package com.whyc.util;

import com.whyc.dto.Point;

public class PointUtil {
    public static void main(String[] args) {
        double a1 = 1, b1 = 2;
        double a2 = 3, b2 = 4;
        double x0 = 9, y0 = 9;
        Point p1 = new Point(1, 2);
        Point p2 = new Point(3, 4);
        Point p0 = new Point(9, 9);

        Point p = findIntersection2(p1, p2, p0);
        System.out.println(p);

        double[] p3 = findIntersection(a1, b1, a2, b2, x0, y0);
        System.out.println("Intersection Point P3: (" + p3[0] + ", " + p3[1] + ")");

        String position = determinePosition(a1, b1, a2, b2, x0, y0);
        System.out.println("Point P is on the " + position + " of the line P1P2.");
    }

    public static double[] findIntersection(double a1, double b1, double a2, double b2, double x0, double y0) {
        // 检查 p1p2 是否为垂直线
        if (a2 == a1) {
            return new double[]{a1, y0};
        }

        // 检查 p1p2 是否为水平线
        if (b2 == b1) {
            return new double[]{x0, b1};
        }
        double m = (b2 - b1) / (a2 - a1);
        double mPerpendicular = (a1 - a2) / (b2 - b1);

        double x = ((b1 - m * a1) - (y0 - mPerpendicular * x0)) / (mPerpendicular - m);
        double y = m * x + (b1 - m * a1);

        return new double[]{x, y};
    }

    public static Point findIntersection2(Point p1, Point p2, Point p0) {
        // 检查 p1p2 是否为垂直线
        int a1 = p1.getX();
        int b1 = p1.getY();

        int a2 = p2.getX();
        int b2 = p2.getY();

        int x0 = p0.getX();
        int y0 = p0.getY();

        if (a2 == a1) {
            return new Point(a1, y0);
        }

        // 检查 p1p2 是否为水平线
        if (b2 == b1) {
            return new Point(x0, b1);
        }
        double m = (b2 - b1) / (a2 - a1);
        double mPerpendicular = (a1 - a2) / (b2 - b1);

        double x = ((b1 - m * a1) - (y0 - mPerpendicular * x0)) / (mPerpendicular - m);
        double y = m * x + (b1 - m * a1);

        return new Point((int) x, (int) y);
    }
    public static String determinePosition(double a1, double b1, double a2, double b2, double x0, double y0) {
        double cross = (a2 - a1) * (y0 - b1) - (x0 - a1) * (b2 - b1);
        if (cross > 0) {
            return "left";
        } else if (cross < 0) {
            return "right";
        } else {
            return "line";
        }
    }
}