop systems.)
    double max_scale = std::max(session->NativeFramebufferScale(), 1.0);

    // Clamp the developer-requested framebuffer size to ensure it's not too
    // small to see or unreasonably large.
    // TODO(bajones): Would be best to have the max value communicated from the
    // service rather than limited to the native res.
    framebuffer_scale = std::clamp(initializer->framebufferScaleFactor(),
                                   kFramebufferMinScale, max_scale);
  }

  gfx::SizeF framebuffers_size = session->RecommendedFramebufferSize();

  gfx::Size desired_size =
      gfx::ToFlooredSize(gfx::ScaleSize(framebuffers_size, framebuffer_scale));

  // Create an opaque WebGL Framebuffer
  WebGLFramebuffer* framebuffer = WebGLFramebuffer::CreateOpaque(
      webgl_context, want_depth_buffer, want_stencil_buffer);

  scoped_refptr<XRWebGLDrawingBuffer> drawing_buffer =
      XRWebGLDrawingBuffer::Create(webgl_context->GetDrawingBuffer(),
                                   framebuffer->Object(), desired_size,
                                   want_alpha_channel, want_depth_buffer,
                                   want_stencil_buffer, want_antialiasing);

  if (!drawing_buffer) {
    exception_state.ThrowDOMException(DOMExceptionCode::kOperationError,
                                      "Unable to create a framebuffer.");
    return nullptr;
  }

  auto* result = MakeGarbageCollected<XRWebGLLayer>(
      session, webgl_context, std::move(drawing_buffer), framebuffer,
      framebuffer_scale, ignore_depth_values);
  result->CreateLayerBackend();
  return result;
}

XRWebGLLayer::XRWebGLLayer(XRSession* session,
                           WebGLRenderingContextBase* webgl_context,
                           scoped_refptr<XRWebGLDrawingBuffer> drawing_buffer,
                           WebGLFramebuffer* framebuffer,
                           double framebuffer_scale,
                           bool ignore_depth_values)
    : XRLayer(session),
      webgl_context_(webgl_context),
      framebuffer_(framebuffer),
      framebuffer_scale_(framebuffer_scale),
      ignore_depth_values_(ignore_depth_values) {
  transport_delegate_ = MakeGarbageCollected<XRWebGLFrameTransportDelegate>(
      MakeGarbageCollected<XRWebGLFrameTransportContextImpl>(webgl_context));
  if (framebuffer) {
    // Must have a drawing buffer for immersive sessions.
    DCHECK(drawing_buffer);
    drawing_buffer_ = std::move(drawing_buffer);
  } else {
    // Only inline sessions are allowed to have a null drawing buffer.
    DCHECK(!session->immersive());
  }

  UpdateViewports();
}

XRWebGLLayer::~XRWebGLLayer() {
  if (drawing_buffer_) {
    drawing_buffer_->BeginDestruction();
  }
}

XRLayerType XRWebGLLayer::LayerType() const {
  return XRLayerType::kWebGLLayer;
}

uint32_t XRWebGLLayer::framebufferWidth() const {
  if (drawing_buffer_) {
    return drawing_buffer_->size().width();
  }
  return webgl_context_->drawingBufferWidth();
}

uint32_t XRWebGLLayer::framebufferHeight() const {
  if (drawing_buffer_) {
    return drawing_buffer_->size().height();
  }
  return webgl_context_->drawingBufferHeight();
}

bool XRWebGLLayer::antialias() const {
  if (drawing_buffer_) {
    return drawing_buffer_->antialias();
  }
  if (!webgl_context_->isContextLost()) {
    return webgl_context_->GetDrawingBuffer()->Multisample();
  }
  return false;
}

XRViewport* XRWebGLLayer::getViewport(XRView* view) {
  if (!view || view->session() != session())
    return nullptr;

  if (view->ViewData()->ApplyViewportScaleForFrame()) {
    UpdateViewports();
  }

  // framebuffer_scale_ is the scale requested by the web developer when this
  // layer was created. The session's recommended framebuffer scale is the scale
  // requested by the XR runtime. Both scales must be applied to the viewport.
  return view->Viewport(framebuffer_scale_ *
                        session()->RecommendedFramebufferScale());
}

XRViewport* XRWebGLLayer::GetViewportForEye(device::mojom::blink::XREye eye) {
  if (viewports_dirty_)
    UpdateViewports();

  if (eye == device::mojom::blink::XREye::kRight)
    return right_viewport_.Get();

