/*
 * Copyright 2021 Google LLC
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "src/gpu/graphite/DrawContext.h"

#include "include/core/SkColorSpace.h"
#include "include/core/SkPixmap.h"
#include "include/private/SkColorData.h"

#include "include/gpu/graphite/Context.h"
#include "include/gpu/graphite/Recorder.h"
#include "src/core/SkTraceEvent.h"
#include "src/gpu/graphite/AtlasProvider.h"
#include "src/gpu/graphite/Buffer.h"
#include "src/gpu/graphite/Caps.h"
#include "src/gpu/graphite/CommandBuffer.h"
#include "src/gpu/graphite/ComputeTask.h"
#include "src/gpu/graphite/ContextPriv.h"
#include "src/gpu/graphite/DrawList.h"
#include "src/gpu/graphite/DrawPass.h"
#include "src/gpu/graphite/PathAtlas.h"
#include "src/gpu/graphite/RasterPathAtlas.h"
#include "src/gpu/graphite/RecorderPriv.h"
#include "src/gpu/graphite/RenderPassTask.h"
#include "src/gpu/graphite/ResourceTypes.h"
#include "src/gpu/graphite/SharedContext.h"
#include "src/gpu/graphite/TextureProxy.h"
#include "src/gpu/graphite/TextureProxyView.h"
#include "src/gpu/graphite/UploadTask.h"
#include "src/gpu/graphite/compute/DispatchGroup.h"
#include "src/gpu/graphite/geom/BoundsManager.h"
#include "src/gpu/graphite/geom/Geometry.h"
#include "src/gpu/graphite/text/TextAtlasManager.h"

namespace skgpu::graphite {

sk_sp<DrawContext> DrawContext::Make(sk_sp<TextureProxy> target,
                                     SkISize deviceSize,
                                     const SkColorInfo& colorInfo,
                                     const SkSurfaceProps& props) {
    if (!target) {
        return nullptr;
    }

    // Accept an approximate-fit texture, but make sure it's at least as large as the device's
    // logical size.
    // TODO: validate that the color type and alpha type are compatible with the target's info
    SkASSERT(target->isFullyLazy() || (target->dimensions().width() >= deviceSize.width() &&
                                       target->dimensions().height() >= deviceSize.height()));
    SkImageInfo imageInfo = SkImageInfo::Make(deviceSize, colorInfo);
    return sk_sp<DrawContext>(new DrawContext(std::move(target), imageInfo, props));
}

DrawContext::DrawContext(sk_sp<TextureProxy> target,
                         const SkImageInfo& ii,
                         const SkSurfaceProps& props)
        : fTarget(std::move(target))
        , fImageInfo(ii)
        , fSurfaceProps(props)
        , fPendingDraws(std::make_unique<DrawList>())
        , fPendingUploads(std::make_unique<UploadList>()) {
    // TBD - Will probably want DrawLists (and its internal commands) to come from an arena
    // that the DC manages.
}

DrawContext::~DrawContext() {
    // If the DC is destroyed and there are pending commands, they won't be drawn.
    fPendingDraws.reset();
    fDrawPasses.clear();
}

TextureProxyView DrawContext::readSurfaceView(const Caps* caps) {
    TextureProxy* proxy = this->target();

    if (!caps->isTexturable(proxy->textureInfo())) {
        return {};
    }

    Swizzle swizzle = caps->getReadSwizzle(this->imageInfo().colorType(),
                                           proxy->textureInfo());

    return TextureProxyView(sk_ref_sp(proxy), swizzle);
}

void DrawContext::clear(const SkColor4f& clearColor) {
    fPendingLoadOp = LoadOp::kClear;
    SkPMColor4f pmColor = clearColor.premul();
    fPendingClearColor = pmColor.array();

