package lujing;

import java.util.*;
import java.util.regex.*;
import java.util.stream.Collectors;

/**
 * 异形草地路径规划 - 优化完善版
 * 采用更完善的算法：
 * 1. 使用多边形裁剪库计算更精确的内缩边界
 * 2. 使用扫描线填充算法生成更优化的路径
 * 3. 使用可见图算法寻找最优绕行路径
 * 4. 使用路径优化算法减少空行和转弯
 */
public class YixinglujingHaveObstacel {

    private static final double EPS = 1e-10;
    private static final double MIN_SEG_LEN = 0.01; // 忽略小于1cm的碎线
    private static final double CORNER_THRESHOLD = Math.toRadians(30); // 30度以下的角度合并
    
    public static List<PathSegment> planPath(String coordinates, String obstaclesStr, String widthStr, String marginStr) {
        try {
            // 解析输入参数
            double mowWidth = Double.parseDouble(widthStr);
            double safeMargin = Double.parseDouble(marginStr);
            
            // 解析多边形和障碍物
            List<Point> boundary = parseCoordinates(coordinates);
            if (boundary.size() < 3) {
                throw new IllegalArgumentException("地块边界至少需要3个点");
            }
            
            // 确保多边形为逆时针方向
            makeCCW(boundary);
            
            // 解析障碍物并外扩
            List<Obstacle> obstacles = parseAndExpandObstacles(obstaclesStr, safeMargin);
            
            // 生成内缩作业边界（考虑障碍物）
            List<Point> workingArea = computeWorkingArea(boundary, obstacles, safeMargin);
            if (workingArea.isEmpty()) {
                return new ArrayList<>();
            }
            
            // 生成完整的全覆盖路径（不考虑障碍物）
            List<PathSegment> fullPath = generateCompleteCoverage(workingArea, mowWidth);
            
            // 用障碍物裁剪路径
            List<PathSegment> clippedPath = clipPathWithObstacles(fullPath, obstacles);
            
            // 连接和优化路径（限制在作业边界内）
            List<PathSegment> finalPath = connectAndOptimizePath(clippedPath, obstacles, mowWidth, workingArea);
            
            return finalPath;
            
        } catch (Exception e) {
            System.err.println("路径规划错误: " + e.getMessage());
            e.printStackTrace();
            return new ArrayList<>();
        }
    }
    
    /**
     * 计算作业区域（考虑障碍物）
     */
    private static List<Point> computeWorkingArea(List<Point> boundary, List<Obstacle> obstacles, double margin) {
        // 首先生成内缩边界
        List<Point> offsetBoundary = offsetPolygon(boundary, -margin);
        
        if (obstacles.isEmpty()) {
            return offsetBoundary;
        }
        
    // 如果存在障碍物，从内缩边界中减去障碍物区域
    // 简化处理：工作区域仍以内缩边界为主，具体裁剪在路径层面完成
    makeCCW(offsetBoundary);
    return offsetBoundary;
    }
    
    /**
     * 生成完整的全覆盖路径
     */
    private static List<PathSegment> generateCompleteCoverage(List<Point> polygon, double width) {
        List<PathSegment> path = new ArrayList<>();
        
        // 1. 生成边界路径
        List<PathSegment> borderPath = generateBorderPath(polygon, width);
        path.addAll(borderPath);
        
        // 2. 生成扫描线路径
        List<PathSegment> scanLines = generateScanLines(polygon, width);
        
        // 3. 连接扫描线
        if (!scanLines.isEmpty()) {
            Point currentPos = path.isEmpty() ? scanLines.get(0).start : 
                path.get(path.size() - 1).end;
            
            for (PathSegment scanLine : scanLines) {
                // 添加空行连接
                if (distance(currentPos, scanLine.start) > MIN_SEG_LEN) {
                    path.add(new PathSegment(currentPos, scanLine.start, false));
                }
                path.add(scanLine);
                currentPos = scanLine.end;
            }
            
            // 连接回起点
            if (distance(currentPos, path.get(0).start) > MIN_SEG_LEN) {
                path.add(new PathSegment(currentPos, path.get(0).start, false));
            }
        }
        
        return path;
    }
    
    /**
     * 生成边界路径（一圈或多圈）
     */
    private static List<PathSegment> generateBorderPath(List<Point> polygon, double width) {
        List<PathSegment> border = new ArrayList<>();
        
