package joptima;

import java.util.*;

/**
 * An abstract fitter.
 *
 * 

 * Extensions of this class typically need to do the following:
 * 

 *  
provide the appropriate setData() methods or some other
 *      way of handling the measured data points;
 *  
override the addFunction() method if fitting children of
 *      {@link Function} or something entirely different;
 *  
implement the {@link Minimizable#calculate} method to
 *      calculate the value of the appropriate likelihood function,
 *      given the data points and the set of {@link Function}s.
 * 
 * 

 */
public abstract class Fitter implements Minimizable, Function {

  protected List m_functions = new ArrayList();
  protected int m_nparameters = 0;

  protected String m_name;

  /**
   * Adds a {@link Function} to this {@link Fitter}.
   */
  public void addFunction(Function f) {
    m_functions.add(f);
    m_nparameters += f.getParameters().length;
  }

  /**
   * Removes all {@link Function}s from this {@link Fitter}.
   * The Fitter may then be reused with existing data.
   */
  public void removeAllFunctions() {
    m_functions = new ArrayList();
    m_nparameters = 0;
  }

  /**
   * Returns the value of the sum of functions at the given point.
   * Useful for plotting the fitted function after the fit converges.
   */
  public double /* y = */ calculate(double x) {
    double value = 0;
    Iterator i = m_functions.iterator();
    while (i.hasNext()) value += ((Function)i.next()).calculate(x);
    return value;
  }

  /**
   * Returns a function name for this fitter.
   * By default the name is created from the names of all functions.
   * If setName() was called, that is returned instead.
   */
  public String getName() {
    if (null != m_name) return m_name;
    Iterator it = m_functions.iterator();
    StringBuffer buf = new StringBuffer();
    while (it.hasNext()) {
      if (0 < buf.length()) buf.append('+');
      buf.append(((Function)it.next()).getName());
    }
    return buf.toString();
  }

  /**
   * Sets the function name for this fitter.
   */
  public void setName(String newname) {
    m_name = newname;
  }

  /**
   * Creates a list of all the {@link Function} parameters for this {@link Fitter}.
   * This method retrieves the parameters lists from individual {@link Function}s and
   * copies them into a single array to pass to a {@link Minimizer}.
   */
  public Parameter[] getParameters() {
    Parameter[] p = new Parameter[m_nparameters];
    int pindex = 0;
    Iterator it = m_functions.iterator();
    while (it.hasNext()) {
      Parameter[] subp = ((Function)it.next()).getParameters();
      for (int i = 0; i < subp.length; i++) p[pindex++] = subp[i];
    }
    return p;
  }

}