/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/

#include "GrVkUniformHandler.h"
#include "glsl/GrGLSLProgramBuilder.h"

// To determine whether a current offset is aligned, we can just 'and' the lowest bits with the
// alignment mask. A value of 0 means aligned, any other value is how many bytes past alignment we
// are. This works since all alignments are powers of 2. The mask is always (alignment - 1).
// This alignment mask will give correct alignments for using the std430 block layout. If you want
// the std140 alignment, you can use this, but then make sure if you have an array type it is
// aligned to 16 bytes (i.e. has mask of 0xF).
uint32_t grsltype_to_alignment_mask(GrSLType type) {
    SkASSERT(GrSLTypeIsFloatType(type));
    static const uint32_t kAlignmentMask[] = {
        0x0, // kVoid_GrSLType, should never return this
        0x3, // kFloat_GrSLType
        0x7, // kVec2f_GrSLType
        0xF, // kVec3f_GrSLType
        0xF, // kVec4f_GrSLType
        0x7, // kMat22f_GrSLType
        0xF, // kMat33f_GrSLType
        0xF, // kMat44f_GrSLType
        0x0, // Sampler2D_GrSLType, should never return this
        0x0, // SamplerExternal_GrSLType, should never return this
        0x0, // Sampler2DRect_GrSLType, should never return this
        0x0, // SamplerBuffer_GrSLType, should never return this
        0x0, // kBool_GrSLType
        0x7, // kInt_GrSLType
        0x7, // kUint_GrSLType
    };
    GR_STATIC_ASSERT(0 == kVoid_GrSLType);
    GR_STATIC_ASSERT(1 == kFloat_GrSLType);
    GR_STATIC_ASSERT(2 == kVec2f_GrSLType);
    GR_STATIC_ASSERT(3 == kVec3f_GrSLType);
    GR_STATIC_ASSERT(4 == kVec4f_GrSLType);
    GR_STATIC_ASSERT(5 == kMat22f_GrSLType);
    GR_STATIC_ASSERT(6 == kMat33f_GrSLType);
    GR_STATIC_ASSERT(7 == kMat44f_GrSLType);
    GR_STATIC_ASSERT(8 == kSampler2D_GrSLType);
    GR_STATIC_ASSERT(9 == kSamplerExternal_GrSLType);
    GR_STATIC_ASSERT(10 == kSampler2DRect_GrSLType);
    GR_STATIC_ASSERT(11 == kSamplerBuffer_GrSLType);
    GR_STATIC_ASSERT(12 == kBool_GrSLType);
    GR_STATIC_ASSERT(13 == kInt_GrSLType);
    GR_STATIC_ASSERT(14 == kUint_GrSLType);
    GR_STATIC_ASSERT(SK_ARRAY_COUNT(kAlignmentMask) == kGrSLTypeCount);
    return kAlignmentMask[type];
}

/** Returns the size in bytes taken up in vulkanbuffers for floating point GrSLTypes.
    For non floating point type returns 0 */
static inline uint32_t grsltype_to_vk_size(GrSLType type) {
    SkASSERT(GrSLTypeIsFloatType(type));
    SkASSERT(kMat22f_GrSLType != type); // TODO: handle mat2 differences between std140 and std430.
    static const uint32_t kSizes[] = {
        0,                        // kVoid_GrSLType
        sizeof(float),            // kFloat_GrSLType
        2 * sizeof(float),        // kVec2f_GrSLType
        3 * sizeof(float),        // kVec3f_GrSLType
        4 * sizeof(float),        // kVec4f_GrSLType
        8 * sizeof(float),        // kMat22f_GrSLType. TODO: this will be 4 * szof(float) on std430.
        12 * sizeof(float),       // kMat33f_GrSLType
        16 * sizeof(float),       // kMat44f_GrSLType
        0,                        // kSampler2D_GrSLType
        0,                        // kSamplerExternal_GrSLType
        0,                        // kSampler2DRect_GrSLType
        0,                        // kSamplerBuffer_GrSLType
        1,                        // kBool_GrSLType
        4,                        // kInt_GrSLType
        4                         // kUint_GrSLType
    };
    return kSizes[type];

