//
//  SuperTuxKart - a fun racing game with go-kart
//  Copyright (C) 2011  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 "modes/linear_world.hpp"
#include "modes/world.hpp"
#include "tracks/check_manager.hpp"
#include "tracks/check_structure.hpp"
#include "tracks/track.hpp"
#include "tracks/track_sector.hpp"
#include "tracks/quad_graph.hpp"

// ----------------------------------------------------------------------------
/** Initialises the object, and sets the current graph node to be undefined.
 */
TrackSector::TrackSector()
{
    reset();
}   // TrackSector

// ----------------------------------------------------------------------------
void TrackSector::reset()
{
    m_current_graph_node       = QuadGraph::UNKNOWN_SECTOR;
    m_last_valid_graph_node    = QuadGraph::UNKNOWN_SECTOR;
    m_on_road                  = false;
    m_last_triggered_checkline = -1;
}   // reset

// ----------------------------------------------------------------------------
/** Updates the current graph node index, and the track coordinates for
 *  the specified point.
 *  \param xyz The new coordinates to search the graph node for.
 */
void TrackSector::update(const Vec3 &xyz)
{
    int prev_sector = m_current_graph_node;

    QuadGraph::get()->findRoadSector(xyz, &m_current_graph_node);
    m_on_road = m_current_graph_node != QuadGraph::UNKNOWN_SECTOR;
    
    // If m_track_sector == UNKNOWN_SECTOR, then the kart is not on top of
    // the road, so we have to use search for the closest graph node.
    if(m_current_graph_node == QuadGraph::UNKNOWN_SECTOR)
    {
        m_current_graph_node = 
            QuadGraph::get()->findOutOfRoadSector(xyz,
                                                  prev_sector);
    }
    else
    {
        // keep the current quad as the latest valid one IF the player has one
        // of the required checklines
        const std::vector<int>& checkline_requirements =
            QuadGraph::get()->getNode(m_current_graph_node).getChecklineRequirements();
        
        if (checkline_requirements.size() == 0)
        {
            m_last_valid_graph_node = m_current_graph_node;
        }
        else
        {
            bool has_prerequisite = false;
            
            for (unsigned int i=0; i<checkline_requirements.size(); i++)
            {                
                if (m_last_triggered_checkline == checkline_requirements[i])
                {
                    has_prerequisite = true;                    
                    m_last_valid_graph_node = m_current_graph_node;
                    break;
                }
            }
            
            // TODO: show a message when we detect a user cheated.
            
        }
    }
    
    // Now determine the 'track' coords, i.e. ow far from the start of the 
    // track, and how far to the left or right of the center driveline.
    QuadGraph::get()->spatialToTrack(&m_current_track_coords, xyz, 
                                     m_current_graph_node);
}   // update

// ----------------------------------------------------------------------------
void TrackSector::rescue()
{
    if (m_last_valid_graph_node != QuadGraph::UNKNOWN_SECTOR)
        m_current_graph_node = m_last_valid_graph_node;

    // Using the predecessor has the additional advantage (besides punishing
    // the player a bit more) that it makes it less likely to fall in a 
    // rescue loop since the kart moves back on each attempt. At this stage
    // STK does not keep track of where the kart is coming from, so always
    // use the first predecessor, which is the one on the main driveline.
    m_current_graph_node = QuadGraph::get()->getNode(m_current_graph_node)
                                               .getPredecessor(0);
    m_last_valid_graph_node = QuadGraph::get()->getNode(m_current_graph_node)
                                               .getPredecessor(0);
}    // rescue

// ----------------------------------------------------------------------------
/** Returns the relative distance of the corresponding kart from the center,
 *  i.e. a value between -1 and 1 inclusive.
 *  \return THe relative distance between -1.0f and +1.0f;
 */
float TrackSector::getRelativeDistanceToCenter() const
{
    float w = QuadGraph::get()->getNode(m_current_graph_node).getPathWidth();
    // w * 0.5 is the distance from center of the quad to the left or right
    // This way we get a value between -1 and 1.
    float ratio = getDistanceToCenter()/(w*0.5f);
    if(ratio>1.0f)
        ratio=1.0f;
    else if(ratio<-1.0f)
        ratio=-1.0f;
    return ratio;
}   // getRelativeDistanceToCenter