package org.opentrafficsim.draw.road;
   
   import java.awt.BasicStroke;
   import java.awt.Color;
   import java.awt.Graphics2D;
   import java.awt.geom.Path2D;
   import java.awt.image.ImageObserver;
   import java.util.ArrayList;
   import java.util.List;
  import java.util.Set;
  
  import org.djunits.value.vdouble.scalar.Length;
  import org.djutils.draw.line.PolyLine2d;
  import org.djutils.draw.point.DirectedPoint2d;
  import org.djutils.draw.point.Point2d;
  import org.opentrafficsim.base.StripeElement;
  import org.opentrafficsim.base.geometry.DirectionalPolyLine;
  import org.opentrafficsim.base.geometry.OtsLine2d.FractionalFallback;
  import org.opentrafficsim.draw.DrawLevel;
  import org.opentrafficsim.draw.LineLocatable;
  import org.opentrafficsim.draw.OtsRenderable;
  import org.opentrafficsim.draw.PaintPolygons;
  import org.opentrafficsim.draw.road.StripeAnimation.StripeData;
  
  import nl.tudelft.simulation.naming.context.Contextualized;
  
  /**
   * Draw road stripes.
   * <p>
   * Copyright (c) 2013-2024 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="https://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
   * </p>
   * @author <a href="https://github.com/averbraeck">Alexander Verbraeck</a>
   * @author <a href="https://github.com/wjschakel">Wouter Schakel</a>
   */
  public class StripeAnimation extends OtsRenderable<StripeData>
  {
      /** Drawable paths. */
      private List<PaintData> paintDatas;
  
      /** Offset that applied when paths were determined. */
      private Length pathOffset;
  
      /**
       * Constructor.
       * @param source stripe data
       * @param contextualized context provider
       */
      public StripeAnimation(final StripeData source, final Contextualized contextualized)
      {
          super(source, contextualized);
      }
  
      /**
       * Generate the points needed to draw the stripe pattern.
       * @param stripe the stripe
       * @return list of paint data
       */
      private List<PaintData> makePaths(final StripeData stripe)
      {
          // TODO implement changing width along the length, when offset line with function for offset is supported
          List<PaintData> paintData = new ArrayList<>();
          double width = stripe.getWidth(Length.ZERO).si;
          double edgeOffset = .5 * width;
          for (StripeElement element : stripe.getElements())
          {
              double w = element.width().si;
              List<Point2d> path = new ArrayList<>();
              if (element.isContinuous())
              {
                  stripe.getCenterLine().directionalOffsetLine(edgeOffset).iterator().forEachRemaining(path::add);
                  stripe.getCenterLine().directionalOffsetLine(edgeOffset - w).reverse().iterator().forEachRemaining(path::add);
              }
              else if (!element.isGap())
              {
                  double[] dashes = element.dashes().getValuesSI();
                  path.addAll(makeDashes(stripe.getCenterLine().directionalOffsetLine(edgeOffset - .5 * w),
                          stripe.getReferenceLine(), w, stripe.getDashOffset().si, dashes));
              }
              edgeOffset -= w;
              // can be empty for a gap element, or when no dash is within the length
              if (!path.isEmpty())
              {
                  paintData.add(new PaintData(PaintPolygons.getPaths(getSource().getLocation(), path), element.color()));
              }
          }
          return paintData;
      }
  
      /**
       * Generate the drawing commands for a dash pattern.
       * @param centerLine the design line of the striped pattern
       * @param referenceLine reference line to which dashes are applied
       * @param width width of the stripes in meters
       * @param startOffset shift the starting point in the pattern by this length in meters
       * @param dashes one or more lengths of the dashes and the gaps between those dashes. The first value in <cite>dashes</cite>
       *            is the length of a gap. If the number of values in <cite>dashes</cite> is odd, the pattern repeats inverted
       *            (gaps become dashes, dashes become gaps).
       * @return the coordinates of the dashes separated and terminated by a <cite>NEWPATH</cite> Coordinate
      */
     private List<Point2d> makeDashes(final DirectionalPolyLine centerLine, final PolyLine2d referenceLine, final double width,
             final double startOffset, final double[] dashes)
     {
         double period = 0;
         for (double length : dashes)
         {
             if (length < 0)
             {
                 throw new Error("Bad pattern - on or off length is < 0");
             }
             period += length;
         }
         if (period <= 0)
         {
             throw new Error("Bad pattern - repeat period length is 0");
         }
         // TODO link length when that is chosen
         double referenceLength = referenceLine.getLength();
         double position = -startOffset + dashes[0];
         int phase = 1;
         ArrayList<Point2d> result = new ArrayList<>();
         boolean first = true;
         boolean sameLine = centerLine.getPointList().equals(referenceLine.getPointList());
         while (position < referenceLength)
         {
             double nextBoundary = position + dashes[phase++ % dashes.length];
             if (nextBoundary > 0) // Skip this one; this entire dash lies within the startOffset
             {
                 if (!first)
                 {
                     result.add(PaintPolygons.NEWPATH);
                 }
                 first = false;
                 if (position < 0)
                 {
                     position = 0; // Draw a partial dash, starting at 0 (begin of the center line)
                 }
                 double endPosition = nextBoundary;
                 if (endPosition > referenceLength)
                 {
                     endPosition = referenceLength; // Draw a partial dash, ending at length (end of the center line)
                 }
 
