#include "ProgramGL.h"
#include "ShaderModuleGL.h"
#include "renderer/backend/Types.h"
#include "base/ccMacros.h"

CC_BACKEND_BEGIN

namespace
{
    GLenum toGLAttributeType(VertexFormat vertexFormat)
    {
        GLenum ret = GL_INT;
        switch (vertexFormat)
        {
            case VertexFormat::FLOAT_R32G32B32A32:
            case VertexFormat::FLOAT_R32G32B32:
            case VertexFormat::FLOAT_R32G32:
            case VertexFormat::FLOAT_R32:
                ret = GL_FLOAT;
                break;
            case VertexFormat::INT_R32G32B32A32:
            case VertexFormat::INT_R32G32B32:
            case VertexFormat::INT_R32G32:
            case VertexFormat::INT_R32:
                ret = GL_INT;
                break;
            case VertexFormat::UBYTE_R8G8B8A8:
                ret = GL_UNSIGNED_BYTE;
                break;
            default:
                break;
        }
        return ret;
    }
    
    GLsizei getGLAttributeSize(VertexFormat vertexFormat)
    {
        GLsizei ret = 0;
        switch (vertexFormat)
        {
            case VertexFormat::FLOAT_R32G32B32A32:
            case VertexFormat::INT_R32G32B32A32:
            case VertexFormat::UBYTE_R8G8B8A8:
                ret = 4;
                break;
            case VertexFormat::FLOAT_R32G32B32:
            case VertexFormat::INT_R32G32B32:
                ret = 3;
                break;
            case VertexFormat::FLOAT_R32G32:
            case VertexFormat::INT_R32G32:
                ret = 2;
                break;
            case VertexFormat::FLOAT_R32:
            case VertexFormat::INT_R32:
                ret = 1;
                break;
            default:
                break;
        }
        return ret;
    }
    
    GLsizei getGLDataTypeSize(GLenum size)
    {
        GLsizei ret = 0;
        switch (size)
        {
            case GL_BOOL:
            case GL_BYTE:
            case GL_UNSIGNED_BYTE:
                ret = sizeof(GLbyte);
                break;
            case GL_BOOL_VEC2:
            case GL_SHORT:
            case GL_UNSIGNED_SHORT:
                ret = sizeof(GLshort);
                break;
            case GL_BOOL_VEC3:
                ret = sizeof(GLboolean);
                break;
            case GL_BOOL_VEC4:
            case GL_INT:
            case GL_UNSIGNED_INT:
            case GL_FLOAT:
                ret = sizeof(GLfloat);
                break;
            case GL_FLOAT_VEC2:
            case GL_INT_VEC2:
                ret = sizeof(GLfloat) * 2;
                break;
            case GL_FLOAT_VEC3:
            case GL_INT_VEC3:
                ret = sizeof(GLfloat) * 3;
                break;
            case GL_FLOAT_MAT2:
            case GL_FLOAT_VEC4:
            case GL_INT_VEC4:
                ret = sizeof(GLfloat) * 4;
                break;
            case GL_FLOAT_MAT3:
                ret = sizeof(GLfloat) * 9;
                break;
            case GL_FLOAT_MAT4:
                ret = sizeof(GLfloat) * 16;
                break;
            default:
                break;
        }
        return ret;
    }
}

ProgramGL::ProgramGL(const std::string& vertexShader, const std::string& fragmentShader)
: Program(vertexShader, fragmentShader)
{
    _vertexShaderModule = static_cast<ShaderModuleGL*>(ShaderCache::newVertexShaderModule(vertexShader));
    _fragmentShaderModule = static_cast<ShaderModuleGL*>(ShaderCache::newFragmentShaderModule(fragmentShader));

    CC_SAFE_RETAIN(_vertexShaderModule);
    CC_SAFE_RETAIN(_fragmentShaderModule);
    compileProgram();
    computeUniformInfos();
}

ProgramGL::~ProgramGL()
{
    CC_SAFE_RELEASE(_vertexShaderModule);
    CC_SAFE_RELEASE(_fragmentShaderModule);
    if (_program)
        glDeleteProgram(_program);
}

void ProgramGL::compileProgram()
{
    if (_vertexShaderModule == nullptr || _fragmentShaderModule == nullptr)
        return;
    
    auto vertShader = _vertexShaderModule->getShader();
    auto fragShader = _fragmentShaderModule->getShader();
    
    assert (vertShader != 0 && fragShader != 0);
    if (vertShader == 0 || fragShader == 0)
        return;
    
    _program = glCreateProgram();
    if (!_program)
        return;
    
    glAttachShader(_program, vertShader);
    glAttachShader(_program, fragShader);
    
    glLinkProgram(_program);
    
    GLint status = 0;
    glGetProgramiv(_program, GL_LINK_STATUS, &status);
    if (GL_FALSE == status)
    {
        printf("cocos2d: ERROR: %s: failed to link program ", __FUNCTION__);
        glDeleteProgram(_program);
        _program = 0;
    }
}

void ProgramGL::computeAttributeInfos(const RenderPipelineDescriptor& descriptor)
{
    _attributeInfos.clear();
    const auto& vertexLayouts = descriptor.vertexLayouts;
    for (const auto& vertexLayout : vertexLayouts)
    {
        if (! vertexLayout.isValid())
            continue;
        
