Grid.java

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Grid extends JPanel implements MouseListener, MouseMotionListener {
    static final int ROWS = 20;
    static final int COLS = 20;

    static final Color BG          = new Color(10, 20, 40);
    static final Color EMPTY       = new Color(20, 40, 80);
    static final Color GRID_LINE   = new Color(30, 55, 110);
    static final Color WALL_TOP    = new Color(180, 190, 210);
    static final Color WALL_FACE   = new Color(90, 100, 130);
    static final Color WALL_SIDE   = new Color(40, 50, 75);
    static final Color START_COL   = new Color(50, 200, 100);
    static final Color END_COL     = new Color(220, 60, 60);
    static final Color PATH_COL    = new Color(255, 200, 50);
    static final Color VISITED_COL = new Color(30, 80, 140);

    int[][] cells        = new int[ROWS][COLS];
    boolean[][] path     = new boolean[ROWS][COLS];
    boolean[][] visited  = new boolean[ROWS][COLS];
    String mode = "wall";
    int startR = -1, startC = -1, endR = -1, endC = -1;

    public Grid() {
        setBackground(BG);
        addMouseListener(this);
        addMouseMotionListener(this);
    }

    boolean isWall(int r, int c) {
        if (r < 0 || r >= ROWS || c < 0 || c >= COLS) return false;
        return cells[r][c] == 1;
    }

    void dijkstra() {
    if (startR == -1 || endR == -1) return;
    Dijkstra d = new Dijkstra();
    path    = new boolean[ROWS][COLS];
    visited = new boolean[ROWS][COLS];
    boolean[][] result = d.run(cells, startR, startC, endR, endC);
    if (result != null) {
        path    = result;
        visited = d.visited;
    } else {
        visited = d.visited;
        JOptionPane.showMessageDialog(this, "No path found!", "Pathfinder", JOptionPane.WARNING_MESSAGE);
    }
    repaint();
}


    void drawCell(Graphics2D g2, int i, int j, Color face, Color top, Color side) {
        int cellW = getWidth() / COLS;
        int cellH = getHeight() / ROWS;
        int depth = 6;
        int x = j * cellW, y = i * cellH;

        if (!isWall(i, j + 1)) {
            g2.setColor(side);
            int[] xR = {x+cellW, x+cellW+depth, x+cellW+depth, x+cellW};
            int[] yR = {y, y-depth, y+cellH-depth, y+cellH};
            g2.fillPolygon(xR, yR, 4);
        }
        if (!isWall(i - 1, j)) {
            g2.setColor(top);
            int[] xT = {x, x+cellW, x+cellW+depth, x+depth};
            int[] yT = {y, y, y-depth, y-depth};
            g2.fillPolygon(xT, yT, 4);
        }
        g2.setColor(face);
        g2.fillRect(x, y, cellW, cellH);
        g2.setColor(side);
        g2.drawRect(x, y, cellW, cellH);
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        int cellW = getWidth() / COLS;
        int cellH = getHeight() / ROWS;

        for (int i = 0; i < ROWS; i++) {
            for (int j = 0; j < COLS; j++) {
                int x = j * cellW, y = i * cellH;
                if (cells[i][j] == 1) {
                    drawCell(g2, i, j, WALL_FACE, WALL_TOP, WALL_SIDE);
                } else if (cells[i][j] == 2) {
                    drawCell(g2, i, j, START_COL, START_COL.brighter(), START_COL.darker());
                } else if (cells[i][j] == 3) {
                    drawCell(g2, i, j, END_COL, END_COL.brighter(), END_COL.darker());
                } else if (path[i][j]) {
                    drawCell(g2, i, j, PATH_COL, PATH_COL.brighter(), PATH_COL.darker());
                } else if (visited[i][j]) {
                    g2.setColor(VISITED_COL);
                    g2.fillRect(x, y, cellW, cellH);
                    g2.setColor(GRID_LINE);
                    g2.drawRect(x, y, cellW, cellH);
                } else {
                    g2.setColor(EMPTY);
                    g2.fillRect(x, y, cellW, cellH);
                    g2.setColor(GRID_LINE);
                    g2.drawRect(x, y, cellW, cellH);
                }
            }
        }
    }

    void handleMouse(MouseEvent e) {
        int cellW = getWidth() / COLS;
        int cellH = getHeight() / ROWS;
        int col = e.getX() / cellW;
        int row = e.getY() / cellH;
        if (row < 0 || row >= ROWS || col < 0 || col >= COLS) return;

        if (mode.equals("start")) {
            if (startR != -1) cells[startR][startC] = 0;
            startR = row; startC = col;
            cells[row][col] = 2;
            mode = "wall";
        } else if (mode.equals("end")) {
            if (endR != -1) cells[endR][endC] = 0;
            endR = row; endC = col;
            cells[row][col] = 3;
            mode = "wall";
        } else {
            if (cells[row][col] == 2 || cells[row][col] == 3) return;
            cells[row][col] = SwingUtilities.isLeftMouseButton(e) ? 1 : 0;
        }
        path    = new boolean[ROWS][COLS];
        visited = new boolean[ROWS][COLS];
        repaint();
    }

    public void mousePressed(MouseEvent e)  { handleMouse(e); }
    public void mouseDragged(MouseEvent e)  { handleMouse(e); }
    public void mouseClicked(MouseEvent e)  {}
    public void mouseReleased(MouseEvent e) {}
    public void mouseEntered(MouseEvent e)  {}
    public void mouseExited(MouseEvent e)   {}
    public void mouseMoved(MouseEvent e)    {}

    public static void main(String[] args) {
        JFrame frame = new JFrame("Pathfinder");
        Grid grid = new Grid();

        JButton startBtn = new JButton("Set Start");
        JButton endBtn   = new JButton("Set End");
        JButton runBtn   = new JButton("Run");
        JButton clearBtn = new JButton("Clear");

        for (JButton btn : new JButton[]{startBtn, endBtn, runBtn, clearBtn}) {
            btn.setBackground(new Color(20, 40, 80));
            btn.setForeground(new Color(160, 180, 220));
            btn.setFocusPainted(false);
            btn.setBorder(BorderFactory.createLineBorder(new Color(60, 90, 150)));
        }

        startBtn.addActionListener(e -> grid.mode = "start");
        endBtn.addActionListener(e -> grid.mode = "end");
        runBtn.addActionListener(e -> grid.dijkstra());
        clearBtn.addActionListener(e -> {
            grid.cells   = new int[ROWS][COLS];
            grid.path    = new boolean[ROWS][COLS];
            grid.visited = new boolean[ROWS][COLS];
            grid.startR  = grid.startC = grid.endR = grid.endC = -1;
            grid.mode    = "wall";
            grid.repaint();
        });

        JPanel bottom = new JPanel();
        bottom.setBackground(new Color(10, 20, 40));
        bottom.add(startBtn);
        bottom.add(endBtn);
        bottom.add(runBtn);
        bottom.add(clearBtn);

        frame.add(grid, BorderLayout.CENTER);
        frame.add(bottom, BorderLayout.SOUTH);
        frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}