#include "renderer_polygon_3d.hpp"

#include <iostream>

#include "state/events/explosion_event.hpp"

namespace endofthejedi {
    void RendererPolygon3d::setup()
    {
        m_lastTime = -1.0;

        std::cout<<"setup polygon 3d" << std::endl;

        std::string vss_game_objects = "../data/shader/gameobjects.vert";
        std::string fss_game_objects = "../data/shader/gameobjects.frag";

        m_shader_game_objects.init();
        m_shader_game_objects.loadFile(vss_game_objects, GL_VERTEX_SHADER);
        m_shader_game_objects.loadFile(fss_game_objects, GL_FRAGMENT_SHADER);


        std::string vss_particles = "../data/shader/particle.vert";
        std::string fss_particles = "../data/shader/particle.frag";

        m_shader_particles.init();
        m_shader_particles.loadFile(vss_particles, GL_VERTEX_SHADER);
        m_shader_particles.loadFile(fss_particles, GL_FRAGMENT_SHADER);


        //addModel("../data/mesh/small_atomic_bomb.stl", &m_missileModel);
        addModel("../data/mesh/rocket.stl",    &m_missileModel);
        addModel("../data/mesh/planet_12.stl", &m_planetModel);
        addModel("../data/mesh/ship_ufo.stl",  &m_shipModel);
    }

    void RendererPolygon3d::render(const game::State *state)
    {
        if (m_lastTime == -1.0) {
            m_lastTime = state->timestamp();
        }

        float dt = state->timestamp() - m_lastTime;
        if (dt < 0.0) {
            dt = 0.0;
        }

        m_state = state;
        advanceGraphicObjects(dt);

        // TODO: add stars (texture)
        // TODO: add dust particles
        // TODO: add little rocks flying around

        //glClearColor(0.0, 0.0, 0.0, 1.0);
        float s = 0.1;
        glClearColor(s, s, 1.2*s, 1.0);

        m_shader_game_objects.bind();

        // TODO: add ONE sun planet
        // TODO: add lights for explosions

        configureLightningInShader();

        //std::cout<<"setting aspect ratio: " << m_aspectRatio << std::endl;
        glUniform1f(m_shader_game_objects.location("aspectRatio"), m_aspectRatio);

        renderPlanets();
        renderShips();
        renderMissiles();

        renderParticles();

        renderTraces();

        //glColor3f(1.0, 0.0, 0.0);
        //glBegin(GL_QUADS);
        //glVertex2f(-1.0f, -1.0f);
        //glVertex2f(1.0f, -1.0f);
        //glVertex2f(1.0f, 1.0f);
        //glVertex2f(-1.0f, 1.0f);
        //glEnd();

        m_lastTime = state->timestamp();
    }

    void RendererPolygon3d::renderParticles()
    {
        m_shader_particles.bind();

        glUniform1f(m_shader_particles.location("aspectRatio"), m_aspectRatio);

        for (ParticleBatch *batch : m_particles) {
            batch->bind();
            batch->render(&m_shader_particles);
        }
    }

    void RendererPolygon3d::addExplosionEffect(
            size_t id, const glm::vec2 &explCenter, const glm::vec2 &missileVelocity,
            bool isPlanetHit,
            size_t n, float duration)
    {
        //float particleRadius = 0.005;
        //float particleRadius = 0.003;
        float particleRadius = 0.02;

        // TODO: use this as shader input too and make the area 2x around this
        // so that it stays hot/yellow for 2/3 of the time
        float explCoreSize = 0.02f;
        float maxVelocity  = 0.4f;

        ParticleBatch *batch = new ParticleBatch(id, n, particleRadius, duration);
        batch->setup(&m_shader_particles);
        batch->setCenter(glm::vec3(explCenter, 0.0));
        batch->setMaxVelocity(maxVelocity);

        for (size_t i=0; i<n; i++) {
            // distribute in a circle
            //float t = 2.0 * M_PI * i / (float) n;
            //t += 0.2*util::randf_m1_1();

            // with random velocities
            // this is 3d because it looks better if some particles leave/enter
            // the space and they are not all on one plane.
            // especially in 3d this would look bad without 3d velocity vector.
            //glm::vec3 v = 0.5f*glm::vec3(sin(t), cos(t), util::randf_m1_1());

            glm::vec3 pos = glm::vec3(explCenter, 0.0) + glm::ballRand(explCoreSize);

            glm::vec3 v = glm::ballRand(maxVelocity);

