#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()
    : followed_implicit(nullptr),
    camera_position(0., 2.5, -10.),
    camera_sight(0, 2.5, 0)
{
    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);
    glutKeyboardFunc(kb_evt_handle);
    glutKeyboardUpFunc(kb_evt_up_handle);

    // ==== Lighting ====
    GLfloat light0_pos[] = {30., 35., 20., 0.};
    GLfloat light0_ambient[] = {0., 0., 0., 1.};
    GLfloat light0_diffuse[] = {1., 1., .85, 1.};
    GLfloat light0_specular[] = {5., 5., .43, 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

    glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE);
    GLfloat material_specular[] = {1., 1., 1., 1.};
    GLfloat material_emission[] = {0., 0., 0., 1.};
    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
    glClearColor(0.15f, 0.08f, 0.5f, 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,
        double resolution)
{
    surfaces.insert(SurfaceDetails(surf, box, resolution));
}

void GlutRender::remove_surface(ImplicitSurface* surf) {
    surfaces.erase(SurfaceDetails(surf, Cuboid::empty(), 0.1));
}

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

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

void GlutRender::add_kb_handler(GlutRender::kb_handler_t handler) {
    kb_handlers.push_back(handler);
}

void GlutRender::add_kb_up_handler(GlutRender::kb_handler_t handler) {
    kb_up_handlers.push_back(handler);
}

void GlutRender::follow_implicit_position(const ImplicitSurface* surf) {
    followed_implicit = surf;
}

void GlutRender::set_camera(const Point& location, const Point& sight) {
    camera_position = location;
    camera_sight = sight;
}

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

#ifdef DEBUG_DISPLAY_WIREFRAME
    glBegin(GL_LINES);
    for(const Face& face: mesh.get_faces()) {
        Point n0 = mesh.get_normal(face[0]),
              n1 = mesh.get_normal(face[1]),
              n2 = mesh.get_normal(face[2]);
        Point p0 = face.pt(0, points) + mesh_center + 0.01 * n0,
              p1 = face.pt(1, points) + mesh_center + 0.01 * n1,
              p2 = face.pt(2, points) + mesh_center + 0.01 * n2;
        glColor3f(0., 1., 0.);
        glVertex3f(p0[0], p0[1], p0[2]);
        glVertex3f(p1[0], p1[1], p1[2]);

        glVertex3f(p1[0], p1[1], p1[2]);
        glVertex3f(p2[0], p2[1], p2[2]);

        glVertex3f(p2[0], p2[1], p2[2]);
        glVertex3f(p0[0], p0[1], p0[2]);
    }
    glEnd();
#endif // DEBUG_DISPLAY_WIREFRAME


    const Color& color = mesh.get_color();
    GLfloat material_specular[] = {
        (float)color[0],
        (float)color[1],
        (float)color[2],
        1.};
    glBegin(GL_TRIANGLES);
    glColor3f(color[0], color[1], color[2]);
    glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, material_specular);
    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]);

        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();

    if(followed_implicit != nullptr) {
        const Point& look_at = followed_implicit->getCenter();
        gluLookAt(camera_position.x, camera_position.y, camera_position.z,
                look_at.x, camera_position.y, look_at.z,
                0, 1, 0);
    }
    else {
        gluLookAt(camera_position.x, camera_position.y, camera_position.z,
                camera_sight.x, camera_position.y, camera_sight.z,
                0, 1, 0);
    }

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

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

    glutSwapBuffers();
}

void GlutRender::on_kb_evt(bool up, unsigned char key, int x, int y) {
    std::vector<kb_handler_t>& handlers = up? kb_up_handlers : kb_handlers;
    for(auto& handler: handlers) {
        handler(key, x, y);
    }
}

void GlutRender::reshape_handle(int wid, int hei) {
    get_instance().reshape(wid, hei);
}
void GlutRender::display_handle() {
    get_instance().display();
}
void GlutRender::kb_evt_handle(unsigned char key, int x, int y) {
    get_instance().on_kb_evt(false, key, x, y);
}
void GlutRender::kb_evt_up_handle(unsigned char key, int x, int y) {
    get_instance().on_kb_evt(true, key, x, y);
}