import java.io.FileReader;
import java.io.IOException;
import java.util.Arrays;
import java.util.Scanner;

public class LowerRelaxationMethod {
    private double[][] augmentedMatrix;
    private double W;
    private double[][] F;
    private double[][] H;
    private double[] x;
    private double[] discrepancy;
    private double normDiscrepancy;
    private int row;
    private int col;
    private int countOfIterations;

    public LowerRelaxationMethod(int row, int col, double W){
        this.W = W;
        this.row = row;
        this.col = col;
        augmentedMatrix = new double[row][col];
        x = new double[row];
    }

    public void formAugmentedMatrix(String fileName) throws IOException {
        try(Scanner sc = new Scanner(new FileReader(fileName))){
            for(int i = 0; i < row; ++i){
                for(int j = 0; j < col; ++j){
                    augmentedMatrix[i][j] = sc.nextDouble();
                }
            }
        }
    }

    public void formFandH() {
        F = new double[row][col];
        H = new double[row][col];
        for (int i = 0; i < row; i++) {
            for (int j = 0; j < col; j++) {
                if (j == col - 1) {
                    F[i][j] = augmentedMatrix[i][j] / augmentedMatrix[i][i];
                }
                else {
                    if (i == j) {
                        F[i][j] = 0;
                        H[i][j] = 0;
                    }
                    else {
                        if (i < j) {
                            F[i][j] = -augmentedMatrix[i][j] / augmentedMatrix[i][i];
                        } else {
                            H[i][j] = -augmentedMatrix[i][j] / augmentedMatrix[i][i];
                        }
                    }
                }
            }
        }
    }

    public void firstIteration(){
        countOfIterations++;
        for(int i = 0; i < row; i++){
            x[i] = F[i][col - 1];
        }
    }

    public void iterations(){
        double[] xPrevious = new double[row];
        while(!stop(xPrevious, x)){
            copyArray(x, xPrevious);
            oneIteration(xPrevious);
            countOfIterations++;
        }
    }

    private void oneIteration(double[] previous){
        for (int i = 0; i < row; i++) {
            x[i] = 0;
            x[i] += (1 - W) * previous[i];
            for(int j = 0; j < i; j++) {
                x[i] += W * H[i][j] * x[j];
            }
            for(int j = i + 1; j < col - 1; j++) {
                x[i] += W * F[i][j] * previous[j];
            }
            x[i] += W * F[i][col - 1];
        }
    }

    private boolean stop(double[] previous, double[] current){
        for(int i = 0; i < row; i++){
            if(previous[i] - current[i] > 0.00001){
                return false;
            }
        }
        return true;
    }

    private void copyArray(double[] from, double[] to){
        for(int i = 0; i < row; i++){
            to[i] = from[i];
        }
    }

    public void findDiscrepancy(){
        discrepancy = new double [row];
        for(int i = 0; i < row; ++i){
            for(int j = 0; j < col - 1; ++j){
                discrepancy[i] += augmentedMatrix[i][j] * x[j];
            }
            discrepancy[i] -= augmentedMatrix[i][col - 1];
        }
    }

    public void discrepancyNorm(){
        normDiscrepancy = 0;
        for(int i = 0; i < row; ++i){
            normDiscrepancy = normDiscrepancy + Math.abs(discrepancy[i]);
        }
        System.out.printf("Норма r = %.5e\n", normDiscrepancy);
    }

    public void printAugmentedMatrix(){
        System.out.println("Матрица системы:");
        for(int i = 0; i < row; ++i){
            for(int j = 0; j < col; ++j){
                if(j == col - 1){
                    System.out.printf("|%8.4f", augmentedMatrix[i][j]);
                }
                else {
                    System.out.printf("%8.4f", augmentedMatrix[i][j]);
                }
            }
            System.out.println();
        }
    }

    public void printX() {
        System.out.println("Вектор решений:");
        Arrays.stream(x).forEach(item -> System.out.printf("%8.5f ", item));
        System.out.println();
    }

    public void printDiscrepancy(){
        System.out.println("Вектор невязки:");
        Arrays.stream(discrepancy).forEach(item -> System.out.printf("%15.5e\n", item));
    }



    public void printCountOfIterations(){
        System.out.println("Количество итераций:");
        System.out.println(countOfIterations);
    }
}