// 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/offscreencanvas2d/OffscreenCanvasRenderingContext2D.h"

#include "bindings/modules/v8/OffscreenCanvasRenderingContext2DOrWebGLRenderingContextOrWebGL2RenderingContext.h"
#include "core/frame/ImageBitmap.h"
#include "core/frame/Settings.h"
#include "core/workers/WorkerGlobalScope.h"
#include "core/workers/WorkerSettings.h"
#include "platform/graphics/ImageBuffer.h"
#include "platform/graphics/StaticBitmapImage.h"
#include "platform/graphics/UnacceleratedImageBufferSurface.h"
#include "platform/graphics/gpu/AcceleratedImageBufferSurface.h"
#include "wtf/Assertions.h"

#define UNIMPLEMENTED ASSERT_NOT_REACHED

namespace blink {

OffscreenCanvasRenderingContext2D::~OffscreenCanvasRenderingContext2D() {}

OffscreenCanvasRenderingContext2D::OffscreenCanvasRenderingContext2D(
    ScriptState* scriptState,
    OffscreenCanvas* canvas,
    const CanvasContextCreationAttributes& attrs)
    : CanvasRenderingContext(nullptr, canvas, attrs) {
  ExecutionContext* executionContext = scriptState->getExecutionContext();
  if (executionContext->isDocument()) {
    if (toDocument(executionContext)->settings()->disableReadingFromCanvas())
      canvas->setDisableReadingFromCanvasTrue();
    return;
  }

  WorkerSettings* workerSettings =
      toWorkerGlobalScope(executionContext)->workerSettings();
  if (workerSettings && workerSettings->disableReadingFromCanvas())
    canvas->setDisableReadingFromCanvasTrue();
}

DEFINE_TRACE(OffscreenCanvasRenderingContext2D) {
  CanvasRenderingContext::trace(visitor);
  BaseRenderingContext2D::trace(visitor);
}

void OffscreenCanvasRenderingContext2D::commit(ExceptionState& exceptionState) {
  if (getOffscreenCanvas()->getAssociatedCanvasId() < 0) {
    // If an OffscreenCanvas has no associated canvas Id, it indicates that
    // it is not an OffscreenCanvas created by transfering control from html
    // canvas.
    exceptionState.throwDOMException(InvalidStateError,
                                     "Commit() was called on a context whose "
                                     "OffscreenCanvas is not associated with a "
                                     "canvas element.");
    return;
  }
  RefPtr<StaticBitmapImage> image = this->transferToStaticBitmapImage();
  getOffscreenCanvas()->getOrCreateFrameDispatcher()->dispatchFrame(
      std::move(image));
}

// BaseRenderingContext2D implementation
bool OffscreenCanvasRenderingContext2D::originClean() const {
  return getOffscreenCanvas()->originClean();
}

void OffscreenCanvasRenderingContext2D::setOriginTainted() {
  return getOffscreenCanvas()->setOriginTainted();
}

bool OffscreenCanvasRenderingContext2D::wouldTaintOrigin(
    CanvasImageSource* source,
    ExecutionContext* executionContext) {
  if (executionContext->isWorkerGlobalScope()) {
    // We only support passing in ImageBitmap and OffscreenCanvases as source
    // images in drawImage() or createPattern() in a OffscreenCanvas2d in
    // worker.
    DCHECK(source->isImageBitmap() || source->isOffscreenCanvas());
  }

  return CanvasRenderingContext::wouldTaintOrigin(
      source, executionContext->getSecurityOrigin());
}

int OffscreenCanvasRenderingContext2D::width() const {
  return getOffscreenCanvas()->width();
}

int OffscreenCanvasRenderingContext2D::height() const {
  return getOffscreenCanvas()->height();
}

bool OffscreenCanvasRenderingContext2D::hasImageBuffer() const {
  return !!m_imageBuffer;
}

ImageBuffer* OffscreenCanvasRenderingContext2D::imageBuffer() const {
  if (!m_imageBuffer) {
    IntSize surfaceSize(width(), height());
    OpacityMode opacityMode = hasAlpha() ? NonOpaque : Opaque;
    std::unique_ptr<ImageBufferSurface> surface;
    if (RuntimeEnabledFeatures::accelerated2dCanvasEnabled()) {
      surface.reset(
          new AcceleratedImageBufferSurface(surfaceSize, opacityMode));
    }

    if (!surface || !surface->isValid()) {
      surface.reset(new UnacceleratedImageBufferSurface(
          surfaceSize, opacityMode, InitializeImagePixels));
    }

