/*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkBitmap.h"
#include "SkBitmapCache.h"
#include "SkColorSpace_Base.h"
#include "SkImage_Base.h"
#include "SkImageCacherator.h"
#include "SkMallocPixelRef.h"
#include "SkNextID.h"
#include "SkPixelRef.h"
#include "SkResourceCache.h"

#if SK_SUPPORT_GPU
#include "GrContext.h"
#include "GrContextPriv.h"
#include "GrGpuResourcePriv.h"
#include "GrImageTextureMaker.h"
#include "GrResourceKey.h"
#include "GrResourceProvider.h"
#include "GrSamplerParams.h"
#include "GrYUVProvider.h"
#include "SkGr.h"
#endif

// Until we actually have codecs/etc. that can contain/support a GPU texture format
// skip this step, since for some generators, returning their encoded data as a SkData
// can be somewhat expensive, and this call doesn't indicate to the generator that we're
// only interested in GPU datas...
// see skbug.com/ 4971, 5128, ...
//#define SK_SUPPORT_COMPRESSED_TEXTURES_IN_CACHERATOR

// Helper for exclusive access to a shared generator.
class SkImageCacherator::ScopedGenerator {
public:
    ScopedGenerator(const sk_sp<SharedGenerator>& gen)
      : fSharedGenerator(gen)
      , fAutoAquire(gen->fMutex) {}

    SkImageGenerator* operator->() const {
        fSharedGenerator->fMutex.assertHeld();
        return fSharedGenerator->fGenerator.get();
    }

    operator SkImageGenerator*() const {
        fSharedGenerator->fMutex.assertHeld();
        return fSharedGenerator->fGenerator.get();
    }

private:
    const sk_sp<SharedGenerator>& fSharedGenerator;
    SkAutoExclusive               fAutoAquire;
};

SkImageCacherator::Validator::Validator(sk_sp<SharedGenerator> gen, const SkIRect* subset)
    : fSharedGenerator(std::move(gen)) {

    if (!fSharedGenerator) {
        return;
    }

    // The following generator accessors are safe without acquiring the mutex (const getters).
    // TODO: refactor to use a ScopedGenerator instead, for clarity.
    const SkImageInfo& info = fSharedGenerator->fGenerator->getInfo();
    if (info.isEmpty()) {
        fSharedGenerator.reset();
        return;
    }

    fUniqueID = fSharedGenerator->fGenerator->uniqueID();
    const SkIRect bounds = SkIRect::MakeWH(info.width(), info.height());
    if (subset) {
        if (!bounds.contains(*subset)) {
            fSharedGenerator.reset();
            return;
        }
        if (*subset != bounds) {
            // we need a different uniqueID since we really are a subset of the raw generator
            fUniqueID = SkNextID::ImageID();
        }
    } else {
        subset = &bounds;
    }

    fInfo   = info.makeWH(subset->width(), subset->height());
    fOrigin = SkIPoint::Make(subset->x(), subset->y());

    // colortables are poorly to not-at-all supported in our resourcecache, so we
    // bully them into N32 (the generator will perform the up-sample)
    if (fInfo.colorType() == kIndex_8_SkColorType) {
        fInfo = fInfo.makeColorType(kN32_SkColorType);
    }
}

SkImageCacherator* SkImageCacherator::NewFromGenerator(std::unique_ptr<SkImageGenerator> gen,
                                                       const SkIRect* subset) {
    Validator validator(SharedGenerator::Make(std::move(gen)), subset);

    return validator ? new SkImageCacherator(&validator) : nullptr;
}

SkImageCacherator::SkImageCacherator(Validator* validator)
    : fSharedGenerator(std::move(validator->fSharedGenerator)) // we take ownership
    , fInfo(validator->fInfo)
    , fOrigin(validator->fOrigin)
{
    SkASSERT(fSharedGenerator);
    SkASSERT(fInfo.colorType() != kIndex_8_SkColorType);
    // We explicit set the legacy format slot, but leave the others uninitialized (via SkOnce)
    // and only resolove them to IDs as needed (by calling getUniqueID()).
    fIDRecs[kLegacy_CachedFormat].fOnce([this, validator] {
        fIDRecs[kLegacy_CachedFormat].fUniqueID = validator->fUniqueID;
    });
}

SkImageCacherator::~SkImageCacherator() {}

uint32_t SkImageCacherator::getUniqueID(CachedFormat format) const {
    IDRec* rec = &fIDRecs[format];
    rec->fOnce([rec] {
        rec->fUniqueID = SkNextID::ImageID();
    });
    return rec->fUniqueID;
}

