import 'dart:async';
import 'dart:ffi';
import 'package:flutter/material.dart';

import 'ros.dart';
import 'request.dart';
import 'dart:math';

typedef ActionHandler = void Function(Map<String, dynamic> response);
typedef UUID = List;
class GoalHandle {
  ActionHandler onSendGoal;
  ActionHandler onFeedback;
  ActionHandler onResult;

  GoalHandle({
    required this.onSendGoal,
    required this.onFeedback,
    required this.onResult,
  });
}
// 每次发送goal都要构造Action
class Action {
  Ros ros;
  String name;
  String type;
  // 每次发送goal时，都会生成唯一一个uuid，不能出现重复，用于后续发送cancel_goal，
  Map<String, List<num>> uuids = {};

  StreamSubscription? goalListener;
  StreamSubscription? feedbackListener;
  StreamSubscription? resultListener;

  StreamSubscription? cancelListener;

  GoalHandle goalHandle;

  Action({
    required this.name,
    required this.ros,
    required this.type,
    required this.goalHandle,
  });
  List<num> generateRandomString(int length) {
    const characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    Random random = Random();
    return List.generate(length, (index) {
      return characters[random.nextInt(characters.length)].codeUnitAt(0);
    });
  }
  void _bindFeedbackAndResult(String callId) {
    final feedbackLis = ros.stream;
    feedbackLis.listen((message) {
      goalHandle.onFeedback(message);
    });

    final resultReceiver = ros.stream.where((message) => message['op'] == 'action_result' && message['id'] == callId)
      .map((Map<String, dynamic> message) => message['result'] == null
            ? message['values']!
            : message['values']);

    resultListener = resultReceiver.listen((d) {
      goalHandle.onResult(d);
      resultListener!.cancel();
    });
  }

  String sendGoal(dynamic req) {
    final callId = ros.requestServiceCaller(name);
    final completer = Completer<List>();
    final uuid = generateRandomString(16);
    var reqObj = Request(
      op: 'send_action_goal',
      id: callId,
      action: req['action'],
      type: req['type'],
      args: {
        "goal_id" : {
          "uuid": uuid,
        },
        "goal": req['args'],
      },
    );
    if (uuids.containsKey(callId)) {
      uuids[callId] = uuid;
    } else {
      uuids.addAll({callId: uuid});
    }
    ros.send(reqObj);

    final receiver = ros.stream.where((message) {
      return message['id'] == callId && message['op'] != 'cancel_goal_response';
    } );
    goalListener = receiver.listen((d) {
      if (d["op"] == "action_result") {
        goalHandle.onResult(d);
        goalListener!.cancel();
      } else if (d["op"] == "action_feedback") {
        goalHandle.onFeedback(d);
      } else if (d["op"] == 'send_goal_response') {
        completer.complete(uuids[callId]);
        goalHandle.onSendGoal(d);
      }
    });

    return callId;
  }

  Future cancelGoal(dynamic req, String callId, ActionHandler onCancel) {
    final completer = Completer();
    var cancelReq = Request(
      op: 'cancel_action_goal',
      id: callId,
      action: req['action'],
    );
    print("cancelReq: ${cancelReq.toJson()}");
    ros.send(cancelReq);
    final receiver = ros.stream.where(
      (message) => message['id'] == callId && message['op'] == 'cancel_goal_response'
    );
    cancelListener = receiver.listen((d) {
      onCancel(d);
      completer.complete();
      cancelListener!.cancel();
    });
    return completer.future;
  }
}