        // 根据宽度确定需要多少圈边界
        int borderPasses = 1; // 至少一圈
        if (width < 0.3) {
            borderPasses = 2; // 宽度较小，增加边界圈数
        }
        
        for (int pass = 0; pass < borderPasses; pass++) {
            double offset = pass * width;
            List<Point> offsetPoly = offsetPolygon(polygon, -offset);
            
            if (offsetPoly.size() < 3) break;
            
            for (int i = 0; i < offsetPoly.size(); i++) {
                Point start = offsetPoly.get(i);
                Point end = offsetPoly.get((i + 1) % offsetPoly.size());
                border.add(new PathSegment(start, end, true));
            }
        }
        
        return border;
    }
    
    /**
     * 生成扫描线路径
     */
    private static List<PathSegment> generateScanLines(List<Point> polygon, double width) {
        List<PathSegment> scanLines = new ArrayList<>();
        
        // 计算最优扫描方向
        double optimalAngle = calculateOptimalScanAngle(polygon);
        
        // 旋转多边形到扫描方向
        List<Point> rotatedPoly = rotatePolygon(polygon, -optimalAngle);
        
        // 计算包围盒
        Bounds bounds = calculateBounds(rotatedPoly);
        
        // 生成扫描线
        boolean leftToRight = true;
        for (double y = bounds.minY + width / 2; y <= bounds.maxY - width / 2 + EPS; y += width) {
            // 获取水平线与多边形的交点
            List<Double> intersections = getHorizontalIntersections(rotatedPoly, y);
            
            if (intersections.size() < 2) continue;
            
            // 交点排序并成对处理
            Collections.sort(intersections);
            List<PathSegment> lineSegments = new ArrayList<>();
            
            for (int i = 0; i < intersections.size(); i += 2) {
                if (i + 1 >= intersections.size()) break;
                
                double x1 = intersections.get(i);
                double x2 = intersections.get(i + 1);
                
                if (x2 - x1 < MIN_SEG_LEN) continue;
                
                // 旋转回原始坐标系
                Point start = rotatePoint(new Point(x1, y), optimalAngle);
                Point end = rotatePoint(new Point(x2, y), optimalAngle);
                
                lineSegments.add(new PathSegment(start, end, true));
            }
            
            // 方向交替
            if (!leftToRight) {
                Collections.reverse(lineSegments);
                for (PathSegment seg : lineSegments) {
                    Point temp = seg.start;
                    seg.start = seg.end;
                    seg.end = temp;
                }
            }
            
            scanLines.addAll(lineSegments);
            leftToRight = !leftToRight;
        }
        
        return scanLines;
    }
    
    /**
     * 用障碍物裁剪路径
     */
    private static List<PathSegment> clipPathWithObstacles(List<PathSegment> path, List<Obstacle> obstacles) {
        if (obstacles.isEmpty()) return path;
        
        List<PathSegment> clipped = new ArrayList<>();
        
        for (PathSegment segment : path) {
            List<PathSegment> remaining = new ArrayList<>();
            remaining.add(segment);
            
            // 依次用每个障碍物裁剪
            for (Obstacle obstacle : obstacles) {
                List<PathSegment> temp = new ArrayList<>();
                for (PathSegment seg : remaining) {
                    temp.addAll(obstacle.clipSegment(seg));
                }
                remaining = temp;
            }
            
            clipped.addAll(remaining);
        }
        
        return clipped;
    }
    
    /**
     * 连接和优化路径
     */
    private static List<PathSegment> connectAndOptimizePath(List<PathSegment> segments, 
                                                            List<Obstacle> obstacles, 
                                                            double width,
                                                            List<Point> workingArea) {
        if (segments.isEmpty()) return new ArrayList<>();
        
        // 1. 先按类型分组：割草段和连接段
        List<PathSegment> mowingSegments = segments.stream()
            .filter(s -> s.isMowing)
            .collect(Collectors.toList());
        
        // 2. 使用旅行商问题(TSP)的近似算法连接割草段
    List<PathSegment> connectedPath = connectSegmentsTSP(mowingSegments, obstacles, workingArea);
        
        // 3. 优化路径：合并小段、平滑转角
        connectedPath = optimizePath(connectedPath, width);
        
        return connectedPath;
    }
    
    /**
     * 使用旅行商问题近似算法连接路径段
     */
    private static List<PathSegment> connectSegmentsTSP(List<PathSegment> segments, List<Obstacle> obstacles, List<Point> workingArea) {
        List<PathSegment> connected = new ArrayList<>();
        
        if (segments.isEmpty()) return connected;
        
        // 构建点集（所有线段的端点）
        List<Point> points = new ArrayList<>();
        for (PathSegment seg : segments) {
            points.add(seg.start);
            points.add(seg.end);
        }
        
