//
//  SuperTuxKart - a fun racing game with go-kart
//  Copyright (C) 2008-2015 Joerg Henrichs
//
//  This program is free software; you can redistribute it and/or
//  modify it under the terms of the GNU General Public License
//  as published by the Free Software Foundation; either version 3
//  of the License, or (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

#include "items/rubber_band.hpp"

#include "graphics/central_settings.hpp"
#include "graphics/irr_driver.hpp"
#include "graphics/material_manager.hpp"
#include "graphics/sp/sp_dynamic_draw_call.hpp"
#include "graphics/sp/sp_shader_manager.hpp"
#include "guiengine/engine.hpp"
#include "items/plunger.hpp"
#include "items/projectile_manager.hpp"
#include "karts/abstract_kart.hpp"
#include "karts/kart_properties.hpp"
#include "karts/max_speed.hpp"
#include "modes/world.hpp"
#include "physics/physics.hpp"
#include "race/race_manager.hpp"
#include "utils/mini_glm.hpp"
#include "utils/string_utils.hpp"

/** RubberBand constructor. It creates a simple quad and attaches it to the
 *  root(!) of the graph. It's easier this way to get the right coordinates
 *  than attaching it to the plunger or kart, and trying to find the other
 *  coordinate.
 *  \param plunger Pointer to the plunger (non const, since the rubber band
 *                 can trigger an explosion)
 *  \param kart    Reference to the kart.
 */
RubberBand::RubberBand(Plunger *plunger, AbstractKart *kart)
          : m_plunger(plunger), m_owner(kart)
{
    m_hit_kart = NULL;
    m_attached_state = RB_TO_PLUNGER;
#ifndef SERVER_ONLY
    if (GUIEngine::isNoGraphics() || !CVS->isGLSL())
    {
        return;
    }
    video::SColor color(255, 179, 0, 0);
    if (CVS->isDeferredEnabled())
    {
        color.setRed(SP::srgb255ToLinear(color.getRed()));
        color.setGreen(SP::srgb255ToLinear(color.getGreen()));
        color.setBlue(SP::srgb255ToLinear(color.getBlue()));
    }
    m_dy_dc = std::make_shared<SP::SPDynamicDrawCall>
        (scene::EPT_TRIANGLE_STRIP, SP::SPShaderManager::get()->getSPShader
        ("unlit"), material_manager->getDefaultSPMaterial("unlit"));
    m_dy_dc->getVerticesVector().resize(4);
    // Set the vertex colors properly, as the new pipeline doesn't use the old
    // light values
    for (unsigned i = 0; i < 4; i++)
    {
        m_dy_dc->getSPMVertex()[i].m_color = color;
    }
    SP::addDynamicDrawCall(m_dy_dc);
#endif
}   // RubberBand

// ----------------------------------------------------------------------------
RubberBand::~RubberBand()
{
    remove();
}   // RubberBand

// ----------------------------------------------------------------------------
void RubberBand::reset()
{
    m_hit_kart = NULL;
    m_attached_state = RB_TO_PLUNGER;
    updatePosition();
}   // reset

// ----------------------------------------------------------------------------
/** Updates the position of the rubber band. It especially sets the
 *  end position of the rubber band, i.e. the side attached to the plunger,
 *  track, or kart hit.
 */
void RubberBand::updatePosition()
{
    const Vec3 &k = m_owner->getXYZ();

    // Get the position to which the band is attached
    // ----------------------------------------------
    switch(m_attached_state)
    {
    case RB_TO_KART:    m_end_position = m_hit_kart->getXYZ(); break;
    case RB_TO_TRACK:   m_end_position = m_hit_position;       break;
    case RB_TO_PLUNGER: m_end_position = m_plunger->getXYZ();
                        checkForHit(k, m_end_position);        break;
    }   // switch(m_attached_state);
}   // updatePosition

// ----------------------------------------------------------------------------
void RubberBand::updateGraphics(float dt)
{
#ifndef SERVER_ONLY
    if (!m_dy_dc)
    {
        return;
    }

