"""
RRT_STAR_SMART 2D
@author: huiming zhou
"""

import os
import sys
import math
import random
import numpy as np
import matplotlib.pyplot as plt
from scipy.spatial.transform import Rotation as Rot
import matplotlib.patches as patches

sys.path.append(os.path.dirname(os.path.abspath(__file__)) +
                "/../../Sampling-based Planning/")

from rrt_2D import env
from rrt_2D import plotting
from rrt_2D import utils


class Node:
    def __init__(self, n):
        self.x = n[0]
        self.y = n[1]
        self.parent = None


class RrtStarSmart:
    def __init__(self, x_start, x_goal, step_len,
                 goal_sample_rate, search_radius, iter_max):
        self.x_start = Node(x_start)
        self.x_goal = Node(x_goal)
        self.step_len = step_len
        self.goal_sample_rate = goal_sample_rate
        self.search_radius = search_radius
        self.iter_max = iter_max

        self.env = env.Env()
        self.plotting = plotting.Plotting(x_start, x_goal)
        self.utils = utils.Utils()

        self.fig, self.ax = plt.subplots()
        self.delta = self.utils.delta
        self.x_range = self.env.x_range
        self.y_range = self.env.y_range
        self.obs_circle = self.env.obs_circle
        self.obs_rectangle = self.env.obs_rectangle
        self.obs_boundary = self.env.obs_boundary

        self.V = [self.x_start]
        self.beacons = []
        self.beacons_radius = 2
        self.direct_cost_old = np.inf
        self.obs_vertex = self.utils.get_obs_vertex()
        self.path = None

    def planning(self):
        n = 0
        b = 2
        InitPathFlag = False
        self.ReformObsVertex()

        for k in range(self.iter_max):
            if k % 200 == 0:
                print(k)

            if (k - n) % b == 0 and len(self.beacons) > 0:
                x_rand = self.Sample(self.beacons)
            else:
                x_rand = self.Sample()

            x_nearest = self.Nearest(self.V, x_rand)
            x_new = self.Steer(x_nearest, x_rand)

            if x_new and not self.utils.is_collision(x_nearest, x_new):
                X_near = self.Near(self.V, x_new)
                self.V.append(x_new)

                if X_near:
                    # choose parent
                    cost_list = [self.Cost(x_near) + self.Line(x_near, x_new) for x_near in X_near]
                    x_new.parent = X_near[int(np.argmin(cost_list))]

                    # rewire
                    c_min = self.Cost(x_new)
                    for x_near in X_near:
                        c_near = self.Cost(x_near)
                        c_new = c_min + self.Line(x_new, x_near)
                        if c_new < c_near:
                            x_near.parent = x_new

                if not InitPathFlag and self.InitialPathFound(x_new):
                    InitPathFlag = True
                    n = k

                if InitPathFlag:
                    self.PathOptimization(x_new)
                if k % 5 == 0:
                    self.animation()

        self.path = self.ExtractPath()
        self.animation()
        plt.plot([x for x, _ in self.path], [y for _, y in self.path], '-r')
        plt.pause(0.01)
        plt.show()

    def PathOptimization(self, node):
        direct_cost_new = 0.0
        node_end = self.x_goal

        while node.parent:
            node_parent = node.parent
            if not self.utils.is_collision(node_parent, node_end):
                node_end.parent = node_parent
            else:
                direct_cost_new += self.Line(node, node_end)
                node_end = node

            node = node_parent

        if direct_cost_new < self.direct_cost_old:
            self.direct_cost_old = direct_cost_new
            self.UpdateBeacons()

    def UpdateBeacons(self):
        node = self.x_goal
        beacons = []

        while node.parent:
            near_vertex = [v for v in self.obs_vertex
                           if (node.x - v[0]) ** 2 + (node.y - v[1]) ** 2 < 9]
            if len(near_vertex) > 0:
                for v in near_vertex:
                    beacons.append(v)

            node = node.parent

        self.beacons = beacons

    def ReformObsVertex(self):
        obs_vertex = []

        for obs in self.obs_vertex:
            for vertex in obs:
                obs_vertex.append(vertex)

        self.obs_vertex = obs_vertex

    def Steer(self, x_start, x_goal):
        dist, theta = self.get_distance_and_angle(x_start, x_goal)
        dist = min(self.step_len, dist)
        node_new = Node((x_start.x + dist * math.cos(theta),
                         x_start.y + dist * math.sin(theta)))
        node_new.parent = x_start

        return node_new

    def Near(self, nodelist, node):
        n = len(self.V) + 1
        r = 50 * math.sqrt((math.log(n) / n))