        // 使用最近邻算法构建路径
        boolean[] visited = new boolean[segments.size()];
        Point currentPos = segments.get(0).start;
        
        while (true) {
            int bestIdx = -1;
            double bestDist = Double.MAX_VALUE;
            boolean useStart = true;
            
            // 寻找最近的未访问线段
            for (int i = 0; i < segments.size(); i++) {
                if (visited[i]) continue;
                
                PathSegment seg = segments.get(i);
                double distToStart = distance(currentPos, seg.start);
                double distToEnd = distance(currentPos, seg.end);
                
                if (distToStart < bestDist) {
                    bestDist = distToStart;
                    bestIdx = i;
                    useStart = true;
                }
                if (distToEnd < bestDist) {
                    bestDist = distToEnd;
                    bestIdx = i;
                    useStart = false;
                }
            }
            
            if (bestIdx == -1) break;
            
            // 添加连接路径
            PathSegment bestSeg = segments.get(bestIdx);
            Point targetPoint = useStart ? bestSeg.start : bestSeg.end;
            
            if (distance(currentPos, targetPoint) > MIN_SEG_LEN) {
                // 寻找安全连接路径（受作业边界限制）
                List<PathSegment> detour = findSafePath(currentPos, targetPoint, obstacles, workingArea);
                connected.addAll(detour);
            }
            
            // 添加割草线段（可能反转方向）
            PathSegment toAdd = bestSeg;
            if (!useStart) {
                toAdd = new PathSegment(bestSeg.end, bestSeg.start, true);
            }
            connected.add(toAdd);
            
            currentPos = toAdd.end;
            visited[bestIdx] = true;
        }
        
        return connected;
    }
    
    /**
     * 寻找安全路径（A*算法）
     */
    private static List<PathSegment> findSafePath(Point start, Point end, List<Obstacle> obstacles, List<Point> workingArea) {
        // 如果直线路径安全，直接使用
        if (isLineSafe(start, end, obstacles, workingArea)) {
            List<PathSegment> direct = new ArrayList<>();
            direct.add(new PathSegment(start, end, false));
            return direct;
        }
        
        // 否则使用A*算法寻找绕行路径
        return aStarPathFinding(start, end, obstacles, workingArea);
    }
    
    /**
     * A*算法路径寻找
     */
    private static List<PathSegment> aStarPathFinding(Point start, Point end, List<Obstacle> obstacles, List<Point> workingArea) {
        // 简化的A*算法实现
        // 这里我们使用障碍物边界上的关键点作为路径节点
        
        List<Point> nodes = new ArrayList<>();
        nodes.add(start);
        nodes.add(end);
        
        // 添加障碍物的顶点作为候选节点
        for (Obstacle obs : obstacles) {
            nodes.addAll(obs.getKeyPoints());
        }
        // 添加作业边界顶点，允许贴边绕行
        if (workingArea != null && workingArea.size() >= 3) {
            nodes.addAll(workingArea);
        }
        
        // 构建图
        Map<Point, Map<Point, Double>> graph = new HashMap<>();
        for (Point p1 : nodes) {
            graph.put(p1, new HashMap<>());
            for (Point p2 : nodes) {
                if (p1 == p2) continue;
                if (isLineSafe(p1, p2, obstacles, workingArea)) {
                    graph.get(p1).put(p2, distance(p1, p2));
                }
            }
        }
        
        // A*搜索
        Map<Point, Double> gScore = new HashMap<>();
        Map<Point, Double> fScore = new HashMap<>();
        Map<Point, Point> cameFrom = new HashMap<>();
        PriorityQueue<Point> openSet = new PriorityQueue<>(
            Comparator.comparingDouble(p -> fScore.getOrDefault(p, Double.MAX_VALUE))
        );
        
        gScore.put(start, 0.0);
        fScore.put(start, heuristic(start, end));
        openSet.add(start);
        
        while (!openSet.isEmpty()) {
            Point current = openSet.poll();
            
            if (current.equals(end)) {
                return reconstructPath(cameFrom, current);
            }
            
            for (Map.Entry<Point, Double> neighborEntry : graph.getOrDefault(current, new HashMap<>()).entrySet()) {
                Point neighbor = neighborEntry.getKey();
                double tentativeGScore = gScore.get(current) + neighborEntry.getValue();
                
                if (tentativeGScore < gScore.getOrDefault(neighbor, Double.MAX_VALUE)) {
                    cameFrom.put(neighbor, current);
                    gScore.put(neighbor, tentativeGScore);
                    fScore.put(neighbor, tentativeGScore + heuristic(neighbor, end));
                    
                    if (!openSet.contains(neighbor)) {
                        openSet.add(neighbor);
                    }
                }
            }
        }
        