SkData* SkImageCacherator::refEncoded() {
    ScopedGenerator generator(fSharedGenerator);
    return generator->refEncodedData();
}

static bool check_output_bitmap(const SkBitmap& bitmap, uint32_t expectedID) {
    SkASSERT(bitmap.getGenerationID() == expectedID);
    SkASSERT(bitmap.isImmutable());
    SkASSERT(bitmap.getPixels());
    return true;
}

bool SkImageCacherator::directGeneratePixels(const SkImageInfo& info, void* pixels, size_t rb,
                                             int srcX, int srcY,
                                             SkTransferFunctionBehavior behavior) {
    ScopedGenerator generator(fSharedGenerator);
    const SkImageInfo& genInfo = generator->getInfo();
    // Currently generators do not natively handle subsets, so check that first.
    if (srcX || srcY || genInfo.width() != info.width() || genInfo.height() != info.height()) {
        return false;
    }

    SkImageGenerator::Options opts;
    opts.fBehavior = behavior;
    return generator->getPixels(info, pixels, rb, &opts);
}

//////////////////////////////////////////////////////////////////////////////////////////////////

bool SkImageCacherator::lockAsBitmapOnlyIfAlreadyCached(SkBitmap* bitmap, CachedFormat format) {
    uint32_t uniqueID = this->getUniqueID(format);
    return SkBitmapCache::Find(SkBitmapCacheDesc::Make(uniqueID,
                                                       fInfo.width(), fInfo.height()), bitmap) &&
           check_output_bitmap(*bitmap, uniqueID);
}

static bool generate_pixels(SkImageGenerator* gen, const SkPixmap& pmap, int originX, int originY) {
    const int genW = gen->getInfo().width();
    const int genH = gen->getInfo().height();
    const SkIRect srcR = SkIRect::MakeWH(genW, genH);
    const SkIRect dstR = SkIRect::MakeXYWH(originX, originY, pmap.width(), pmap.height());
    if (!srcR.contains(dstR)) {
        return false;
    }

    // If they are requesting a subset, we have to have a temp allocation for full image, and
    // then copy the subset into their allocation
    SkBitmap full;
    SkPixmap fullPM;
    const SkPixmap* dstPM = &pmap;
    if (srcR != dstR) {
        if (!full.tryAllocPixels(pmap.info().makeWH(genW, genH))) {
            return false;
        }
        if (!full.peekPixels(&fullPM)) {
            return false;
        }
        dstPM = &fullPM;
    }

    if (!gen->getPixels(dstPM->info(), dstPM->writable_addr(), dstPM->rowBytes())) {
        return false;
    }

    if (srcR != dstR) {
        if (!full.readPixels(pmap, originX, originY)) {
            return false;
        }
    }
    return true;
}

bool SkImageCacherator::lockAsBitmap(SkBitmap* bitmap, const SkImage* client,
                                     SkImage::CachingHint chint, CachedFormat format,
                                     const SkImageInfo& info) {
    if (this->lockAsBitmapOnlyIfAlreadyCached(bitmap, format)) {
        return true;
    }

    uint32_t uniqueID = this->getUniqueID(format);

    SkBitmap tmpBitmap;
    SkBitmapCache::RecPtr cacheRec;
    SkPixmap pmap;
    if (SkImage::kAllow_CachingHint == chint) {
        auto desc = SkBitmapCacheDesc::Make(uniqueID, info.width(), info.height());
        cacheRec = SkBitmapCache::Alloc(desc, info, &pmap);
        if (!cacheRec) {
            return false;
        }
    } else {
        if (!tmpBitmap.tryAllocPixels(info)) {
            return false;
        }
        if (!tmpBitmap.peekPixels(&pmap)) {
            return false;
        }
    }

    ScopedGenerator generator(fSharedGenerator);
    if (!generate_pixels(generator, pmap, fOrigin.x(), fOrigin.y())) {
        return false;
    }

    if (cacheRec) {
        SkBitmapCache::Add(std::move(cacheRec), bitmap);
        SkASSERT(bitmap->getPixels());  // we're locked
        SkASSERT(bitmap->isImmutable());
        SkASSERT(bitmap->getGenerationID() == uniqueID);
        if (client) {
            as_IB(client)->notifyAddedToCache();
        }
    } else {
        *bitmap = tmpBitmap;
        bitmap->pixelRef()->setImmutableWithID(uniqueID);
    }

    check_output_bitmap(*bitmap, uniqueID);
    return true;
}

//////////////////////////////////////////////////////////////////////////////////////////////////

