#include "Shader.hpp"
#include "ShaderException.hpp"

#include <glrage_util/ErrorUtils.hpp>
#include <glrage_util/StringUtils.hpp>

#include <fstream>
#include <sstream>
#include <string>

namespace glrage {
namespace gl {

Shader::Shader(GLenum type)
{
    m_id = glCreateShader(type);
    if (!m_id) {
        throw ShaderException("Can't create shader");
    }
}

Shader::~Shader()
{
    if (m_id) {
        glDeleteShader(m_id);
    }
}

void Shader::bind()
{}

Shader& Shader::fromFile(const std::string& path)
{
    // open and check shader file
    std::ifstream file;
    file.open(path.c_str());
    if (!file.good()) {
        throw std::runtime_error("Can't open shader file '" + path +
                                 "': " + ErrorUtils::getSystemErrorString());
    }

    // read file to a string stream
    std::stringstream stream;
    stream << file.rdbuf();
    file.close();

    // convert stream to string
    fromString(stream.str());

    return *this;
}

Shader& Shader::fromString(const std::string& program)
{
    // create shader source
    const char* programChars = program.c_str();
    glShaderSource(m_id, 1, &programChars, nullptr);

    // compile the shader
    glCompileShader(m_id);

    // check the compilation status and throw exception if shader compilation
    // failed
    if (!compiled()) {
        std::string message = infoLog();
        if (message.empty()) {
            message = "Shader compilation failed.";
        }
        throw ShaderException(message);
    }

    return *this;
}

std::string Shader::infoLog()
{
    GLint infoLogLength;
    std::string infoLogString;
    infoLogString.resize(4096);
    glGetShaderInfoLog(
        m_id, infoLogString.size(), &infoLogLength, &infoLogString[0]);
    infoLogString.resize(infoLogLength);
    return infoLogString;
}

bool Shader::compiled()
{
    int compileStatus;
    glGetShaderiv(m_id, GL_COMPILE_STATUS, &compileStatus);
    return compileStatus == GL_TRUE;
}

} // namespace gl
} // namespace glrage