Unit-App/lib/Util/Util.dart

import 'dart:async';
import 'dart:convert';
import 'dart:io';
import 'package:flutter/services.dart';
import 'package:flutter/material.dart';
import 'package:flushbar/flushbar.dart';
import 'package:http/io_client.dart';
import '../main.dart';
import 'package:location/location.dart';
import 'package:permission_handler/permission_handler.dart' as pHandler;
import 'Prefs.dart';
import 'package:oauth2/oauth2.dart' as oauth2;

class Util{
  bool tokenValidity = true;
  bool useLocal = false;

  getOauth2Client() async {
    bool resetClient = false;
    oauth2.Credentials restData = (prefs.getString(keyClass.rest_data)!=null&&prefs.getString(keyClass.rest_data).contains("accessToken"))?oauth2.Credentials.fromJson(prefs.getString(keyClass.rest_data)):null;
    if(restData == null)resetClient = true;
    else{
      if(DateTime.now().isAfter(restData.expiration))resetClient = true;
    }
    oauth2.Client client;
    if(resetClient||!tokenValidity){
      final tokenEndpoint = Uri.parse(prefs.getString(keyClass.restTokenAddress));
      if(prefs.getString(keyClass.client_credential)==null){
        client = await initRest();
      }
      else{
        var clients =  JsonDecoder().convert(prefs.getString(keyClass.client_credential));
        client = await oauth2.clientCredentialsGrant(tokenEndpoint, clients["id"], clients["secret"],httpClient: http);
        prefs.setString(keyClass.rest_data, client.credentials.toJson());
      }
    }
    else {
      if (prefs.getString(keyClass.client_credential) == null) {
        client = await initRest();
      }
      else {
        var clients =  JsonDecoder().convert(prefs.getString(keyClass.client_credential));
        client = new oauth2.Client(restData, identifier: clients["id"],
            secret: clients["secret"],
            httpClient: http);

      }
    }
    return client;
  }

  JsonDataPostRaw(Map jsonData, String url,{secure:true,timeout:false}) async{
    var httpClient;
    const JsonDecoder decoder = const JsonDecoder();
    var headers = {'Content-type': 'application/json'};
    try {
      var response;
      if(secure) {
        httpClient = await getOauth2Client();
        oauth2.Credentials tokenRestData = oauth2.Credentials.fromJson(prefs.getString(keyClass.rest_data));
        headers["Authorization"] =
        "bearer ${tokenRestData.accessToken}";
      }
      else {
        httpClient = http;
      }
      if (timeout)
        response = await httpClient.post(
            Uri.parse(url), headers: headers,
            body: json.encode(jsonData)).timeout(
            const Duration(seconds: 10));
      else
        response = await httpClient.post(
            Uri.parse(url), headers: {'Content-type': 'application/json'},
            body: json.encode(jsonData));
      if(response.statusCode == 403) tokenValidity = false;
      if(htmlErrorTitle(response.body.toString())!=""){
        return {"STATUS":(response.statusCode != 200)?0:1,"DATA":htmlErrorTitle(response.body.toString())};
      }
      final Map data = decoder.convert(response.body);
      try{data["DATA"] = decoder.convert(data["DATA"]);}catch(e){}
      return data;
    } on TimeoutException catch(e){
      return {"STATUS":0,"DATA":"Request Timeout"};
    }
    on HandshakeException catch(e){
      if(useLocal){
        return {"STATUS":0,"DATA":"Not Connected to Server. $e"};
      }
      else{
        useLocal = true;
        http = IOClient(HttpClient(context: clientContext));
        return await JsonDataPostRaw(jsonData, url,timeout:timeout,secure: secure);
      }

    }
    on Exception catch(exception){
      print(url);
//      Toast("Not Connected to Server", Colors.red);
      return {"STATUS":0,"DATA":"Not Connected to Server. $exception"};
    }
  }

