/*
 * Copyright 2013 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "GrGLProgramEffects.h"
#include "GrDrawEffect.h"
#include "gl/GrGLEffect.h"
#include "gl/GrGLShaderBuilder.h"
#include "gl/GrGpuGL.h"

typedef GrGLProgramEffects::EffectKey EffectKey;
typedef GrGLProgramEffects::TransformedCoords TransformedCoords;
typedef GrGLProgramEffects::TransformedCoordsArray TransformedCoordsArray;
typedef GrGLProgramEffects::TextureSampler TextureSampler;
typedef GrGLProgramEffects::TextureSamplerArray TextureSamplerArray;

/**
 * We specialize the vertex code for each of these matrix types.
 */
enum MatrixType {
    kIdentity_MatrixType = 0,
    kTrans_MatrixType    = 1,
    kNoPersp_MatrixType  = 2,
    kGeneral_MatrixType  = 3,
};

/**
 * The key for an individual coord transform is made up of a matrix type and a bit that
 * indicates the source of the input coords.
 */
enum {
    kMatrixTypeKeyBits   = 2,
    kMatrixTypeKeyMask   = (1 << kMatrixTypeKeyBits) - 1,
    kPositionCoords_Flag = (1 << kMatrixTypeKeyBits),
    kTransformKeyBits    = kMatrixTypeKeyBits + 1,
    kTransformKeyMask    = (1 << kTransformKeyBits) - 1,
};

namespace {

/**
 * Do we need to either map r,g,b->a or a->r. configComponentMask indicates which channels are
 * present in the texture's config. swizzleComponentMask indicates the channels present in the
 * shader swizzle.
 */
inline bool swizzle_requires_alpha_remapping(const GrGLCaps& caps,
                                             uint32_t configComponentMask,
                                             uint32_t swizzleComponentMask) {
    if (caps.textureSwizzleSupport()) {
        // Any remapping is handled using texture swizzling not shader modifications.
        return false;
    }
    // check if the texture is alpha-only
    if (kA_GrColorComponentFlag == configComponentMask) {
        if (caps.textureRedSupport() && (kA_GrColorComponentFlag & swizzleComponentMask)) {
            // we must map the swizzle 'a's to 'r'.
            return true;
        }
        if (kRGB_GrColorComponentFlags & swizzleComponentMask) {
            // The 'r', 'g', and/or 'b's must be mapped to 'a' according to our semantics that
            // alpha-only textures smear alpha across all four channels when read.
            return true;
        }
    }
    return false;
}

}

EffectKey GrGLProgramEffects::GenAttribKey(const GrDrawEffect& drawEffect) {
    EffectKey key = 0;
    int numAttributes = drawEffect.getVertexAttribIndexCount();
    SkASSERT(numAttributes <= 2);
    const int* attributeIndices = drawEffect.getVertexAttribIndices();
    for (int a = 0; a < numAttributes; ++a) {
        EffectKey value = attributeIndices[a] << 3 * a;
        SkASSERT(0 == (value & key)); // keys for each attribute ought not to overlap
        key |= value;
    }
    return key;
}

EffectKey GrGLProgramEffects::GenTransformKey(const GrDrawEffect& drawEffect) {
    EffectKey totalKey = 0;
    int numTransforms = (*drawEffect.effect())->numTransforms();
    for (int t = 0; t < numTransforms; ++t) {
        EffectKey key = 0;
        const GrCoordTransform& coordTransform = (*drawEffect.effect())->coordTransform(t);
        SkMatrix::TypeMask type0 = coordTransform.getMatrix().getType();
        SkMatrix::TypeMask type1;
        if (kLocal_GrCoordSet == coordTransform.sourceCoords()) {
            type1 = drawEffect.getCoordChangeMatrix().getType();
        } else {
            if (drawEffect.programHasExplicitLocalCoords()) {
                // We only make the key indicate that device coords are referenced when the local coords
                // are not actually determined by positions. Otherwise the local coords var and position
                // var are identical.
                key |= kPositionCoords_Flag;
            }
            type1 = SkMatrix::kIdentity_Mask;
        }

        int combinedTypes = type0 | type1;

        bool reverseY = coordTransform.reverseY();

        if (SkMatrix::kPerspective_Mask & combinedTypes) {
            key |= kGeneral_MatrixType;
        } else if (((SkMatrix::kAffine_Mask | SkMatrix::kScale_Mask) & combinedTypes) || reverseY) {
            key |= kNoPersp_MatrixType;
        } else if (SkMatrix::kTranslate_Mask & combinedTypes) {
            key |= kTrans_MatrixType;
        } else {
            key |= kIdentity_MatrixType;
        }
        key <<= kTransformKeyBits * t;
        SkASSERT(0 == (totalKey & key)); // keys for each transform ought not to overlap
        totalKey |= key;
    }
    return totalKey;
}

