/*
 * 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 "GrNonAAFillRectBatch.h"

#include "GrBatchFlushState.h"
#include "GrColor.h"
#include "GrDefaultGeoProcFactory.h"
#include "GrPrimitiveProcessor.h"
#include "GrResourceProvider.h"
#include "GrTInstanceBatch.h"
#include "GrQuad.h"
#include "GrVertexBatch.h"

// Common functions
class NonAAFillRectBatchBase {
public:
    static const int kVertsPerInstance = 4;
    static const int kIndicesPerInstance = 6;

    static void InitInvariantOutputCoverage(GrInitInvariantOutput* out) {
        out->setKnownSingleComponent(0xff);
    }

    static const GrIndexBuffer* GetIndexBuffer(GrResourceProvider* rp) {
        return rp->refQuadIndexBuffer();
    }

    template <typename Geometry>
    static void SetBounds(const Geometry& geo, SkRect* outBounds) {
        geo.fViewMatrix.mapRect(outBounds, geo.fRect);
    }
};

/** We always use per-vertex colors so that rects can be batched across color changes. Sometimes
    we  have explicit local coords and sometimes not. We *could* always provide explicit local
    coords and just duplicate the positions when the caller hasn't provided a local coord rect,
    but we haven't seen a use case which frequently switches between local rect and no local
    rect draws.

    The vertex attrib order is always pos, color, [local coords].
 */
static const GrGeometryProcessor* create_gp(const SkMatrix& viewMatrix,
                                            bool readsCoverage,
                                            bool hasExplicitLocalCoords,
                                            const SkMatrix* localMatrix) {
    using namespace GrDefaultGeoProcFactory;
    Color color(Color::kAttribute_Type);
    Coverage coverage(readsCoverage ? Coverage::kSolid_Type : Coverage::kNone_Type);

    // If we have perspective on the viewMatrix then we won't map on the CPU, nor will we map
    // the local rect on the cpu (in case the localMatrix also has perspective).
    // Otherwise, if we have a local rect, then we apply the localMatrix directly to the localRect
    // to generate vertex local coords
    if (viewMatrix.hasPerspective()) {
        LocalCoords localCoords(hasExplicitLocalCoords ? LocalCoords::kHasExplicit_Type :
                                                         LocalCoords::kUsePosition_Type,
                                localMatrix);
        return GrDefaultGeoProcFactory::Create(color, coverage, localCoords, viewMatrix);
    } else if (hasExplicitLocalCoords) {
        LocalCoords localCoords(LocalCoords::kHasExplicit_Type);
        return GrDefaultGeoProcFactory::Create(color, coverage, localCoords, SkMatrix::I());
    } else {
        LocalCoords localCoords(LocalCoords::kUsePosition_Type, localMatrix);
        return GrDefaultGeoProcFactory::CreateForDeviceSpace(color, coverage, localCoords,
                                                             viewMatrix);
    }
}

static void tesselate(intptr_t vertices,
                      size_t vertexStride,
                      GrColor color,
                      const SkMatrix& viewMatrix,
                      const SkRect& rect,
                      const GrQuad* localQuad) {
    SkPoint* positions = reinterpret_cast<SkPoint*>(vertices);

    positions->setRectFan(rect.fLeft, rect.fTop,
                          rect.fRight, rect.fBottom, vertexStride);

    if (!viewMatrix.hasPerspective()) {
        viewMatrix.mapPointsWithStride(positions, vertexStride,
                                       NonAAFillRectBatchBase::kVertsPerInstance);
    }

    // Setup local coords
    // TODO we should only do this if local coords are being read
    if (localQuad) {
        static const int kLocalOffset = sizeof(SkPoint) + sizeof(GrColor);
        for (int i = 0; i < NonAAFillRectBatchBase::kVertsPerInstance; i++) {
            SkPoint* coords = reinterpret_cast<SkPoint*>(vertices + kLocalOffset +
                              i * vertexStride);
            *coords = localQuad->point(i);
        }
    }

    static const int kColorOffset = sizeof(SkPoint);
    GrColor* vertColor = reinterpret_cast<GrColor*>(vertices + kColorOffset);
    for (int j = 0; j < 4; ++j) {
        *vertColor = color;
        vertColor = (GrColor*) ((intptr_t) vertColor + vertexStride);
    }
}

class NonAAFillRectBatchImp : public NonAAFillRectBatchBase {
public:
    struct Geometry {
        SkMatrix fViewMatrix;
        SkRect fRect;
        GrQuad fLocalQuad;
        GrColor fColor;
    };

    static const char* Name() { return "NonAAFillRectBatch"; }

    static bool CanCombine(const Geometry& mine, const Geometry& theirs,
                           const GrPipelineOptimizations& opts) {
        return true;
    }

    static const GrGeometryProcessor* CreateGP(const Geometry& geo,
                                               const GrPipelineOptimizations& opts) {
        const GrGeometryProcessor* gp = create_gp(geo.fViewMatrix, opts.readsCoverage(), true,
                                                  nullptr);

