#include <cstdint>
#include <memory>
#include <vector>
#include <GL/glew.h>
#include <cstring>
#include <glog/logging.h>
#include "glutils.hpp"

using namespace fmri;
using namespace std;

/**
 * Utility function to send OpenGL info dumps to the log
 *
 * @param object The GLObject to get info for
 * @param glGet__iv The function to query log length with
 * @param glGet__InfoLog The function to get the log with
 */
static void show_info_log(
        GLuint object,
        PFNGLGETSHADERIVPROC glGet__iv,
        PFNGLGETSHADERINFOLOGPROC glGet__InfoLog
)
{
    GLint log_length;
    glGet__iv(object, GL_INFO_LOG_LENGTH, &log_length);
    unique_ptr<char[]> log(new char[log_length]);
    glGet__InfoLog(object, log_length, nullptr, log.get());

    LOG(INFO) << log.get() << endl;
}

GLuint fmri::loadTexture(DType const *data, int width, int height)
{
    // Load and scale texture
    vector<DType> textureBuffer(data, data + (width * height));
    rescale(textureBuffer.begin(), textureBuffer.end(), 0, 1);

    const float color[] = {0, 0, 0}; // Background color for textures.
    GLuint texture;
    glGenTextures(1, &texture);

    glBindTexture(GL_TEXTURE_2D, texture);

    // Set up (lack of) repetition
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_BORDER);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
    glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, color);

    static_assert(sizeof(DType) == 4); // verify data type for texture.
    glTexImage2D(GL_TEXTURE_2D, 0, GL_R32F, 2, 2, 0, GL_R32F, GL_FLOAT, textureBuffer.data());

    // Set up texture scaling
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); // Use mipmapping for scaling down
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); // Use nearest pixel when scaling up.

    glGenerateMipmap(GL_TEXTURE_2D);


    return texture;
}

void fmri::changeWindowSize(int w, int h)
{
    // Prevent a divide by zero, when window is too short
    // (you cant make a window of zero width).
    if (h == 0)
        h = 1;

    float ratio = w * 1.0f / h;

    // Use the Projection Matrix
    glMatrixMode(GL_PROJECTION);

    // Reset Matrix
    glLoadIdentity();

    // Set the viewport to be the entire window
    glViewport(0, 0, w, h);

    // Set the correct perspective.
    gluPerspective(45.0f, ratio, 0.1f, 100.0f);

    // Get Back to the Modelview
    glMatrixMode(GL_MODELVIEW);
}

GLuint fmri::compileShader(GLenum type, char const *source)
{
    GLuint shader = glCreateShader(type);
    auto length = static_cast<GLint>(strlen(source));
    GLint compileOK;

    glShaderSource(shader, 1, &source, &length);
    glCompileShader(shader);

    glGetShaderiv(shader, GL_COMPILE_STATUS, &compileOK);
    if (!compileOK) {
        LOG(WARNING) << "Failed to compile " << source << endl;
        show_info_log(shader, glGetShaderiv, glGetShaderInfoLog);
        glDeleteShader(shader);
        abort();
    }
}