    OffscreenCanvasRenderingContext2D* nonConstThis =
        const_cast<OffscreenCanvasRenderingContext2D*>(this);
    nonConstThis->m_imageBuffer = ImageBuffer::create(std::move(surface));

    if (m_needsMatrixClipRestore) {
      restoreMatrixClipStack(m_imageBuffer->canvas());
      nonConstThis->m_needsMatrixClipRestore = false;
    }
  }

  return m_imageBuffer.get();
}

RefPtr<StaticBitmapImage>
OffscreenCanvasRenderingContext2D::transferToStaticBitmapImage() {
  if (!imageBuffer())
    return nullptr;
  sk_sp<SkImage> skImage = m_imageBuffer->newSkImageSnapshot(
      PreferAcceleration, SnapshotReasonTransferToImageBitmap);
  RefPtr<StaticBitmapImage> image =
      StaticBitmapImage::create(std::move(skImage));
  image->setOriginClean(this->originClean());
  return image;
}

ImageBitmap* OffscreenCanvasRenderingContext2D::transferToImageBitmap(
    ExceptionState& exceptionState) {
  RefPtr<StaticBitmapImage> image = transferToStaticBitmapImage();
  if (!image)
    return nullptr;
  m_imageBuffer.reset();  // "Transfer" means no retained buffer
  m_needsMatrixClipRestore = true;
  return ImageBitmap::create(std::move(image));
}

PassRefPtr<Image> OffscreenCanvasRenderingContext2D::getImage(
    AccelerationHint hint,
    SnapshotReason reason) const {
  if (!imageBuffer())
    return nullptr;
  sk_sp<SkImage> skImage = m_imageBuffer->newSkImageSnapshot(hint, reason);
  RefPtr<StaticBitmapImage> image =
      StaticBitmapImage::create(std::move(skImage));
  return image;
}

void OffscreenCanvasRenderingContext2D::setOffscreenCanvasGetContextResult(
    OffscreenRenderingContext& result) {
  result.setOffscreenCanvasRenderingContext2D(this);
}

bool OffscreenCanvasRenderingContext2D::parseColorOrCurrentColor(
    Color& color,
    const String& colorString) const {
  return ::blink::parseColorOrCurrentColor(color, colorString, nullptr);
}

SkCanvas* OffscreenCanvasRenderingContext2D::drawingCanvas() const {
  ImageBuffer* buffer = imageBuffer();
  if (!buffer)
    return nullptr;
  return imageBuffer()->canvas();
}

SkCanvas* OffscreenCanvasRenderingContext2D::existingDrawingCanvas() const {
  if (!m_imageBuffer)
    return nullptr;
  return m_imageBuffer->canvas();
}

void OffscreenCanvasRenderingContext2D::disableDeferral(DisableDeferralReason) {
}

AffineTransform OffscreenCanvasRenderingContext2D::baseTransform() const {
  if (!m_imageBuffer)
    return AffineTransform();  // identity
  return m_imageBuffer->baseTransform();
}

void OffscreenCanvasRenderingContext2D::didDraw(const SkIRect& dirtyRect) {}

bool OffscreenCanvasRenderingContext2D::stateHasFilter() {
  // TODO: crbug.com/593838 make hasFilter accept nullptr
  // return state().hasFilter(nullptr, nullptr, IntSize(width(), height()),
  // this);
  return false;
}

SkImageFilter* OffscreenCanvasRenderingContext2D::stateGetFilter() {
  // TODO: make getFilter accept nullptr
  // return state().getFilter(nullptr, nullptr, IntSize(width(), height()),
  // this);
  return nullptr;
}

void OffscreenCanvasRenderingContext2D::validateStateStack() const {
#if ENABLE(ASSERT)
  SkCanvas* skCanvas = existingDrawingCanvas();
  if (skCanvas) {
    ASSERT(static_cast<size_t>(skCanvas->getSaveCount()) ==
           m_stateStack.size());
  }
#endif
}

bool OffscreenCanvasRenderingContext2D::isContextLost() const {
  return false;
}

bool OffscreenCanvasRenderingContext2D::isPaintable() const {
  return this->imageBuffer();
}
}