package zhuye;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Stroke;
import java.awt.geom.Path2D;
import java.awt.geom.Point2D;

/**
 * 割草机拖尾绘制工具类。
 */
public final class tuowei {
    private static final Color TRAIL_COLOR = new Color(30, 144, 255, 220);

    private tuowei() {
        // 工具类无需实例化
    }

    /**
     * 绘制拖尾路径。
     *
     * @param g2d     画笔对象
     * @param samples 拖尾采样点集合
     * @param scale   当前缩放比例
     */
    public static void draw(Graphics2D g2d, Iterable<TrailSample> samples, double scale) {
        if (g2d == null || samples == null) {
            return;
        }

        Path2D.Double path = new Path2D.Double();
        boolean started = false;
        for (TrailSample sample : samples) {
            if (sample == null) {
                continue;
            }
            Point2D.Double point = sample.getPoint();
            if (point == null || !Double.isFinite(point.x) || !Double.isFinite(point.y)) {
                continue;
            }
            if (!started) {
                path.moveTo(point.x, point.y);
                started = true;
            } else {
                path.lineTo(point.x, point.y);
            }
        }

        if (!started) {
            return;
        }

        Stroke originalStroke = g2d.getStroke();
        Color originalColor = g2d.getColor();

        float strokeWidth = (float) Math.max(0.08f, 1.4f / (float) Math.max(scale, 0.2));
        g2d.setStroke(new BasicStroke(strokeWidth, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND));
        g2d.setColor(TRAIL_COLOR);
        g2d.draw(path);

        g2d.setStroke(originalStroke);
        g2d.setColor(originalColor);
    }

    /**
     * 拖尾采样点。
     */
    public static final class TrailSample {
        private final long timestamp;
        private final Point2D.Double point;

        public TrailSample(long timestamp, Point2D.Double point) {
            this.timestamp = timestamp;
            this.point = point;
        }

        public long getTimestamp() {
            return timestamp;
        }

        public Point2D.Double getPoint() {
            return point;
        }
    }
}