    GR_STATIC_ASSERT(0 == kVoid_GrSLType);
    GR_STATIC_ASSERT(1 == kFloat_GrSLType);
    GR_STATIC_ASSERT(2 == kVec2f_GrSLType);
    GR_STATIC_ASSERT(3 == kVec3f_GrSLType);
    GR_STATIC_ASSERT(4 == kVec4f_GrSLType);
    GR_STATIC_ASSERT(5 == kMat22f_GrSLType);
    GR_STATIC_ASSERT(6 == kMat33f_GrSLType);
    GR_STATIC_ASSERT(7 == kMat44f_GrSLType);
    GR_STATIC_ASSERT(8 == kSampler2D_GrSLType);
    GR_STATIC_ASSERT(9 == kSamplerExternal_GrSLType);
    GR_STATIC_ASSERT(10 == kSampler2DRect_GrSLType);
    GR_STATIC_ASSERT(11 == kSamplerBuffer_GrSLType);
    GR_STATIC_ASSERT(12 == kBool_GrSLType);
    GR_STATIC_ASSERT(13 == kInt_GrSLType);
    GR_STATIC_ASSERT(14 == kUint_GrSLType);
    GR_STATIC_ASSERT(SK_ARRAY_COUNT(kSizes) == kGrSLTypeCount);
}


// Given the current offset into the ubo, calculate the offset for the uniform we're trying to add
// taking into consideration all alignment requirements. The uniformOffset is set to the offset for
// the new uniform, and currentOffset is updated to be the offset to the end of the new uniform.
void get_ubo_aligned_offset(uint32_t* uniformOffset,
                            uint32_t* currentOffset,
                            GrSLType type,
                            int arrayCount) {
    uint32_t alignmentMask = grsltype_to_alignment_mask(type);
    // We want to use the std140 layout here, so we must make arrays align to 16 bytes.
    SkASSERT(type != kMat22f_GrSLType); // TODO: support mat2.
    if (arrayCount) {
        alignmentMask = 0xF;
    }
    uint32_t offsetDiff = *currentOffset & alignmentMask;
    if (offsetDiff != 0) {
        offsetDiff = alignmentMask - offsetDiff + 1;
    }
    *uniformOffset = *currentOffset + offsetDiff;
    SkASSERT(sizeof(float) == 4);
    if (arrayCount) {
        uint32_t elementSize = SkTMax<uint32_t>(16, grsltype_to_vk_size(type));
        SkASSERT(0 == (elementSize & 0xF));
        *currentOffset = *uniformOffset + elementSize * arrayCount;
    } else {
        *currentOffset = *uniformOffset + grsltype_to_vk_size(type);
    }
}

GrGLSLUniformHandler::UniformHandle GrVkUniformHandler::internalAddUniformArray(
                                                                            uint32_t visibility,
                                                                            GrSLType type,
                                                                            GrSLPrecision precision,
                                                                            const char* name,
                                                                            bool mangleName,
                                                                            int arrayCount,
                                                                            const char** outName) {
    SkASSERT(name && strlen(name));
    SkDEBUGCODE(static const uint32_t kVisibilityMask = kVertex_GrShaderFlag|kFragment_GrShaderFlag);
    SkASSERT(0 == (~kVisibilityMask & visibility));
    SkASSERT(0 != visibility);
    SkASSERT(kDefault_GrSLPrecision == precision || GrSLTypeIsFloatType(type));
    GrSLTypeIsFloatType(type);