    // a fullscreen clear will overwrite anything that came before, so start a new DrawList
    // and clear any drawpasses that haven't been snapped yet
    fPendingDraws = std::make_unique<DrawList>();
    if (fComputePathAtlas) {
        fComputePathAtlas->reset();
    }
    fDispatchGroups.clear();
    fDrawPasses.clear();
}

void DrawContext::recordDraw(const Renderer* renderer,
                             const Transform& localToDevice,
                             const Geometry& geometry,
                             const Clip& clip,
                             DrawOrder ordering,
                             const PaintParams* paint,
                             const StrokeStyle* stroke) {
    SkASSERT(SkIRect::MakeSize(this->imageInfo().dimensions()).contains(clip.scissor()));
    fPendingDraws->recordDraw(renderer, localToDevice, geometry, clip, ordering, paint, stroke);
}

bool DrawContext::recordUpload(Recorder* recorder,
                               sk_sp<TextureProxy> targetProxy,
                               const SkColorInfo& srcColorInfo,
                               const SkColorInfo& dstColorInfo,
                               const std::vector<MipLevel>& levels,
                               const SkIRect& dstRect,
                               std::unique_ptr<ConditionalUploadContext> condContext) {
    // Our caller should have clipped to the bounds of the surface already.
    SkASSERT(targetProxy->isFullyLazy() ||
             SkIRect::MakeSize(targetProxy->dimensions()).contains(dstRect));
    return fPendingUploads->recordUpload(recorder,
                                         std::move(targetProxy),
                                         srcColorInfo,
                                         dstColorInfo,
                                         levels,
                                         dstRect,
                                         std::move(condContext));
}

PathAtlas* DrawContext::getComputePathAtlas(Recorder* recorder) {
    if (!fComputePathAtlas) {
        fComputePathAtlas = recorder->priv().atlasProvider()->createComputePathAtlas(recorder);
    }
    return fComputePathAtlas.get();
}

void DrawContext::snapDrawPass(Recorder* recorder) {
    if (fPendingDraws->renderStepCount() == 0 && fPendingLoadOp != LoadOp::kClear) {
        return;
    }

    // Instantiate the compute pass that may render an atlas texture used by this draw pass.
    this->snapPathAtlasDispatches(recorder);

    auto pass = DrawPass::Make(recorder,
                               std::move(fPendingDraws),
                               fTarget,
                               this->imageInfo(),
                               std::make_pair(fPendingLoadOp, fPendingStoreOp),
                               fPendingClearColor);
    if (pass) {
        fDrawPasses.push_back(std::move(pass));
    }
    fPendingDraws = std::make_unique<DrawList>();
    fPendingLoadOp = LoadOp::kLoad;
    fPendingStoreOp = StoreOp::kStore;
}

RenderPassDesc RenderPassDesc::Make(const Caps* caps,
                                    const TextureInfo& targetInfo,
                                    LoadOp loadOp,
                                    StoreOp storeOp,
                                    SkEnumBitMask<DepthStencilFlags> depthStencilFlags,
                                    const std::array<float, 4>& clearColor,
                                    bool requiresMSAA,
                                    Swizzle writeSwizzle) {
    RenderPassDesc desc;
    desc.fWriteSwizzle = writeSwizzle;
    desc.fSampleCount = 1;
    // It doesn't make sense to have a storeOp for our main target not be store. Why are we doing
    // this DrawPass then
    SkASSERT(storeOp == StoreOp::kStore);
    if (requiresMSAA) {
        if (caps->msaaRenderToSingleSampledSupport()) {
            desc.fColorAttachment.fTextureInfo = targetInfo;
            desc.fColorAttachment.fLoadOp = loadOp;
            desc.fColorAttachment.fStoreOp = storeOp;
            desc.fSampleCount = caps->defaultMSAASamplesCount();
        } else {
            // TODO: If the resolve texture isn't readable, the MSAA color attachment will need to
            // be persistently associated with the framebuffer, in which case it's not discardable.
            auto msaaTextureInfo = caps->getDefaultMSAATextureInfo(targetInfo, Discardable::kYes);
            if (msaaTextureInfo.isValid()) {
                desc.fColorAttachment.fTextureInfo = msaaTextureInfo;
                if (loadOp != LoadOp::kClear) {
                    desc.fColorAttachment.fLoadOp = LoadOp::kDiscard;
                } else {
                    desc.fColorAttachment.fLoadOp = LoadOp::kClear;
                }
                desc.fColorAttachment.fStoreOp = StoreOp::kDiscard;

                desc.fColorResolveAttachment.fTextureInfo = targetInfo;
                if (loadOp != LoadOp::kLoad) {
                    desc.fColorResolveAttachment.fLoadOp = LoadOp::kDiscard;
                } else {
                    desc.fColorResolveAttachment.fLoadOp = LoadOp::kLoad;
                }
                desc.fColorResolveAttachment.fStoreOp = storeOp;