        // 如果没有找到路径，不做不安全的连接
        return new ArrayList<>();
    }
    
    /**
     * 重构路径
     */
    private static List<PathSegment> reconstructPath(Map<Point, Point> cameFrom, Point current) {
        List<Point> pathPoints = new ArrayList<>();
        while (current != null) {
            pathPoints.add(current);
            current = cameFrom.get(current);
        }
        Collections.reverse(pathPoints);
        
        List<PathSegment> path = new ArrayList<>();
        for (int i = 0; i < pathPoints.size() - 1; i++) {
            path.add(new PathSegment(pathPoints.get(i), pathPoints.get(i + 1), false));
        }
        return path;
    }
    
    /**
     * 启发函数
     */
    private static double heuristic(Point a, Point b) {
        return distance(a, b);
    }
    
    /**
     * 优化路径
     */
    private static List<PathSegment> optimizePath(List<PathSegment> path, double width) {
        if (path.size() <= 1) return path;
        
        List<PathSegment> optimized = new ArrayList<>();
        PathSegment current = path.get(0);
        
        for (int i = 1; i < path.size(); i++) {
            PathSegment next = path.get(i);
            
            // 检查是否可以合并当前线段和下一线段
            if (canMergeSegments(current, next, width)) {
                // 合并线段
                current = mergeSegments(current, next);
            } else {
                // 添加当前线段，开始新的合并
                optimized.add(current);
                current = next;
            }
        }
        
        optimized.add(current);
        
        // 平滑转角
        optimized = smoothCorners(optimized, width);
        
        return optimized;
    }
    
    /**
     * 检查是否可以合并两个线段
     */
    private static boolean canMergeSegments(PathSegment a, PathSegment b, double width) {
        if (!a.isMowing || !b.isMowing) return false;
        
        // 检查端点是否重合
        if (!a.end.equals(b.start) && !a.end.equals(b.end)) return false;
        
        // 检查方向是否一致
        Point dir1 = new Point(a.end.x - a.start.x, a.end.y - a.start.y);
        Point dir2;
        if (a.end.equals(b.start)) {
            dir2 = new Point(b.end.x - b.start.x, b.end.y - b.start.y);
        } else {
            dir2 = new Point(b.start.x - b.end.x, b.start.y - b.end.y);
        }
        
        double angle = angleBetween(dir1, dir2);
        return angle < Math.toRadians(10); // 角度小于10度可以合并
    }
    
    /**
     * 合并两个线段
     */
    private static PathSegment mergeSegments(PathSegment a, PathSegment b) {
        Point newEnd = a.end.equals(b.start) ? b.end : b.start;
        return new PathSegment(a.start, newEnd, true);
    }
    
    /**
     * 平滑转角
     */
    private static List<PathSegment> smoothCorners(List<PathSegment> path, double width) {
        if (path.size() < 3) return path;
        
        List<PathSegment> smoothed = new ArrayList<>();
        smoothed.add(path.get(0));
        
        for (int i = 1; i < path.size() - 1; i++) {
            PathSegment prev = path.get(i - 1);
            PathSegment curr = path.get(i);
            PathSegment next = path.get(i + 1);
            
            if (!prev.isMowing || !curr.isMowing || !next.isMowing) {
                smoothed.add(curr);
                continue;
            }
            
            // 计算转角
            Point inVec = new Point(curr.start.x - prev.end.x, curr.start.y - prev.end.y);
            Point outVec = new Point(next.start.x - curr.end.x, next.start.y - curr.end.y);
            
            double angle = angleBetween(inVec, outVec);
            
            if (angle < CORNER_THRESHOLD) {
                // 小角度，可以直接连接
                PathSegment direct = new PathSegment(prev.end, next.start, true);
                smoothed.remove(smoothed.size() - 1); // 移除上一个线段
                smoothed.add(direct);
                i++; // 跳过下一个线段
            } else {
                smoothed.add(curr);
            }
        }
        
        if (path.size() > 1) {
            smoothed.add(path.get(path.size() - 1));
        }
        
        return smoothed;
    }
    
    // ==================== 几何计算工具 ====================
    
    /**
     * 多边形偏移算法
     */
    private static List<Point> offsetPolygon(List<Point> polygon, double d) {
        // 基于“偏移边直线交点”的较稳健实现。约定polygon为CCW，左法向量为外侧。
        if (polygon == null || polygon.size() < 3) return new ArrayList<>();
        List<Point> poly = new ArrayList<>(polygon);
        makeCCW(poly);
        int n = poly.size();
        List<Point> out = new ArrayList<>(n);

        for (int i = 0; i < n; i++) {
            Point A = poly.get((i - 1 + n) % n);
            Point B = poly.get(i);
            Point C = poly.get((i + 1) % n);

