#include "../../../include/RenderBackend/OpenGL/PixelShader.hpp"
#include "../../../include/RenderBackend/OpenGL/opengl.hpp"
#include "../../../include/RenderBackend/OpenGL/CompiledShader.hpp"

namespace amalgine
{
    PixelShader::PixelShader()
    {
        glGetIntegerv(GL_MAX_DRAW_BUFFERS, &maxAttribs);
    }

    void PixelShader::defineMain(PixelShaderMainFunc mainFunc)
    {
        if(mainFuncDefined)
            throw ShaderFunctionAlreadyDefined("main");
        
        writeBody("void main() {\n");
        mainFunc();
        mainFuncDefined = true;
        writeBody("}\n\n");
    }
    
    Result<CompiledPixelShader*> PixelShader::compile()
    {
        if(!mainFuncDefined)
            return Result<CompiledPixelShader*>::Err("main function not defined (defineMain not called)");

        GLuint fragmentShaderId = glCreateShader(GL_FRAGMENT_SHADER);
        std::string verterShaderSource = build();
        const char *verterShaderSourcePtr = verterShaderSource.c_str();
        printf("Vertex shader:\n%s\n", verterShaderSourcePtr);
        glShaderSource(fragmentShaderId, 1, &verterShaderSourcePtr, NULL);
        glCompileShader(fragmentShaderId);
        
        GLint status;
        glGetShaderiv(fragmentShaderId, GL_COMPILE_STATUS, &status);
        std::string compileLog = getShaderCompileLog((u32)fragmentShaderId);
        if(status == GL_TRUE)
        {
            if(!compileLog.empty())
                printf("Pixel shader compile log:\n%s", compileLog.c_str());
            return Result<CompiledPixelShader*>::Ok(new CompiledPixelShader(fragmentShaderId, move(inputAttributes)));
        }
        else
            return Result<CompiledPixelShader*>::Err(compileLog);
    }
}