/*
 * Jalview - A Sequence Alignment Editor and Viewer ($$Version-Rel$$)
 * Copyright (C) $$Year-Rel$$ The Jalview Authors
 * 
 * This file is part of Jalview.
 * 
 * Jalview 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.
 *  
 * Jalview 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 Jalview.  If not, see <http://www.gnu.org/licenses/>.
 * The Jalview Authors are detailed in the 'AUTHORS' file.
 */
package jalview.datamodel;

import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;

/**
 * An iterator which iterates over all visible columns in an alignment
 * 
 * @author kmourao
 *
 */
public class VisibleColsIterator implements Iterator<Integer>
{
  private int last;

  private int current;

  private int next;

  private List<int[]> hidden;

  private int lasthiddenregion;

  public VisibleColsIterator(int firstcol, int lastcol,
          HiddenColumns hiddenCols)
  {
    last = lastcol;
    current = firstcol;
    next = firstcol;
    hidden = hiddenCols.getHiddenColumnsCopy();
    lasthiddenregion = -1;

    if (hidden != null)
    {
      int i = 0;
      for (i = 0; i < hidden.size(); ++i)
      {
        if (current >= hidden.get(i)[0] && current <= hidden.get(i)[1])
        {
          // current is hidden, move to right
          current = hidden.get(i)[1] + 1;
          next = current;
        }
        if (current < hidden.get(i)[0])
        {
          break;
        }
      }
      lasthiddenregion = i - 1;

      for (i = hidden.size() - 1; i >= 0; --i)
      {
        if (last >= hidden.get(i)[0] && last <= hidden.get(i)[1])
        {
          // last is hidden, move to left
          last = hidden.get(i)[0] - 1;
        }
        if (last > hidden.get(i)[1])
        {
          break;
        }
      }
    }
  }

  @Override
  public boolean hasNext()
  {
    return next <= last;
  }

  @Override
  public Integer next()
  {
    if (next > last)
    {
      throw new NoSuchElementException();
    }
    current = next;
    if ((hidden != null) && (lasthiddenregion + 1 < hidden.size()))
    {
      // still some more hidden regions
      if (next + 1 < hidden.get(lasthiddenregion + 1)[0])
      {
        // next+1 is still before the next hidden region
        next++;
      }
      else if ((next + 1 >= hidden.get(lasthiddenregion + 1)[0])
              && (next + 1 <= hidden.get(lasthiddenregion + 1)[1]))
      {
        // next + 1 is in the next hidden region
        next = hidden.get(lasthiddenregion + 1)[1] + 1;
        lasthiddenregion++;
      }
    }
    else
    {
      // finished with hidden regions, just increment normally
      next++;
    }
    return current;
  }

  @Override
  public void remove()
  {
    throw new UnsupportedOperationException();
  }
}