#include "GlutRender.hpp"
#include "../MarchingCubes.hpp"

#include <GL/gl.h>
#include <GL/glut.h>
#include <cstring>
#include <random>
#include <ctime>

GlutRender& GlutRender::get_instance() {
    static GlutRender instance;
    return instance;
}

GlutRender::GlutRender() {
    std::default_random_engine rand_engine(time(NULL));
    std::uniform_real_distribution<double> distribution;
    rand_color = std::bind(distribution, rand_engine);
}

void GlutRender::init(int* argc, char** argv,
        int wid, int hei, const char* win_name)
{
    glutInit(argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH);
    glutInitWindowSize(wid, hei);
    glutCreateWindow(win_name);

    // ==== Callbacks ====
    glutDisplayFunc(display_handle);
    glutReshapeFunc(reshape_handle);

    // ==== Lighting ====
    GLfloat light0_pos[] = {2., 10., 2.};
    GLfloat light0_ambient[] = {0., 0., 0., 1.};
    GLfloat light0_diffuse[] = {1., 1., 1., 1.};
    GLfloat light0_specular[] = {1., 1., 1., 1.};
    glLightfv(GL_LIGHT0, GL_POSITION, light0_pos);
    glLightfv(GL_LIGHT0, GL_AMBIENT, light0_ambient);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, light0_diffuse);
    glLightfv(GL_LIGHT0, GL_SPECULAR, light0_specular);

    GLfloat light_ambient[] = {.2, .2, .2, 1.};
    glLightModelfv(GL_LIGHT_MODEL_AMBIENT, light_ambient);

    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    glShadeModel(GL_SMOOTH); // Enable smooth shading

    GLfloat material_specular[] = {1., 1., 1., 1.};
    GLfloat material_emission[] = {0., 0., 0., 1.};
    glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE);
    glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, material_specular);
    glMaterialfv(GL_FRONT_AND_BACK, GL_EMISSION, material_emission);
    glEnable(GL_COLOR_MATERIAL);

    // ==== Misc ====
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Background color
    glClearDepth(1.0f);                   // Set background depth to farthest
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
}

void GlutRender::cleanup() {
}

void GlutRender::add_mesh(Mesh* mesh) {
    meshes.insert(mesh);
}

void GlutRender::remove_mesh(Mesh* mesh) {
    meshes.erase(mesh);
}

void GlutRender::add_surface(ImplicitSurface* surf, const Cuboid& box) {
    surfaces.insert(SurfaceDetails(surf, box));
}

void GlutRender::remove_surface(ImplicitSurface* surf) {
    surfaces.erase(SurfaceDetails(surf, Cuboid::empty()));
}

void GlutRender::run() {
    glutMainLoop();
}

void GlutRender::set_idle_func(void (*func)(void)) {
    glutIdleFunc(func);
}

void GlutRender::reshape(int wid, int hei) {
    if (hei == 0)
        hei = 1;
    GLfloat aspect = (GLfloat)wid / (GLfloat)hei;

    glViewport(0, 0, wid, hei);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    // Enable perspective projection with fovy, aspect, zNear and zFar
    gluPerspective(45.0f, aspect, 0.1f, 100.0f);
}

void GlutRender::display_mesh(Mesh& mesh) const {
    const Point& mesh_center = mesh.get_center();

    const std::vector<Point>& points = mesh.get_vertices();

#ifdef DEBUG_DISPLAY_NORMAL

    glBegin(GL_LINES);
    for(size_t vert_id=0; vert_id < points.size(); ++vert_id) {
        const Point& pt = points[vert_id];
        Point normal = mesh.get_normal(vert_id);
        Point locVert = pt + mesh.get_center();
        Point outwards = locVert + normal;
        Point inwards = locVert + ((-0.2) * normal);
        glColor3f(1., 0., 0.);
        glVertex3f(locVert[0], locVert[1], locVert[2]);
        glVertex3f(outwards[0], outwards[1], outwards[2]);
        glColor3f(0., 0., 1.);
        glVertex3f(locVert[0], locVert[1], locVert[2]);
        glVertex3f(inwards[0], inwards[1], inwards[2]);
    }
    glEnd();
#endif // DEBUG_DISPLAY_NORMAL


    glBegin(GL_TRIANGLES);
    for(const Face& face: mesh.get_faces()) {
        Point p0 = face.pt(0, points) + mesh_center,
              p1 = face.pt(1, points) + mesh_center,
              p2 = face.pt(2, points) + mesh_center;
        Point n0 = mesh.get_normal(face[0]),
              n1 = mesh.get_normal(face[1]),
              n2 = mesh.get_normal(face[2]);

        glColor3f(rand_color(), rand_color(), rand_color());

        glNormal3f(n0[0], n0[1], n0[2]); glVertex3f(p0[0], p0[1], p0[2]);
        glNormal3f(n1[0], n1[1], n1[2]); glVertex3f(p1[0], p1[1], p1[2]);
        glNormal3f(n2[0], n2[1], n2[2]); glVertex3f(p2[0], p2[1], p2[2]);
    }
    glEnd();
}

void GlutRender::display() {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glMatrixMode(GL_MODELVIEW);

    // Camera position and orientation
    glLoadIdentity();
    //glTranslatef(1., 2., -10.);
    gluLookAt(0, 5, -20,
            0, 5, 0,
            0, 1, 0);

    for(Mesh* mesh: meshes) {
        display_mesh(*mesh);
    }

    for(const SurfaceDetails& surface: surfaces) {
        Mesh mesh = MarchingCubes(*surface.surface, surface.box)();
        display_mesh(mesh);
    }

    glutSwapBuffers();
}

void GlutRender::reshape_handle(int wid, int hei) {
    get_instance().reshape(wid, hei);
}
void GlutRender::display_handle() {
    get_instance().display();
}