    // Update the rubber band positions
    // --------------------------------
    // Todo: make height dependent on length (i.e. rubber band gets
    // thinner). And call explosion if the band is too long.
    const Vec3 &k = m_owner->getXYZ();
    const float hh=.1f;  // half height of the band
    const Vec3 &p=m_end_position;  // for shorter typing
    auto& v = m_dy_dc->getVerticesVector();
    v[0].m_position.X = p.getX()-hh; v[0].m_position.Y=p.getY(); v[0].m_position.Z = p.getZ()-hh;
    v[1].m_position.X = p.getX()+hh; v[1].m_position.Y=p.getY(); v[1].m_position.Z = p.getZ()+hh;
    v[2].m_position.X = k.getX()-hh; v[2].m_position.Y=k.getY(); v[2].m_position.Z = k.getZ()-hh;
    v[3].m_position.X = k.getX()+hh; v[3].m_position.Y=k.getY(); v[3].m_position.Z = k.getZ()+hh;
    v[0].m_normal = 0x1FF << 10;
    v[1].m_normal = 0x1FF << 10;
    v[2].m_normal = 0x1FF << 10;
    v[3].m_normal = 0x1FF << 10;
    core::vector3df normal = (v[1].m_position - v[0].m_position)
        .crossProduct(v[2].m_position - v[0].m_position);
    core::vector3df kart_pos = Vec3(m_owner->getTrans()(Vec3(0, 5.0f, -2.0f))).toIrrVector();
    float dot_product = (v[0].m_position - kart_pos).dotProduct(normal);
    // For avoiding cull face
    if (dot_product >= 0.0f)
    {
        video::S3DVertexSkinnedMesh tmp = v[1];
        v[1] = v[2];
        v[2] = tmp;
    }
    m_dy_dc->setUpdateOffset(0);
    m_dy_dc->recalculateBoundingBox();
#endif
}   // updateGraphics

// ----------------------------------------------------------------------------
/** Updates the rubber band. It takes the new position of the kart and the
 *  plunger, and sets the quad representing the rubber band appropriately.
 *  It then casts a ray along the rubber band to detect if anything is hit. If
 *  so, an explosion is triggered.
 *  \param dt: Time step size.
 */
void RubberBand::update(int ticks)
{
    const KartProperties *kp = m_owner->getKartProperties();

    if(m_owner->isEliminated())
    {
        // Rubber band snaps
        m_plunger->hit(NULL);
        // This causes the plunger to be removed at the next update
        m_plunger->setKeepAlive(0);
        return;
    }

    updatePosition();
    const Vec3 &k = m_owner->getXYZ();

    // Check for rubber band snapping
    // ------------------------------
    float l = (m_end_position-k).length2();
    float max_len = kp->getPlungerBandMaxLength();
    if(l>max_len*max_len)
    {
        // Rubber band snaps
        m_plunger->hit(NULL);
        // This causes the plunger to be removed at the next update
        m_plunger->setKeepAlive(0);
    }

    // Apply forces (if applicable)
    // ----------------------------
    if(m_attached_state!=RB_TO_PLUNGER)
    {
        float force = kp->getPlungerBandForce();
        Vec3 diff   = m_end_position-k;

        // detach rubber band if kart gets very close to hit point
        if(m_attached_state==RB_TO_TRACK && diff.length2() < 10*10)
        {
            // Rubber band snaps
            m_plunger->hit(NULL);
            // This causes the plunger to be removed at the next update
            m_plunger->setKeepAlive(0);
            return;
        }

        diff.normalize();   // diff can't be zero here
        m_owner->getBody()->applyCentralForce(diff*force);
        m_owner->increaseMaxSpeed(MaxSpeed::MS_INCREASE_RUBBER,
            kp->getPlungerBandSpeedIncrease(),
            /*engine_force*/ 0.0f,
            /*duration*/stk_config->time2Ticks(0.1f),
            stk_config->time2Ticks(kp->getPlungerBandFadeOutTime()));
        if(m_attached_state==RB_TO_KART)
            m_hit_kart->getBody()->applyCentralForce(diff*(-force));
    }
}   // update

