import java.io.*;

public class Driver {
    /* Driver routine -- test out the code on a sample problem
     */
    public static void driver(int n, int single maxiter, Sparse aMat, 
			      Preconditioner pMat)
    {
	try {
	    double [1d] single [1d] b = new double [0:Ti.numProcs()-1][1d];
	    double [1d] single [1d] x = new double [0:Ti.numProcs()-1][1d];
	    double [1d] rhist = new double [0:maxiter-1];

	    int myCount = PVector.numPer(n);
	    int myLow = PVector.lowPer(n);
	    b.exchange(new double [myLow:myLow+myCount-1]);
	    x.exchange(new double [myLow:myLow+myCount-1]);
	    double single rtol = 1e-3;

	    int i, retval;

	    DataOutputStream rhistOutFile; 
	    DataOutputStream xOutFile; 
	    if (Ti.thisProc() == 0) {
		try {
		    rhistOutFile = 
			new DataOutputStream(new FileOutputStream("rhist.out"));
		    xOutFile = 
			new DataOutputStream(new FileOutputStream("x.out"));
		} catch (IOException e) {
		    System.out.println("Unable to open output files.");
		    System.exit(1);
		}
	    }
	    b[Ti.thisProc()].set(1);

	    retval = CG.precondCG(aMat, pMat, b, x, rtol, n, rhist, maxiter);

	    if (Ti.thisProc() == 0) {
		for (int p = 0; p < Ti.numProcs(); p++) {
		    for (i = x[p].domain().min()[1]; 
			 i <= x[p].domain().max()[1]; i++) {
			xOutFile.writeBytes(Double.toString(x[p][i]) + "\n");
		    }
		}
	    }

	    int lastIter;
	    if (Ti.thisProc() == 0) {
		if (retval < 0) {
		    lastIter = maxiter;
		    System.out.println("Iteration failed to converge!\n");
		} else {
		    lastIter = retval;
		    System.out.println("Converged after " + retval + 
				       " iterations.");
		}
		for (i = 0; i < lastIter; ++i) {
		    rhistOutFile.writeBytes(Double.toString(rhist[i])+"\n");
		}
	
		rhistOutFile.close();
		xOutFile.close();
	    }
	    
	} catch (IOException e) {
	    System.out.println("Unable to open or use output files: " + e);
	    return;
	}
    }


    public static single void main(String [] args)
    {
	int single maxIter = 500;

	int n;
	Sparse aMat;
	Preconditioner pMat;
	MatMarket single aMM;
	MatMarket aMMOnZero;

	if (Ti.thisProc() == 0) {
	    if (args.length <= 0 || Character.isDigit(args[0].charAt(0))) { 
		if (args.length <= 0) {
		    n = 10;
		} else {
		    try {
			n = Integer.parseInt(args[0]);
		    } catch (Exception e) {
			System.out.println("Unable to parse argument, using default.");
			n = 10;
		    }
		}
		System.out.println("Using 1-d Poisson on a " + 
				   n + " point mesh.\n");
		aMat = null; // new Poisson1D(n) if parallelized
		pMat = null; // put preconditioner here if one exists.
		
	    } else {
		try {
		    aMMOnZero = MMIO.CSRLoad(args[0]); 
		    n = aMMOnZero.n;
		} catch (IOException e) {
		    System.out.println(e);
		    System.exit(1);
		}
		pMat = null;
		System.out.println("Using problem " + args[0]);
	    }
	}

	aMM = broadcast aMMOnZero from 0;
	if (aMM.n == 0) {  // no matrix was created, so give up
	    return;
	}
	n = broadcast n from 0;
	aMat = new CSR(broadcast aMM.entries from 0, aMM.n);

	driver(n, maxIter, aMat, new IdentityPrecond());

	/* Add this code to run with preconditioner 
	    if (Ti.thisProc() == 0) {
		System.out.println("Using block Jacobi Preconditioner\n");
	    }
	    driver(n, maxIter, aMat, pMat);
	*/
    }
}