        VertexAttributeArray vertexAttributeArray;
        
        const auto& attributes = vertexLayout.getAttributes();
        for (const auto& attribute : attributes)
        {
            AttributeInfo attributeInfo;
            
            if (!getAttributeLocation(attribute.name, attributeInfo.location))
                continue;
            
            attributeInfo.stride = vertexLayout.getStride();
            attributeInfo.offset = attribute.offset;
            attributeInfo.type = toGLAttributeType(attribute.format);
            attributeInfo.size = getGLAttributeSize(attribute.format);
            attributeInfo.needToBeNormallized = attribute.needToBeNormallized;
            
            vertexAttributeArray.push_back(attributeInfo);
        }
        
        _attributeInfos.push_back(std::move(vertexAttributeArray));
    }
}

bool ProgramGL::getAttributeLocation(const std::string& attributeName, unsigned int& location) const
{
    GLint loc = glGetAttribLocation(_program, attributeName.c_str());
    if (-1 == loc)
    {
        CCLOG("Cocos2d: %s: can not find vertex attribute of %s", __FUNCTION__, attributeName.c_str());
        return false;
    }
    
    location = GLuint(loc);
    return true;
}

std::vector<AttributeBindInfo> ProgramGL::getActiveAttributes() const {

    std::vector<AttributeBindInfo> attributes;

    if (!_program) return attributes;

    GLint numOfActiveAttributes = 0;
    glGetProgramiv(_program, GL_ACTIVE_ATTRIBUTES, &numOfActiveAttributes);


    if (numOfActiveAttributes <= 0)
        return attributes;

    attributes.reserve(numOfActiveAttributes);

    int MAX_ATTRIBUTE_NAME_LENGTH = 256;
    glGetProgramiv(_program, GL_ACTIVE_ATTRIBUTE_MAX_LENGTH, &MAX_ATTRIBUTE_NAME_LENGTH);

    std::vector<char> attrName(MAX_ATTRIBUTE_NAME_LENGTH + 1);

    GLint attrNameLen = 0;
    GLenum attrType;
    GLint attrSize;
    backend::AttributeBindInfo info;

    for (int i = 0; i < numOfActiveAttributes; i++)
    {
        glGetActiveAttrib(_program, i, MAX_ATTRIBUTE_NAME_LENGTH, &attrNameLen, &attrSize, &attrType, attrName.data());
        CHECK_GL_ERROR_DEBUG();
        info.attributeName = std::string(attrName.data(), attrName.data() + attrNameLen);
        info.location = glGetAttribLocation(_program, info.attributeName.c_str());
        info.type = attrType;
        info.size = getGLDataTypeSize(attrType) * attrSize;
        CHECK_GL_ERROR_DEBUG();
        attributes.push_back(info);
    }

    return attributes;

}


void ProgramGL::computeUniformInfos()
{
    if (!_program)
    return;
    
    GLint numOfUniforms = 0;
    glGetProgramiv(_program, GL_ACTIVE_UNIFORMS, &numOfUniforms);
    if (!numOfUniforms)
    return;
    
#define MAX_UNIFORM_NAME_LENGTH 256
    UniformInfo uniform;
    GLint length = 0;
    GLchar* uniformName = (GLchar*)malloc(MAX_UNIFORM_NAME_LENGTH + 1);
    for (int i = 0; i < numOfUniforms; ++i)
    {
        glGetActiveUniform(_program, i, MAX_UNIFORM_NAME_LENGTH, &length, &uniform.count, &uniform.type, uniformName);
        uniformName[length] = '\0';
        
        if (length > 3)
        {
            char* c = strrchr(uniformName, '[');
            if (c)
            {
                *c = '\0';
                uniform.isArray = true;
            }
        }
        uniform.location = glGetUniformLocation(_program, uniformName);
        uniform.bufferSize = getGLDataTypeSize(uniform.type);
        _uniformInfos[uniformName] = uniform;

        _maxLocation = _maxLocation <= uniform.location ? (uniform.location + 1) : _maxLocation;
    }
    free(uniformName);
}

UniformLocation ProgramGL::getUniformLocation(const std::string& uniform) const
{
    UniformLocation uniformLocation;
    uniformLocation.location = glGetUniformLocation(_program, uniform.c_str());
    return uniformLocation;
}

const std::unordered_map<std::string, UniformInfo>& ProgramGL::getVertexUniformInfos() const
{
    return _uniformInfos;
}

const std::unordered_map<std::string, UniformInfo>& ProgramGL::getFragmentUniformInfos() const
{
    return _uniformInfos;
}

int ProgramGL::getMaxVertexLocation() const
{
    return _maxLocation;
}
int ProgramGL::getMaxFragmentLocation() const
{
    return _maxLocation;
}

CC_BACKEND_END