import dataclasses
import socket
import subprocess
import threading
import time

import flask
import rospy
import werkzeug.serving
from flask import jsonify, request

import gazebo_ctrl
from heartbeat import HeartbeatServer
from model_mgr.manager import ModelManager
from scene_mgr.manager import SceneManager


@dataclasses.dataclass
class HttpHost():
    """
    HTTP主机信息
    """
    hostname: str
    port: int

    def __post_init__(self):
        if not self.hostname:
            raise ValueError('Hostname cannot be empty')
        if not (0 <= self.port <= 65535):
            raise ValueError(f'Invalid port: {self.port}')


class HttpRPCServer():
    """
    来自ability-sdk-python的http服务器。
    HTTP RPC服务端实现。
    使用add_route方法添加路由，重写类以实现自定义功能。
    """

    def __init__(self):
        self._server = None
        self._app = flask.Flask(__name__)

    def add_route(self, uri: str, handler, methods: list):
        """
        添加HTTP路由，handler应符合Flask视图函数的规范。
        """
        if not callable(handler):
            raise ValueError('Handler must be a callable function')
        self._app.add_url_rule(uri, view_func=handler, methods=methods)

    def start(self, hostname: str = '0.0.0.0', port: int = None):
        """
        启动并以阻塞方式提供服务。
        """
        if self._server:
            raise RuntimeError('Server is already running')
        self.host = HttpHost(
            hostname=hostname, port=port if port else self.find_free_port())
        self._server = werkzeug.serving.make_server(
            self.host.hostname, self.host.port, self._app, threaded=True)
        self._server.serve_forever()

    def stop(self):
        """
        停止服务。
        """
        if self._server:
            self._server.shutdown()
            self._server.server_close()
            self._server = None

    def find_free_port(self):
        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
            s.bind(('127.0.0.1', 0))
            return s.getsockname()[1]


class GazeboSimHttpServer(HttpRPCServer):
    """
    Gazebo仿真环境的HTTP服务器。
    """

    def __init__(self):
        super().__init__()
        # 模块与数据
        self.rlock = threading.RLock()
        self.scene_mgr = SceneManager()
        self.model_mgr = ModelManager()
        self.heartbeat_server = HeartbeatServer()
        # 启动roscore
        self.roscore_proc = subprocess.Popen(
            ['roscore'], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
        time.sleep(2)
        rospy.init_node('gazebo_world_manager', anonymous=True)

        # 添加接口
        self._app.add_url_rule('/api/v1/scenes', view_func=self.query_scenes, methods=['GET'])
        self._app.add_url_rule('/api/v1/scene/load', view_func=self.load_scene, methods=['GET'])
        self._app.add_url_rule('/api/v1/scene/objects', view_func=self.get_scene_objects, methods=['GET'])
        self._app.add_url_rule('/api/v1/scene/object', view_func=self.modify_scene_object, methods=['POST'])
        self._app.add_url_rule('/api/v1/scene/object', view_func=self.add_scene_object, methods=['PUT'])
        self._app.add_url_rule('/api/v1/scene/object', view_func=self.remove_scene_object, methods=['DELETE'])

    def query_scenes(self):
        # 查询场景
        with self.rlock:
            pass

    def start_scene(self):
        # 启动场景
        with self.rlock:
            pass

    def shut_scene(self):
        # 关闭场景，仅供start_scene、心跳线程使用
        with self.rlock:
            pass

    def get_all_models(self):
        # 获取所有模型
        with self.rlock:
            pass

    def modify_model(self):
        # 修改模型
        with self.rlock:
            pass

    def add_model(self):
        # 添加模型
        with self.rlock:
            pass

    def remove_model(self):
        # 删除模型
        with self.rlock:
            pass

if __name__ == '__main__':
    server = GazeboSimHttpServer()
    server.start(hostname='0.0.0.0', port=12300)