    UniformInfo& uni = fUniforms.push_back();
    uni.fVariable.setType(type);
    // TODO this is a bit hacky, lets think of a better way.  Basically we need to be able to use
    // the uniform view matrix name in the GP, and the GP is immutable so it has to tell the PB
    // exactly what name it wants to use for the uniform view matrix.  If we prefix anythings, then
    // the names will mismatch.  I think the correct solution is to have all GPs which need the
    // uniform view matrix, they should upload the view matrix in their setData along with regular
    // uniforms.
    char prefix = 'u';
    if ('u' == name[0]) {
        prefix = '\0';
    }
    fProgramBuilder->nameVariable(uni.fVariable.accessName(), prefix, name, mangleName);
    uni.fVariable.setArrayCount(arrayCount);
    // For now asserting the the visibility is either only vertex or only fragment
    SkASSERT(kVertex_GrShaderFlag == visibility || kFragment_GrShaderFlag == visibility);
    uni.fVisibility = visibility;
    uni.fVariable.setPrecision(precision);
    // When outputing the GLSL, only the outer uniform block will get the Uniform modifier. Thus
    // we set the modifier to none for all uniforms declared inside the block.
    uni.fVariable.setTypeModifier(GrGLSLShaderVar::kNone_TypeModifier);

    uint32_t* currentOffset = kVertex_GrShaderFlag == visibility ? &fCurrentVertexUBOOffset
                                                                   : &fCurrentFragmentUBOOffset;
    get_ubo_aligned_offset(&uni.fUBOffset, currentOffset, type, arrayCount);

    if (outName) {
        *outName = uni.fVariable.c_str();
    }

    return GrGLSLUniformHandler::UniformHandle(fUniforms.count() - 1);
}

GrGLSLUniformHandler::SamplerHandle GrVkUniformHandler::internalAddSampler(uint32_t visibility,
                                                                           GrPixelConfig config,
                                                                           GrSLType type,
                                                                           GrSLPrecision precision,
                                                                           const char* name) {
    SkASSERT(name && strlen(name));
    SkDEBUGCODE(static const uint32_t kVisMask = kVertex_GrShaderFlag | kFragment_GrShaderFlag);
    SkASSERT(0 == (~kVisMask & visibility));
    SkASSERT(0 != visibility);
    SkString mangleName;
    char prefix = 'u';
    fProgramBuilder->nameVariable(&mangleName, prefix, name, true);
    fSamplers.emplace_back(visibility, config, type, precision, mangleName.c_str(),
                           (uint32_t)fSamplers.count(), kSamplerDescSet);
    return GrGLSLUniformHandler::SamplerHandle(fSamplers.count() - 1);
}

void GrVkUniformHandler::appendUniformDecls(GrShaderFlags visibility, SkString* out) const {
    SkASSERT(kVertex_GrShaderFlag == visibility || kFragment_GrShaderFlag == visibility);

    for (int i = 0; i < fSamplers.count(); ++i) {
        const GrVkGLSLSampler& sampler = fSamplers[i];
        SkASSERT(sampler.type() == kSampler2D_GrSLType);
        if (visibility == sampler.visibility()) {
            sampler.fShaderVar.appendDecl(fProgramBuilder->glslCaps(), out);
            out->append(";\n");
        }
    }

    SkString uniformsString;
    for (int i = 0; i < fUniforms.count(); ++i) {
        const UniformInfo& localUniform = fUniforms[i];
        if (visibility == localUniform.fVisibility) {
            if (GrSLTypeIsFloatType(localUniform.fVariable.getType())) {
                localUniform.fVariable.appendDecl(fProgramBuilder->glslCaps(), &uniformsString);
                uniformsString.append(";\n");
            }
        }
    }
    if (!uniformsString.isEmpty()) {
        uint32_t uniformBinding = (visibility == kVertex_GrShaderFlag) ? kVertexBinding
                                                                       : kFragBinding;
        const char* stage = (visibility == kVertex_GrShaderFlag) ? "vertex" : "fragment";
        out->appendf("layout (set=%d, binding=%d) uniform %sUniformBuffer\n{\n",
                     kUniformBufferDescSet, uniformBinding, stage);
        out->appendf("%s\n};\n", uniformsString.c_str());
    }
}