// Abstraction of GrCaps that handles the cases where we don't have a caps pointer (because
// we're in raster mode), or where GPU support is entirely missing. In theory, we only need the
// chosen format to be texturable, but that lets us choose F16 on GLES implemenations where we
// won't be able to read the texture back. We'd like to ensure that SkImake::makeNonTextureImage
// works, so we require that the formats we choose are renderable (as a proxy for being readable).
struct CacheCaps {
    CacheCaps(const GrCaps* caps) : fCaps(caps) {}

#if SK_SUPPORT_GPU
    bool supportsHalfFloat() const {
        return !fCaps ||
            (fCaps->isConfigTexturable(kRGBA_half_GrPixelConfig) &&
             fCaps->isConfigRenderable(kRGBA_half_GrPixelConfig, false));
    }

    bool supportsSRGB() const {
        return !fCaps ||
            (fCaps->srgbSupport() && fCaps->isConfigTexturable(kSRGBA_8888_GrPixelConfig));
    }

    bool supportsSBGR() const {
        return !fCaps || fCaps->srgbSupport();
    }
#else
    bool supportsHalfFloat() const { return true; }
    bool supportsSRGB() const { return true; }
    bool supportsSBGR() const { return true; }
#endif

    const GrCaps* fCaps;
};

SkImageCacherator::CachedFormat SkImageCacherator::chooseCacheFormat(SkColorSpace* dstColorSpace,
                                                                     const GrCaps* grCaps) {
    SkColorSpace* cs = fInfo.colorSpace();
    if (!cs || !dstColorSpace) {
        return kLegacy_CachedFormat;
    }

    CacheCaps caps(grCaps);
    switch (fInfo.colorType()) {
        case kUnknown_SkColorType:
        case kAlpha_8_SkColorType:
        case kRGB_565_SkColorType:
        case kARGB_4444_SkColorType:
            // We don't support color space on these formats, so always decode in legacy mode:
            // TODO: Ask the codec to decode these to something else (at least sRGB 8888)?
            return kLegacy_CachedFormat;

        case kIndex_8_SkColorType:
            SkDEBUGFAIL("Index_8 should have been remapped at construction time.");
            return kLegacy_CachedFormat;

        case kGray_8_SkColorType:
            // TODO: What do we do with grayscale sources that have strange color spaces attached?
            // The codecs and color space xform don't handle this correctly (yet), so drop it on
            // the floor. (Also, inflating by a factor of 8 is going to be unfortunate).
            // As it is, we don't directly support sRGB grayscale, so ask the codec to convert
            // it for us. This bypasses some really sketchy code GrUploadPixmapToTexture.
            if (cs->gammaCloseToSRGB() && caps.supportsSRGB()) {
                return kSRGB8888_CachedFormat;
            } else {
                return kLegacy_CachedFormat;
            }

        case kRGBA_8888_SkColorType:
            if (cs->gammaCloseToSRGB()) {
                if (caps.supportsSRGB()) {
                    return kSRGB8888_CachedFormat;
                } else if (caps.supportsHalfFloat()) {
                    return kLinearF16_CachedFormat;
                } else {
                    return kLegacy_CachedFormat;
                }
            } else {
                if (caps.supportsHalfFloat()) {
                    return kLinearF16_CachedFormat;
                } else if (caps.supportsSRGB()) {
                    return kSRGB8888_CachedFormat;
                } else {
                    return kLegacy_CachedFormat;
                }
            }

        case kBGRA_8888_SkColorType:
            // Odd case. sBGRA isn't a real thing, so we may not have this texturable.
            if (caps.supportsSBGR()) {
                if (cs->gammaCloseToSRGB()) {
                    return kSBGR8888_CachedFormat;
                } else if (caps.supportsHalfFloat()) {
                    return kLinearF16_CachedFormat;
                } else if (caps.supportsSRGB()) {
                    return kSRGB8888_CachedFormat;
                } else {
                    // sBGRA support without sRGBA is highly unlikely (impossible?) Nevertheless.
                    return kLegacy_CachedFormat;
                }
            } else {
                if (cs->gammaCloseToSRGB()) {
                    if (caps.supportsSRGB()) {
                        return kSRGB8888_CachedFormat;
                    } else if (caps.supportsHalfFloat()) {
                        return kLinearF16_CachedFormat;
                    } else {
                        return kLegacy_CachedFormat;
                    }
                } else {
                    if (caps.supportsHalfFloat()) {
                        return kLinearF16_CachedFormat;
                    } else if (caps.supportsSRGB()) {
                        return kSRGB8888_CachedFormat;
                    } else {
                        return kLegacy_CachedFormat;
                    }
                }
            }

        case kRGBA_F16_SkColorType:
            if (caps.supportsHalfFloat()) {
                return kLinearF16_CachedFormat;
            } else if (caps.supportsSRGB()) {
                return kSRGB8888_CachedFormat;
            } else {
                return kLegacy_CachedFormat;
            }
    }
    SkDEBUGFAIL("Unreachable");
    return kLegacy_CachedFormat;
}

