package lujing;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * 异形草地路径规划 - 障碍物裁剪优化版 V9.0
 * 核心逻辑：先生成全覆盖扫描路径，再利用外扩后的障碍物对路径进行裁剪。
 */
public class YixinglujingHaveObstacel {

    /**
     * 规划路径主入口
     */
    public static List<PathSegment> planPath(String coordinates, String obstaclesStr, String widthStr, String marginStr) {
        // 1. 解析参数
        List<Point> rawPoints = parseCoordinates(coordinates);
        if (rawPoints.size() < 3) return new ArrayList<>();

        double mowWidth = Double.parseDouble(widthStr);
        double safeMargin = Double.parseDouble(marginStr);

        // 2. 预处理地块边界 (确保逆时针)
        ensureCounterClockwise(rawPoints);
        
        // 3. 生成地块内缩的安全作业边界 (Inset)
        List<Point> mowingBoundary = getOffsetPolygon(rawPoints, safeMargin); // 正数内缩
        if (mowingBoundary.size() < 3) return new ArrayList<>();

        // 4. 第一步：生成“无视障碍物”的全覆盖扫描路径
        // 直接使用扫描线算法生成填满整个内缩边界的路径
        List<PathSegment> rawPath = generateFullCoveragePath(mowingBoundary, mowWidth);

        // 5. 解析障碍物并进行外扩 (Outset)
        // 注意：障碍物外扩距离 = 割草机安全边距，确保不发生碰撞
        List<Obstacle> obstacles = parseObstacles(obstaclesStr, safeMargin);

        // 6. 第二步：使用障碍物裁剪路径 (核心步骤)
        return clipPathWithObstacles(rawPath, obstacles);
    }

    /**
     * 使用障碍物集合裁剪原始路径
     */
    private static List<PathSegment> clipPathWithObstacles(List<PathSegment> rawPath, List<Obstacle> obstacles) {
        List<PathSegment> finalPath = new ArrayList<>();
        Point currentPos = (rawPath.isEmpty()) ? new Point(0,0) : rawPath.get(0).start;

        for (PathSegment segment : rawPath) {
            // 将当前这一段路径，拿去跟所有障碍物进行碰撞检测和裁剪
            // 初始时，这一段是完整的
            List<PathSegment> segmentsToProcess = new ArrayList<>();
            segmentsToProcess.add(segment);

            for (Obstacle obs : obstacles) {
                List<PathSegment> nextIterSegments = new ArrayList<>();
                for (PathSegment seg : segmentsToProcess) {
                    // 如果是割草路径，需要裁剪；如果是空走路径，通常也需要避障，
                    // 但这里主要处理扫描线的裁剪。
                    if (seg.isMowing) {
                        nextIterSegments.addAll(obs.clip(seg));
                    } else {
                        // 空走路径暂时保留（高级避障需要A*算法，此处简化为保留）
                        nextIterSegments.add(seg);
                    }
                }
                segmentsToProcess = nextIterSegments;
            }

            // 将裁剪后剩余的线段加入最终路径
            for (PathSegment s : segmentsToProcess) {
                // 过滤掉因为裁剪产生的极短线段
                if (distance(s.start, s.end) < 0.05) continue;

                // 如果当前点和线段起点不连贯，加入连接路径（空走）
                if (distance(currentPos, s.start) > 0.05) {
                    finalPath.add(new PathSegment(currentPos, s.start, false));
                }
                
                finalPath.add(s);
                currentPos = s.end;
            }
        }
        return finalPath;
    }

    // --- 路径生成核心算法 (移植自 NoObstacle 类) ---

    private static List<PathSegment> generateFullCoveragePath(List<Point> boundary, double width) {
        // 1. 寻找最优角度
        double angle = findOptimalAngle(boundary);
        
        // 2. 旋转多边形以对齐坐标轴
        List<Point> rotatedPoly = new ArrayList<>();
        for (Point p : boundary) rotatedPoly.add(rotatePoint(p, -angle));

        double minY = Double.MAX_VALUE, maxY = -Double.MAX_VALUE;
        for (Point p : rotatedPoly) {
            minY = Math.min(minY, p.y);
            maxY = Math.max(maxY, p.y);
        }

        // 3. 生成扫描线
        List<PathSegment> segments = new ArrayList<>();
        boolean l2r = true;
        // 围边路径先生成
        Point scanStartPoint = null;