EffectKey GrGLProgramEffects::GenTextureKey(const GrDrawEffect& drawEffect, const GrGLCaps& caps) {
    EffectKey key = 0;
    int numTextures = (*drawEffect.effect())->numTextures();
    for (int t = 0; t < numTextures; ++t) {
        const GrTextureAccess& access = (*drawEffect.effect())->textureAccess(t);
        uint32_t configComponentMask = GrPixelConfigComponentMask(access.getTexture()->config());
        if (swizzle_requires_alpha_remapping(caps, configComponentMask, access.swizzleMask())) {
            key |= 1 << t;
        }
    }
    return key;
}

GrGLProgramEffects::~GrGLProgramEffects() {
    int numEffects = fGLEffects.count();
    for (int e = 0; e < numEffects; ++e) {
        SkDELETE(fGLEffects[e]);
    }
}

void GrGLProgramEffects::initSamplers(const GrGLUniformManager& uniformManager, int* texUnitIdx) {
    int numEffects = fGLEffects.count();
    SkASSERT(numEffects == fSamplers.count());
    for (int e = 0; e < numEffects; ++e) {
        SkTArray<Sampler, true>& samplers = fSamplers[e];
        int numSamplers = samplers.count();
        for (int s = 0; s < numSamplers; ++s) {
            SkASSERT(samplers[s].fUniform.isValid());
            uniformManager.setSampler(samplers[s].fUniform, *texUnitIdx);
            samplers[s].fTextureUnit = (*texUnitIdx)++;
        }
    }
}

void GrGLProgramEffects::setData(GrGpuGL* gpu,
                                 const GrGLUniformManager& uniformManager,
                                 const GrEffectStage* effectStages[]) {
    int numEffects = fGLEffects.count();
    SkASSERT(numEffects == fTransforms.count());
    SkASSERT(numEffects == fSamplers.count());
    for (int e = 0; e < numEffects; ++e) {
        GrDrawEffect drawEffect(*effectStages[e], fHasExplicitLocalCoords);
        fGLEffects[e]->setData(uniformManager, drawEffect);
        this->setTransformData(uniformManager, drawEffect, e);
        this->bindTextures(gpu, *drawEffect.effect(), e);
    }
}

void GrGLProgramEffects::setTransformData(const GrGLUniformManager& uniformManager,
                                          const GrDrawEffect& drawEffect,
                                          int effectIdx) {
    SkTArray<Transform, true>& transforms = fTransforms[effectIdx];
    int numTransforms = transforms.count();
    SkASSERT(numTransforms == (*drawEffect.effect())->numTransforms());
    for (int t = 0; t < numTransforms; ++t) {
        const GrCoordTransform& coordTransform = (*drawEffect.effect())->coordTransform(t);
        const SkMatrix& matrix = coordTransform.getMatrix();
        const SkMatrix& coordChangeMatrix = kLocal_GrCoordSet == coordTransform.sourceCoords() ?
                                                drawEffect.getCoordChangeMatrix() :
                                                SkMatrix::I();
        SkASSERT(transforms[t].fHandle.isValid() != (kVoid_GrSLType == transforms[t].fType));
        switch (transforms[t].fType) {
            case kVoid_GrSLType:
                SkASSERT(matrix.isIdentity());
                SkASSERT(coordChangeMatrix.isIdentity());
                SkASSERT(!coordTransform.reverseY());
                return;
            case kVec2f_GrSLType: {
                SkASSERT(SkMatrix::kTranslate_Mask == (matrix.getType() | coordChangeMatrix.getType()));
                SkASSERT(!coordTransform.reverseY());
                SkScalar tx = matrix[SkMatrix::kMTransX] + (coordChangeMatrix)[SkMatrix::kMTransX];
                SkScalar ty = matrix[SkMatrix::kMTransY] + (coordChangeMatrix)[SkMatrix::kMTransY];
                if (transforms[t].fCurrentValue.get(SkMatrix::kMTransX) != tx ||
                    transforms[t].fCurrentValue.get(SkMatrix::kMTransY) != ty) {
                    uniformManager.set2f(transforms[t].fHandle, tx, ty);
                    transforms[t].fCurrentValue.set(SkMatrix::kMTransX, tx);
                    transforms[t].fCurrentValue.set(SkMatrix::kMTransY, ty);
                }
                break;
            }
            case kMat33f_GrSLType: {
                SkMatrix combined;
                combined.setConcat(matrix, coordChangeMatrix);
                if (coordTransform.reverseY()) {
                    // combined.postScale(1,-1);
                    // combined.postTranslate(0,1);
                    combined.set(SkMatrix::kMSkewY,
                        combined[SkMatrix::kMPersp0] - combined[SkMatrix::kMSkewY]);
                    combined.set(SkMatrix::kMScaleY,
                        combined[SkMatrix::kMPersp1] - combined[SkMatrix::kMScaleY]);
                    combined.set(SkMatrix::kMTransY,
                        combined[SkMatrix::kMPersp2] - combined[SkMatrix::kMTransY]);
                }
                if (!transforms[t].fCurrentValue.cheapEqualTo(combined)) {
                    uniformManager.setSkMatrix(transforms[t].fHandle, combined);
                    transforms[t].fCurrentValue = combined;
                }
                break;
            }
            default:
                GrCrash("Unexpected uniform type.");
        }
    }
}