  JsonDataPutRaw(Map jsonData, String url,{secure:true,timeout:false}) async{
    var httpClient;
    const JsonDecoder decoder = const JsonDecoder();
    var headers = {'Content-type': 'application/json'};
    try {
      var response;
      if(secure) {
        httpClient = await getOauth2Client();
        oauth2.Credentials tokenRestData = oauth2.Credentials.fromJson(prefs.getString(keyClass.rest_data));
        headers["Authorization"] =
        "bearer ${tokenRestData.accessToken}";
      }
      else {
        httpClient = http;
      }
      if (timeout)
        response = await httpClient.put(
            Uri.parse(url), headers: headers,
            body: json.encode(jsonData)).timeout(
            const Duration(seconds: 10));
      else
        response = await httpClient.put(
            Uri.parse(url), headers: {'Content-type': 'application/json'},
            body: json.encode(jsonData));
      if(response.statusCode == 403) tokenValidity = false;
      if(htmlErrorTitle(response.body.toString())!=""){
        return {"STATUS":(response.statusCode != 200)?0:1,"DATA":htmlErrorTitle(response.body.toString())};
      }
      final Map data = decoder.convert(response.body);
      try{data["DATA"] = decoder.convert(data["DATA"]);}catch(e){}
      return data;
    } on TimeoutException catch(e){
      return {"STATUS":0,"DATA":"Request Timeout"};
    }
    on HandshakeException catch(e){
      if(useLocal){
        return {"STATUS":0,"DATA":"Not Connected to Server. $e"};
      }
      else{
        useLocal = true;
        http = IOClient(HttpClient(context: clientContext));
        return await JsonDataPostRaw(jsonData, url,timeout:timeout,secure: secure);
      }

    }
    on Exception catch(exception){
      print(url);
//      Toast("Not Connected to Server", Colors.red);
      return {"STATUS":0,"DATA":"Not Connected to Server. $exception"};
    }
  }

  htmlErrorTitle(String html){
    try{
      if(html.contains('<title>')) {
        String titleElement = html.substring(html.indexOf("<title>")+7,html.indexOf("<\/title>"));
        return titleElement;
      }
      else return '';
    }
    catch(e){
      return '';
    }
  }
  initRest()async{
    try{
      if(prefs.getString(keyClass.client_credential)==null){
        prefs.setString(keyClass.client_credential, json.encode({
          "id": "IZ4W8u8YZmLtUV0p1zd-_A..",
          "secret" : "AQ16v4bzGWm9AsWHvUcu2Q.."
        }).toString());
      }
      return await getOauth2Client();
    }
    catch(e){
      print(e);
      print("error fetching Rest token");
    }
  }
  showLoading(context,{dissmissable=false,onwillpop}){
    showDialog(
        context: context,
        builder: (BuildContext context) {
      return WillPopScope(
        onWillPop: onwillpop??()async{return true;},
        child: new Center(
          child: new CircularProgressIndicator(),
        ),
      );
    },
    barrierDismissible: dissmissable,
    );
  }
  permissionCheck(context,pHandler.Permission permissionType,ifGranted,{customMessage=''})async{
    pHandler.PermissionStatus permission = await permissionType.status;
    if(permission!= pHandler.PermissionStatus.granted){
      if(permission== pHandler.PermissionStatus.denied || permission== pHandler.PermissionStatus.restricted){
        showFlushbar(context,'${permissionType.toString().substring(permissionType.toString().lastIndexOf('.')+1)} permission is needed$customMessage. Please grant the permission!');
        await Future.delayed(Duration(seconds: 3));
        permission = await permissionType.request();
      }
      if(permission== pHandler.PermissionStatus.permanentlyDenied) {
        showFlushbar(context,'It seems, your system security explicitly denied access to your ${permissionType.toString().substring(permissionType.toString().lastIndexOf('.')+1)} permission. Please MANUALLY enable it in setings!');
        await Future.delayed(Duration(seconds: 3));
        pHandler.openAppSettings();
        SystemChannels.platform.invokeMethod('SystemNavigator.pop');
      }
      if(permission== pHandler.PermissionStatus.denied || permission== pHandler.PermissionStatus.restricted){
        showFlushbar(context,'${permissionType.toString().substring(permissionType.toString().lastIndexOf('.')+1)} permission is needed$customMessage. Please grant the permission!');
        await Future.delayed(Duration(seconds: 3));
        permission = await permissionType.request();
      }
      await permissionCheck(context,permissionType,ifGranted);
    }
    else{
      await ifGranted();
    }
  }
  showFlushbar(context,text,{color:Colors.grey}){
    Flushbar(
        message:  "$text",
        backgroundColor: color,
        duration:  Duration(seconds: 5),
      )..show(context);
  }
  streamLocation(context)async{
    print('checking location');
    await permissionCheck(context,pHandler.Permission.locationWhenInUse,()async{
      location.changeSettings(accuracy: LocationAccuracy.high);
      bool gpsEnabled = false;
      if(await location.serviceEnabled()){
        gpsEnabled = await location.serviceEnabled();
      }
      else{
        print('requesting gps');
        gpsEnabled = await location.requestService();
        await streamLocation(context);
      }
//    print([gpsEnabled,permissionEnabled]);
      if(gpsEnabled){
          if(locationStream==null){
            locationStream = location.onLocationChanged.listen((LocationData event) {
              currentPosisiton = event;
            });
          }
      }
    },customMessage: " to locate your REAL location");
  }
}