package jcgp;

import java.util.Random;

import jcgp.function.Function;
import jcgp.function.FunctionSet;
import jcgp.population.*;

public class Utilities {
	
	private static Random numberGenerator;
	private static FunctionSet functionSet;
	
	public static void setResources(Random numberGenerator, FunctionSet functionSet) {
		Utilities.numberGenerator = numberGenerator;
		Utilities.functionSet = functionSet;
	}

	public static int getRandomInt(int limit){
		return numberGenerator.nextInt(limit);
	}

	public static double getRandomDouble(int limit){
		return numberGenerator.nextDouble() * limit;
	}

	/**
	 * Returns a random allowed connection respecting levels back.
	 * This method may always pick inputs, as they can be picked
	 * regardless of the column.
	 * 
	 * TODO remove?
	 * 
	 * @param chromosome the chromosome to pick from
	 * @param column the column to use as reference
	 * @return a random connection
	 */
	public static Connection getRandomConnection(Chromosome chromosome, int column){
		// work out the allowed range obeying levels back
		int allowedColumns = ((column >= Parameters.getLevelsBack()) ? Parameters.getLevelsBack() : column);
		int offset = column - allowedColumns;

		// choose input or node
		int connectionType = getRandomInt(Parameters.getInputs() + (Parameters.getRows() * allowedColumns));
		if (connectionType < Parameters.getInputs()) {
			// input
			return chromosome.getInput(getRandomInt(Parameters.getInputs()));
		} else {
			// node				
			return chromosome.getNode(getRandomInt(Parameters.getRows()), getRandomInt(allowedColumns) + offset);
		}
	}

	/**
	 * Returns a random allowed connection. 
	 * 
	 * This method may always pick inputs, as they can be picked
	 * regardless of the column.
	 * 
	 * TODO remove?
	 * 
	 * @param chromosome the chromosome to pick from
	 * @param column the column to use as reference
	 * @param levelsBack whether or not to respect levels back
	 * @return a random connection
	 */
	public static Connection getRandomConnection(Chromosome chromosome, int column, boolean levelsBack){
		if (levelsBack) {
			return getRandomConnection(chromosome, column);
		} else {
			// choose input or node
			int connectionType = getRandomInt(Parameters.getInputs() + (Parameters.getRows() * column));
			if (connectionType < Parameters.getInputs()) {
				// input
				return chromosome.getInput(getRandomInt(Parameters.getInputs()));
			} else {
				// node				
				return chromosome.getNode(getRandomInt(Parameters.getRows()), getRandomInt(column));
			}
		}
	}

	/**
	 * @param chromosome the chromosome to choose from
	 * @return a random input
	 */
	public static Input getRandomInput(Chromosome chromosome){
		return chromosome.getInput(getRandomInt(Parameters.getInputs()));
	}

	/**
	 * Returns a random allowed node respecting levels back.
	 * 
	 * This method will NOT pick inputs.
	 * 
	 * @param chromosome the chromosome to pick from
	 * @param column the column to use as reference
	 * @return a random node
	 */
	public static Node getRandomNode(Chromosome chromosome, int column){
		// work out the allowed range obeying levels back
		int allowedColumns = ((column >= Parameters.getLevelsBack()) ? Parameters.getLevelsBack() : column);
		int offset = column - allowedColumns;

		// pick a random allowed column and row
		int randomColumn = (getRandomInt(allowedColumns) + offset);
		int randomRow = (getRandomInt(Parameters.getRows()));

		return chromosome.getNode(randomRow, randomColumn);
	}

	/**
	 * Returns a random allowed node.
	 * 
	 * This method will NOT pick inputs.
	 * 
	 * @param chromosome the chromosome to pick from
	 * @param column the column to use as reference
	 * @param levelsBack whether or not to respect levels back
	 * @return a random node
	 */
	public static Node getRandomNode(Chromosome chromosome, int column, boolean levelsBack){
		if (levelsBack) {
			return getRandomNode(chromosome, column);
		} else {
			// pick any random column before the given column
			int randomColumn = (getRandomInt(column));
			// pick a random rowgetColumns
			int randomRow = (getRandomInt(Parameters.getRows()));
			return chromosome.getNode(randomRow, randomColumn);
		}
	}

	/**
	 * This method picks a random mutable element from the given chromosome.
	 * 
	 * It will pick outputs or nodes fairly.
	 * 
	 * TODO probably remove this
	 * 
	 * @param chromosome the chromosome to pick from
	 * @return a random mutable element
	 */
	public static MutableElement getRandomMutable(Chromosome chromosome){
		// choose output or node
		int connectionType = getRandomInt(Parameters.getOutputs() + Parameters.getNodeCount());

		if (connectionType < Parameters.getOutputs()) {
			// outputs
			return chromosome.getOutput(getRandomInt(Parameters.getOutputs()));
		} else {
			// node				
			return chromosome.getNode(getRandomInt(Parameters.getRows()), getRandomInt(Parameters.getRows()));
		}
	}		

	/**
	 * pick from any column - use this for setting outputs
	 * 
	 * @param chromosome
	 * @return
	 */
	public static Node getRandomNode(Chromosome chromosome) {
		return chromosome.getNode(getRandomInt(Parameters.getRows()), getRandomInt(Parameters.getColumns()));
	}

	public static Function getRandomFunction() {
		return functionSet.getFunction(Utilities.getRandomInt(functionSet.getFunctionCount()));
	}

	public static Function getFunction(int index) {
		return functionSet.getFunction(index);
	}

}