/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "ContainerLayerMLGPU.h"
#include "mozilla/StaticPrefs_layers.h"
#include "LayerManagerMLGPU.h"
#include "MLGDevice.h"
#include "mozilla/gfx/Rect.h"
#include "mozilla/gfx/Types.h"
#include "UnitTransforms.h"
#include "UtilityMLGPU.h"

namespace mozilla {
namespace layers {

using namespace gfx;

ContainerLayerMLGPU::ContainerLayerMLGPU(LayerManagerMLGPU* aManager)
    : ContainerLayer(aManager, nullptr),
      LayerMLGPU(aManager),
      mInvalidateEntireSurface(false),
      mSurfaceCopyNeeded(false),
      mView(nullptr) {}

ContainerLayerMLGPU::~ContainerLayerMLGPU() {
  while (mFirstChild) {
    RemoveChild(mFirstChild);
  }
}

bool ContainerLayerMLGPU::OnPrepareToRender(FrameBuilder* aBuilder) {
  mView = nullptr;

  if (!UseIntermediateSurface()) {
    // Set this so we invalidate the entire cached render target (if any)
    // if our container uses an intermediate surface again later.
    mInvalidateEntireSurface = true;
    return true;
  }

  mChildrenChanged = false;

  mTargetOffset = GetIntermediateSurfaceRect().TopLeft().ToUnknownPoint();
  mTargetSize = GetIntermediateSurfaceRect().Size().ToUnknownSize();

  if (mRenderTarget && mRenderTarget->GetSize() != mTargetSize) {
    mRenderTarget = nullptr;
  }

  // Note that if a surface copy is needed, we always redraw the
  // whole surface (on-demand). This is a rare case - the old
  // Compositor already does this - and it saves us having to
  // do much more complicated invalidation.
  bool surfaceCopyNeeded = false;
  DefaultComputeSupportsComponentAlphaChildren(&surfaceCopyNeeded);
  if (surfaceCopyNeeded != mSurfaceCopyNeeded || surfaceCopyNeeded) {
    mInvalidateEntireSurface = true;
  }
  mSurfaceCopyNeeded = surfaceCopyNeeded;

  gfx::IntRect viewport(gfx::IntPoint(0, 0), mTargetSize);
  if (!mRenderTarget || !StaticPrefs::layers_mlgpu_enable_invalidation() ||
      mInvalidateEntireSurface) {
    // Fine-grained invalidation is disabled, invalidate everything.
    mInvalidRect = viewport;
  } else {
    // Clamp the invalid rect to the viewport.
    mInvalidRect -= mTargetOffset;
    mInvalidRect = mInvalidRect.Intersect(viewport);
  }

  mInvalidateEntireSurface = false;
  return true;
}

static IntRect GetTransformedBounds(Layer* aLayer) {
  IntRect bounds = aLayer->GetLocalVisibleRegion().GetBounds().ToUnknownRect();
  if (bounds.IsEmpty()) {
    return bounds;
  }

  const Matrix4x4& transform = aLayer->GetEffectiveTransform();
  Rect rect =
      transform.TransformAndClipBounds(Rect(bounds), Rect::MaxIntRect());
  rect.RoundOut();
  rect.ToIntRect(&bounds);
  return bounds;
}

/* static */
Maybe<IntRect> ContainerLayerMLGPU::FindVisibleBounds(
    Layer* aLayer, const Maybe<RenderTargetIntRect>& aClip) {
  AL_LOG("  visiting child %p\n", aLayer);
  AL_LOG_IF(aClip, "  parent clip: %s\n", Stringify(aClip.value()).c_str());

  ContainerLayer* container = aLayer->AsContainerLayer();
  if (container) {
    if (container->UseIntermediateSurface()) {
      ContainerLayerMLGPU* c =
          container->AsHostLayer()->AsLayerMLGPU()->AsContainerLayerMLGPU();
      if (!c) {
        gfxCriticalError()
            << "not container: "
            << container->AsHostLayer()->AsLayerMLGPU()->GetType();
      }
      MOZ_RELEASE_ASSERT(c);
      c->ComputeIntermediateSurfaceBounds();
    } else {
      Maybe<IntRect> accumulated = Some(IntRect());

