// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "modules/vr/VRDisplay.h"

#include "core/dom/DOMException.h"
#include "core/dom/FrameRequestCallback.h"
#include "core/dom/Fullscreen.h"
#include "core/dom/ScriptedAnimationController.h"
#include "core/frame/UseCounter.h"
#include "core/inspector/ConsoleMessage.h"
#include "gpu/command_buffer/client/gles2_interface.h"
#include "modules/vr/NavigatorVR.h"
#include "modules/vr/VRController.h"
#include "modules/vr/VRDisplayCapabilities.h"
#include "modules/vr/VREyeParameters.h"
#include "modules/vr/VRFrameData.h"
#include "modules/vr/VRLayer.h"
#include "modules/vr/VRPose.h"
#include "modules/vr/VRStageParameters.h"
#include "modules/webgl/WebGLRenderingContextBase.h"
#include "platform/Histogram.h"
#include "platform/UserGestureIndicator.h"
#include "public/platform/Platform.h"
#include "wtf/AutoReset.h"

namespace blink {

namespace {

VREye stringToVREye(const String& whichEye) {
  if (whichEye == "left")
    return VREyeLeft;
  if (whichEye == "right")
    return VREyeRight;
  return VREyeNone;
}

class VRDisplayFrameRequestCallback : public FrameRequestCallback {
 public:
  VRDisplayFrameRequestCallback(VRDisplay* vrDisplay)
      : m_vrDisplay(vrDisplay) {}
  ~VRDisplayFrameRequestCallback() override {}
  void handleEvent(double highResTimeMs) override {
    m_vrDisplay->serviceScriptedAnimations(highResTimeMs);
  }

  DEFINE_INLINE_VIRTUAL_TRACE() {
    visitor->trace(m_vrDisplay);

    FrameRequestCallback::trace(visitor);
  }

  Member<VRDisplay> m_vrDisplay;
};

}  // namespace

VRDisplay::VRDisplay(NavigatorVR* navigatorVR)
    : m_navigatorVR(navigatorVR),
      m_displayId(0),
      m_isConnected(false),
      m_isPresenting(false),
      m_canUpdateFramePose(true),
      m_capabilities(new VRDisplayCapabilities()),
      m_eyeParametersLeft(new VREyeParameters()),
      m_eyeParametersRight(new VREyeParameters()),
      m_depthNear(0.01),
      m_depthFar(10000.0),
      m_fullscreenCheckTimer(this, &VRDisplay::onFullscreenCheck),
      m_animationCallbackRequested(false),
      m_inAnimationFrame(false) {}

VRDisplay::~VRDisplay() {}

VRController* VRDisplay::controller() {
  return m_navigatorVR->controller();
}

void VRDisplay::update(const device::blink::VRDisplayPtr& display) {
  m_displayId = display->index;
  m_displayName = display->displayName;
  m_isConnected = true;

  m_capabilities->setHasOrientation(display->capabilities->hasOrientation);
  m_capabilities->setHasPosition(display->capabilities->hasPosition);
  m_capabilities->setHasExternalDisplay(
      display->capabilities->hasExternalDisplay);
  m_capabilities->setCanPresent(display->capabilities->canPresent);
  m_capabilities->setMaxLayers(display->capabilities->canPresent ? 1 : 0);

  m_eyeParametersLeft->update(display->leftEye);
  m_eyeParametersRight->update(display->rightEye);

  if (!display->stageParameters.is_null()) {
    if (!m_stageParameters)
      m_stageParameters = new VRStageParameters();
    m_stageParameters->update(display->stageParameters);
  } else {
    m_stageParameters = nullptr;
  }
}

void VRDisplay::disconnected() {
  if (m_isConnected)
    m_isConnected = !m_isConnected;
}

bool VRDisplay::getFrameData(VRFrameData* frameData) {
  updatePose();

  if (!frameData)
    return false;

  if (m_depthNear == m_depthFar)
    return false;

  return frameData->update(m_framePose, m_eyeParametersLeft,
                           m_eyeParametersRight, m_depthNear, m_depthFar);
}

VRPose* VRDisplay::getPose() {
  updatePose();

  if (!m_framePose)
    return nullptr;

