/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community License, Version 2.0 (the "License"); you may not use this file
    * except in compliance with the License. You may obtain a copy of the License
   * at:
   *
   *   http://opensource.org/licenses/ecl2.txt
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
   * License for the specific language governing permissions and limitations under
   * the License.
   *
   */
  
  package org.opencastproject.composer.layout;
  
  import static org.opencastproject.util.data.Monadics.mlist;
  
  import org.opencastproject.util.data.Function;
  import org.opencastproject.util.data.Tuple;
  
  import java.util.List;
  
  public final class LayoutManager {
    private LayoutManager() {
    }
  
    /**
     * Compose two shapes on a canvas.
     * It is guaranteed that shapes to not extend the underlying canvas.
     *
     * @param canvas
     *         the dimension of the target canvas
     * @param upper
     *         the dimension of the upper (z-axis) source shape
     * @param lower
     *         the dimension of the lower (z-axis) source shape
     * @param spec
     *         the layout specification
     */
    public static TwoShapeLayout twoShapeLayout(Dimension canvas,
                                                Dimension upper,
                                                Dimension lower,
                                                TwoShapeLayouts.TwoShapeLayoutSpec spec) {
      return new TwoShapeLayout(canvas,
                                calcLayout(canvas, upper, spec.getUpper()),
                                calcLayout(canvas, lower, spec.getLower()));
    }
  
    private static Layout calcLayout(Dimension canvas,
                                     Dimension shape,
                                     HorizontalCoverageLayoutSpec posSpec) {
      final Dimension slice = new Dimension(limitMin(canvas.getWidth() * posSpec.getHorizontalCoverage(), 0),
                                            canvas.getHeight());
      final Dimension scaled = scaleToFit(slice, shape);
      final AnchorOffset dist = posSpec.getAnchorOffset();
      final Offset anchorOfReference = offset(dist.getReferenceAnchor(), canvas);
      final Offset anchorOfReferring = offset(dist.getReferringAnchor(), scaled);
      return new Layout(
              scaled,
              new Offset(limitMin(anchorOfReference.getX() + dist.getOffset().getX() - anchorOfReferring.getX(), 0),
                         limitMin(anchorOfReference.getY() + dist.getOffset().getY() - anchorOfReferring.getY(), 0)));
    }
  
    private static Layout calcLayout(Dimension canvas,
                                     Dimension shape,
                                     AbsolutePositionLayoutSpec posSpec) {
      final AnchorOffset dist = posSpec.getAnchorOffset();
      final Offset anchorOfReference = offset(dist.getReferenceAnchor(), canvas);
      final Offset anchorOfReferring = offset(dist.getReferringAnchor(), shape);
      return new Layout(
              shape,
              new Offset(limitMin(anchorOfReference.getX() + dist.getOffset().getX() - anchorOfReferring.getX(), 0),
                         limitMin(anchorOfReference.getY() + dist.getOffset().getY() - anchorOfReferring.getY(), 0)));
    }
  
    /**
     * Compose a list of shapes on a canvas.
     *
     * @param canvas
     *         the dimension of the target canvas
     * @param shapes
     *         A list of shapes sorted in z-order with the first shape in the list being the lowermost one.
     *         The list consists of the dimension of the source shape tupled with a layout specification.
     */
    public static MultiShapeLayout multiShapeLayout(final Dimension canvas,
                                                    final List<Tuple<Dimension, HorizontalCoverageLayoutSpec>> shapes) {
      return new MultiShapeLayout(
              canvas,
              mlist(shapes).map(new Function<Tuple<Dimension, HorizontalCoverageLayoutSpec>, Layout>() {
                @Override public Layout apply(Tuple<Dimension, HorizontalCoverageLayoutSpec> a) {
                  return calcLayout(canvas, a.getA(), a.getB());
               }
             }).value());
   }
 