SkImageInfo SkImageCacherator::buildCacheInfo(CachedFormat format) {
    switch (format) {
        case kLegacy_CachedFormat:
            return fInfo.makeColorSpace(nullptr);
        case kLinearF16_CachedFormat:
            return fInfo.makeColorType(kRGBA_F16_SkColorType)
                        .makeColorSpace(as_CSB(fInfo.colorSpace())->makeLinearGamma());
        case kSRGB8888_CachedFormat:
            // If the transfer function is nearly (but not exactly) sRGB, we don't want the codec
            // to bother trans-coding. It would be slow, and do more harm than good visually,
            // so we make sure to leave the colorspace as-is.
            if (fInfo.colorSpace()->gammaCloseToSRGB()) {
                return fInfo.makeColorType(kRGBA_8888_SkColorType);
            } else {
                return fInfo.makeColorType(kRGBA_8888_SkColorType)
                            .makeColorSpace(as_CSB(fInfo.colorSpace())->makeSRGBGamma());
            }
        case kSBGR8888_CachedFormat:
            // See note above about not-quite-sRGB transfer functions.
            if (fInfo.colorSpace()->gammaCloseToSRGB()) {
                return fInfo.makeColorType(kBGRA_8888_SkColorType);
            } else {
                return fInfo.makeColorType(kBGRA_8888_SkColorType)
                            .makeColorSpace(as_CSB(fInfo.colorSpace())->makeSRGBGamma());
            }
        default:
            SkDEBUGFAIL("Invalid cached format");
            return fInfo;
    }
}

//////////////////////////////////////////////////////////////////////////////////////////////////

#if SK_SUPPORT_GPU

void SkImageCacherator::makeCacheKeyFromOrigKey(const GrUniqueKey& origKey, CachedFormat format,
                                                GrUniqueKey* cacheKey) {
    SkASSERT(!cacheKey->isValid());
    if (origKey.isValid()) {
        static const GrUniqueKey::Domain kDomain = GrUniqueKey::GenerateDomain();
        GrUniqueKey::Builder builder(cacheKey, origKey, kDomain, 1);
        builder[0] = format;
    }
}

class Generator_GrYUVProvider : public GrYUVProvider {
    SkImageGenerator* fGen;

public:
    Generator_GrYUVProvider(SkImageGenerator* gen) : fGen(gen) {}

    uint32_t onGetID() override { return fGen->uniqueID(); }
    bool onQueryYUV8(SkYUVSizeInfo* sizeInfo, SkYUVColorSpace* colorSpace) const override {
        return fGen->queryYUV8(sizeInfo, colorSpace);
    }
    bool onGetYUV8Planes(const SkYUVSizeInfo& sizeInfo, void* planes[3]) override {
        return fGen->getYUV8Planes(sizeInfo, planes);
    }
};

static void set_key_on_proxy(GrResourceProvider* resourceProvider,
                             GrTextureProxy* proxy, const GrUniqueKey& key) {
    if (key.isValid()) {
        resourceProvider->assignUniqueKeyToProxy(key, proxy);
    }
}

sk_sp<SkColorSpace> SkImageCacherator::getColorSpace(GrContext* ctx, SkColorSpace* dstColorSpace) {
    // TODO: This isn't always correct. Picture generator currently produces textures in N32,
    // and will (soon) emit them in an arbitrary (destination) space. We will need to stash that
    // information in/on the key so we can return the correct space in case #1 of lockTexture.
    CachedFormat format = this->chooseCacheFormat(dstColorSpace, ctx->caps());
    SkImageInfo cacheInfo = this->buildCacheInfo(format);
    return sk_ref_sp(cacheInfo.colorSpace());
}

