package realApps;

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

public class GraphDrawing implements ActionListener {

    GraphicsDevice gd = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice(); // Takes in display size.
    final int unit = 20, wWidth = 1000, wHeight = 1060, sWidth = gd.getDisplayMode().getWidth(), sHeight = gd.getDisplayMode().getHeight();
    JFrame frame;
    JTextField fa, fb, fc; // Text fields where to enter the coefficients.
    ArrayList<Line> ay = new ArrayList<Line>(); // ArrayList to hold the lines.
    JPanel lines, cofs; // Panel that lists drawn lines and their respective equation & panel with coefficients.
    MyDrawPanel panel;
    JSplitPane splitPane;
    Line line;
    JLabel vertexLabel;

    public static void main(String[] args) {

        new GraphDrawing();
    }

    public GraphDrawing() {

        frame = new JFrame("Graph tool");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        fa = new JTextField(7);
        fb = new JTextField(7);
        fc = new JTextField(7);
        JLabel la = new JLabel("a: ");
        JLabel lb = new JLabel("b: ");
        JLabel lc = new JLabel("c: ");

        JButton drawLine = new JButton("Draw line!");
        drawLine.addActionListener(this);

        cofs = new JPanel(); // Panel where the coefficients can be entered.
        cofs.setBackground(Color.lightGray);

        cofs.add(la);
        cofs.add(fa);
        cofs.add(lb);
        cofs.add(fb);
        cofs.add(lc);
        cofs.add(fc);
        cofs.add(drawLine);

        lines = new JPanel();
        lines.setBackground(Color.lightGray);
        lines.setLayout(new BoxLayout(lines, BoxLayout.Y_AXIS)); // Sets layout for the side-bar, giving a new line to each equation.
        lines.setPreferredSize(new Dimension(20, frame.getHeight()));

        panel = new MyDrawPanel();
        splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, lines, panel); // Used for resizing of side-bar.

        frame.getContentPane().add(BorderLayout.CENTER, splitPane);
        frame.getContentPane().add(BorderLayout.SOUTH, cofs);

        frame.setSize(wWidth, wHeight);
        frame.setVisible(true);
    }

    String toEquation() { // Returns the coefficients in the format y = ax^2 + bx + c as a String.

        double a = line.getA(), b = line.getB(), c = line.getC(); // Local variables to store the coefficients of the line.

        String as = Double.toString(a); // Converts values to strings.
        String bs = Double.toString(b);
        String cs = Double.toString(c);

        int ai = as.length(), bi = bs.length(), ci = cs.length(); // Lengths of values.

        if(Character.toString(as.charAt(ai - 1)).equals("0")) { // If a number is an integer, remove the .0 bit from the end.

            as = as.substring(0, ai - 2);
        }
        if(Character.toString(bs.charAt(bi - 1)).equals("0")) {

            bs = bs.substring(0, bi - 2);
        }
        if(Character.toString(cs.charAt(ci - 1)).equals("0")) {

            cs = cs.substring(0, ci - 2);
        }

        String af = a == 1 ? "x\u00B2 " : a == -1 ? "-x\u00B2 " : a == 0 ? "" : as + "x\u00B2 "; // Code for showing a (u00B2 is Unicode for superscript 2).
        String bf = b == -1 ? a == 0 ? "-x " : "- x " : a == 0 && b != 0 && b != 1 ? bs + "x " : b < 0 ? "- " + bs.substring(1) + "x " : b == 1 ? a == 0 ? "x " : "+ x " : a == 0 ? b == 0 ? "" : bs + "x " : b == 0 ? "" : "+ " + bs + "x "; // Forgive me lord for I have sinned.
        String cf = a == 0 && b == 0 ? cs : c < 0 ? "- " + cs.substring(1) : c == 0 ? "" : "+ " + cs; // Code for y-intercept string.

        return "y = " + af + bf + cf;
    }

    void listEquation(String s) { // Adds the equation to the side-bar.

        JLabel label = new JLabel(s);
        JPanel lineButton = new JPanel();

        lineButton.setMaximumSize(new Dimension(frame.getWidth(), 30)); // Makes the different panels stack over each other.
        lineButton.add(BorderLayout.EAST, label);
        lines.add(BorderLayout.SOUTH, lineButton);
        splitPane.resetToPreferredSizes();
    }

    public void actionPerformed(ActionEvent ae) {
        try { // Take in a, b & c from text boxes.
            if(!(fa.getText().equals("") && fb.getText().equals("") && fc.getText().equals(""))) { // Don't draw a line if all 3 boxes are empty.