  // This code path also handles an eye of "none".
  return left_viewport_.Get();
}

double XRWebGLLayer::getNativeFramebufferScaleFactor(XRSession* session) {
  return session->NativeFramebufferScale();
}

void XRWebGLLayer::UpdateViewports() {
  uint32_t framebuffer_width = framebufferWidth();
  uint32_t framebuffer_height = framebufferHeight();
  if (framebuffer_width == 0U || framebuffer_height == 0U) {
    LOG_IF(ERROR, !webgl_context_->isContextLost())
        << __func__ << " Received width=" << framebuffer_width
        << " height=" << framebuffer_height << " without having lost context";
    return;
  }

  viewports_dirty_ = false;

  // When calculating the scaled viewport size, round down to integer value, but
  // ensure that the value is nonzero and doesn't overflow. See
  // https://immersive-web.github.io/webxr/#xrview-obtain-a-scaled-viewport
  auto rounded = [](double v) {
    return std::max(1, base::saturated_cast<int>(v));
  };

  if (session()->immersive()) {
    // Calculate new sizes with optional viewport scale applied. This assumes
    // that XRSession::views() returns views in matching order.
    if (session()->StereoscopicViews()) {
      // TODO(1275873): This technically works fine because the entire bounds is
      // still sent to the XR process, but if there are more than two views,
      // the terms "left" and "right" are not accurate. The entire bounds of
      // all viewports should be sent instead.
      double left_scale =
          session()
              ->ViewDataForEye(device::mojom::blink::XREye::kLeft)
              ->CurrentViewportScale();
      left_viewport_ = MakeGarbageCollected<XRViewport>(
          0, 0, rounded(framebuffer_width * 0.5 * left_scale),
          rounded(framebuffer_height * left_scale));
      double right_scale =
          session()
              ->ViewDataForEye(device::mojom::blink::XREye::kRight)
              ->CurrentViewportScale();
      right_viewport_ = MakeGarbageCollected<XRViewport>(
          framebuffer_width * 0.5, 0,
          rounded(framebuffer_width * 0.5 * right_scale),
          rounded(framebuffer_height * right_scale));
    } else {
      // Phone immersive AR only uses one viewport, but the second viewport is
      // needed for the UpdateLayerBounds mojo call which currently expects
      // exactly two views. This should be revisited as part of a refactor to
      // handle a more general list of viewports, cf. https://crbug.com/928433.
      double mono_scale =
          session()
              ->ViewDataForEye(device::mojom::blink::XREye::kNone)
              ->CurrentViewportScale();
      left_viewport_ = MakeGarbageCollected<XRViewport>(
          0, 0, rounded(framebuffer_width * mono_scale),
          rounded(framebuffer_height * mono_scale));
      right_viewport_ = nullptr;
    }

    session()->xr()->frameProvider()->UpdateWebGLLayerViewports(this);
  } else {
    // Currently, only immersive sessions implement dynamic viewport scaling.
    // Ignore the setting for non-immersive sessions, effectively treating
    // the minimum viewport scale as 1.0 which disables the feature.
    left_viewport_ = MakeGarbageCollected<XRViewport>(0, 0, framebuffer_width,
                                                      framebuffer_height);
  }
}

HTMLCanvasElement* XRWebGLLayer::output_canvas() const {
  if (!framebuffer_) {
    return webgl_context_->canvas();
  }
  return nullptr;
}

std::unique_ptr<SharedImageHolder> XRWebGLLayer::DoneWithSharedBuffer() {
  std::unique_ptr<SharedImageHolder> image_ref;

  if (is_direct_draw_frame) {
    image_ref = drawing_buffer_->DoneWithSharedBuffer();
    is_direct_draw_frame = false;
  }

  return image_ref;
}

void XRWebGLLayer::OnFrameStart() {
  if (framebuffer_) {
    framebuffer_->MarkOpaqueBufferComplete(true);
    framebuffer_->SetContentsChanged(false);

    const XRSharedImageData& content_image_data = SharedImage();

    if (content_image_data.shared_image) {
      drawing_buffer_->UseSharedBuffer(content_image_data.shared_image,
                                       content_image_data.sync_token);
      DVLOG(3) << __func__ << ": content_image_data.shared_image->mailbox()="
               << content_image_data.shared_image->mailbox().ToDebugString();
      is_direct_draw_frame = true;
    } else {
      is_direct_draw_frame = false;
    }
  }
}

void XRWebGLLayer::OnFrameEnd() {
  // The session might have ended in the middle of the frame. Only perform the
  // main work of OnFrameEnd if it's still valid. Otherwise, simply ensure the
  // shared image access is properly ended.
  if (session()->ended()) {
    DoneWithSharedBuffer();
    return;
  }

  if (framebuffer_) {
    framebuffer_->MarkOpaqueBufferComplete(false);