        dist_table = [(nd.x - node.x) ** 2 + (nd.y - node.y) ** 2 for nd in nodelist]
        X_near = [nodelist[ind] for ind in range(len(dist_table)) if dist_table[ind] <= r ** 2 and
                  not self.utils.is_collision(node, nodelist[ind])]

        return X_near

    def Sample(self, goal=None):
        if goal is None:
            delta = self.utils.delta
            goal_sample_rate = self.goal_sample_rate

            if np.random.random() > goal_sample_rate:
                return Node((np.random.uniform(self.x_range[0] + delta, self.x_range[1] - delta),
                             np.random.uniform(self.y_range[0] + delta, self.y_range[1] - delta)))

            return self.x_goal
        else:
            R = self.beacons_radius
            r = random.uniform(0, R)
            theta = random.uniform(0, 2 * math.pi)
            ind = random.randint(0, len(goal) - 1)

            return Node((goal[ind][0] + r * math.cos(theta),
                         goal[ind][1] + r * math.sin(theta)))

    def SampleFreeSpace(self):
        delta = self.delta

        if np.random.random() > self.goal_sample_rate:
            return Node((np.random.uniform(self.x_range[0] + delta, self.x_range[1] - delta),
                         np.random.uniform(self.y_range[0] + delta, self.y_range[1] - delta)))

        return self.x_goal

    def ExtractPath(self):
        path = []
        node = self.x_goal

        while node.parent:
            path.append([node.x, node.y])
            node = node.parent

        path.append([self.x_start.x, self.x_start.y])

        return path

    def InitialPathFound(self, node):
        if self.Line(node, self.x_goal) < self.step_len:
            return True

        return False

    @staticmethod
    def Nearest(nodelist, n):
        return nodelist[int(np.argmin([(nd.x - n.x) ** 2 + (nd.y - n.y) ** 2
                                       for nd in nodelist]))]

    @staticmethod
    def Line(x_start, x_goal):
        return math.hypot(x_goal.x - x_start.x, x_goal.y - x_start.y)

    @staticmethod
    def Cost(node):
        cost = 0.0
        if node.parent is None:
            return cost

        while node.parent:
            cost += math.hypot(node.x - node.parent.x, node.y - node.parent.y)
            node = node.parent

        return cost

    @staticmethod
    def get_distance_and_angle(node_start, node_end):
        dx = node_end.x - node_start.x
        dy = node_end.y - node_start.y
        return math.hypot(dx, dy), math.atan2(dy, dx)

    def animation(self):
        plt.cla()
        self.plot_grid("rrt*-Smart, N = " + str(self.iter_max))
        plt.gcf().canvas.mpl_connect(
            'key_release_event',
            lambda event: [exit(0) if event.key == 'escape' else None])

        for node in self.V:
            if node.parent:
                plt.plot([node.x, node.parent.x], [node.y, node.parent.y], "-g")

        if self.beacons:
            theta = np.arange(0, 2 * math.pi, 0.1)
            r = self.beacons_radius

            for v in self.beacons:
                x = v[0] + r * np.cos(theta)
                y = v[1] + r * np.sin(theta)
                plt.plot(x, y, linestyle='--', linewidth=2, color='darkorange')

        plt.pause(0.01)

    def plot_grid(self, name):

        for (ox, oy, w, h) in self.obs_boundary:
            self.ax.add_patch(
                patches.Rectangle(
                    (ox, oy), w, h,
                    edgecolor='black',
                    facecolor='black',
                    fill=True
                )
            )

        for (ox, oy, w, h) in self.obs_rectangle:
            self.ax.add_patch(
                patches.Rectangle(
                    (ox, oy), w, h,
                    edgecolor='black',
                    facecolor='gray',
                    fill=True
                )
            )

        for (ox, oy, r) in self.obs_circle:
            self.ax.add_patch(
                patches.Circle(
                    (ox, oy), r,
                    edgecolor='black',
                    facecolor='gray',
                    fill=True
                )
            )

        plt.plot(self.x_start.x, self.x_start.y, "bs", linewidth=3)
        plt.plot(self.x_goal.x, self.x_goal.y, "rs", linewidth=3)

        plt.title(name)
        plt.axis("equal")


def main():
    x_start = (18, 8)  # Starting node
    x_goal = (37, 18)  # Goal node

    rrt = RrtStarSmart(x_start, x_goal, 1.5, 0.10, 0, 1000)
    rrt.planning()


if __name__ == '__main__':
    main()