        // 这里我们先计算扫描线，最后再决定围边起点以减少空走
        List<List<PathSegment>> scanRows = new ArrayList<>();

        for (double y = minY + width/2; y <= maxY - width/2; y += width) {
            List<Double> xInters = getXIntersections(rotatedPoly, y);
            if (xInters.size() < 2) continue;
            Collections.sort(xInters);

            List<PathSegment> row = new ArrayList<>();
            // 两两配对形成线段
            for (int i = 0; i < xInters.size() - 1; i += 2) {
                Point s = rotatePoint(new Point(xInters.get(i), y), angle);
                Point e = rotatePoint(new Point(xInters.get(i + 1), y), angle);
                row.add(new PathSegment(s, e, true));
            }

            // 蛇形排序
            if (!l2r) {
                Collections.reverse(row);
                for (PathSegment s : row) {
                    Point tmp = s.start; s.start = s.end; s.end = tmp;
                }
            }
            scanRows.add(row);
            if (scanStartPoint == null && !row.isEmpty()) scanStartPoint = row.get(0).start;
            l2r = !l2r;
        }

        // 4. 生成围边路径 (对齐到第一个扫描点)
        List<Point> alignedBoundary = alignBoundaryStart(boundary, scanStartPoint);
        for (int i = 0; i < alignedBoundary.size(); i++) {
            segments.add(new PathSegment(alignedBoundary.get(i), alignedBoundary.get((i+1)%alignedBoundary.size()), true));
        }

        // 5. 加入扫描路径
        for (List<PathSegment> row : scanRows) {
            segments.addAll(row);
        }

        return segments;
    }

    // --- 障碍物处理类 ---

    private static List<Obstacle> parseObstacles(String obsStr, double margin) {
        List<Obstacle> list = new ArrayList<>();
        if (obsStr == null || obsStr.trim().isEmpty()) return list;

        // 处理格式 (x,y;...)(x,y;...) 或 $ 分隔
        String cleanStr = obsStr.replaceAll("\\s+", "");
        String[] parts;
        if (cleanStr.contains("(") && cleanStr.contains(")")) {
            List<String> matches = new ArrayList<>();
            java.util.regex.Matcher m = java.util.regex.Pattern.compile("\\(([^)]+)\\)").matcher(cleanStr);
            while (m.find()) matches.add(m.group(1));
            parts = matches.toArray(new String[0]);
        } else {
            parts = cleanStr.split("\\$");
        }

        for (String pStr : parts) {
            List<Point> pts = parseCoordinates(pStr);
            if (pts.isEmpty()) continue;
            
            if (pts.size() == 2) {
                // 圆形障碍物
                double r = distance(pts.get(0), pts.get(1));
                list.add(new CircleObstacle(pts.get(0), r + margin)); // 半径增加margin
            } else {
                // 多边形障碍物
                ensureCounterClockwise(pts);
                // 外扩障碍物 (Offset Out)
                // 注意：在通用偏移算法中，逆时针多边形，负数通常表示外扩，或者使用特定算法
                // 这里我们复用 getOffsetPolygon，并传入负的margin来实现外扩
                // *但在本类目前的 getOffsetPolygon 实现中（基于角平分线），如果是逆时针：
                // 正数是向左（内缩），负数是向右（外扩）*
                List<Point> expanded = getOffsetPolygon(pts, -margin); 
                list.add(new PolyObstacle(expanded));
            }
        }
        return list;
    }

    abstract static class Obstacle {
        // 返回裁剪后的线段列表（即保留在障碍物外部的线段）
        abstract List<PathSegment> clip(PathSegment seg);
    }

    static class CircleObstacle extends Obstacle {
        Point c; double r;
        CircleObstacle(Point c, double r) { this.c = c; this.r = r; }
        
        @Override
        List<PathSegment> clip(PathSegment seg) {
            // 计算直线与圆的交点 t值 (0..1)
            double dx = seg.end.x - seg.start.x;
            double dy = seg.end.y - seg.start.y;
            double fx = seg.start.x - c.x;
            double fy = seg.start.y - c.y;
            
            double A = dx*dx + dy*dy;
            double B = 2*(fx*dx + fy*dy);
            double C = (fx*fx + fy*fy) - r*r;
            double delta = B*B - 4*A*C;

            List<PathSegment> result = new ArrayList<>();
            if (delta < 0) {
                // 无交点，全保留或全剔除
                if (!isInside(seg.start)) result.add(seg);
                return result;
            }

            double t1 = (-B - Math.sqrt(delta)) / (2*A);
            double t2 = (-B + Math.sqrt(delta)) / (2*A);
            