/*
 *  We have 4 ways to try to return a texture (in sorted order)
 *
 *  1. Check the cache for a pre-existing one
 *  2. Ask the generator to natively create one
 *  3. Ask the generator to return YUV planes, which the GPU can convert
 *  4. Ask the generator to return RGB(A) data, which the GPU can convert
 */
sk_sp<GrTextureProxy> SkImageCacherator::lockTextureProxy(GrContext* ctx,
                                                          const GrUniqueKey& origKey,
                                                          const SkImage* client,
                                                          SkImage::CachingHint chint,
                                                          bool willBeMipped,
                                                          SkColorSpace* dstColorSpace) {
    // Values representing the various texture lock paths we can take. Used for logging the path
    // taken to a histogram.
    enum LockTexturePath {
        kFailure_LockTexturePath,
        kPreExisting_LockTexturePath,
        kNative_LockTexturePath,
        kCompressed_LockTexturePath, // Deprecated
        kYUV_LockTexturePath,
        kRGBA_LockTexturePath,
    };

    enum { kLockTexturePathCount = kRGBA_LockTexturePath + 1 };

    // Determine which cached format we're going to use (which may involve decoding to a different
    // info than the generator provides).
    CachedFormat format = this->chooseCacheFormat(dstColorSpace, ctx->caps());

    // Fold the cache format into our texture key
    GrUniqueKey key;
    this->makeCacheKeyFromOrigKey(origKey, format, &key);

    // 1. Check the cache for a pre-existing one
    if (key.isValid()) {
        if (sk_sp<GrTextureProxy> proxy = ctx->resourceProvider()->findProxyByUniqueKey(key)) {
            SK_HISTOGRAM_ENUMERATION("LockTexturePath", kPreExisting_LockTexturePath,
                                     kLockTexturePathCount);
            return proxy;
        }
    }

    // The CachedFormat is both an index for which cache "slot" we'll use to store this particular
    // decoded variant of the encoded data, and also a recipe for how to transform the original
    // info to get the one that we're going to decode to.
    SkImageInfo cacheInfo = this->buildCacheInfo(format);

    // 2. Ask the generator to natively create one
    {
        ScopedGenerator generator(fSharedGenerator);
        if (sk_sp<GrTextureProxy> proxy = generator->generateTexture(ctx, cacheInfo, fOrigin)) {
            SK_HISTOGRAM_ENUMERATION("LockTexturePath", kNative_LockTexturePath,
                                     kLockTexturePathCount);
            set_key_on_proxy(ctx->resourceProvider(), proxy.get(), key);
            return proxy;
        }
    }

    // 3. Ask the generator to return YUV planes, which the GPU can convert
    if (!ctx->contextPriv().disableGpuYUVConversion()) {
        const GrSurfaceDesc desc = GrImageInfoToSurfaceDesc(cacheInfo, *ctx->caps());
        ScopedGenerator generator(fSharedGenerator);
        Generator_GrYUVProvider provider(generator);
        if (sk_sp<GrTextureProxy> proxy = provider.refAsTextureProxy(ctx, desc, true)) {
            SK_HISTOGRAM_ENUMERATION("LockTexturePath", kYUV_LockTexturePath,
                                     kLockTexturePathCount);
            set_key_on_proxy(ctx->resourceProvider(), proxy.get(), key);
            return proxy;
        }
    }

    // 4. Ask the generator to return RGB(A) data, which the GPU can convert
    SkBitmap bitmap;
    if (this->lockAsBitmap(&bitmap, client, chint, format, cacheInfo)) {
        sk_sp<GrTextureProxy> proxy;
        if (willBeMipped) {
            proxy = GrGenerateMipMapsAndUploadToTextureProxy(ctx, bitmap, dstColorSpace);
        }
        if (!proxy) {
            proxy = GrUploadBitmapToTextureProxy(ctx->resourceProvider(), bitmap);
        }
        if (proxy) {
            SK_HISTOGRAM_ENUMERATION("LockTexturePath", kRGBA_LockTexturePath,
                                     kLockTexturePathCount);
            set_key_on_proxy(ctx->resourceProvider(), proxy.get(), key);
            return proxy;
        }
    }
    SK_HISTOGRAM_ENUMERATION("LockTexturePath", kFailure_LockTexturePath,
                             kLockTexturePathCount);
    return nullptr;
}

///////////////////////////////////////////////////////////////////////////////////////////////////

sk_sp<GrTextureProxy> SkImageCacherator::lockAsTextureProxy(GrContext* ctx,
                                                            const GrSamplerParams& params,
                                                            SkColorSpace* dstColorSpace,
                                                            sk_sp<SkColorSpace>* texColorSpace,
                                                            const SkImage* client,
                                                            SkScalar scaleAdjust[2],
                                                            SkImage::CachingHint chint) {
    if (!ctx) {
        return nullptr;
    }

    return GrImageTextureMaker(ctx, this, client, chint).refTextureProxyForParams(params,
                                                                                  dstColorSpace,
                                                                                  texColorSpace,
                                                                                  scaleAdjust);
}

#endif