  VRPose* pose = VRPose::create();
  pose->setPose(m_framePose);
  return pose;
}

void VRDisplay::updatePose() {
  if (m_canUpdateFramePose) {
    m_framePose = controller()->getPose(m_displayId);
    if (m_isPresenting)
      m_canUpdateFramePose = false;
  }
}

void VRDisplay::resetPose() {
  controller()->resetPose(m_displayId);
}

VREyeParameters* VRDisplay::getEyeParameters(const String& whichEye) {
  switch (stringToVREye(whichEye)) {
    case VREyeLeft:
      return m_eyeParametersLeft;
    case VREyeRight:
      return m_eyeParametersRight;
    default:
      return nullptr;
  }
}

int VRDisplay::requestAnimationFrame(FrameRequestCallback* callback) {
  Document* doc = m_navigatorVR->document();
  if (!doc)
    return 0;

  if (!m_animationCallbackRequested) {
    doc->requestAnimationFrame(new VRDisplayFrameRequestCallback(this));
    m_animationCallbackRequested = true;
  }

  callback->m_useLegacyTimeBase = false;
  return ensureScriptedAnimationController(doc).registerCallback(callback);
}

void VRDisplay::cancelAnimationFrame(int id) {
  if (!m_scriptedAnimationController)
    return;
  m_scriptedAnimationController->cancelCallback(id);
}

void VRDisplay::serviceScriptedAnimations(double monotonicAnimationStartTime) {
  if (!m_scriptedAnimationController)
    return;
  AutoReset<bool> animating(&m_inAnimationFrame, true);
  m_animationCallbackRequested = false;
  m_scriptedAnimationController->serviceScriptedAnimations(
      monotonicAnimationStartTime);
}

void ReportPresentationResult(PresentationResult result) {
  // Note that this is called twice for each call to requestPresent -
  // one to declare that requestPresent was called, and one for the
  // result.
  DEFINE_STATIC_LOCAL(
      EnumerationHistogram, vrPresentationResultHistogram,
      ("VRDisplayPresentResult",
       static_cast<int>(PresentationResult::PresentationResultMax)));
  vrPresentationResultHistogram.count(static_cast<int>(result));
}

ScriptPromise VRDisplay::requestPresent(ScriptState* scriptState,
                                        const HeapVector<VRLayer>& layers) {
  ExecutionContext* executionContext = scriptState->getExecutionContext();
  UseCounter::count(executionContext, UseCounter::VRRequestPresent);
  String errorMessage;
  if (!executionContext->isSecureContext(errorMessage)) {
    UseCounter::count(executionContext,
                      UseCounter::VRRequestPresentInsecureOrigin);
  }

  ReportPresentationResult(PresentationResult::Requested);

  ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
  ScriptPromise promise = resolver->promise();

  // If the VRDisplay does not advertise the ability to present reject the
  // request.
  if (!m_capabilities->canPresent()) {
    DOMException* exception =
        DOMException::create(InvalidStateError, "VRDisplay cannot present.");
    resolver->reject(exception);
    ReportPresentationResult(PresentationResult::VRDisplayCannotPresent);
    return promise;
  }

  bool firstPresent = !m_isPresenting;

  // Initiating VR presentation is only allowed in response to a user gesture.
  // If the VRDisplay is already presenting, however, repeated calls are
  // allowed outside a user gesture so that the presented content may be
  // updated.
  if (firstPresent && !UserGestureIndicator::utilizeUserGesture()) {
    DOMException* exception = DOMException::create(
        InvalidStateError, "API can only be initiated by a user gesture.");
    resolver->reject(exception);
    ReportPresentationResult(PresentationResult::NotInitiatedByUserGesture);
    return promise;
  }

  m_isPresenting = false;

  // A valid number of layers must be provided in order to present.
  if (layers.size() == 0 || layers.size() > m_capabilities->maxLayers()) {
    forceExitPresent();
    DOMException* exception =
        DOMException::create(InvalidStateError, "Invalid number of layers.");
    resolver->reject(exception);
    ReportPresentationResult(PresentationResult::InvalidNumberOfLayers);
    return promise;
  }

  m_layer = layers[0];

  if (!m_layer.source()) {
    forceExitPresent();
    DOMException* exception =
        DOMException::create(InvalidStateError, "Invalid layer source.");
    resolver->reject(exception);
    ReportPresentationResult(PresentationResult::InvalidLayerSource);
    return promise;
  }

