/* Copyright (c) 2008-2013, Avian Contributors

   Permission to use, copy, modify, and/or distribute this software
   for any purpose with or without fee is hereby granted, provided
   that the above copyright notice and this permission notice appear
   in all copies.

   There is NO WARRANTY for this software.  See license.txt for
   details. */

package java.util;

import java.lang.reflect.Array;

public class Arrays {
  private Arrays() { }

  public static String toString(Object[] a) {
    return asList(a).toString();
  }

  public static String toString(boolean[] a) {
    if (a == null) {
      return "null";
    } else {
      StringBuilder sb = new StringBuilder();
      sb.append("[");
      for (int i = 0; i < a.length; ++i) {
        sb.append(String.valueOf(a[i]));
        if (i + 1 != a.length) {
          sb.append(", ");
        }
      }
      sb.append("]");
      return sb.toString();
    }
  }

  public static String toString(byte[] a) {
    if (a == null) {
      return "null";
    } else {
      StringBuilder sb = new StringBuilder();
      sb.append("[");
      for (int i = 0; i < a.length; ++i) {
        sb.append(String.valueOf(a[i]));
        if (i + 1 != a.length) {
          sb.append(", ");
        }
      }
      sb.append("]");
      return sb.toString();
    }
  }

  public static String toString(short[] a) {
    if (a == null) {
      return "null";
    } else {
      StringBuilder sb = new StringBuilder();
      sb.append("[");
      for (int i = 0; i < a.length; ++i) {
        sb.append(String.valueOf(a[i]));
        if (i + 1 != a.length) {
          sb.append(", ");
        }
      }
      sb.append("]");
      return sb.toString();
    }
  }

  public static String toString(int[] a) {
    if (a == null) {
      return "null";
    } else {
      StringBuilder sb = new StringBuilder();
      sb.append("[");
      for (int i = 0; i < a.length; ++i) {
        sb.append(String.valueOf(a[i]));
        if (i + 1 != a.length) {
          sb.append(", ");
        }
      }
      sb.append("]");
      return sb.toString();
    }
  }

  public static String toString(long[] a) {
    if (a == null) {
      return "null";
    } else {
      StringBuilder sb = new StringBuilder();
      sb.append("[");
      for (int i = 0; i < a.length; ++i) {
        sb.append(String.valueOf(a[i]));
        if (i + 1 != a.length) {
          sb.append(", ");
        }
      }
      sb.append("]");
      return sb.toString();
    }
  }

  public static String toString(float[] a) {
    if (a == null) {
      return "null";
    } else {
      StringBuilder sb = new StringBuilder();
      sb.append("[");
      for (int i = 0; i < a.length; ++i) {
        sb.append(String.valueOf(a[i]));
        if (i + 1 != a.length) {
          sb.append(", ");
        }
      }
      sb.append("]");
      return sb.toString();
    }
  }

  public static String toString(double[] a) {
    if (a == null) {
      return "null";
    } else {
      StringBuilder sb = new StringBuilder();
      sb.append("[");
      for (int i = 0; i < a.length; ++i) {
        sb.append(String.valueOf(a[i]));
        if (i + 1 != a.length) {
          sb.append(", ");
        }
      }
      sb.append("]");
      return sb.toString();
    }
  }

  private static boolean equal(Object a, Object b) {
    return (a == null && b == null) || (a != null && a.equals(b));
  }

  public static void sort(Object[] array) {
    sort(array, new Comparator() {
        public int compare(Object a, Object b) {
          return ((Comparable) a).compareTo(b);
        }
      });
  }

  private final static int SORT_SIZE_THRESHOLD = 16;

  public static <T> void sort(T[] array, Comparator<? super T> comparator) {
    introSort(array, comparator, 0, array.length, array.length);
    insertionSort(array, comparator);
  }

  private static <T > void introSort(T[] array,
    Comparator<? super T> comparator, int begin, int end, int limit)
  {
    while (end - begin > SORT_SIZE_THRESHOLD) {
      if (limit == 0) {
        heapSort(array, comparator, begin, end);
        return;
      }
      limit >>= 1;

      // median of three
      T a = array[begin];
      T b = array[begin + (end - begin) / 2 + 1];
      T c = array[end - 1];
      T median;
      if (comparator.compare(a, b) < 0) {
        median = comparator.compare(b, c) < 0 ?
          b : (comparator.compare(a, c) < 0 ? c : a);
      } else {
        median = comparator.compare(b, c) > 0 ?
          b : (comparator.compare(a, c) > 0 ? c : a);
      }

      // partition
      int pivot, i = begin, j = end;
      for (;;) {
        while (comparator.compare(array[i], median) < 0) {
          ++i;
        }
        --j;
        while (comparator.compare(median, array[j]) < 0) {
          --j;
        }
        if (i >= j) {
          pivot = i;
          break;
        }
        T swap = array[i];
        array[i] = array[j];
        array[j] = swap;
        ++i;
      }

      introSort(array, comparator, pivot, end, limit);
      end = pivot;
    }
  }

  private static <T> void heapSort(T[] array, Comparator<? super T> comparator,
    int begin, int end)
  {
    int count = end - begin;
    for (int i = count / 2 - 1; i >= 0; --i) {
      siftDown(array, comparator, i, count, begin);
    }
    for (int i = count - 1; i > 0; --i) {
      // swap begin and begin + i
      T swap = array[begin + i];
      array[begin + i] = array[begin];
      array[begin] = swap;

