package edu.neu.ccs.evergreen;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;

import org.apache.log4j.PropertyConfigurator;

import edu.neu.ccs.demeter.dj.ClassGraph;
import edu.neu.ccs.evergreen.demeterj.CSP;
import edu.neu.ccs.evergreen.demeterj.ParseException;
import edu.neu.ccs.evergreen.state.NextState;
import edu.neu.ccs.evergreen.state.NextStateFactory;
import edu.neu.ccs.evergreen.visitor.Preprocessor;

/**
 * Wrapper class for solving CSP problems.
 */
public class CSPSolver {
	/**
	 * Class graph in use.
	 */
	public static ClassGraph CG = new ClassGraph(
			"edu.neu.ccs.evergreen.demeterj", true, false);

	static {
		PropertyConfigurator.configure(CSPSolver.class.getClassLoader().getResource("log4j.config"));
	}

	/**
	 * The command line entry point.
	 * 
	 * @param args
	 *            Command line arguments
	 */
	public static void main(String[] args) {
		if ((args == null) || (args.length < 2)) {
			System.out.println("Usage: CSPSolver <filename.alt> <next state>");
			System.out.println("Next State Options:");
			System.out.println("appmean");
			System.out.println("fair [seed = 1]");
			System.out.println("maxbias [refresh % = 0.5] [seed = 1]");
		} else {
			try {
				String optionalArgs[] = new String[args.length - 2];
				System.arraycopy(args, 2, optionalArgs, 0, optionalArgs.length);
				NextState nextState = NextStateFactory.createNextState(args[1], optionalArgs);
				solve(new BufferedInputStream(new FileInputStream(args[0])), nextState);
			} catch (FileNotFoundException e) {
				throw new RuntimeException(e);
			}
		}
	}

	/**
	 * Solve the given input string.
	 * 
	 * @param input
	 *            CSP to solve
	 *            @param nextState Determine next state of the system
	 */
	public static void solve(String input, NextState nextState) {
		solve(CSP.parse(input), nextState);
	}

	/**
	 * Solve the given input stream.
	 * 
	 * @param input
	 *            CSP to solve
	 *            @param nextState Determine next state of the system
	 */
	public static void solve(InputStream input, NextState nextState) {
		try {
			solve(CSP.parse(input), nextState);
		} catch (ParseException e) {
			throw new RuntimeException(e);
		}
	}

	/**
	 * Solve the given CSP.
	 * 
	 * @param csp
	 *            CSP to solve
	 *            @param nextState Determine next state of the system
	 */
	private static void solve(CSP csp, NextState nextState) {
		Preprocessor preprocessor = new Preprocessor(csp.getMaxVariable());
		CSPSolver.CG
				.traverse(
						csp,
						"from edu.neu.ccs.evergreen.demeterj.CSP to edu.neu.ccs.evergreen.demeterj.Variable",
						preprocessor);

		if (csp.getConstraintCount() != preprocessor.constraintCount) {
			throw new IllegalArgumentException("Wrong number of constraints");
		}
		Solver solver = new Solver(preprocessor.weights,
				preprocessor.variables, preprocessor.constraintCount, nextState);
		System.exit(solver.solve());
	}
}