/*
 * Copyright 2010 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "GrAtlas.h"
#include "GrGpu.h"
#include "GrRectanizer.h"
#include "GrTextStrike.h"
#include "GrTextStrike_impl.h"
#include "SkString.h"

#if SK_DISTANCEFIELD_FONTS
#include "edtaa3.h"
#endif

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

#define FONT_CACHE_STATS 0
#if FONT_CACHE_STATS
static int g_PurgeCount = 0;
#endif

GrFontCache::GrFontCache(GrGpu* gpu) : fGpu(gpu) {
    gpu->ref();
    for (int i = 0; i < kAtlasCount; ++i) {
        fAtlasMgr[i] = NULL;
    }

    fHead = fTail = NULL;
}

GrFontCache::~GrFontCache() {
    fCache.deleteAll();
    for (int i = 0; i < kAtlasCount; ++i) {
        delete fAtlasMgr[i];
    }
    fGpu->unref();
#if FONT_CACHE_STATS
      GrPrintf("Num purges: %d\n", g_PurgeCount);
#endif
}

static GrPixelConfig mask_format_to_pixel_config(GrMaskFormat format) {
    static const GrPixelConfig sPixelConfigs[] = {
        kAlpha_8_GrPixelConfig,
        kRGB_565_GrPixelConfig,
        kSkia8888_GrPixelConfig,
        kSkia8888_GrPixelConfig
    };
    SK_COMPILE_ASSERT(SK_ARRAY_COUNT(sPixelConfigs) == kMaskFormatCount, array_size_mismatch);

    return sPixelConfigs[format];
}

static int mask_format_to_atlas_index(GrMaskFormat format) {
    static const int sAtlasIndices[] = {
        GrFontCache::kA8_AtlasType,
        GrFontCache::k565_AtlasType,
        GrFontCache::k8888_AtlasType,
        GrFontCache::k8888_AtlasType
    };
    SK_COMPILE_ASSERT(SK_ARRAY_COUNT(sAtlasIndices) == kMaskFormatCount, array_size_mismatch);

    SkASSERT(sAtlasIndices[format] < GrFontCache::kAtlasCount);
    return sAtlasIndices[format];
}

GrTextStrike* GrFontCache::generateStrike(GrFontScaler* scaler,
                                          const Key& key) {
    GrMaskFormat format = scaler->getMaskFormat();
    GrPixelConfig config = mask_format_to_pixel_config(format);
    int atlasIndex = mask_format_to_atlas_index(format);
    if (NULL == fAtlasMgr[atlasIndex]) {
        fAtlasMgr[atlasIndex] = SkNEW_ARGS(GrAtlasMgr, (fGpu, config));
    }
    GrTextStrike* strike = SkNEW_ARGS(GrTextStrike,
                                      (this, scaler->getKey(), format, fAtlasMgr[atlasIndex]));
    fCache.insert(key, strike);

    if (fHead) {
        fHead->fPrev = strike;
    } else {
        SkASSERT(NULL == fTail);
        fTail = strike;
    }
    strike->fPrev = NULL;
    strike->fNext = fHead;
    fHead = strike;

    return strike;
}

void GrFontCache::freeAll() {
    fCache.deleteAll();
    for (int i = 0; i < kAtlasCount; ++i) {
        delete fAtlasMgr[i];
        fAtlasMgr[i] = NULL;
    }
    fHead = NULL;
    fTail = NULL;
}

void GrFontCache::purgeStrike(GrTextStrike* strike) {
    const GrFontCache::Key key(strike->fFontScalerKey);
    fCache.remove(key, strike);
    this->detachStrikeFromList(strike);
    delete strike;
}

void GrFontCache::purgeExceptFor(GrTextStrike* preserveStrike) {
    SkASSERT(NULL != preserveStrike);
    GrTextStrike* strike = fTail;
    bool purge = true;
    GrMaskFormat maskFormat = preserveStrike->fMaskFormat;
    while (strike) {
        if (strike == preserveStrike || maskFormat != strike->fMaskFormat) {
            strike = strike->fPrev;
            continue;
        }
        GrTextStrike* strikeToPurge = strike;
        strike = strikeToPurge->fPrev;
        if (purge) {
            // keep purging if we won't free up any atlases with this strike.
            purge = strikeToPurge->fAtlas.isEmpty();
            this->purgeStrike(strikeToPurge);
        }
    }
#if FONT_CACHE_STATS
    ++g_PurgeCount;
#endif
}

void GrFontCache::freePlotExceptFor(GrTextStrike* preserveStrike) {
    SkASSERT(NULL != preserveStrike);
    GrTextStrike* strike = fTail;
    GrMaskFormat maskFormat = preserveStrike->fMaskFormat;
    while (strike) {
        if (strike == preserveStrike || maskFormat != strike->fMaskFormat) {
            strike = strike->fPrev;
            continue;
        }
        GrTextStrike* strikeToPurge = strike;
        strike = strikeToPurge->fPrev;
        if (strikeToPurge->removeUnusedPlots()) {
            if (strikeToPurge->fAtlas.isEmpty()) {
                this->purgeStrike(strikeToPurge);
            }
            break;
        }
    }
}

