content: /*
    This file is part of Subsonic.
      Subsonic 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.
      Subsonic 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 Subsonic. If not, see <http://www.gnu.org/licenses/>.
      Copyright 2015 (C) Scott Jackson
  */
  
  package net.nullsum.audinaut.view;
  
  import android.graphics.Rect;
  import android.util.TypedValue;
  import android.view.View;
  import android.view.ViewGroup;
  import android.widget.FrameLayout;
  import android.widget.LinearLayout;
  
  import androidx.recyclerview.widget.GridLayoutManager;
  import androidx.recyclerview.widget.RecyclerView;
  
  public class GridSpacingDecoration extends RecyclerView.ItemDecoration {
      public static final int SPACING = 10;
  
      @Override
      public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
          super.getItemOffsets(outRect, view, parent, state);
  
          int spacing = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, SPACING, view.getResources().getDisplayMetrics());
          int halfSpacing = spacing / 2;
  
          int childCount = parent.getChildCount();
          int childIndex = parent.getChildAdapterPosition(view);
          // Not an actual child (ie: during delete event)
          if (childIndex == -1) {
              return;
          }
          int spanCount = getTotalSpan(parent);
          int spanIndex = childIndex % spanCount;
  
          // If we can, use the SpanSizeLookup since headers screw up the index calculation
          RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
          if (layoutManager instanceof GridLayoutManager) {
              GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
              GridLayoutManager.SpanSizeLookup spanSizeLookup = gridLayoutManager.getSpanSizeLookup();
              if (spanSizeLookup != null) {
                  spanIndex = spanSizeLookup.getSpanIndex(childIndex, spanCount);
              }
          }
          int spanSize = getSpanSize(parent, childIndex);
  
          /* INVALID SPAN */
          if (spanCount < 1 || spanSize > 1) return;
  
          int margins = 0;
          if (view instanceof UpdateView) {
              View firstChild = ((ViewGroup) view).getChildAt(0);
              ViewGroup.LayoutParams layoutParams = firstChild.getLayoutParams();
              if (layoutParams instanceof LinearLayout.LayoutParams) {
                  margins = ((LinearLayout.LayoutParams) layoutParams).bottomMargin;
              } else if (layoutParams instanceof FrameLayout.LayoutParams) {
                  margins = ((FrameLayout.LayoutParams) layoutParams).bottomMargin;
              }
          }
          int doubleMargins = margins * 2;
  
          outRect.top = halfSpacing - margins;
          outRect.bottom = halfSpacing - margins;
          outRect.left = halfSpacing - margins;
          outRect.right = halfSpacing - margins;
  
          if (isTopEdge(childIndex, spanIndex, spanCount)) {
              outRect.top = spacing - doubleMargins;
          }
  
          if (isLeftEdge(spanIndex)) {
              outRect.left = spacing - doubleMargins;
          }
  
          if (isRightEdge(spanIndex, spanCount)) {
              outRect.right = spacing - doubleMargins;
          }
  
          if (isBottomEdge(childIndex, childCount, spanCount)) {
              outRect.bottom = spacing - doubleMargins;
          }
      }
  
      private int getTotalSpan(RecyclerView parent) {
          RecyclerView.LayoutManager mgr = parent.getLayoutManager();
          if (mgr instanceof GridLayoutManager) {
              return ((GridLayoutManager) mgr).getSpanCount();
          }
  
          return -1;
      }
  
      private int getSpanSize(RecyclerView parent, int childIndex) {
          RecyclerView.LayoutManager mgr = parent.getLayoutManager();
          if (mgr instanceof GridLayoutManager) {
              GridLayoutManager.SpanSizeLookup lookup = ((GridLayoutManager) mgr).getSpanSizeLookup();
              if (lookup != null) {
                  return lookup.getSpanSize(childIndex);
              }
          }
  
          return 1;
      }
  
      private boolean isLeftEdge(int spanIndex) {
          return spanIndex == 0;
      }
  
      private boolean isRightEdge(int spanIndex, int spanCount) {
          return spanIndex == spanCount - 1;
      }
  
      private boolean isTopEdge(int childIndex, int spanIndex, int spanCount) {
          return childIndex < spanCount && childIndex == spanIndex;
      }
  
      private boolean isBottomEdge(int childIndex, int childCount, int spanCount) {
          return childIndex >= childCount - spanCount;
      }
  }
  