  CanvasRenderingContext* renderingContext =
      m_layer.source()->renderingContext();

  if (!renderingContext || !renderingContext->is3d()) {
    forceExitPresent();
    DOMException* exception = DOMException::create(
        InvalidStateError, "Layer source must have a WebGLRenderingContext");
    resolver->reject(exception);
    ReportPresentationResult(
        PresentationResult::LayerSourceMissingWebGLContext);
    return promise;
  }

  // Save the WebGL script and underlying GL contexts for use by submitFrame().
  m_renderingContext = toWebGLRenderingContextBase(renderingContext);
  m_contextGL = m_renderingContext->contextGL();

  if ((m_layer.leftBounds().size() != 0 && m_layer.leftBounds().size() != 4) ||
      (m_layer.rightBounds().size() != 0 &&
       m_layer.rightBounds().size() != 4)) {
    forceExitPresent();
    DOMException* exception = DOMException::create(
        InvalidStateError,
        "Layer bounds must either be an empty array or have 4 values");
    resolver->reject(exception);
    ReportPresentationResult(PresentationResult::InvalidLayerBounds);
    return promise;
  }

  if (!m_capabilities->hasExternalDisplay()) {
    // TODO: Need a proper VR compositor, but for the moment on mobile
    // we'll just make the canvas fullscreen so that VrShell can pick it
    // up through the standard (high latency) compositing path.
    Fullscreen::requestFullscreen(*m_layer.source(),
                                  Fullscreen::UnprefixedRequest);

    // Check to see if the canvas is still the current fullscreen
    // element once per second.
    m_fullscreenCheckTimer.startRepeating(1.0, BLINK_FROM_HERE);
  }

  if (firstPresent) {
    bool secureContext = scriptState->getExecutionContext()->isSecureContext();
    controller()->requestPresent(resolver, m_displayId, secureContext);
  } else {
    updateLayerBounds();
    resolver->resolve();
    ReportPresentationResult(PresentationResult::SuccessAlreadyPresenting);
  }

  return promise;
}

ScriptPromise VRDisplay::exitPresent(ScriptState* scriptState) {
  ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
  ScriptPromise promise = resolver->promise();

  if (!m_isPresenting) {
    // Can't stop presenting if we're not presenting.
    DOMException* exception =
        DOMException::create(InvalidStateError, "VRDisplay is not presenting.");
    resolver->reject(exception);
    return promise;
  }

  controller()->exitPresent(m_displayId);

  resolver->resolve();

  forceExitPresent();

  return promise;
}

void VRDisplay::beginPresent(ScriptPromiseResolver* resolver) {
  if (m_capabilities->hasExternalDisplay()) {
    forceExitPresent();
    DOMException* exception = DOMException::create(
        InvalidStateError,
        "VR Presentation not implemented for this VRDisplay.");
    resolver->reject(exception);
    ReportPresentationResult(
        PresentationResult::PresentationNotSupportedByDisplay);
    return;
  }

  m_isPresenting = true;
  ReportPresentationResult(PresentationResult::Success);

  updateLayerBounds();

  resolver->resolve();
  m_navigatorVR->fireVRDisplayPresentChange(this);
}

void VRDisplay::forceExitPresent() {
  if (m_isPresenting) {
    if (!m_capabilities->hasExternalDisplay()) {
      Fullscreen::fullyExitFullscreen(m_layer.source()->document());
      m_fullscreenCheckTimer.stop();
    } else {
      // Can't get into this presentation mode, so nothing to do here.
    }
    m_navigatorVR->fireVRDisplayPresentChange(this);
  }

  m_isPresenting = false;
  m_renderingContext = nullptr;
  m_contextGL = nullptr;
}

void VRDisplay::updateLayerBounds() {
  // Set up the texture bounds for the provided layer
  device::blink::VRLayerBoundsPtr leftBounds =
      device::blink::VRLayerBounds::New();
  device::blink::VRLayerBoundsPtr rightBounds =
      device::blink::VRLayerBounds::New();

  if (m_layer.leftBounds().size() == 4) {
    leftBounds->left = m_layer.leftBounds()[0];
    leftBounds->top = m_layer.leftBounds()[1];
    leftBounds->width = m_layer.leftBounds()[2];
    leftBounds->height = m_layer.leftBounds()[3];
  } else {
    // Left eye defaults
    leftBounds->left = 0.0f;
    leftBounds->top = 0.0f;
    leftBounds->width = 0.5f;
    leftBounds->height = 1.0f;
  }

  if (m_layer.rightBounds().size() == 4) {
    rightBounds->left = m_layer.rightBounds()[0];
    rightBounds->top = m_layer.rightBounds()[1];
    rightBounds->width = m_layer.rightBounds()[2];
    rightBounds->height = m_layer.rightBounds()[3];
  } else {
    // Right eye defaults
    rightBounds->left = 0.5f;
    rightBounds->top = 0.0f;
    rightBounds->width = 0.5f;
    rightBounds->height = 1.0f;
  }

  controller()->updateLayerBounds(m_displayId, std::move(leftBounds),
                                  std::move(rightBounds));
}

