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

namespace amalgine {
    VertexShader::VertexShader()
    {
        glGetIntegerv(GL_MAX_VERTEX_ATTRIBS, &maxAttribs);
    }

    void VertexShader::defineMain(VertexShaderMainFunc mainFunc)
    {
        if(mainFuncDefined)
            throw ShaderFunctionAlreadyDefined("main");
        
        writeBody("void main() {\n");
        ShaderVec4 glPosition = mainFunc();
        mainFuncDefined = true;
        writeBody("gl_Position = ");
        writeBody(glPosition.getOutput());
        writeBody(";\n}\n\n");
    }

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