/*
 * 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 "src/gpu/GrCoordTransform.h"
#include "src/gpu/GrFragmentProcessor.h"
#include "src/gpu/GrProcessor.h"
#include "src/gpu/glsl/GrGLSLFragmentProcessor.h"
#include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
#include "src/gpu/glsl/GrGLSLUniformHandler.h"

void GrGLSLFragmentProcessor::setData(const GrGLSLProgramDataManager& pdman,
                                      const GrFragmentProcessor& processor) {
    this->onSetData(pdman, processor);
}

void GrGLSLFragmentProcessor::invokeChild(int childIndex, const char* inputColor, EmitArgs& args,
                                          SkSL::String skslCoords) {
    while (childIndex >= (int) fFunctionNames.size()) {
        fFunctionNames.emplace_back();
    }
    this->internalInvokeChild(childIndex, inputColor, args.fOutputColor, args, skslCoords);
}

void GrGLSLFragmentProcessor::writeChildCall(GrGLSLFPFragmentBuilder* fragBuilder, int childIndex,
                                             TransformedCoordVars coordVars, const char* inputColor,
                                             const char* outputColor, EmitArgs& args,
                                             SkSL::String skslCoords) {
    std::vector<SkString> coordParams;
    for (int i = 0; i < coordVars.count(); ++i) {
        coordParams.push_back(fragBuilder->ensureCoords2D(coordVars[i].fVaryingPoint));
    }
    // if the fragment processor is invoked with overridden coordinates, it must *always* be invoked
    // with overridden coords
    SkASSERT(args.fFp.computeLocalCoordsInVertexShader() == (skslCoords.length() == 0));
    fragBuilder->codeAppendf("%s = %s(%s", outputColor, fFunctionNames[childIndex].c_str(),
                             inputColor ? inputColor : "half4(1)");
    if (skslCoords.length()) {
        fragBuilder->codeAppendf(", %s", skslCoords.c_str());
    }
    fragBuilder->codeAppend(");\n");
}

void GrGLSLFragmentProcessor::invokeChild(int childIndex, const char* inputColor,
                                          SkString* outputColor, EmitArgs& args,
                                          SkSL::String skslCoords) {
    SkASSERT(outputColor);
    GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
    outputColor->append(fragBuilder->getMangleString());
    fragBuilder->codeAppendf("half4 %s;", outputColor->c_str());
    while (childIndex >= (int) fFunctionNames.size()) {
        fFunctionNames.emplace_back();
    }
    if (!args.fFp.computeLocalCoordsInVertexShader() && skslCoords.length() == 0) {
        skslCoords = "_coords";
    }
    if (fFunctionNames[childIndex].size() == 0) {
        this->internalInvokeChild(childIndex, inputColor, outputColor->c_str(), args, skslCoords);
    } else {
        const GrFragmentProcessor& childProc = args.fFp.childProcessor(childIndex);

        TransformedCoordVars coordVars = args.fTransformedCoords.childInputs(childIndex);
        TextureSamplers textureSamplers = args.fTexSamplers.childInputs(childIndex);
        EmitArgs childArgs(fragBuilder,
                           args.fUniformHandler,
                           args.fShaderCaps,
                           childProc,
                           outputColor->c_str(),
                           "_input",
                           coordVars,
                           textureSamplers);
        this->writeChildCall(fragBuilder, childIndex, coordVars, inputColor, outputColor->c_str(),
                             childArgs, skslCoords);
    }
}

void GrGLSLFragmentProcessor::internalInvokeChild(int childIndex, const char* inputColor,
                                                  const char* outputColor, EmitArgs& args,
                                                  SkSL::String skslCoords) {
    GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;

    fragBuilder->onBeforeChildProcEmitCode();  // call first so mangleString is updated

    // Prepare a mangled input color variable if the default is not used,
    // inputName remains the empty string if no variable is needed.
    SkString inputName;
    if (inputColor&& strcmp("half4(1.0)", inputColor) != 0 && strcmp("half4(1)", inputColor) != 0) {
        // The input name is based off of the current mangle string, and
        // since this is called after onBeforeChildProcEmitCode(), it will be
        // unique to the child processor (exactly what we want for its input).
        inputName.appendf("_childInput%s", fragBuilder->getMangleString().c_str());
        fragBuilder->codeAppendf("half4 %s = %s;", inputName.c_str(), inputColor);
    }

    const GrFragmentProcessor& childProc = args.fFp.childProcessor(childIndex);
    TransformedCoordVars coordVars = args.fTransformedCoords.childInputs(childIndex);
    TextureSamplers textureSamplers = args.fTexSamplers.childInputs(childIndex);

    EmitArgs childArgs(fragBuilder,
                       args.fUniformHandler,
                       args.fShaderCaps,
                       childProc,
                       outputColor,
                       "_input",
                       coordVars,
                       textureSamplers);
    fFunctionNames[childIndex] = fragBuilder->writeProcessorFunction(
                                                               this->childProcessor(childIndex),
                                                               childArgs);
    this->writeChildCall(fragBuilder, childIndex, coordVars, inputColor, outputColor, childArgs,
                         skslCoords);
    fragBuilder->onAfterChildProcEmitCode();
}

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

GrGLSLFragmentProcessor* GrGLSLFragmentProcessor::Iter::next() {
    if (fFPStack.empty()) {
        return nullptr;
    }
    GrGLSLFragmentProcessor* back = fFPStack.back();
    fFPStack.pop_back();
    for (int i = back->numChildProcessors() - 1; i >= 0; --i) {
        fFPStack.push_back(back->childProcessor(i));
    }
    return back;
}