HeapVector<VRLayer> VRDisplay::getLayers() {
  HeapVector<VRLayer> layers;

  if (m_isPresenting) {
    layers.append(m_layer);
  }

  return layers;
}

void VRDisplay::submitFrame() {
  Document* doc = m_navigatorVR->document();
  if (!m_isPresenting) {
    if (doc) {
      doc->addConsoleMessage(ConsoleMessage::create(
          RenderingMessageSource, WarningMessageLevel,
          "submitFrame has no effect when the VRDisplay is not presenting."));
    }
    return;
  }

  if (!m_inAnimationFrame) {
    if (doc) {
      doc->addConsoleMessage(
          ConsoleMessage::create(RenderingMessageSource, WarningMessageLevel,
                                 "submitFrame must be called within a "
                                 "VRDisplay.requestAnimationFrame callback."));
    }
    return;
  }

  if (!m_contextGL) {
    // Something got confused, we can't submit frames without a GL context.
    return;
  }

  // Write the frame number for the pose used into a bottom left pixel block.
  // It is read by chrome/browser/android/vr_shell/vr_shell.cc to associate
  // the correct corresponding pose for submission.
  auto gl = m_contextGL;

  // We must ensure that the WebGL app's GL state is preserved. We do this by
  // calling low-level GL commands directly so that the rendering context's
  // saved parameters don't get overwritten.

  gl->Enable(GL_SCISSOR_TEST);
  // Use a few pixels to ensure we get a clean color. The resolution for the
  // WebGL buffer may not match the final rendered destination size, and
  // texture filtering could interfere for single pixels. This isn't visible
  // since the final rendering hides the edges via a vignette effect.
  gl->Scissor(0, 0, 4, 4);
  gl->ColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
  int idx = m_framePose->poseIndex;
  // Careful with the arithmetic here. Float color 1.f is equivalent to int 255.
  gl->ClearColor((idx & 255) / 255.0f, ((idx >> 8) & 255) / 255.0f,
                 ((idx >> 16) & 255) / 255.0f, 1.0f);
  gl->Clear(GL_COLOR_BUFFER_BIT);

  // Set the GL state back to what was set by the WebVR application.
  m_renderingContext->restoreScissorEnabled();
  m_renderingContext->restoreScissorBox();
  m_renderingContext->restoreColorMask();
  m_renderingContext->restoreClearColor();

  controller()->submitFrame(m_displayId, m_framePose.Clone());
  m_canUpdateFramePose = true;
}

void VRDisplay::onFullscreenCheck(TimerBase*) {
  // TODO: This is a temporary measure to track if fullscreen mode has been
  // exited by the UA. If so we need to end VR presentation. Soon we won't
  // depend on the Fullscreen API to fake VR presentation, so this will
  // become unnessecary. Until that point, though, this seems preferable to
  // adding a bunch of notification plumbing to Fullscreen.
  if (!Fullscreen::isCurrentFullScreenElement(*m_layer.source())) {
    m_isPresenting = false;
    m_navigatorVR->fireVRDisplayPresentChange(this);
    m_fullscreenCheckTimer.stop();
    controller()->exitPresent(m_displayId);
  }
}

ScriptedAnimationController& VRDisplay::ensureScriptedAnimationController(
    Document* doc) {
  if (!m_scriptedAnimationController)
    m_scriptedAnimationController = ScriptedAnimationController::create(doc);

  return *m_scriptedAnimationController;
}

DEFINE_TRACE(VRDisplay) {
  visitor->trace(m_navigatorVR);
  visitor->trace(m_capabilities);
  visitor->trace(m_stageParameters);
  visitor->trace(m_eyeParametersLeft);
  visitor->trace(m_eyeParametersRight);
  visitor->trace(m_layer);
  visitor->trace(m_renderingContext);
  visitor->trace(m_scriptedAnimationController);
}

}  // namespace blink