//
// Copyright (c) 2016 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// TranslatorVulkan:
//   A GLSL-based translator that outputs shaders that fit GL_KHR_vulkan_glsl.
//   The shaders are then fed into glslang to spit out SPIR-V (libANGLE-side).
//   See: https://www.khronos.org/registry/vulkan/specs/misc/GL_KHR_vulkan_glsl.txt
//

#include "compiler/translator/TranslatorVulkan.h"

#include "angle_gl.h"
#include "compiler/translator/OutputVulkanGLSL.h"
#include "compiler/translator/util.h"

namespace sh
{

class DeclareDefaultUniformsTraverser : public TIntermTraverser
{
  public:
    DeclareDefaultUniformsTraverser(TInfoSinkBase *sink,
                                    ShHashFunction64 hashFunction,
                                    NameMap *nameMap)
        : TIntermTraverser(true, true, true),
          mSink(sink),
          mHashFunction(hashFunction),
          mNameMap(nameMap),
          mInDefaultUniform(false)
    {
    }

    bool visitDeclaration(Visit visit, TIntermDeclaration *node) override
    {
        const TIntermSequence &sequence = *(node->getSequence());

        // TODO(jmadill): Compound declarations.
        ASSERT(sequence.size() == 1);

        TIntermTyped *variable = sequence.front()->getAsTyped();
        const TType &type      = variable->getType();
        bool isUniform         = (type.getQualifier() == EvqUniform);

        if (visit == PreVisit)
        {
            if (isUniform)
            {
                (*mSink) << "    " << GetTypeName(type, mHashFunction, mNameMap) << " ";
                mInDefaultUniform = true;
            }
        }
        else if (visit == InVisit)
        {
            mInDefaultUniform = isUniform;
        }
        else if (visit == PostVisit)
        {
            if (isUniform)
            {
                (*mSink) << ";\n";

                // Remove the uniform declaration from the tree so it isn't parsed again.
                TIntermSequence emptyReplacement;
                mMultiReplacements.push_back(NodeReplaceWithMultipleEntry(
                    getParentNode()->getAsBlock(), node, emptyReplacement));
            }

            mInDefaultUniform = false;
        }
        return true;
    }

    void visitSymbol(TIntermSymbol *symbol) override
    {
        if (mInDefaultUniform)
        {
            const TName &name = symbol->getName();
            ASSERT(name.getString().substr(0, 3) != "gl_");
            (*mSink) << HashName(name, mHashFunction, mNameMap);
        }
    }

  private:
    TInfoSinkBase *mSink;
    ShHashFunction64 mHashFunction;
    NameMap *mNameMap;
    bool mInDefaultUniform;
};

TranslatorVulkan::TranslatorVulkan(sh::GLenum type, ShShaderSpec spec)
    : TCompiler(type, spec, SH_GLSL_450_CORE_OUTPUT)
{
}

void TranslatorVulkan::translate(TIntermBlock *root, ShCompileOptions compileOptions)
{
    TInfoSinkBase &sink = getInfoSink().obj;

    sink << "#version 450 core\n";

    // Write out default uniforms into a uniform block assigned to a specific set/binding.
    if (!getUniforms().empty())
    {
        sink << "\nlayout(@@ DEFAULT-UNIFORMS-SET-BINDING @@) uniform defaultUniforms\n{\n";

        DeclareDefaultUniformsTraverser defaultTraverser(&sink, getHashFunction(), &getNameMap());
        root->traverse(&defaultTraverser);
        defaultTraverser.updateTree();

        sink << "};\n";
    }

    // Declare gl_FragColor and glFragData as webgl_FragColor and webgl_FragData
    // if it's core profile shaders and they are used.
    if (getShaderType() == GL_FRAGMENT_SHADER)
    {
        bool hasGLFragColor = false;
        bool hasGLFragData  = false;

        for (const auto &outputVar : outputVariables)
        {
            if (outputVar.name == "gl_FragColor")
            {
                ASSERT(!hasGLFragColor);
                hasGLFragColor = true;
                continue;
            }
            else if (outputVar.name == "gl_FragData")
            {
                ASSERT(!hasGLFragData);
                hasGLFragData = true;
                continue;
            }
        }
        ASSERT(!(hasGLFragColor && hasGLFragData));
        if (hasGLFragColor)
        {
            sink << "layout(location = 0) out vec4 webgl_FragColor;\n";
        }
        if (hasGLFragData)
        {
            sink << "layout(location = 0) out vec4 webgl_FragData[gl_MaxDrawBuffers];\n";
        }
    }

    // Write translated shader.
    TOutputVulkanGLSL outputGLSL(sink, getArrayIndexClampingStrategy(), getHashFunction(),
                                 getNameMap(), &getSymbolTable(), getShaderType(),
                                 getShaderVersion(), getOutputType(), compileOptions);
    root->traverse(&outputGLSL);
}

bool TranslatorVulkan::shouldFlattenPragmaStdglInvariantAll()
{
    // Not necessary.
    return false;
}

}  // namespace sh