void GrGLProgramEffects::bindTextures(GrGpuGL* gpu, const GrEffectRef& effect, int effectIdx) {
    const SkTArray<Sampler, true>& samplers = fSamplers[effectIdx];
    int numSamplers = samplers.count();
    SkASSERT(numSamplers == effect->numTextures());
    for (int s = 0; s < numSamplers; ++s) {
        SkASSERT(samplers[s].fTextureUnit >= 0);
        const GrTextureAccess& textureAccess = effect->textureAccess(s);
        gpu->bindTexture(samplers[s].fTextureUnit,
                         textureAccess.getParams(),
                         static_cast<GrGLTexture*>(textureAccess.getTexture()));
    }
}

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

GrGLProgramEffectsBuilder::GrGLProgramEffectsBuilder(GrGLShaderBuilder* builder, int reserveCount)
    : fBuilder(builder) {
    GrGLShaderBuilder::VertexBuilder* vertexBuilder = fBuilder->getVertexBuilder();
    SkASSERT(NULL != vertexBuilder);
    fProgramEffects.reset(SkNEW_ARGS(GrGLProgramEffects,
                                     (reserveCount, vertexBuilder->hasExplicitLocalCoords())));
}

void GrGLProgramEffectsBuilder::emitEffect(const GrEffectStage& stage,
                                           EffectKey key,
                                           const char* outColor,
                                           const char* inColor,
                                           int stageIndex) {
    GrGLShaderBuilder::VertexBuilder* vertexBuilder = fBuilder->getVertexBuilder();
    SkASSERT(NULL != vertexBuilder);
    SkASSERT(NULL != fProgramEffects.get());

    GrDrawEffect drawEffect(stage, fProgramEffects->fHasExplicitLocalCoords);
    const GrEffectRef& effect = *stage.getEffect();
    SkSTArray<2, TransformedCoords> coords(effect->numTransforms());
    SkSTArray<4, TextureSampler> samplers(effect->numTextures());

    this->emitAttributes(stage);
    this->emitTransforms(effect, key, &coords);
    this->emitSamplers(effect, &samplers);

    GrGLEffect* glEffect = effect->getFactory().createGLInstance(drawEffect);
    fProgramEffects->fGLEffects.push_back(glEffect);

    // Enclose custom code in a block to avoid namespace conflicts
    SkString openBrace;
    openBrace.printf("\t{ // Stage %d: %s\n", stageIndex, glEffect->name());
    vertexBuilder->vsCodeAppend(openBrace.c_str());
    fBuilder->fsCodeAppend(openBrace.c_str());

    glEffect->emitCode(fBuilder, drawEffect, key, outColor, inColor, coords, samplers);

    vertexBuilder->vsCodeAppend("\t}\n");
    fBuilder->fsCodeAppend("\t}\n");
}

void GrGLProgramEffectsBuilder::emitAttributes(const GrEffectStage& stage) {
    GrGLShaderBuilder::VertexBuilder* vertexBuilder = fBuilder->getVertexBuilder();
    SkASSERT(NULL != vertexBuilder);

    int numAttributes = stage.getVertexAttribIndexCount();
    const int* attributeIndices = stage.getVertexAttribIndices();
    for (int a = 0; a < numAttributes; ++a) {
        // TODO: Make addAttribute mangle the name.
        SkString attributeName("aAttr");
        attributeName.appendS32(attributeIndices[a]);
        vertexBuilder->addEffectAttribute(attributeIndices[a],
                                          (*stage.getEffect())->vertexAttribType(a),
                                          attributeName);
    }
}

void GrGLProgramEffectsBuilder::emitTransforms(const GrEffectRef& effect,
                                               EffectKey effectKey,
                                               TransformedCoordsArray* outCoords) {
    GrGLShaderBuilder::VertexBuilder* vertexBuilder = fBuilder->getVertexBuilder();
    SkASSERT(NULL != vertexBuilder);