      siftDown(array, comparator, 0, i, begin);
    }
  }

  private static <T> void siftDown(T[] array, Comparator<? super T> comparator,
    int i, int count, int offset)
  {
    T value = array[offset + i];
    while (i < count / 2) {
      int child = 2 * i + 1;
      if (child + 1 < count &&
          comparator.compare(array[child], array[child + 1]) < 0) {
        ++child;
      }
      if (comparator.compare(value, array[child]) >= 0) {
        break;
      }
      array[offset + i] = array[offset + child];
      i = child;
    }
    array[offset + i] = value;
  }

  private static <T> void insertionSort(T[] array,
    Comparator<? super T> comparator)
  {
    for (int j = 1; j < array.length; ++j) {
      T t = array[j];
      int i = j - 1;
      while (i >= 0 && comparator.compare(array[i], t) > 0) {
        array[i + 1] = array[i];
        i = i - 1;
      }
      array[i + 1] = t;
    }
  }

  public static int hashCode(Object[] array) {
    if(array == null) {
      return 9023;
    }

    int hc = 823347;
    for(Object o : array) {
      hc += o != null ? o.hashCode() : 54267;
      hc *= 3;
    }
    return hc;
  }

  public static boolean equals(Object[] a, Object[] b) {
    if(a == b) {
      return true;
    }
    if(a == null || b == null) {
      return false;
    }
    if(a.length != b.length) {
      return false;
    }
    for(int i = 0; i < a.length; i++) {
      if(!equal(a[i], b[i])) {
        return false;
      }
    }
    return true;
  }

  public static <T> List<T> asList(final T ... array) {
    return new AbstractList<T>() {
      public int size() {
        return array.length;
      }

      public void add(int index, T element) {
        throw new UnsupportedOperationException();
      }
      
      public int indexOf(Object element) {
        for (int i = 0; i < array.length; ++i) {
          if (equal(element, array[i])) {
            return i;
          }
        }
        return -1;
      }

      public int lastIndexOf(Object element) {
        for (int i = array.length - 1; i >= 0; --i) {
          if (equal(element, array[i])) {
            return i;
          }
        }
        return -1;
      }
      
      public T get(int index) {
        return array[index];
      }

      public T set(int index, T value) {
        throw new UnsupportedOperationException();
      }

      public T remove(int index) {
        throw new UnsupportedOperationException();
      }

      public ListIterator<T> listIterator(int index) {
        return new Collections.ArrayListIterator(this, index);
      }
    };
  }

  public static void fill(int[] array, int value) {
    for (int i=0;i<array.length;i++) {
      array[i] = value;
    }
  }

  public static void fill(char[] array, char value) {
    for (int i=0;i<array.length;i++) {
      array[i] = value;
    }
  }
  
  public static <T> void fill(T[] array, T value) {
    for (int i=0;i<array.length;i++) {
      array[i] = value;
    }
  }

  public static boolean[] copyOf(boolean[] array, int newLength) {
    boolean[] result = new boolean[newLength];
    int length = array.length > newLength ? newLength : array.length;
    System.arraycopy(array, 0, result, 0, length);
    return result;
  }

  public static byte[] copyOf(byte[] array, int newLength) {
    byte[] result = new byte[newLength];
    int length = array.length > newLength ? newLength : array.length;
    System.arraycopy(array, 0, result, 0, length);
    return result;
  }

  public static char[] copyOf(char[] array, int newLength) {
    char[] result = new char[newLength];
    int length = array.length > newLength ? newLength : array.length;
    System.arraycopy(array, 0, result, 0, length);
    return result;
  }

  public static double[] copyOf(double[] array, int newLength) {
    double[] result = new double[newLength];
    int length = array.length > newLength ? newLength : array.length;
    System.arraycopy(array, 0, result, 0, length);
    return result;
  }

  public static float[] copyOf(float[] array, int newLength) {
    float[] result = new float[newLength];
    int length = array.length > newLength ? newLength : array.length;
    System.arraycopy(array, 0, result, 0, length);
    return result;
  }

  public static int[] copyOf(int[] array, int newLength) {
    int[] result = new int[newLength];
    int length = array.length > newLength ? newLength : array.length;
    System.arraycopy(array, 0, result, 0, length);
    return result;
  }

  public static long[] copyOf(long[] array, int newLength) {
    long[] result = new long[newLength];
    int length = array.length > newLength ? newLength : array.length;
    System.arraycopy(array, 0, result, 0, length);
    return result;
  }

  public static short[] copyOf(short[] array, int newLength) {
    short[] result = new short[newLength];
    int length = array.length > newLength ? newLength : array.length;
    System.arraycopy(array, 0, result, 0, length);
    return result;
  }

  public static <T> T[] copyOf(T[] array, int newLength) {
    Class<?> clazz = array.getClass().getComponentType();
    T[] result = (T[])Array.newInstance(clazz, newLength);
    int length = array.length > newLength ? newLength : array.length;
    System.arraycopy(array, 0, result, 0, length);
    return result;
  }

  public static <T, U> T[] copyOf(U[] array, int newLength,
    Class<? extends T[]> newType)
  {
    T[] result = (T[])Array.newInstance(newType.getComponentType(), newLength);
    int length = array.length > newLength ? newLength : array.length;
    System.arraycopy(array, 0, result, 0, length);
    return result;
  }
}