                 double fraction1 = position / referenceLength;
                 double fraction2 = endPosition / referenceLength;
                 if (!sameLine)
                 {
                     // project dash from reference line on the own center line, using fractional projection (i.e. pizza slices)
                     DirectedPoint2d p1 = referenceLine.getLocationFraction(fraction1);
                     DirectedPoint2d p2 = referenceLine.getLocationFraction(fraction2);
                     fraction1 = centerLine.projectFractional(p1.x, p1.y, FractionalFallback.ENDPOINT);
                     fraction2 = centerLine.projectFractional(p2.x, p2.y, FractionalFallback.ENDPOINT);
                 }
                 DirectionalPolyLine dashCenter = centerLine.extractFractional(fraction1, fraction2);
 
                 // create offsets on dash center line to add dash contour line
                 dashCenter.directionalOffsetLine(width / 2).iterator().forEachRemaining(result::add);
                 dashCenter.directionalOffsetLine(-width / 2).reverse().iterator().forEachRemaining(result::add);
             }
             position = nextBoundary + dashes[phase++ % dashes.length];
         }
         return result;
     }
 
     @Override
     public final void paint(final Graphics2D graphics, final ImageObserver observer)
     {
         update();
         if (this.paintDatas != null)
         {
             for (PaintData paintData : this.paintDatas)
             {
                 setRendering(graphics);
                 graphics.setStroke(new BasicStroke(2.0f));
                 PaintPolygons.paintPaths(graphics, paintData.color(), paintData.path(), true);
                 resetRendering(graphics);
             }
         }
     }
 
     /**
      * Updates paths to draw when new offset applies.
      */
     private void update()
     {
         if (!getSource().getDashOffset().equals(this.pathOffset))
         {
             this.paintDatas = makePaths(getSource());
             this.pathOffset = getSource().getDashOffset();
         }
     }
 
     @Override
     public final String toString()
     {
         return "StripeAnimation [source = " + getSource().toString() + ", paintDatas=" + this.paintDatas + "]";
     }
 
     /**
      * StripeData provides the information required to draw a stripe.
      * <p>
      * Copyright (c) 2023-2024 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved.
      * <br>
      * BSD-style license. See <a href="https://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
      * </p>
      * @author <a href="https://github.com/wjschakel">Wouter Schakel</a>
      */
     public interface StripeData extends LineLocatable
     {
         @Override
         DirectedPoint2d getLocation();
 
         /**
          * Returns the center line in world coordinates, with directions of end-points.
          * @return the center line in world coordinates, with directions of end-points
          */
         DirectionalPolyLine getCenterLine();
 
         /**
          * Returns the line along which dashes are applied. At these fractions, parts of the centerline are taken.
          * @return line along which dashes are applied
          */
         PolyLine2d getReferenceLine();
 
         /**
          * Returns the stripe elements.
          * @return stripe elements
          */
         List<StripeElement> getElements();
 
         /**
          * Return dash offset.
          * @return dash offset
          */
         Length getDashOffset();
 
         /**
          * Returns the line width.
          * @param position where to obtain width
          * @return line width
          */
         Length getWidth(Length position);
 
         @Override
         default double getZ()
         {
             return DrawLevel.MARKING.getZ();
         }
     }
 
     /**
      * Paint data.
      * @param path path
      * @param color color
      */
     private record PaintData(Set<Path2D.Float> path, Color color)
     {
     }
 }