#ifdef SK_DEBUG
void GrFontCache::validate() const {
    int count = fCache.count();
    if (0 == count) {
        SkASSERT(!fHead);
        SkASSERT(!fTail);
    } else if (1 == count) {
        SkASSERT(fHead == fTail);
    } else {
        SkASSERT(fHead != fTail);
    }

    int count2 = 0;
    const GrTextStrike* strike = fHead;
    while (strike) {
        count2 += 1;
        strike = strike->fNext;
    }
    SkASSERT(count == count2);

    count2 = 0;
    strike = fTail;
    while (strike) {
        count2 += 1;
        strike = strike->fPrev;
    }
    SkASSERT(count == count2);
}
#endif

#ifdef SK_DEVELOPER
void GrFontCache::dump() const {
    static int gDumpCount = 0;
    for (int i = 0; i < kAtlasCount; ++i) {
        if (NULL != fAtlasMgr[i]) {
            GrTexture* texture = fAtlasMgr[i]->getTexture();
            if (NULL != texture) {
                SkString filename;
                filename.printf("fontcache_%d%d.png", gDumpCount, i);
                texture->savePixels(filename.c_str());
            }
        }
    }
    ++gDumpCount;
}
#endif

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

#ifdef SK_DEBUG
    static int gCounter;
#endif

#if SK_DISTANCEFIELD_FONTS
#define DISTANCE_FIELD_PAD   4
#define DISTANCE_FIELD_RANGE (4.0)
#endif

/*
    The text strike is specific to a given font/style/matrix setup, which is
    represented by the GrHostFontScaler object we are given in getGlyph().

    We map a 32bit glyphID to a GrGlyph record, which in turn points to a
    atlas and a position within that texture.
 */

GrTextStrike::GrTextStrike(GrFontCache* cache, const GrKey* key,
                           GrMaskFormat format,
                           GrAtlasMgr* atlasMgr) : fPool(64), fAtlas(atlasMgr) {
    fFontScalerKey = key;
    fFontScalerKey->ref();

    fFontCache = cache;     // no need to ref, it won't go away before we do
    fAtlasMgr = atlasMgr;   // no need to ref, it won't go away before we do

    fMaskFormat = format;

#ifdef SK_DEBUG
//    GrPrintf(" GrTextStrike %p %d\n", this, gCounter);
    gCounter += 1;
#endif
}

// these signatures are needed because they're used with
// SkTDArray::visitAll() (see destructor & removeUnusedAtlases())
static void free_glyph(GrGlyph*& glyph) { glyph->free(); }

static void invalidate_glyph(GrGlyph*& glyph) {
    if (glyph->fPlot && glyph->fPlot->drawToken().isIssued()) {
        glyph->fPlot = NULL;
    }
}

GrTextStrike::~GrTextStrike() {
    fFontScalerKey->unref();
    fCache.getArray().visitAll(free_glyph);

#ifdef SK_DEBUG
    gCounter -= 1;
//    GrPrintf("~GrTextStrike %p %d\n", this, gCounter);
#endif
}

GrGlyph* GrTextStrike::generateGlyph(GrGlyph::PackedID packed,
                                     GrFontScaler* scaler) {
    SkIRect bounds;
    if (!scaler->getPackedGlyphBounds(packed, &bounds)) {
        return NULL;
    }

    GrGlyph* glyph = fPool.alloc();
#if SK_DISTANCEFIELD_FONTS
    // expand bounds to hold full distance field data
    if (fUseDistanceField) {
        bounds.fLeft   -= DISTANCE_FIELD_PAD;
        bounds.fRight  += DISTANCE_FIELD_PAD;
        bounds.fTop    -= DISTANCE_FIELD_PAD;
        bounds.fBottom += DISTANCE_FIELD_PAD;
    }
#endif
    glyph->init(packed, bounds);
    fCache.insert(packed, glyph);
    return glyph;
}

bool GrTextStrike::removeUnusedPlots() {
    fCache.getArray().visitAll(invalidate_glyph);
    return fAtlasMgr->removeUnusedPlots(&fAtlas);
}


bool GrTextStrike::getGlyphAtlas(GrGlyph* glyph, GrFontScaler* scaler) {
#if 0   // testing hack to force us to flush our cache often
    static int gCounter;
    if ((++gCounter % 10) == 0) return false;
#endif

    SkASSERT(glyph);
    SkASSERT(scaler);
    SkASSERT(fCache.contains(glyph));
    SkASSERT(NULL == glyph->fPlot);

    SkAutoRef ar(scaler);

    int bytesPerPixel = GrMaskFormatBytesPerPixel(fMaskFormat);

