package btools.mapaccess;

import java.util.List;

import btools.codec.WaypointMatcher;
import btools.util.CheapRuler;

/**
 * the WaypointMatcher is feeded by the decoder with geoemtries of ways that are
 * already check for allowed access according to the current routing profile
 * <p>
 * It matches these geometries against the list of waypoints to find the best
 * match for each waypoint
 */
public final class WaypointMatcherImpl implements WaypointMatcher {
  private List<MatchedWaypoint> waypoints;
  private OsmNodePairSet islandPairs;

  private int lonStart;
  private int latStart;
  private int lonTarget;
  private int latTarget;
  private boolean anyUpdate;
  private int lonLast;
  private int latLast;

  public WaypointMatcherImpl(List<MatchedWaypoint> waypoints, double maxDistance, OsmNodePairSet islandPairs) {
    this.waypoints = waypoints;
    this.islandPairs = islandPairs;
    for (MatchedWaypoint mwp : waypoints) {
      mwp.radius = maxDistance;
    }
  }

  private void checkSegment(int lon1, int lat1, int lon2, int lat2) {
    // todo: bounding-box pre-filter

    double[] lonlat2m = CheapRuler.getLonLatToMeterScales((lat1 + lat2) >> 1);
    double dlon2m = lonlat2m[0];
    double dlat2m = lonlat2m[1];

    double dx = (lon2 - lon1) * dlon2m;
    double dy = (lat2 - lat1) * dlat2m;
    double d = Math.sqrt(dy * dy + dx * dx);

    if (d == 0.)
      return;

    for (MatchedWaypoint mwp : waypoints) {
      OsmNode wp = mwp.waypoint;

      double x1 = (lon1 - wp.ilon) * dlon2m;
      double y1 = (lat1 - wp.ilat) * dlat2m;
      double x2 = (lon2 - wp.ilon) * dlon2m;
      double y2 = (lat2 - wp.ilat) * dlat2m;
      double r12 = x1 * x1 + y1 * y1;
      double r22 = x2 * x2 + y2 * y2;
      double radius = Math.abs(r12 < r22 ? y1 * dx - x1 * dy : y2 * dx - x2 * dy) / d;

      if (radius < mwp.radius) {
        double s1 = x1 * dx + y1 * dy;
        double s2 = x2 * dx + y2 * dy;

        if (s1 < 0.) {
          s1 = -s1;
          s2 = -s2;
        }
        if (s2 > 0.) {
          radius = Math.sqrt(s1 < s2 ? r12 : r22);
          if (radius > mwp.radius)
            continue;
        }
        // new match for that waypoint
        mwp.radius = radius; // shortest distance to way
        mwp.hasUpdate = true;
        anyUpdate = true;
        // calculate crosspoint
        if (mwp.crosspoint == null)
          mwp.crosspoint = new OsmNode();
        if (s2 < 0.) {
          double wayfraction = -s2 / (d * d);
          double xm = x2 - wayfraction * dx;
          double ym = y2 - wayfraction * dy;
          mwp.crosspoint.ilon = (int) (xm / dlon2m + wp.ilon);
          mwp.crosspoint.ilat = (int) (ym / dlat2m + wp.ilat);
        } else if (s1 > s2) {
          mwp.crosspoint.ilon = lon2;
          mwp.crosspoint.ilat = lat2;
        } else {
          mwp.crosspoint.ilon = lon1;
          mwp.crosspoint.ilat = lat1;
        }
      }
    }
  }

  @Override
  public boolean start(int ilonStart, int ilatStart, int ilonTarget, int ilatTarget) {
    if (islandPairs.size() > 0) {
      long n1 = ((long) ilonStart) << 32 | ilatStart;
      long n2 = ((long) ilonTarget) << 32 | ilatTarget;
      if (islandPairs.hasPair(n1, n2)) {
        return false;
      }
    }
    lonLast = lonStart = ilonStart;
    latLast = latStart = ilatStart;
    lonTarget = ilonTarget;
    latTarget = ilatTarget;
    anyUpdate = false;
    return true;
  }

  @Override
  public void transferNode(int ilon, int ilat) {
    checkSegment(lonLast, latLast, ilon, ilat);
    lonLast = ilon;
    latLast = ilat;
  }

  @Override
  public void end() {
    checkSegment(lonLast, latLast, lonTarget, latTarget);
    if (anyUpdate) {
      for (MatchedWaypoint mwp : waypoints) {
        if (mwp.hasUpdate) {
          mwp.hasUpdate = false;
          mwp.node1 = new OsmNode(lonStart, latStart);
          mwp.node2 = new OsmNode(lonTarget, latTarget);
        }
      }
    }
  }
}