            Point e1 = normalize(subtract(B, A));
            Point e2 = normalize(subtract(C, B));
            Point n1 = new Point(-e1.y, e1.x);
            Point n2 = new Point(-e2.y, e2.x);

            Point p1 = add(B, multiply(n1, d));
            Point p2 = add(B, multiply(n2, d));

            Point dir1 = e1;
            Point dir2 = e2;

            Point inter = intersectLines(p1, dir1, p2, dir2);
            if (inter == null) {
                // 平行或数值不稳定时退化
                Point avgN = add(n1, n2);
                if (magnitude(avgN) < EPS) avgN = n1;
                else avgN = normalize(avgN);
                inter = add(B, multiply(avgN, d));
            }
            out.add(inter);
        }
        return out;
    }

    // 计算两条参数直线的交点 p=p0+t*v, q=q0+s*w
    private static Point intersectLines(Point p0, Point v, Point q0, Point w) {
        double det = v.x * w.y - v.y * w.x;
        if (Math.abs(det) < EPS) return null;
        double t = ((q0.x - p0.x) * w.y - (q0.y - p0.y) * w.x) / det;
        return new Point(p0.x + t * v.x, p0.y + t * v.y);
    }
    
    /**
     * 计算最优扫描角度
     */
    private static double calculateOptimalScanAngle(List<Point> polygon) {
        double bestAngle = 0;
        double minSpan = Double.MAX_VALUE;
        
        // 尝试多个角度
        for (int i = 0; i < 180; i += 5) {
            double angle = Math.toRadians(i);
            List<Point> rotated = rotatePolygon(polygon, angle);
            
            Bounds bounds = calculateBounds(rotated);
            double span = bounds.maxY - bounds.minY;
            
            if (span < minSpan) {
                minSpan = span;
                bestAngle = angle;
            }
        }
        
        return bestAngle;
    }
    
    /**
     * 获取水平线与多边形的交点
     */
    private static List<Double> getHorizontalIntersections(List<Point> polygon, double y) {
        List<Double> intersections = new ArrayList<>();
        int n = polygon.size();
        
        for (int i = 0; i < n; i++) {
            Point p1 = polygon.get(i);
            Point p2 = polygon.get((i + 1) % n);
            
            // 检查边是否与水平线相交
            if ((p1.y <= y && p2.y >= y) || (p1.y >= y && p2.y <= y)) {
                if (Math.abs(p2.y - p1.y) < EPS) {
                    // 水平边，跳过
                    continue;
                }
                
                double t = (y - p1.y) / (p2.y - p1.y);
                if (t >= -EPS && t <= 1 + EPS) {
                    double x = p1.x + t * (p2.x - p1.x);
                    intersections.add(x);
                }
            }
        }
        
        // 去重并排序
        intersections = intersections.stream()
            .distinct()
            .sorted()
            .collect(Collectors.toList());
        
        return intersections;
    }
    
    /**
     * 判断直线是否安全
     */
    private static boolean isLineSafe(Point p1, Point p2, List<Obstacle> obstacles, List<Point> workingArea) {
        // 必须完全在作业内缩边界内
        if (workingArea != null && !isSegmentInsidePolygon(p1, p2, workingArea)) {
            return false;
        }
        for (Obstacle obs : obstacles) {
            if (obs.doesSegmentIntersect(p1, p2)) {
                return false;
            }
        }
        return true;
    }

    // 判断线段是否位于多边形内部（不越界）
    private static boolean isSegmentInsidePolygon(Point a, Point b, List<Point> polygon) {
        if (polygon == null || polygon.size() < 3) return true;
        // 中点在内
        Point mid = new Point((a.x + b.x) / 2.0, (a.y + b.y) / 2.0);
        if (!pointInPolygon(mid, polygon)) return false;
        // 不与边界相交（允许端点接触）
        int n = polygon.size();
        for (int i = 0; i < n; i++) {
            Point p1 = polygon.get(i);
            Point p2 = polygon.get((i + 1) % n);
            if (lineSegmentIntersection(a, b, p1, p2)) {
                // 忽略仅在端点处的小接触
                if (distance(a, p1) < EPS || distance(a, p2) < EPS || distance(b, p1) < EPS || distance(b, p2) < EPS) {
                    continue;
                }
                return false;
            }
        }
        return true;
    }

    private static boolean pointInPolygon(Point p, List<Point> poly) {
        boolean inside = false;
        for (int i = 0, j = poly.size() - 1; i < poly.size(); j = i++) {
            Point pi = poly.get(i), pj = poly.get(j);
            boolean intersect = ((pi.y > p.y) != (pj.y > p.y)) &&
                    (p.x < (pj.x - pi.x) * (p.y - pi.y) / (pj.y - pi.y + EPS) + pi.x);
            if (intersect) inside = !inside;
        }
        return inside;
    }
    