            // TODO: is that good?
            if (isPlanetHit) {
                v *= util::randf_0_1() * util::randf_0_1() * util::randf_0_1();
            } else {
                v *= util::randf_0_1();
            }

            // find collisions with planetns and limit max distance so particles
            // won't fly through planets
            //float maxDist = 0.1;
            //float maxDist = 0.1*util::randf_0_1();
            bool isInsidePlanet = false;
            float maxParticleDist = INFINITY;

            const game::Planet *nearestPlanet = nullptr;
            for (const game::Planet *planet : m_state->planets) {
                const glm::vec3 ppos3 = glm::vec3(planet->position, 0.0f);

                // TODO: that's slightly wrong. use intersection for this.
                float dist = glm::distance(ppos3, pos);
                if (dist <= planet->radius) {
                    isInsidePlanet = true;
                    nearestPlanet = planet;
                }
                if (isInsidePlanet) {
                    // skip searching for nearer planets once we are inside some
                    // planet as the position/velocity will be changed to start
                    // at the surface of the planet we were in with
                    // reflected or planet-normal velocity.
                    continue;
                }
                // TODO: if inside, move position so that it looks like
                // reflecting the particle from the planet
                bool fliesInPlanetDirection = glm::dot(v, ppos3-pos) > 0.0f;
                if (dist < maxParticleDist && fliesInPlanetDirection) {
                    nearestPlanet = planet;
                    maxParticleDist = dist;
                }
            }

            bool makeStationary = false;

            if (isInsidePlanet && isPlanetHit) {
                util::IntersectionTest intersect;
                if (!intersect.raySphere(
                    glm::vec3(explCenter, 0.0f), v,
                    glm::vec3(nearestPlanet->position, 0.0f), nearestPlanet->radius))
                {
                    makeStationary = true;
                    //std::cout<<"warning: intersection should be valid!" << std::endl;
                    // TODO: must be as they lie on a plane and the dist is < as
                    // the radius.
                    // handle if this is wrong.

                } else {
                    // simple reflection, ignoring the missile velocity: this looks good enough
                    (void) missileVelocity;
                    glm::vec3 planetNormal = glm::normalize(pos - glm::vec3(nearestPlanet->position, 0.0f));
                    v = glm::length(v) * planetNormal;

                    // TODO
                    // considering the missile velocity is not yet working:

                    // set position to the intersection point between explosion
                    // center and planet surface
                    //pos = intersect.pointAtDistance(intersect.distance());
                    //v = glm::vec3(missileVelocity, 0.0f);
                    //v = v - 2.0f*glm::dot(v, planetNormal) * planetNormal;
                    //v *= 4.0;
                    //maxParticleDist = 100.0;
                    //v = -v;

                    //pos = glm::vec3(nearestPlanet->position, 0.0f) + nearestPlanet->radius*planetNormal;

                    // set position to the intersection point between explosion
                    // center and planet surface
                    //const glm::vec3 planetNormal = glm::vec3(glm::normalize(explCenter - nearestPlanet->position), 0.0f);

                    //pos = glm::vec3(nearestPlanet->position, 0.0f) + nearestPlanet->radius*planetNormal;

                    // build new velocity by reflecting the old velocity on the
                    // planet normal
                    // TODO: add a bit random
                    // TODO: add reflection
                    // TODO: distribute particles around main reflection angle and
                    // TODO: add material exhaust that is specific for the planet.
                    // TODO: spawn waves on water planet
                    // TODO: start fire on gas planet
                    //v = glm::length(v) * planetNormal;
                    //v = v - 2.0f*glm::dot(v, planetNormal) * planetNormal;
                    //v = glm::length(v) * planetNormal;

                    //glm::vec3 r  = v - 2.0f*glm::dot(v, planetNormal) * planetNormal;
                    //glm::vec3 vn = glm::length(v) * planetNormal;
                    //v = (r+vn) / 2.0f;