      // Traverse children.
      for (Layer* child = container->GetFirstChild(); child;
           child = child->GetNextSibling()) {
        Maybe<RenderTargetIntRect> clip = aClip;
        if (const Maybe<ParentLayerIntRect>& childClip =
                child->AsHostLayer()->GetShadowClipRect()) {
          RenderTargetIntRect rtChildClip = TransformBy(
              ViewAs<ParentLayerToRenderTargetMatrix4x4>(
                  aLayer->GetEffectiveTransform(),
                  PixelCastJustification::RenderTargetIsParentLayerForRoot),
              childClip.value());
          clip = IntersectMaybeRects(clip, Some(rtChildClip));
          AL_LOG("    target clip: %s\n", Stringify(rtChildClip).c_str());
          AL_LOG_IF(clip, "    full clip: %s\n",
                    Stringify(clip.value()).c_str());
        }

        Maybe<IntRect> childBounds = FindVisibleBounds(child, clip);
        if (!childBounds) {
          return Nothing();
        }

        accumulated = accumulated->SafeUnion(childBounds.value());
        if (!accumulated) {
          return Nothing();
        }
      }
      return accumulated;
    }
  }

  IntRect bounds = GetTransformedBounds(aLayer);
  AL_LOG("    layer bounds: %s\n", Stringify(bounds).c_str());

  if (aClip) {
    bounds = bounds.Intersect(aClip.value().ToUnknownRect());
    AL_LOG("    clipped bounds: %s\n", Stringify(bounds).c_str());
  }
  return Some(bounds);
}

void ContainerLayerMLGPU::ComputeIntermediateSurfaceBounds() {
  Maybe<IntRect> bounds = Some(IntRect());
  for (Layer* child = GetFirstChild(); child; child = child->GetNextSibling()) {
    Maybe<RenderTargetIntRect> clip = ViewAs<RenderTargetPixel>(
        child->AsHostLayer()->GetShadowClipRect(),
        PixelCastJustification::RenderTargetIsParentLayerForRoot);
    Maybe<IntRect> childBounds = FindVisibleBounds(child, clip);
    if (!childBounds) {
      return;
    }

    bounds = bounds->SafeUnion(childBounds.value());
    if (!bounds) {
      return;
    }
  }

  SetShadowVisibleRegion(LayerIntRect::FromUnknownRect(bounds.value()));
}

void ContainerLayerMLGPU::OnLayerManagerChange(LayerManagerMLGPU* aManager) {
  ClearCachedResources();
}

RefPtr<MLGRenderTarget> ContainerLayerMLGPU::UpdateRenderTarget(
    MLGDevice* aDevice, MLGRenderTargetFlags aFlags) {
  if (mRenderTarget) {
    return mRenderTarget;
  }

  mRenderTarget = aDevice->CreateRenderTarget(mTargetSize, aFlags);
  if (!mRenderTarget) {
    gfxWarning()
        << "Failed to create an intermediate render target for ContainerLayer";
    return nullptr;
  }

  return mRenderTarget;
}

void ContainerLayerMLGPU::SetInvalidCompositeRect(const gfx::IntRect* aRect) {
  // For simplicity we only track the bounds of the invalid area, since regions
  // are expensive.
  //
  // Note we add the bounds to the invalid rect from the last frame, since we
  // only clear the area that we actually paint. If this overflows we use the
  // last render target size, since if that changes we'll invalidate everything
  // anyway.
  if (aRect) {
    if (Maybe<gfx::IntRect> result = mInvalidRect.SafeUnion(*aRect)) {
      mInvalidRect = result.value();
    } else {
      mInvalidateEntireSurface = true;
    }
  } else {
    mInvalidateEntireSurface = true;
  }
}

void ContainerLayerMLGPU::ClearCachedResources() { mRenderTarget = nullptr; }

bool ContainerLayerMLGPU::IsContentOpaque() {
  if (GetMixBlendMode() != gfx::CompositionOp::OP_OVER) {
    // We need to read from what's underneath us, so we consider our content to
    // be not opaque.
    return false;
  }
  return LayerMLGPU::IsContentOpaque();
}

const LayerIntRegion& ContainerLayerMLGPU::GetShadowVisibleRegion() {
  if (!UseIntermediateSurface()) {
    RecomputeShadowVisibleRegionFromChildren();
  }

  return mShadowVisibleRegion;
}

const LayerIntRegion& RefLayerMLGPU::GetShadowVisibleRegion() {
  if (!UseIntermediateSurface()) {
    RecomputeShadowVisibleRegionFromChildren();
  }

  return mShadowVisibleRegion;
}

}  // namespace layers
}  // namespace mozilla