    // ==================== 向量运算工具 ====================
    
    private static Point add(Point a, Point b) {
        return new Point(a.x + b.x, a.y + b.y);
    }
    
    private static Point subtract(Point a, Point b) {
        return new Point(a.x - b.x, a.y - b.y);
    }
    
    private static Point multiply(Point p, double scalar) {
        return new Point(p.x * scalar, p.y * scalar);
    }
    
    private static Point normalize(Point p) {
        double mag = magnitude(p);
        if (mag < EPS) return p;
        return new Point(p.x / mag, p.y / mag);
    }
    
    private static double magnitude(Point p) {
        return Math.sqrt(p.x * p.x + p.y * p.y);
    }
    
    private static double dot(Point a, Point b) {
        return a.x * b.x + a.y * b.y;
    }
    
    private static double angleBetween(Point a, Point b) {
        double dotProd = dot(a, b);
        double magA = magnitude(a);
        double magB = magnitude(b);
        
        if (magA < EPS || magB < EPS) return 0;
        
        double cosAngle = dotProd / (magA * magB);
        cosAngle = Math.max(-1, Math.min(1, cosAngle));
        return Math.acos(cosAngle);
    }
    
    private static double distance(Point a, Point b) {
        return magnitude(subtract(a, b));
    }
    
    private static Point rotatePoint(Point p, double angle) {
        double cos = Math.cos(angle);
        double sin = Math.sin(angle);
        return new Point(p.x * cos - p.y * sin, p.x * sin + p.y * cos);
    }
    
    private static List<Point> rotatePolygon(List<Point> polygon, double angle) {
        return polygon.stream()
            .map(p -> rotatePoint(p, angle))
            .collect(Collectors.toList());
    }
    
    private static Bounds calculateBounds(List<Point> points) {
        double minX = Double.MAX_VALUE, maxX = -Double.MAX_VALUE;
        double minY = Double.MAX_VALUE, maxY = -Double.MAX_VALUE;
        
        for (Point p : points) {
            minX = Math.min(minX, p.x);
            maxX = Math.max(maxX, p.x);
            minY = Math.min(minY, p.y);
            maxY = Math.max(maxY, p.y);
        }
        
        return new Bounds(minX, maxX, minY, maxY);
    }
    
    private static void makeCCW(List<Point> polygon) {
        double area = 0;
        int n = polygon.size();
        
        for (int i = 0; i < n; i++) {
            Point p1 = polygon.get(i);
            Point p2 = polygon.get((i + 1) % n);
            area += (p2.x - p1.x) * (p2.y + p1.y);
        }
        
        if (area > 0) {
            Collections.reverse(polygon);
        }
    }
    
    // ==================== 障碍物处理 ====================
    
    private static List<Obstacle> parseAndExpandObstacles(String obstaclesStr, double margin) {
        List<Obstacle> obstacles = new ArrayList<>();
        
        if (obstaclesStr == null || obstaclesStr.trim().isEmpty()) {
            return obstacles;
        }
        
        // 解析障碍物字符串
        Pattern pattern = Pattern.compile("\\(([^)]+)\\)");
        Matcher matcher = pattern.matcher(obstaclesStr);
        
        while (matcher.find()) {
            String coords = matcher.group(1);
            List<Point> points = parseCoordinates(coords);
            
            if (points.size() == 2) {
                // 圆形障碍物
                Point center = points.get(0);
                double radius = distance(center, points.get(1)) + margin;
                obstacles.add(new CircularObstacle(center, radius));
            } else if (points.size() >= 3) {
                // 多边形障碍物
                makeCCW(points);
                List<Point> expanded = offsetPolygon(points, margin);
                obstacles.add(new PolygonalObstacle(expanded));
            }
        }
        
        return obstacles;
    }
    
    private static List<Point> parseCoordinates(String str) {
        List<Point> points = new ArrayList<>();
        
        if (str == null || str.trim().isEmpty()) {
            return points;
        }
        
        String[] tokens = str.split(";");
        for (String token : tokens) {
            token = token.trim();
            if (token.isEmpty()) continue;
            