                    //glm::vec3 vc = glm::vec3(nearestPlanet->position-explCenter, 0.0f);
                    //glm::vec3 r  = vc - 2.0f*glm::dot(vc, planetNormal) * planetNormal;
                    //v = r;
                }
            } else if (isInsidePlanet && !isPlanetHit) {
                // if a planet is just hit by explosions particles but not the
                // missile itself, don't reflect the particles in the planet.
                // just set them as stationary at place of explosion
                makeStationary = true;
            }

            if (makeStationary) {
                v = glm::vec3(0.0f, 0.0f, 0.0f);
                pos = glm::vec3(explCenter, 0.0f);;
            }

            batch->setParticle(i, pos, v, maxParticleDist);
        }

        batch->upload();

        m_particles.push_back(batch);
    }

    void RendererPolygon3d::advanceGraphicObjects(float dt)
    {
#if 0
        for (const game::Explosion *expl : m_state->explosions) {
            bool gotIt = false;
            for (ParticleBatch *batch : m_particles) {
                if (batch->id() == expl->id) {
                    gotIt = true;
                    break;
                }
            }

            if (!gotIt) {
                addExplosionEffect(
                        expl->id, expl->position,
                        expl->missileVelocity,
                        (expl->hit == game::Hit::Planet),
                        1000, 1.0);
            }
        }
#endif

        for (game::StateUpdateEvent *evt : m_state->currentStateUpdateEvents()) {
            if (evt->eventType() == game::StateUpdateEvent::EventType::Explosion) {
                auto cycle = evt->lifeCycle();
                if (cycle == game::StateUpdateEvent::LifeCycle::Create) {
                    game::ExplosionEvent *ee = static_cast<game::ExplosionEvent*>(evt);
                    const game::Explosion *expl = ee->explosion;
                    addExplosionEffect(
                            expl->id, expl->position,
                            expl->missileVelocity,
                            (expl->hit == game::Hit::Planet),
                            1000, 1.0);

                    std::cout<<"adding [graphic] explosion for #" << expl->id << std::endl;
                }
            }
        }

        //if (m_particles.size() == 0) {
        //    addExplosionEffect(0, glm::vec2(0.0, 0.0), glm::vec2(0.0, 0.0), false, 10000, 2.0);
        //}

        std::vector<ParticleBatch*> rm;

        for (ParticleBatch *batch : m_particles) {
            batch->tick(dt);
            if (batch->done()) {
                rm.push_back(batch);
            }
        }

        for (ParticleBatch *batch : rm) {
            m_particles.remove(batch);
            delete(batch);
        }
    }

    void RendererPolygon3d::renderPlanets()
    {
        m_planetModel->bind();

        // TODO: put material into attributes and render witd glDrawInstanced
        // too (same for missiles)
        for (const game::Planet *planet : m_state->planets) {
            glm::mat4 model = computeModelMatrix(planet);
            glUniformMatrix4fv(m_shader_game_objects.location("model"), 1, GL_FALSE, glm::value_ptr(model));

            glm::vec3 c = planet->getColor();
            glUniform3f(m_shader_game_objects.location("materialColor"), c.x, c.y, c.z);
            glUniform1i(m_shader_game_objects.location("materialSeed"), planet->seed);
            glUniform1i(m_shader_game_objects.location("materialKind"), (int) planet->material);

            m_planetModel->render();
        }
    }

    void RendererPolygon3d::renderMissiles()
    {
        // TODO: add fire trail for missiles near the sun

        m_missileModel->bind();

        for (const game::Player *player : m_state->players) {
            for (const game::Missile *missile : player->missiles) {
                glm::vec3 c = glm::vec3(1.0, 1.0, 0.3);
                glUniform3f(m_shader_game_objects.location("materialColor"), c.x, c.y, c.z);

                glm::mat4 model = computeModelMatrix(missile);
                glUniformMatrix4fv(m_shader_game_objects.location("model"), 1, GL_FALSE, glm::value_ptr(model));

                m_missileModel->render();
            }
        }
    }

    void RendererPolygon3d::renderShips()
    {
        m_shipModel->bind();

        for (const game::Ship *ship : m_state->ships) {
            glm::mat4 model = computeModelMatrix(ship);
            glUniformMatrix4fv(m_shader_game_objects.location("model"), 1, GL_FALSE, glm::value_ptr(model));

            glm::vec3 c = glm::vec3(0.1, 1.0, 0.2);
            glUniform3f(m_shader_game_objects.location("materialColor"), c.x, c.y, c.z);

            m_shipModel->render();
        }
    }

    void RendererPolygon3d::addModel(const std::string &filename, PolygonModel **dest)
    {
        //std::cout<<"adding a model: " << filename << std::endl;