// ----------------------------------------------------------------------------
/** Uses a raycast to see if anything has hit the rubber band.
 *  \param k Position of the kart = one end of the rubber band
 *  \param p Position of the plunger = other end of the rubber band.
 */
void RubberBand::checkForHit(const Vec3 &k, const Vec3 &p)
{
    btCollisionWorld::ClosestRayResultCallback ray_callback(k, p);
    // Disable raycast collision detection for this plunger and this kart!
    short int old_plunger_group = m_plunger->getBody()->getBroadphaseHandle()->m_collisionFilterGroup;
    short int old_kart_group=0;

    // If the owner is being rescued, the broadphase handle does not exist!
    if(m_owner->getBody()->getBroadphaseHandle())
        old_kart_group = m_owner->getBody()->getBroadphaseHandle()->m_collisionFilterGroup;
    m_plunger->getBody()->getBroadphaseHandle()->m_collisionFilterGroup = 0;
    if(m_owner->getBody()->getBroadphaseHandle())
        m_owner->getBody()->getBroadphaseHandle()->m_collisionFilterGroup = 0;

    // Do the raycast
    Physics::get()->getPhysicsWorld()->rayTest(k, p, ray_callback);
    // Reset collision groups
    m_plunger->getBody()->getBroadphaseHandle()->m_collisionFilterGroup = old_plunger_group;
    if(m_owner->getBody()->getBroadphaseHandle())
        m_owner->getBody()->getBroadphaseHandle()->m_collisionFilterGroup = old_kart_group;
    if(ray_callback.hasHit())
    {
        Vec3 pos(ray_callback.m_hitPointWorld);
        UserPointer *up = (UserPointer*)ray_callback.m_collisionObject->getUserPointer();
        if(up && up->is(UserPointer::UP_KART))
            hit(up->getPointerKart(), &pos);
        else
            hit(NULL, &pos);
    }  // if raycast hast hit

}   // checkForHit

// ----------------------------------------------------------------------------
/** The plunger hit a kart or the track.
 *  \param kart_hit The kart hit, or NULL if the track was hit.
 *  \param track _xyz The coordinated where the track was hit (NULL if a kart
 *                    was hit.
 */
void RubberBand::hit(AbstractKart *kart_hit, const Vec3 *track_xyz)
{
    // More than one report of a hit. This can happen if the raycast detects
    // a hit as well as the bullet physics.
    if(m_attached_state!=RB_TO_PLUNGER) return;


    // A kart was hit
    // ==============
    if(kart_hit)
    {
        if(kart_hit->isShielded())
        {
            kart_hit->decreaseShieldTime();
            m_plunger->setKeepAlive(0);

            return;
        }

        m_hit_kart       = kart_hit;
        m_attached_state = RB_TO_KART;
        return;
    }

    // The track was hit
    // =================
    m_hit_position   = *track_xyz;
    m_attached_state = RB_TO_TRACK;
    m_hit_kart       = NULL;
}   // hit

// ----------------------------------------------------------------------------
void RubberBand::remove()
{
#ifndef SERVER_ONLY
    if (m_dy_dc)
    {
        m_dy_dc->removeFromSP();
        m_dy_dc = nullptr;
    }
#endif
}   // remove

// ----------------------------------------------------------------------------
uint8_t RubberBand::get8BitState() const
{
    uint8_t state = (uint8_t)(m_attached_state & 3);
    state |= m_attached_state == RB_TO_KART && m_hit_kart ?
        (m_hit_kart->getWorldKartId() << 3) : 0;
    return state;
}   // get8BitState

// ----------------------------------------------------------------------------
void RubberBand::set8BitState(uint8_t bit_state)
{
    m_hit_kart = NULL;
    m_attached_state = (RubberBandTo)(bit_state & 3);
    if (m_attached_state == RB_TO_KART)
    {
        unsigned kart = bit_state >> 3;
        m_hit_kart = World::getWorld()->getKart(kart);
    }
}   // set8BitState