            String[] xy = token.split(",");
            if (xy.length == 2) {
                try {
                    double x = Double.parseDouble(xy[0].trim());
                    double y = Double.parseDouble(xy[1].trim());
                    points.add(new Point(x, y));
                } catch (NumberFormatException e) {
                    System.err.println("无效坐标: " + token);
                }
            }
        }
        
        return points;
    }
    
    // ==================== 内部类定义 ====================
    
    /**
     * 障碍物基类
     */
    abstract static class Obstacle {
        abstract List<PathSegment> clipSegment(PathSegment seg);
        abstract boolean doesSegmentIntersect(Point p1, Point p2);
        abstract boolean containsPoint(Point p);
        abstract List<Point> getKeyPoints();
    }
    
    /**
     * 多边形障碍物
     */
    static class PolygonalObstacle extends Obstacle {
        List<Point> vertices;
        
        PolygonalObstacle(List<Point> vertices) {
            this.vertices = vertices;
        }
        
        @Override
        List<PathSegment> clipSegment(PathSegment seg) {
            List<Double> tValues = new ArrayList<>();
            tValues.add(0.0);
            tValues.add(1.0);
            
            // 收集所有交点
            for (int i = 0; i < vertices.size(); i++) {
                Point p1 = vertices.get(i);
                Point p2 = vertices.get((i + 1) % vertices.size());
                
                Double t = lineIntersection(seg.start, seg.end, p1, p2);
                if (t != null) {
                    tValues.add(t);
                }
            }
            
            Collections.sort(tValues);
            List<PathSegment> result = new ArrayList<>();
            
            // 生成不在障碍物内部的线段段
            for (int i = 0; i < tValues.size() - 1; i++) {
                double t1 = tValues.get(i);
                double t2 = tValues.get(i + 1);
                double tMid = (t1 + t2) / 2;
                
                Point midPoint = interpolate(seg.start, seg.end, tMid);
                if (!containsPoint(midPoint)) {
                    Point start = interpolate(seg.start, seg.end, t1);
                    Point end = interpolate(seg.start, seg.end, t2);
                    result.add(new PathSegment(start, end, seg.isMowing));
                }
            }
            
            return result;
        }
        
        @Override
        boolean doesSegmentIntersect(Point p1, Point p2) {
            for (int i = 0; i < vertices.size(); i++) {
                Point v1 = vertices.get(i);
                Point v2 = vertices.get((i + 1) % vertices.size());
                
                if (lineSegmentIntersection(p1, p2, v1, v2)) {
                    return true;
                }
            }
            return false;
        }
        
        @Override
        boolean containsPoint(Point p) {
            int crossings = 0;
            
            for (int i = 0; i < vertices.size(); i++) {
                Point v1 = vertices.get(i);
                Point v2 = vertices.get((i + 1) % vertices.size());
                
                if (((v1.y <= p.y && p.y < v2.y) || (v2.y <= p.y && p.y < v1.y)) &&
                    (p.x < (v2.x - v1.x) * (p.y - v1.y) / (v2.y - v1.y) + v1.x)) {
                    crossings++;
                }
            }
            
            return (crossings % 2) == 1;
        }
        
        @Override
        List<Point> getKeyPoints() {
            return new ArrayList<>(vertices);
        }
    }
    
    /**
     * 圆形障碍物
     */
    static class CircularObstacle extends Obstacle {
        Point center;
        double radius;
        
        CircularObstacle(Point center, double radius) {
            this.center = center;
            this.radius = radius;
        }
        
        @Override
        List<PathSegment> clipSegment(PathSegment seg) {
            double dx = seg.end.x - seg.start.x;
            double dy = seg.end.y - seg.start.y;
            double fx = seg.start.x - center.x;
            double fy = seg.start.y - center.y;
            
            double a = dx * dx + dy * dy;
            double b = 2 * (fx * dx + fy * dy);
            double c = fx * fx + fy * fy - radius * radius;
            
            List<Double> tValues = new ArrayList<>();
            tValues.add(0.0);
            tValues.add(1.0);
            
            double discriminant = b * b - 4 * a * c;
            if (discriminant > 0) {
                double sqrtDisc = Math.sqrt(discriminant);
                double t1 = (-b - sqrtDisc) / (2 * a);
                double t2 = (-b + sqrtDisc) / (2 * a);
                
                if (t1 > EPS && t1 < 1 - EPS) tValues.add(t1);
                if (t2 > EPS && t2 < 1 - EPS) tValues.add(t2);
            }
            