    typedef GrGLProgramEffects::Transform Transform;
    SkTArray<Transform, true>& transforms = fProgramEffects->fTransforms.push_back();
    EffectKey totalKey = GrBackendEffectFactory::GetTransformKey(effectKey);
    int numTransforms = effect->numTransforms();
    transforms.push_back_n(numTransforms);
    for (int t = 0; t < numTransforms; t++) {
        EffectKey key = (totalKey >> (kTransformKeyBits * t)) & kTransformKeyMask;
        GrSLType varyingType = kVoid_GrSLType;
        const char* uniName;
        switch (key & kMatrixTypeKeyMask) {
            case kIdentity_MatrixType:
                transforms[t].fType = kVoid_GrSLType;
                uniName = NULL;
                varyingType = kVec2f_GrSLType;
                break;
            case kTrans_MatrixType:
                transforms[t].fType = kVec2f_GrSLType;
                uniName = "StageTranslate";
                varyingType = kVec2f_GrSLType;
                break;
            case kNoPersp_MatrixType:
                transforms[t].fType = kMat33f_GrSLType;
                uniName = "StageMatrix";
                varyingType = kVec2f_GrSLType;
                break;
            case kGeneral_MatrixType:
                transforms[t].fType = kMat33f_GrSLType;
                uniName = "StageMatrix";
                varyingType = kVec3f_GrSLType;
                break;
            default:
                GrCrash("Unexpected key.");
        }
        SkString suffixedUniName;
        if (kVoid_GrSLType != transforms[t].fType) {
            if (0 != t) {
                suffixedUniName.append(uniName);
                suffixedUniName.appendf("_%i", t);
                uniName = suffixedUniName.c_str();
            }
            transforms[t].fHandle = fBuilder->addUniform(GrGLShaderBuilder::kVertex_Visibility,
                                                         transforms[t].fType,
                                                         uniName,
                                                         &uniName);
        }

        const char* varyingName = "MatrixCoord";
        SkString suffixedVaryingName;
        if (0 != t) {
            suffixedVaryingName.append(varyingName);
            suffixedVaryingName.appendf("_%i", t);
            varyingName = suffixedVaryingName.c_str();
        }
        const char* vsVaryingName;
        const char* fsVaryingName;
        vertexBuilder->addVarying(varyingType, varyingName, &vsVaryingName, &fsVaryingName);

        const GrGLShaderVar& coords = (kPositionCoords_Flag & key) ?
                                          vertexBuilder->positionAttribute() :
                                          vertexBuilder->localCoordsAttribute();
        // varying = matrix * coords (logically)
        switch (transforms[t].fType) {
            case kVoid_GrSLType:
                SkASSERT(kVec2f_GrSLType == varyingType);
                vertexBuilder->vsCodeAppendf("\t%s = %s;\n", vsVaryingName, coords.c_str());
                break;
            case kVec2f_GrSLType:
                SkASSERT(kVec2f_GrSLType == varyingType);
                vertexBuilder->vsCodeAppendf("\t%s = %s + %s;\n",
                                             vsVaryingName, uniName, coords.c_str());
                break;
            case kMat33f_GrSLType: {
                SkASSERT(kVec2f_GrSLType == varyingType || kVec3f_GrSLType == varyingType);
                if (kVec2f_GrSLType == varyingType) {
                    vertexBuilder->vsCodeAppendf("\t%s = (%s * vec3(%s, 1)).xy;\n",
                                                 vsVaryingName, uniName, coords.c_str());
                } else {
                    vertexBuilder->vsCodeAppendf("\t%s = %s * vec3(%s, 1);\n",
                                                 vsVaryingName, uniName, coords.c_str());
                }
                break;
            }
            default:
                GrCrash("Unexpected uniform type.");
        }
        SkNEW_APPEND_TO_TARRAY(outCoords, TransformedCoords, (fsVaryingName, varyingType));
    }
}

void GrGLProgramEffectsBuilder::emitSamplers(const GrEffectRef& effect,
                                             TextureSamplerArray* outSamplers) {
    typedef GrGLProgramEffects::Sampler Sampler;
    SkTArray<Sampler, true>& samplers = fProgramEffects->fSamplers.push_back();
    int numTextures = effect->numTextures();
    samplers.push_back_n(numTextures);
    SkString name;
    for (int t = 0; t < numTextures; ++t) {
        name.printf("Sampler%d", t);
        samplers[t].fUniform = fBuilder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
                                                    kSampler2D_GrSLType,
                                                    name.c_str());
        SkNEW_APPEND_TO_TARRAY(outSamplers, TextureSampler,
                               (samplers[t].fUniform, effect->textureAccess(t)));
    }
}