        SkASSERT(gp->getVertexStride() ==
                sizeof(GrDefaultGeoProcFactory::PositionColorLocalCoordAttr));
        return gp;
    }

    static void Tesselate(intptr_t vertices, size_t vertexStride, const Geometry& geo,
                          const GrPipelineOptimizations& opts) {
        tesselate(vertices, vertexStride, geo.fColor, geo.fViewMatrix, geo.fRect, &geo.fLocalQuad);
    }
};

// We handle perspective in the local matrix or viewmatrix with special batches
class NonAAFillRectBatchPerspectiveImp : public NonAAFillRectBatchBase {
public:
    struct Geometry {
        SkMatrix fViewMatrix;
        SkMatrix fLocalMatrix;
        SkRect fRect;
        SkRect fLocalRect;
        GrColor fColor;
        bool fHasLocalMatrix;
        bool fHasLocalRect;
    };

    static const char* Name() { return "NonAAFillRectBatchPerspective"; }

    static bool CanCombine(const Geometry& mine, const Geometry& theirs,
                           const GrPipelineOptimizations& opts) {
        // We could batch across perspective vm changes if we really wanted to
        return mine.fViewMatrix.cheapEqualTo(theirs.fViewMatrix) &&
               (!mine.fHasLocalMatrix || mine.fLocalMatrix.cheapEqualTo(theirs.fLocalMatrix));
    }

    static const GrGeometryProcessor* CreateGP(const Geometry& geo,
                                               const GrPipelineOptimizations& opts) {
        const GrGeometryProcessor* gp = create_gp(geo.fViewMatrix, opts.readsCoverage(),
                                                  geo.fHasLocalRect,
                                                  geo.fHasLocalMatrix ? &geo.fLocalMatrix :
                                                                        nullptr);

        SkASSERT(geo.fHasLocalRect ?
             gp->getVertexStride() == sizeof(GrDefaultGeoProcFactory::PositionColorLocalCoordAttr) :
             gp->getVertexStride() == sizeof(GrDefaultGeoProcFactory::PositionColorAttr));
        return gp;
    }

    static void Tesselate(intptr_t vertices, size_t vertexStride, const Geometry& geo,
                          const GrPipelineOptimizations& opts) {
        if (geo.fHasLocalRect) {
            GrQuad quad(geo.fLocalRect);
            tesselate(vertices, vertexStride, geo.fColor, geo.fViewMatrix, geo.fRect, &quad);
        } else {
            tesselate(vertices, vertexStride, geo.fColor, geo.fViewMatrix, geo.fRect, nullptr);
        }
    }
};

typedef GrTInstanceBatch<NonAAFillRectBatchImp> NonAAFillRectBatchSimple;
typedef GrTInstanceBatch<NonAAFillRectBatchPerspectiveImp> NonAAFillRectBatchPerspective;

namespace GrNonAAFillRectBatch {
GrDrawBatch* Create(GrColor color,
                    const SkMatrix& viewMatrix,
                    const SkRect& rect,
                    const SkRect* localRect,
                    const SkMatrix* localMatrix) {

    /* Perspective has to be handled in a slow path for now */
    if (viewMatrix.hasPerspective() || (localMatrix && localMatrix->hasPerspective())) {
        NonAAFillRectBatchPerspective* batch = NonAAFillRectBatchPerspective::Create();
        NonAAFillRectBatchPerspective::Geometry& geo = *batch->geometry();

        geo.fColor = color;
        geo.fViewMatrix = viewMatrix;
        geo.fRect = rect;
        geo.fHasLocalRect = SkToBool(localRect);
        geo.fHasLocalMatrix = SkToBool(localMatrix);
        if (localMatrix) {
            geo.fLocalMatrix = *localMatrix;
        }
        if (localRect) {
            geo.fLocalRect = *localRect;
        }

        batch->init();
        return batch;
    } else {
        // TODO bubble these up as separate calls
        NonAAFillRectBatchSimple* batch = NonAAFillRectBatchSimple::Create();
        NonAAFillRectBatchSimple::Geometry& geo = *batch->geometry();

        geo.fColor = color;
        geo.fViewMatrix = viewMatrix;
        geo.fRect = rect;

        if (localRect && localMatrix) {
            geo.fLocalQuad.setFromMappedRect(*localRect, *localMatrix);
        } else if (localRect) {
            geo.fLocalQuad.set(*localRect);
        } else if (localMatrix) {
            geo.fLocalQuad.setFromMappedRect(rect, *localMatrix);
        } else {
            geo.fLocalQuad.set(rect);
        }

        batch->init();
        return batch;
    }
}
};

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

#ifdef GR_TEST_UTILS

#include "GrBatchTest.h"

DRAW_BATCH_TEST_DEFINE(RectBatch) {
    GrColor color = GrRandomColor(random);
    SkRect rect = GrTest::TestRect(random);
    SkRect localRect = GrTest::TestRect(random);
    SkMatrix viewMatrix = GrTest::TestMatrixInvertible(random);
    SkMatrix localMatrix = GrTest::TestMatrix(random);

    bool hasLocalRect = random->nextBool();
    bool hasLocalMatrix = random->nextBool();
    return GrNonAAFillRectBatch::Create(color, viewMatrix, rect,
                                        hasLocalRect ? &localRect : nullptr,
                                        hasLocalMatrix ? &localMatrix : nullptr);
}

#endif