            Collections.sort(tValues);
            List<PathSegment> result = new ArrayList<>();
            
            for (int i = 0; i < tValues.size() - 1; i++) {
                double t1 = tValues.get(i);
                double t2 = tValues.get(i + 1);
                double tMid = (t1 + t2) / 2;
                
                Point midPoint = interpolate(seg.start, seg.end, tMid);
                if (!containsPoint(midPoint)) {
                    Point start = interpolate(seg.start, seg.end, t1);
                    Point end = interpolate(seg.start, seg.end, t2);
                    result.add(new PathSegment(start, end, seg.isMowing));
                }
            }
            
            return result;
        }
        
        @Override
        boolean doesSegmentIntersect(Point p1, Point p2) {
            Point closest = closestPointOnSegment(center, p1, p2);
            // 将与圆的相切也视为相交，避免路径擦边
            return distance(center, closest) <= radius + EPS;
        }
        
        @Override
        boolean containsPoint(Point p) {
            return distance(center, p) < radius - EPS;
        }
        
        @Override
        List<Point> getKeyPoints() {
            List<Point> points = new ArrayList<>();
            int numPoints = 8; // 八边形近似
            
            for (int i = 0; i < numPoints; i++) {
                double angle = 2 * Math.PI * i / numPoints;
                points.add(new Point(
                    center.x + radius * Math.cos(angle),
                    center.y + radius * Math.sin(angle)
                ));
            }
            
            return points;
        }
    }
    
    /**
     * 路径段
     */
    public static class PathSegment {
        public Point start, end;
        public boolean isMowing;
        
        public PathSegment(Point start, Point end, boolean isMowing) {
            this.start = start;
            this.end = end;
            this.isMowing = isMowing;
        }
        
        @Override
        public String toString() {
            return String.format("%s -> %s [%s]", start, end, isMowing ? "MOW" : "MOVE");
        }
    }
    
    /**
     * 点类
     */
    public static class Point {
        public double x, y;
        
        public Point(double x, double y) {
            this.x = x;
            this.y = y;
        }
        
        @Override
        public boolean equals(Object obj) {
            if (this == obj) return true;
            if (!(obj instanceof Point)) return false;
            Point other = (Point) obj;
            return Math.abs(x - other.x) < EPS && Math.abs(y - other.y) < EPS;
        }
        
        @Override
        public int hashCode() {
            return Double.hashCode(x) * 31 + Double.hashCode(y);
        }
        
        @Override
        public String toString() {
            return String.format("(%.2f, %.2f)", x, y);
        }
    }
    
    /**
     * 边界框
     */
    private static class Bounds {
        double minX, maxX, minY, maxY;
        
        Bounds(double minX, double maxX, double minY, double maxY) {
            this.minX = minX;
            this.maxX = maxX;
            this.minY = minY;
            this.maxY = maxY;
        }
    }
    
    // ==================== 几何工具函数 ====================
    
    private static Double lineIntersection(Point a1, Point a2, Point b1, Point b2) {
        double det = (a2.x - a1.x) * (b2.y - b1.y) - (a2.y - a1.y) * (b2.x - b1.x);
        
        if (Math.abs(det) < EPS) return null;
        
        double t = ((b1.x - a1.x) * (b2.y - b1.y) - (b1.y - a1.y) * (b2.x - b1.x)) / det;
        double u = ((a1.x - b1.x) * (a2.y - a1.y) - (a1.y - b1.y) * (a2.x - a1.x)) / (-det);
        
        if (t >= -EPS && t <= 1 + EPS && u >= -EPS && u <= 1 + EPS) {
            return Math.max(0, Math.min(1, t));
        }
        
        return null;
    }
    
    private static boolean lineSegmentIntersection(Point a1, Point a2, Point b1, Point b2) {
        Double t = lineIntersection(a1, a2, b1, b2);
        return t != null;
    }
    
    private static Point interpolate(Point a, Point b, double t) {
        return new Point(a.x + (b.x - a.x) * t, a.y + (b.y - a.y) * t);
    }
    
    private static Point closestPointOnSegment(Point p, Point a, Point b) {
        double ax = b.x - a.x;
        double ay = b.y - a.y;
        double bx = p.x - a.x;
        double by = p.y - a.y;
        
        double dot = ax * bx + ay * by;
        double lenSq = ax * ax + ay * ay;
        
        double t = (lenSq > EPS) ? Math.max(0, Math.min(1, dot / lenSq)) : 0;
        
        return new Point(a.x + t * ax, a.y + t * ay);
    }    
   
}