// Copyright (C) 2003 Adam Megacz <adam@xwt.org> all rights reserved.
//
// You may modify, copy, and redistribute this code under the terms of
// the GNU Library Public License version 2.1, with the exception of
// the portion of clause 6a after the semicolon (aka the "obnoxious
// relink clause")

package org.xwt.util;

import java.util.*;
import java.io.*;

/** 
 *  An unsynchronized Vector implementation; same semantics as
 *  java.util.Vector. Useful for JDK1.1 platforms that don't have
 *  java.util.ArrayList.
 *
 *  May contain nulls.
 *
 *  @see java.util.Vector
 */
public final class Vec implements Serializable {
    
    private Object[] store;
    private int size = 0;
    
    public Vec() { this(10); }
    public Vec(int i) { store = new Object[i]; }
    public Vec(int i, Object[] store) { size = i; this.store = store; }
    
    private void grow() { grow(store.length * 2); }
    private void grow(int newsize) {
        Object[] newstore = new Object[newsize];
        System.arraycopy(store, 0, newstore, 0, size);
        store = newstore;
    }

    public void removeAllElements() {
        for(int i=0; i<size; i++) store[i] = null;
        size = 0;
    }

    public void toArray(Object[] o) {
        for(int i=0; i<size; i++)
            o[i] = store[i];
    }
    
    public int indexOf(Object o) {
        for(int i=0; i<size; i++)
            if (o == null ? store[i] == null : store[i].equals(o)) return i;
        
        return -1;
    }
    
    public void addElement(Object o) {
        if (size >= store.length - 1) grow();
        store[size++] = o;
    }

    public Object peek() {
        return lastElement();
    }

    public Object elementAt(int i) {
        return store[i];
    }
    
    public Object lastElement() {
        if (size == 0) return null;
        return store[size - 1];
    }

    public void push(Object o) { addElement(o); }
    public Object pop() {
        Object ret = lastElement();
        if (size > 0) store[size--] = null;
        return ret;
    }

    public int size() { return size; }

    public void setSize(int newSize) {
        if (newSize < 0) throw new RuntimeException("tried to set size to negative value");
        if (newSize > store.length) grow(newSize * 2);
        if (newSize < size)
            for(int i=newSize; i<size; i++)
                store[i] = null;
        size = newSize;
    }

    public void copyInto(Object[] out) {
        for(int i=0; i<size; i++)
            out[i] = store[i];
    }

    public void fromArray(Object[] in) {
        setSize(in.length);
        for(int i=0; i<size; i++)
            store[i] = in[i];
    }

    public void removeElementAt(int i) {
        if (i >= size || i < 0) throw new RuntimeException("tried to remove an element outside the vector's limits");
        for(int j=i; j<size - 1; j++)
            store[j] = store[j + 1];
        setSize(size - 1);
    }

    public void setElementAt(Object o, int i) {
        if (i >= size) setSize(i);
        store[i] = o;
    }

    public void removeElement(Object o) {
        int idx = indexOf(o);
        if (idx != -1) removeElementAt(idx);
    }

    public void insertElementAt(Object o, int at) {
        if (size == store.length) grow();
        for(int i=size; i>at; i--)
            store[i] = store[i-1];
        store[at] = o;
        size++;
    }

    public interface CompareFunc {
        public int compare(Object a, Object b);
    }

    public void sort(CompareFunc c) {
        sort(this, null, c, 0, size-1);
    }

    public static void sort(Vec a, Vec b, CompareFunc c) {
        if (b != null && a.size != b.size) throw new IllegalArgumentException("Vec a and b must be of equal size");
        sort(a, b, c, 0, a.size-1);
    }

    private static final void sort(Vec a, Vec b, CompareFunc c, int start, int end) {
        ObjectObject tmpb = null;
        if(start >= end) return;
        if(end-start <= 6) {
            for(int i=start+1;i<=end;i++) {
                tmpa = a.store[i];
                if (b != null) tmpb = b.store[i];
                int j;
                for(j=i-1;j>=start;j--) {
                    if(c.compare(a.store[j],tmpa) <= 0) break;
                    a.store[j+1] = a.store[j];
                    if (b != null) b.store[j+1] = b.store[j];
                }
                a.store[j+1] = tmpa;
                if (b != null) b.store[j+1] = tmpb;
            }
            return;
        }

        Object pivot = a.store[end];
        int lo = start - 1;
        int hi = end;

        do {
            while(c.compare(a.store[++lo],pivot) < 0) { }
            while((hi > lo) && c.compare(a.store[--hi],pivot) > 0) { }
            swap(a, lo,hi);
            if (b != null) swap(b, lo,hi);
        } while(lo < hi);

        swap(a, lo,end);
        if (b != null) swap(b, lo,end);

        sort(a, b, c, start, lo-1);
        sort(a, b, c, lo+1, end);
    }

    private static final void swap(Vec vec, int a, int b) {
        if(a != b) {
            Object tmp = vec.store[a];
            vec.store[a] = vec.store[b];
            vec.store[b] = tmp;
        }
    }
}