            List<Double> ts = new ArrayList<>();
            ts.add(0.0);
            if (t1 > 0 && t1 < 1) ts.add(t1);
            if (t2 > 0 && t2 < 1) ts.add(t2);
            ts.add(1.0);
            Collections.sort(ts);

            for (int i = 0; i < ts.size()-1; i++) {
                double midT = (ts.get(i) + ts.get(i+1)) / 2;
                Point mid = interpolate(seg.start, seg.end, midT);
                if (!isInside(mid)) {
                    result.add(new PathSegment(interpolate(seg.start, seg.end, ts.get(i)),
                                               interpolate(seg.start, seg.end, ts.get(i+1)), 
                                               seg.isMowing));
                }
            }
            return result;
        }

        boolean isInside(Point p) {
            return (p.x-c.x)*(p.x-c.x) + (p.y-c.y)*(p.y-c.y) < r*r;
        }
    }

    static class PolyObstacle extends Obstacle {
        List<Point> points;
        double minX, maxX, minY, maxY;

        PolyObstacle(List<Point> pts) {
            this.points = pts;
            updateBounds();
        }

        void updateBounds() {
            minX = minY = Double.MAX_VALUE;
            maxX = 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);
            }
        }

        boolean isInside(Point p) {
            if (p.x < minX || p.x > maxX || p.y < minY || p.y > maxY) return false;
            boolean result = false;
            for (int i = 0, j = points.size() - 1; i < points.size(); j = i++) {
                if ((points.get(i).y > p.y) != (points.get(j).y > p.y) &&
                    (p.x < (points.get(j).x - points.get(i).x) * (p.y - points.get(i).y) / (points.get(j).y - points.get(i).y) + points.get(i).x)) {
                    result = !result;
                }
            }
            return result;
        }

        @Override
        List<PathSegment> clip(PathSegment seg) {
            List<Double> ts = new ArrayList<>();
            ts.add(0.0);
            ts.add(1.0);

            // 计算线段与障碍物每一条边的交点
            for (int i = 0; i < points.size(); i++) {
                Point p1 = points.get(i);
                Point p2 = points.get((i+1)%points.size());
                double t = getIntersectionT(seg.start, seg.end, p1, p2);
                if (t > 1e-6 && t < 1 - 1e-6) {
                    ts.add(t);
                }
            }
            Collections.sort(ts);

            List<PathSegment> result = new ArrayList<>();
            // 检查每一小段的中点是否在障碍物内
            for (int i = 0; i < ts.size() - 1; i++) {
                double tMid = (ts.get(i) + ts.get(i+1)) / 2.0;
                // 如果两点极其接近，跳过
                if (ts.get(i+1) - ts.get(i) < 1e-6) continue;
                
                Point mid = interpolate(seg.start, seg.end, tMid);
                if (!isInside(mid)) {
                    // 在外部，保留
                    Point s = interpolate(seg.start, seg.end, ts.get(i));
                    Point e = interpolate(seg.start, seg.end, ts.get(i+1));
                    result.add(new PathSegment(s, e, seg.isMowing));
                }
            }
            return result;
        }
    }

    // --- 通用几何算法 ---

    private static List<Point> getOffsetPolygon(List<Point> points, double offset) {
        List<Point> result = new ArrayList<>();
        int n = points.size();
        for (int i = 0; i < n; i++) {
            Point p1 = points.get((i - 1 + n) % n);
            Point p2 = points.get(i);
            Point p3 = points.get((i + 1) % n);
            
            // 向量 p1->p2 和 p2->p3
            double v1x = p2.x - p1.x, v1y = p2.y - p1.y;
            double v2x = p3.x - p2.x, v2y = p3.y - p2.y;
            double l1 = Math.hypot(v1x, v1y), l2 = Math.hypot(v2x, v2y);
            
            if (l1 < 1e-5 || l2 < 1e-5) continue;

            // 法向量 (向左转90度: -y, x)
            double n1x = -v1y / l1, n1y = v1x / l1;
            double n2x = -v2y / l2, n2y = v2x / l2;

            // 角平分线
            double bx = n1x + n2x, by = n1y + n2y;
            double bl = Math.hypot(bx, by);
            if (bl < 1e-5) { bx = n1x; by = n1y; } 
            else { bx /= bl; by /= bl; }

            // 修正长度 offset / sin(theta/2) = offset / dot(n1, b)
            double dot = n1x * bx + n1y * by;
            double dist = offset / Math.max(Math.abs(dot), 0.1); // 防止尖角过长
            
