package net.vulkanmod.render.chunk.util;

import java.util.Iterator;
import org.apache.commons.lang3.Validate;

public class CircularIntList {
   private final int size;
   private final int[] list;
   private int startIndex;
   private final OwnIterator iterator;
   private final RangeIterator rangeIterator;

   public CircularIntList(int size) {
      this.size = size;
      this.list = new int[size + 2];
      this.iterator = new OwnIterator();
      this.rangeIterator = new RangeIterator();
   }

   public void updateStartIdx(int startIndex) {
      int[] list = this.list;
      this.startIndex = startIndex;
      list[0] = -1;
      list[this.size + 1] = -1;
      int k = 1;

      for(int i = startIndex; i < this.size; ++i) {
         list[k] = i;
         ++k;
      }

      for(int i = 0; i < startIndex; ++i) {
         list[k] = i;
         ++k;
      }

   }

   public int getNext(int i) {
      return this.list[i + 1];
   }

   public int getPrevious(int i) {
      return this.list[i - 1];
   }

   public OwnIterator iterator() {
      return this.iterator;
   }

   public RangeIterator getRangeIterator(int startIndex, int endIndex) {
      this.rangeIterator.update(startIndex, endIndex);
      return this.rangeIterator;
   }

   public RangeIterator createRangeIterator() {
      return new RangeIterator();
   }

   public class OwnIterator implements Iterator<Integer> {
      private int currentIndex = 0;
      private final int maxIndex;

      public OwnIterator() {
         this.maxIndex = CircularIntList.this.size;
      }

      public boolean hasNext() {
         return this.currentIndex < this.maxIndex;
      }

      public Integer next() {
         ++this.currentIndex;
         return CircularIntList.this.list[this.currentIndex];
      }

      public int getCurrentIndex() {
         return this.currentIndex;
      }

      public void restart() {
         this.currentIndex = 0;
      }
   }

   public class RangeIterator implements Iterator<Integer> {
      private int currentIndex;
      private int startIndex;
      private int endIndex;

      public void update(int startIndex, int endIndex) {
         Validate.isTrue(endIndex < CircularIntList.this.list.length, "Beyond max size", new Object[0]);
         this.startIndex = startIndex + 1;
         this.endIndex = endIndex + 1;
         this.restart();
      }

      public boolean hasNext() {
         return this.currentIndex < this.endIndex;
      }

      public Integer next() {
         ++this.currentIndex;
         return CircularIntList.this.list[this.currentIndex];
      }

      public int getCurrentIndex() {
         return this.currentIndex;
      }

      public void restart() {
         this.currentIndex = this.startIndex - 1;
      }
   }
}