/*
    * License : The MIT License
    * Copyright(c) 2022 olyutorskii
    */
   
   package io.github.olyutorskii.aletojio.rng.dull;
   
   import io.github.olyutorskii.aletojio.rng.RndInt32;
   import io.github.olyutorskii.aletojio.rng.RndInt64;
  import java.util.List;
  import java.util.Objects;
  
  /**
   * Just repeating integer sequence generator.
   *
   * <p>If X0,X1,X2 is specified, outputs {X0, X1, X2, X0, X1, X2, X0...} forever.
   *
   * <p>Yes, all pseudo-random generators on finite state automaton are repeated.
   */
  public class SeqRepeater implements RndInt32, RndInt64 {
  
      private final int[] iVec;
      private final int size;
  
      private int pos;
  
  
      /**
       * Constructor.
       *
       * @param iVecArg int values sequence
       * @throws NullPointerException null argument
       * @throws IllegalArgumentException no values
       */
      public SeqRepeater(int... iVecArg)
              throws NullPointerException, IllegalArgumentException {
          super();
          Objects.requireNonNull(iVecArg);
  
          this.size = iVecArg.length;
          if (this.size < 1) throw new IllegalArgumentException();
  
          this.iVec = new int[this.size];
          System.arraycopy(iVecArg, 0, this.iVec, 0, this.size);
  
          this.pos = 0;
  
          return;
      }
  
      /**
       * Constructor.
       *
       * @param iVecList int values sequence
       * @throws NullPointerException argument is null
       * @throws IllegalArgumentException no values
       */
      public SeqRepeater(List<Integer> iVecList)
              throws NullPointerException, IllegalArgumentException {
          super();
          Objects.requireNonNull(iVecList);
  
          this.size = iVecList.size();
          if (this.size < 1) throw new IllegalArgumentException();
  
          this.iVec = new int[this.size];
  
          int idx = 0;
          for (int iVal : iVecList) {
              this.iVec[idx++] = iVal;
          }
          assert idx == this.size;
  
          this.pos = 0;
  
          return;
      }
  
  
      /**
       * {@inheritDoc}
       *
       * @return {@inheritDoc}
       */
      @Override
      public int nextInt32() {
          int result = this.iVec[this.pos++];
  
          if (this.pos >= this.size) {
              this.pos = 0;
          }
  
          return result;
      }
  
      /**
       * {@inheritDoc}
       *
       * @return {@inheritDoc}
      */
     @Override
     public long nextInt64() {
         long rndHigh = Integer.toUnsignedLong(nextInt32());
         long rndLow  = Integer.toUnsignedLong(nextInt32());
         long result = (rndHigh << Integer.SIZE) | rndLow;
         return result;
     }
 
 }