import numpy as np


def random_normal_distribution(a, b, n=5):
    output = np.mean(np.random.uniform(a, b, size=n))
    return output


def random_theta():
    theta = np.random.uniform(0, 2 * np.pi)
    return np.array([np.sin(theta), np.cos(theta)])


def random_rho(dis):
    return random_normal_distribution(-dis, dis)



def insert_swipe(p0, p3, speed=15, min_distance=10):
    """
    从起点到终点插入路径点。
    首先生成三次贝塞尔曲线

    参数：
        p0：起点。
        p3：终点。
        速度：平均移动速度，每 10 毫秒的像素数。
        min_distance：

    返回：
        list[list[int]]：点列表。

    例子：
        > insert_swipe（（400， 400）， （600， 600）， 20）
        [[400, 400], [406, 406], [416, 415], [429, 428], [444, 442], [462, 459], [481, 478], [504, 500], [527, 522],
        [545, 540], [560, 557], [573, 570], [584, 582], [592, 590], [597, 596], [600, 600]]
    """
    p0 = np.array(p0)
    p3 = np.array(p3)

    # Random control points in Bézier curve
    distance = np.linalg.norm(p3 - p0)
    p1 = 2 / 3 * p0 + 1 / 3 * p3 + random_theta() * random_rho(distance * 0.1)
    p2 = 1 / 3 * p0 + 2 / 3 * p3 + random_theta() * random_rho(distance * 0.1)

    # Random `t` on Bézier curve, sparse in the middle, dense at start and end
    segments = max(int(distance / speed) + 1, 5)
    lower = random_normal_distribution(-85, -60)
    upper = random_normal_distribution(80, 90)
    theta = np.arange(lower + 0., upper + 0.0001, (upper - lower) / segments)
    ts = np.sin(theta / 180 * np.pi)
    ts = np.sign(ts) * abs(ts) ** 0.9
    ts = (ts - min(ts)) / (max(ts) - min(ts))

    # Generate cubic Bézier curve
    points = []
    prev = (-100, -100)
    for t in ts:
        point = p0 * (1 - t) ** 3 + 3 * p1 * t * (1 - t) ** 2 + 3 * p2 * t ** 2 * (1 - t) + p3 * t ** 3
        point = point.astype(int).tolist()
        if np.linalg.norm(np.subtract(point, prev)) < min_distance:
            continue

        points.append(point)
        prev = point

    # Delete nearing points
    if len(points[1:]):
        distance = np.linalg.norm(np.subtract(points[1:], points[0]), axis=1)
        mask = np.append(True, distance > min_distance)
        points = np.array(points)[mask].tolist()
        if len(points) <= 1:
            points = [p0, p3]
    else:
        points = [p0, p3]
    return points