    // Submit the frame to the XR compositor.
    if (session()->immersive()) {
      bool framebuffer_dirty = framebuffer_->HaveContentsChanged();

      // Not drawing to the framebuffer during a session's rAF callback is
      // usually a sign that something is wrong, such as the app drawing to
      // the wrong render target. Show a warning in the console if we see that
      // happen too many times.
      if (!framebuffer_dirty) {
        // If the session doesn't have a pose then the framebuffer being clean
        // may be expected, so we won't count those frames.
        bool frame_had_pose = !!session()->GetMojoFrom(
            device::mojom::blink::XRReferenceSpaceType::kViewer);
        if (frame_had_pose) {
          clean_frame_count++;
          if (clean_frame_count == kCleanFrameWarningLimit) {
            session()->xr()->GetExecutionContext()->AddConsoleMessage(
                MakeGarbageCollected<ConsoleMessage>(
                    mojom::blink::ConsoleMessageSource::kRendering,
                    mojom::blink::ConsoleMessageLevel::kWarning,
                    kCleanFrameWarning));
          }
        }
      }

      // Always call submit, but notify if the contents were changed or not.
      session()->xr()->frameProvider()->SubmitLayer(
          layer_id(), this, framebuffer_->HaveContentsChanged());
    }
  }
}

void XRWebGLLayer::OnResize() {
  if (drawing_buffer_) {
    gfx::SizeF framebuffers_size = session()->RecommendedFramebufferSize();

    gfx::Size desired_size = gfx::ToFlooredSize(
        gfx::ScaleSize(framebuffers_size, framebuffer_scale_));
    drawing_buffer_->Resize(desired_size);
  }

  // With both immersive and non-immersive session the viewports should be
  // recomputed when the output canvas resizes.
  viewports_dirty_ = true;
}

std::unique_ptr<SharedImageHolder> XRWebGLLayer::TransferToSharedImageHolder() {
  if (drawing_buffer_) {
    return drawing_buffer_->TransferToSharedImageHolder();
  }
  return nullptr;
}

XRSession* XRWebGLLayer::session() const {
  return XRLayer::session();
}

XRFrameTransportDelegate* XRWebGLLayer::GetTransportDelegate() {
  return transport_delegate_;
}

XrLayerClient* XRWebGLLayer::LayerClient() {
  return this;
}

device::mojom::blink::XRCompositionLayerDataPtr XRWebGLLayer::CreateLayerData()
    const {
  auto layer_data = device::mojom::blink::XRCompositionLayerData::New();
  // Readonly data.
  layer_data->read_only_data = device::mojom::blink::XRLayerReadOnlyData::New();
  layer_data->read_only_data->layer_id = layer_id();
  layer_data->read_only_data->texture_width = framebufferWidth();
  layer_data->read_only_data->texture_height = framebufferHeight();
  layer_data->read_only_data->is_static = false;
  layer_data->read_only_data->needs_raster_access = false;
  layer_data->read_only_data->layout = V8ToMojomLayerLayout(
      session()->StereoscopicViews() ? V8XRLayerLayout::Enum::kStereoLeftRight
                                     : V8XRLayerLayout::Enum::kMono);
  // Mutable data.
  layer_data->mutable_data = device::mojom::blink::XRLayerMutableData::New();
  layer_data->mutable_data->blend_texture_source_alpha = true;
  layer_data->mutable_data->force_mono_presentation = false;
  layer_data->mutable_data->opacity = 1UL;
  layer_data->mutable_data->native_origin_information =
      device::mojom::blink::XRNativeOriginInformation::NewReferenceSpaceType(
          device::mojom::blink::XRReferenceSpaceType::kLocal);

  // Applies an empty projection layer data.
  layer_data->mutable_data->layer_data =
      device::mojom::blink::XRLayerSpecificData::NewProjection(
          device::mojom::blink::XRProjectionLayerData::New());

  return layer_data;
}

void XRWebGLLayer::Trace(Visitor* visitor) const {
  visitor->Trace(left_viewport_);
  visitor->Trace(right_viewport_);
  visitor->Trace(webgl_context_);
  visitor->Trace(framebuffer_);
  visitor->Trace(transport_delegate_);
  XRLayer::Trace(visitor);
}

}  // namespace blink