        *dest = new PolygonModel(filename);
        if (!(*dest)->import()) {
            std::cout<<"error: failed to load needed model!!!" << std::endl << std::endl;
            exit(-1);
        }

		(*dest)->setup(&m_shader_game_objects);
        (*dest)->uploadToOpenGl();

        m_models.push_back(*dest);
    }

    glm::mat4 RendererPolygon3d::computeModelMatrix(const game::Planet *planet)
    {
        return computeModelMatrix(planet->position, planet->radius);
    }

    glm::mat4 RendererPolygon3d::computeModelMatrix(const game::Missile *missile)
    {
        glm::vec2 vn = glm::normalize(missile->velocity);
        float a = std::atan2(vn.y, vn.x);

        glm::mat4 mat = computeModelMatrix(missile->position, 0.1f, a);

        // TODO: which visual size has the rocket? in game its just a point with
        // no size because all others have size.
        //for atomic bomb
        //return computeModelMatrix(missile->position, 0.03f, a);

        // flipped too
        mat = glm::rotate(mat, (float) M_PI/2.0f, glm::vec3(0.0f, 1.0f, 0.0f));

        return mat;
    }

    glm::mat4 RendererPolygon3d::computeModelMatrix(const game::Ship *ship)
    {
        // TODO: rotate them before shooting, that looks better
        glm::mat4 mat = computeModelMatrix(ship->position, m_state->shipRadius());

        // XXX model is flipped
        //glm::mat4 mat = computeModelMatrix(ship->position, 0.3);
        mat = glm::rotate(mat, (float) M_PI, glm::vec3(0.0f, 1.0f, 0.0f));
        return mat;
    }

    glm::mat4 RendererPolygon3d::computeModelMatrix(const glm::vec2 &pos, float scale, float angle)
    {
        // init as identity matrix
        glm::mat4 model;

        model = glm::translate(model, glm::vec3(pos, 0.0));

        if (scale != 1.0) {
            model = glm::scale(model, glm::vec3(scale));
        }

        if (angle != 0.0) {
            model = glm::rotate(model, angle, glm::vec3(0.0f, 0.0f, 1.0f));
        }

        return model;
    }

    void RendererPolygon3d::renderTraces()
    {
        // revert to default
        glUseProgram(0);

        // TODO dont use line mode. make that with own quads
        glPolygonMode(GL_FRONT, GL_LINE);
        for (const game::Trace *trace : m_state->traces) {
            float fade_out = 1.0;
            if (trace->missile == nullptr) {
                fade_out = 1.0 - (trace->age / trace->maxAge);
            }

            glColor3f(0.0, 0.5*fade_out, 0.5*fade_out);
            glBegin(GL_LINE_STRIP);
            for (const game::Trace::TracePoint &tp : trace->points) {
                glVertex2f(tp.position.x, tp.position.y);
            }
            glEnd();
        }
        glPolygonMode(GL_FRONT, GL_FILL);
    }

    void RendererPolygon3d::configureLightningInShader()
    {
        // TODO: add a few small lights for explosions so they lit the
        // surroundsings

        // TODO: use the sun planet color for this!
        glm::vec3 c = glm::vec3(1.0, 1.0, 0.8);
		glm::vec3 p = glm::vec3(0.3f, 0.4f, 0.0f);

        for (const game::Planet *planet : m_state->planets) {
            if (planet->material == game::Planet::Material::Sun) {
                p = glm::vec3(planet->position, 0.0);
                c = planet->getColor();
                break;
            }
        }

        glUniform3f(m_shader_game_objects.location("lightPosition"), p.x, p.y, p.z);
        glUniform3f(m_shader_game_objects.location("lightColor"),    c.x, c.y, c.z);
    }

    void RendererPolygon3d::setWindowSize(int px, int py)
    {
        m_aspectRatio = (float) px / (float) py;
    }

    void RendererPolygon3d::setCameraMatrix(const glm::mat4 &cam)
    {
        (void) cam;
    }
}