            // 阈值限制，防止自交或畸变过大
            dist = Math.signum(offset) * Math.min(Math.abs(dist), Math.abs(offset) * 3);

            result.add(new Point(p2.x + bx * dist, p2.y + by * dist));
        }
        return result;
    }

    private static double findOptimalAngle(List<Point> poly) {
        double bestA = 0, minH = Double.MAX_VALUE;
        for (int i = 0; i < poly.size(); i++) {
            Point p1 = poly.get(i), p2 = poly.get((i + 1) % poly.size());
            double a = Math.atan2(p2.y - p1.y, p2.x - p1.x);
            double h = calcHeight(poly, a);
            if (h < minH) { minH = h; bestA = a; }
        }
        return bestA;
    }

    private static double calcHeight(List<Point> poly, double ang) {
        double min = Double.MAX_VALUE, max = -Double.MAX_VALUE;
        for (Point p : poly) {
            Point r = rotatePoint(p, -ang);
            min = Math.min(min, r.y); max = Math.max(max, r.y);
        }
        return max - min;
    }

    private static double getIntersectionT(Point a, Point b, Point c, Point d) {
        double ux = b.x - a.x, uy = b.y - a.y;
        double vx = d.x - c.x, vy = d.y - c.y;
        double det = vx * uy - vy * ux;
        if (Math.abs(det) < 1e-8) return -1;
        
        double wx = c.x - a.x, wy = c.y - a.y;
        double t = (vx * wy - vy * wx) / det;
        double u = (ux * wy - uy * wx) / det;
        
        if (u >= 0 && u <= 1) return t; // 只保证交点在线段CD上，t是AB上的比例
        return -1;
    }

    private static List<Double> getXIntersections(List<Point> poly, double y) {
        List<Double> res = new ArrayList<>();
        for (int i = 0; i < poly.size(); i++) {
            Point p1 = poly.get(i), p2 = poly.get((i + 1) % poly.size());
            if ((p1.y <= y && p2.y > y) || (p2.y <= y && p1.y > y)) {
                res.add(p1.x + (y - p1.y) * (p2.x - p1.x) / (p2.y - p1.y));
            }
        }
        return res;
    }

    private static List<Point> alignBoundaryStart(List<Point> poly, Point target) {
        if (target == null) return poly;
        int idx = 0; double minD = Double.MAX_VALUE;
        for (int i = 0; i < poly.size(); i++) {
            double d = distance(poly.get(i), target);
            if (d < minD) { minD = d; idx = i; }
        }
        List<Point> res = new ArrayList<>();
        for (int i = 0; i < poly.size(); i++) res.add(poly.get((idx + i) % poly.size()));
        return res;
    }

    private static void ensureCounterClockwise(List<Point> pts) {
        double s = 0;
        for (int i = 0; i < pts.size(); i++) {
            Point p1 = pts.get(i), p2 = pts.get((i + 1) % pts.size());
            s += (p2.x - p1.x) * (p2.y + p1.y);
        }
        if (s > 0) Collections.reverse(pts); // 假设屏幕坐标系Y向下？通常多边形面积公式s>0是顺时针(Y向下)或逆时针(Y向上)
        // 此处沿用您代码的逻辑：如果Sum>0 则反转。
    }

    private static Point rotatePoint(Point p, double a) {
        double c = Math.cos(a), s = Math.sin(a);
        return new Point(p.x * c - p.y * s, p.x * s + p.y * c);
    }
    
    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 double distance(Point a, Point b) {
        return Math.hypot(a.x - b.x, a.y - b.y);
    }

    private static List<Point> parseCoordinates(String s) {
        List<Point> pts = new ArrayList<>();
        if (s == null || s.isEmpty()) return pts;
        for (String p : s.split(";")) {
            String[] xy = p.split(",");
            if (xy.length >= 2) pts.add(new Point(Double.parseDouble(xy[0]), Double.parseDouble(xy[1])));
        }
        if (pts.size() > 1 && distance(pts.get(0), pts.get(pts.size() - 1)) < 1e-4) pts.remove(pts.size() - 1);
        return pts;
    }

    // --- 数据结构 ---
    public static class Point {
        public double x, y;
        public Point(double x, double y) { this.x = x; this.y = y; }
    }

    public static class PathSegment {
        public Point start, end;
        public boolean isMowing;
        public PathSegment(Point s, Point e, boolean m) { this.start = s; this.end = e; this.isMowing = m; }
        @Override
        public String toString() { return String.format("%.6f,%.6f;%.6f,%.6f", start.x, start.y, end.x, end.y); }
    }
}