   /**
    * Compose a list of shapes on a canvas.
    *
    * @param canvas
    *         the dimension of the target canvas
    * @param shapes
    *         A list of shapes sorted in z-order with the first shape in the list being the lowermost one.
    *         The list consists of the dimension of the source shape tupled with a layout specification.
    */
   public static MultiShapeLayout absoluteMultiShapeLayout(
           final Dimension canvas,
           final List<Tuple<Dimension, AbsolutePositionLayoutSpec>> shapes) {
     return new MultiShapeLayout(
             canvas,
             mlist(shapes).map(new Function<Tuple<Dimension, AbsolutePositionLayoutSpec>, Layout>() {
               @Override public Layout apply(Tuple<Dimension, AbsolutePositionLayoutSpec> a) {
                 return calcLayout(canvas, a.getA(), a.getB());
               }
             }).value());
   }
 
   public static int limitMax(double v, int max) {
     return (int) Math.min(Math.round(v), max);
   }
 
   public static int limitMin(double v, int min) {
     return (int) Math.max(Math.round(v), min);
   }
 
   /** Test if <code>shape</code> fits into <code>into</code>. */
   public static boolean fits(Dimension into, Dimension shape) {
     return shape.getHeight() <= into.getHeight() && shape.getWidth() <= into.getHeight();
   }
 
   /** Calculate the area of a dimension. */
   public static int area(Dimension a) {
     return a.getWidth() * a.getHeight();
   }
 
   /** Return the dimension with the bigger area. */
   public static Dimension max(Dimension a, Dimension b) {
     return area(a) > area(b) ? a : b;
   }
 
   /** Get the aspect ratio of a dimension. */
   public static double aspectRatio(Dimension a) {
     return d(a.getWidth()) / d(a.getHeight());
   }
 
   /** Test if layouts <code>a</code> and <code>b</code> overlap. */
   public static boolean overlap(Layout a, Layout b) {
     return (between(left(a), right(a), left(b)) || between(left(a), right(a), right(b)))
             && (between(top(a), bottom(a), top(b)) || between(top(a), bottom(a), bottom(b)));
   }
 
   /** Get the X coordinate of the left bound of the layout. */
   public static int left(Layout a) {
     return a.getOffset().getX();
   }
 
   /** Get the X coordinate of the right bound of the layout. */
   public static int right(Layout a) {
     return a.getOffset().getX() + a.getDimension().getWidth();
   }
 
   /** Get the Y coordinate of the top bound of the layout. */
   public static int top(Layout a) {
     return a.getOffset().getY();
   }
 
   /** Get the Y coordinate of the bottom bound of the layout. */
   public static int bottom(Layout a) {
     return a.getOffset().getY() + a.getDimension().getHeight();
   }
 
   /** Calculate the offset of an anchor point for a given shape relative to its upper left corner. */
   public static Offset offset(Anchor a, Dimension dim) {
     return new Offset(limitMax(a.getLeft() * d(dim.getWidth()), dim.getWidth()),
                       limitMax(a.getTop() * d(dim.getHeight()), dim.getHeight()));
   }
 
   /**
    * Scale <code>shape</code> by <code>scale</code> and ensure that any rounding errors are limited so that
    * the resulting dimension does not exceed <code>limit</code>.
    */
   public static Dimension scale(Dimension limit, Dimension shape, double scale) {
     return Dimension.dimension(
             limitMax(d(shape.getWidth()) * scale, limit.getWidth()),
             limitMax(d(shape.getHeight()) * scale, limit.getHeight()));
   }
 
   /** Scale <code>d</code> to fit into <code>canvas</code> . */
   public static Dimension scaleToFit(Dimension canvas, Dimension d) {
     final double scaleToWidth = d(canvas.getWidth()) / d(d.getWidth());
     if (d.getHeight() * scaleToWidth > canvas.getHeight()) {
       final double scaleToHeight = d(canvas.getHeight()) / d(d.getHeight());
       return scale(canvas, d, scaleToHeight);
     } else {
       return scale(canvas, d, scaleToWidth);
     }
   }
 
   /** a &lt;= x &lt;= b */
   public static boolean between(int a, int b, int x) {
     return a <= x && x <= b;
   }
 
   private static double d(int v) {
     return v;
   }
 }