    GrPlot* plot;
#if SK_DISTANCEFIELD_FONTS
    if (fUseDistanceField) {
        SkASSERT(1 == bytesPerPixel);

        // we've already expanded the glyph dimensions to match the final size
        // but must shrink back down to get the packed glyph data
        int dfWidth = glyph->width();
        int dfHeight = glyph->height();
        int width = dfWidth - 2*DISTANCE_FIELD_PAD;
        int height = dfHeight - 2*DISTANCE_FIELD_PAD;
        size_t stride = width*bytesPerPixel;

        size_t size = width * height * bytesPerPixel;
        SkAutoSMalloc<1024> storage(size);
        if (!scaler->getPackedGlyphImage(glyph->fPackedID, width, height, stride, storage.get())) {
            return false;
        }

        // alloc storage for distance field glyph
        size_t dfSize = dfWidth * dfHeight * bytesPerPixel;
        SkAutoSMalloc<1024> dfStorage(dfSize);

        // copy glyph into distance field storage
        sk_bzero(dfStorage.get(), dfSize);

        unsigned char* ptr = (unsigned char*) storage.get();
        unsigned char* dfPtr = (unsigned char*) dfStorage.get();
        size_t dfStride = dfWidth*bytesPerPixel;
        dfPtr += DISTANCE_FIELD_PAD*dfStride;
        dfPtr += DISTANCE_FIELD_PAD*bytesPerPixel;

        for (int i = 0; i < height; ++i) {
            memcpy(dfPtr, ptr, stride);

            dfPtr += dfStride;
            ptr += stride;
        }

        // generate distance field data
        SkAutoSMalloc<1024> distXStorage(dfWidth*dfHeight*sizeof(short));
        SkAutoSMalloc<1024> distYStorage(dfWidth*dfHeight*sizeof(short));
        SkAutoSMalloc<1024> outerDistStorage(dfWidth*dfHeight*sizeof(double));
        SkAutoSMalloc<1024> innerDistStorage(dfWidth*dfHeight*sizeof(double));
        SkAutoSMalloc<1024> gxStorage(dfWidth*dfHeight*sizeof(double));
        SkAutoSMalloc<1024> gyStorage(dfWidth*dfHeight*sizeof(double));

        short* distX = (short*) distXStorage.get();
        short* distY = (short*) distYStorage.get();
        double* outerDist = (double*) outerDistStorage.get();
        double* innerDist = (double*) innerDistStorage.get();
        double* gx = (double*) gxStorage.get();
        double* gy = (double*) gyStorage.get();

        dfPtr = (unsigned char*) dfStorage.get();
        EDTAA::computegradient(dfPtr, dfWidth, dfHeight, gx, gy);
        EDTAA::edtaa3(dfPtr, gx, gy, dfWidth, dfHeight, distX, distY, outerDist);

        for (int i = 0; i < dfWidth*dfHeight; ++i) {
            *dfPtr = 255 - *dfPtr;
            dfPtr++;
        }
        dfPtr = (unsigned char*) dfStorage.get();
        sk_bzero(gx, sizeof(double)*dfWidth*dfHeight);
        sk_bzero(gy, sizeof(double)*dfWidth*dfHeight);
        EDTAA::computegradient(dfPtr, dfWidth, dfHeight, gx, gy);
        EDTAA::edtaa3(dfPtr, gx, gy, dfWidth, dfHeight, distX, distY, innerDist);

        for (int i = 0; i < dfWidth*dfHeight; ++i) {
            unsigned char val;
            double outerval = outerDist[i];
            if (outerval < 0.0) {
                outerval = 0.0;
            }
            double innerval = innerDist[i];
            if (innerval < 0.0) {
                innerval = 0.0;
            }
            double dist = outerval - innerval;
            if (dist <= -DISTANCE_FIELD_RANGE) {
                val = 255;
            } else if (dist > DISTANCE_FIELD_RANGE) {
                val = 0;
            } else {
                val = (unsigned char)((DISTANCE_FIELD_RANGE-dist)*128.0/DISTANCE_FIELD_RANGE);
            }
            *dfPtr++ = val;
        }

        // copy to atlas
        plot = fAtlasMgr->addToAtlas(&fAtlas, dfWidth, dfHeight, dfStorage.get(),
                                     &glyph->fAtlasLocation);

    } else {
#endif
        size_t size = glyph->fBounds.area() * bytesPerPixel;
        SkAutoSMalloc<1024> storage(size);
        if (!scaler->getPackedGlyphImage(glyph->fPackedID, glyph->width(),
                                         glyph->height(),
                                         glyph->width() * bytesPerPixel,
                                         storage.get())) {
            return false;
        }

        plot = fAtlasMgr->addToAtlas(&fAtlas, glyph->width(),
                                     glyph->height(), storage.get(),
                                     &glyph->fAtlasLocation);
#if SK_DISTANCEFIELD_FONTS
    }
#endif

    if (NULL == plot) {
        return false;
    }

    glyph->fPlot = plot;
    return true;
}