                String[] sabc = { fa.getText(), fb.getText(), fc.getText() };
                double[] abc = new double[3];

                for(int i = 0; i < sabc.length; i++) {

                    abc[i] = (sabc[i].equals("") ? 0 : Double.parseDouble(sabc[i]));
                }

                line = new Line(abc[0], abc[1], abc[2], unit, sHeight, sWidth);
                listEquation(toEquation()); // Add equation to the side-bar.
                ay.add(line); // Add line to the array.
            }
        } catch (Exception ex) {} // Does nothing if a, b or c aren't numbers.

        frame.repaint();
    }

    class MyDrawPanel extends JPanel { // Draws the graph.

        private static final long serialVersionUID = 6193278998208292577L;

        public void paintComponent(Graphics g) {

            Graphics2D g2d = (Graphics2D) g;

            for(int i = 0; i <= sWidth; i += unit) { // Draws grid.

                g2d.drawLine(i, 0, i, sHeight);
                g2d.drawLine(0, i, sWidth, i);
            }

            int h = ((int) ((frame.getHeight() - cofs.getHeight()) / unit / 2)) * unit; // Gives values for height and width based on the unit.
            int w = ((int) ((frame.getWidth() - lines.getWidth()) / unit / 2)) * unit;
            g2d.fillRect(0, h - 1, w * sWidth, 3); // Draws x-axis.
            g2d.fillRect(w - 1, 0, 3, h * sHeight); // Draws y-axis.

            g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); // Makes the curve nice and smooth.

            for(int i = 0, ays = ay.size(); i < ays; i++) {

                Line l = ay.get(i);
                g2d.setColor(l.getColor());
                g2d.setStroke(new BasicStroke(l.getThickness())); // Sets thickness of parabola.

                for(int j = 1, size = l.getCoords().size(); j < size; j++) { // Draws a line from point to point.

                    g2d.drawLine(w + (int) Math.round(unit * l.getCoords().get(j - 1)[0]), h - (int) Math.round(unit * l.getCoords().get(j - 1)[1]), w + (int) Math.round(unit * l.getCoords().get(j)[0]), h - (int) Math.round(unit * l.getCoords().get(j)[1])); // Draws line from dot to dot.
                }
            }
        }
    }
}



package realApps;

import java.awt.Color;
import java.util.ArrayList;

final public class Line {

    private double a, b, c;
    private Color lineColor;
    private int thickness, unit, sHeight, sWidth;
    private double vX, vY;
    private ArrayList<double[]> cords = new ArrayList<double[]>();

    public Line(double tA, double tB, double tC, Color color, int thick, int nUnit, int height, int width) {

        a = tA;
        b = tB;
        c = tC;
        lineColor = color;
        thickness = thick;
        unit = nUnit;
        sHeight = height;
        sWidth = width;
        setVertex();
        setCoords();
    }

    public Line(double tA, double tB, double tC, int nUnit, int height, int width) {

        a = tA;
        b = tB;
        c = tC;
        lineColor = Color.blue;
        thickness = 2;
        unit = nUnit;
        sHeight = height;
        sWidth = width;
        setVertex();
        setCoords();
    }

    double getA() {

        return a;
    }
    void setA(double tA) {

        a = tA;
    }

    double getB() {

        return b;
    }
    void setB(double tB) {

        b = tB;
    }

    double getC() {

        return c;
    }
    void setC(double tC) {

        c = tC;
    }

    Color getColor() {

        return lineColor;
    }
    void setColor(Color cl) {

        lineColor = cl;
    }

    int getThickness() {

        return thickness;
    }
    void setThickness(int nThickness) {

        thickness = nThickness;
    }

    String getVertexAsString() {

        return "(" + vX + ", " + vY + ")";
    }

    double[] getVertex() {

        return new double[] {vX, vY};
    }

    private void setVertex() {

        vX = -(b/a/2);
        vY = c - a * Math.pow((b/a/2), 2);
    }

    void setCoords() {

        double px, nx, y;

        if(!(a == 0 && b == 0)) {
            for(int i = 0; true; i++) {

                y = a * i * i + b * i + c;
                if(y > sHeight / unit) {
                    px = i;
                    break;
                }
            }

            for(int i = 0; true; i--) {

                y = a * i * i + b * i + c;
                if(y > sHeight / unit) {
                    nx = i;
                    break;
                }
            }

            for(double i = nx; i < 0; i += 0.1) {

                y = a * i * i + b * i + c;
                cords.add(new double[] {i, y});

            }

            for(double i = 0; i < px; i += 0.1) {

                y = a * i * i + b * i + c;
                cords.add(new double[] {i, y});
            }
        } else {

            cords.add(new double[] {-sWidth, c});
            cords.add(new double[] {sWidth, c});
        }
    }

    ArrayList<double[]> getCoords() {

        return cords;
    }
}