                desc.fSampleCount = msaaTextureInfo.numSamples();
            } else {
                // fall back to single sampled
                desc.fColorAttachment.fTextureInfo = targetInfo;
                desc.fColorAttachment.fLoadOp = loadOp;
                desc.fColorAttachment.fStoreOp = storeOp;
            }
        }
    } else {
        desc.fColorAttachment.fTextureInfo = targetInfo;
        desc.fColorAttachment.fLoadOp = loadOp;
        desc.fColorAttachment.fStoreOp = storeOp;
    }
    desc.fClearColor = clearColor;

    if (depthStencilFlags != DepthStencilFlags::kNone) {
        desc.fDepthStencilAttachment.fTextureInfo = caps->getDefaultDepthStencilTextureInfo(
                depthStencilFlags, desc.fSampleCount, targetInfo.isProtected());
        // Always clear the depth and stencil to 0 at the start of a DrawPass, but discard at the
        // end since their contents do not affect the next frame.
        desc.fDepthStencilAttachment.fLoadOp = LoadOp::kClear;
        desc.fClearDepth = 0.f;
        desc.fClearStencil = 0;
        desc.fDepthStencilAttachment.fStoreOp = StoreOp::kDiscard;
    }

    return desc;
}

sk_sp<Task> DrawContext::snapRenderPassTask(Recorder* recorder) {
    this->snapDrawPass(recorder);
    if (fDrawPasses.empty()) {
        return nullptr;
    }

    TRACE_EVENT_INSTANT1("skia.gpu", TRACE_FUNC, TRACE_EVENT_SCOPE_THREAD,
                         "# passes", fDrawPasses.size());

    const Caps* caps = recorder->priv().caps();

    // TODO: At this point we would determine all the targets used by the drawPasses,
    // build up the union of them and store them in the RenderPassDesc. However, for
    // the moment we should have only one drawPass.
    SkASSERT(fDrawPasses.size() == 1);
    auto& drawPass = fDrawPasses[0];
    const TextureInfo& targetInfo = drawPass->target()->textureInfo();
    auto [loadOp, storeOp] = drawPass->ops();
    auto writeSwizzle = caps->getWriteSwizzle(this->colorInfo().colorType(), targetInfo);

    RenderPassDesc desc = RenderPassDesc::Make(caps, targetInfo, loadOp, storeOp,
                                               drawPass->depthStencilFlags(),
                                               drawPass->clearColor(),
                                               drawPass->requiresMSAA(),
                                               writeSwizzle);
    sk_sp<TextureProxy> targetProxy = sk_ref_sp(fDrawPasses[0]->target());
    return RenderPassTask::Make(std::move(fDrawPasses), desc, std::move(targetProxy));
}

sk_sp<Task> DrawContext::snapUploadTask(Recorder* recorder) {
    if (!fPendingUploads || fPendingUploads->size() == 0) {
        return nullptr;
    }

    TRACE_EVENT_INSTANT1("skia.gpu", TRACE_FUNC, TRACE_EVENT_SCOPE_THREAD,
                         "# uploads", fPendingUploads->size());
    sk_sp<Task> uploadTask = UploadTask::Make(fPendingUploads.get());

    fPendingUploads = std::make_unique<UploadList>();

    return uploadTask;
}

sk_sp<Task> DrawContext::snapComputeTask(Recorder* recorder) {
    if (fDispatchGroups.empty()) {
        return nullptr;
    }

    TRACE_EVENT_INSTANT1("skia.gpu", TRACE_FUNC, TRACE_EVENT_SCOPE_THREAD,
                         "# groups", fDispatchGroups.size());

    SkASSERT(fDispatchGroups.size() == 1);
    return ComputeTask::Make(std::move(fDispatchGroups));
}

void DrawContext::snapPathAtlasDispatches(Recorder* recorder) {
    if (!fComputePathAtlas) {
        // Platform doesn't support compute or atlas was never initialized.
        return;
    }
    auto dispatchGroup = fComputePathAtlas->recordDispatches(recorder);
    if (dispatchGroup) {
        // For now this check is valid as all coverage mask draws involve dispatches
        SkASSERT(fPendingDraws->hasCoverageMaskDraws());
        fDispatchGroups.push_back(std::move(dispatchGroup));
    }
    fComputePathAtlas->reset();
}

} // namespace skgpu::graphite