import 'package:comunic/helpers/calls_helper.dart';
import 'package:comunic/helpers/conversations_helper.dart';
import 'package:comunic/helpers/events_helper.dart';
import 'package:comunic/helpers/users_helper.dart';
import 'package:comunic/lists/call_members_list.dart';
import 'package:comunic/lists/users_list.dart';
import 'package:comunic/models/call_config.dart';
import 'package:comunic/models/call_member.dart';
import 'package:comunic/models/conversation.dart';
import 'package:comunic/ui/routes/main_route.dart';
import 'package:comunic/ui/widgets/safe_state.dart';
import 'package:comunic/utils/account_utils.dart';
import 'package:comunic/utils/intl_utils.dart';
import 'package:comunic/utils/ui_utils.dart';
import 'package:flutter/material.dart';
import 'package:flutter_webrtc/rtc_peerconnection.dart';
import 'package:flutter_webrtc/webrtc.dart';

/// Call screen
///
/// @author Pierre Hubert

class CallScreen extends StatefulWidget {
  final int convID;

  const CallScreen({Key key, @required this.convID})
      : assert(convID != null),
        assert(convID > 0),
        super(key: key);

  @override
  _CallScreenState createState() => _CallScreenState();
}

class _CallScreenState extends SafeState<CallScreen> {
  // Widget properties
  int get convID => widget.convID;

  // State properties
  Conversation _conversation;
  String _convName;
  CallConfig _conf;
  var _error = false;
  CallMembersList _membersList;
  UsersList _usersList;
  final _peersConnections = Map<int, RTCPeerConnection>();

  @override
  void initState() {
    super.initState();
    _initCall();
  }

  @override
  void dispose() {
    super.dispose();
    _endCall();
  }

  void _initCall() async {
    try {
      setState(() => _error = false);

      // First, load information about the conversation
      _conversation = await ConversationsHelper().getSingleOrThrow(convID);
      _convName =
          await ConversationsHelper.getConversationNameAsync(_conversation);
      assert(_convName != null);

      setState(() {});

      // Join the call
      await CallsHelper.join(convID);

      // Get call configuration
      _conf = await CallsHelper.getConfig();

      // Get current members of the call
      final membersList = await CallsHelper.getMembers(convID);
      membersList.removeUser(userID());
      _usersList = await UsersHelper().getListWithThrow(membersList.usersID);
      _membersList = membersList;

      setState(() {});

      // Register to events
      this.listenChangeState<UserJoinedCallEvent>((e) {
        // TODO : get user information if required
        if (e.callID == convID) _membersList.add(CallMember(userID: e.userID));
      });

      this.listen<UserLeftCallEvent>((e) {
        if (e.callID == convID) _removeMember(e.userID);
      });

      this.listen<NewCallSignalEvent>((e) {
        if (e.callID == convID) _newSignal(e);
      });

      this.listen<CallPeerReadyEvent>((e) {
        if (e.callID == convID) _memberReady(e.peerID);
      });

      this.listen<CallPeerInterruptedStreamingEvent>((e) {
        if (e.callID == convID) _removeRemotePeerConnection(e.peerID);
      });

      this.listen<CallClosedEvent>((e) {
        if (e.callID == convID) _leaveCall(needConfirm: false);
      });

      // Connect to ready peers
      for (final peer in _membersList.readyPeers)
        await this._memberReady(peer.userID);
    } catch (e, stack) {
      print("Could not initialize call! $e\n$stack");
      setState(() => _error = true);
    }
  }

  /// Do clean up operations when call screen is destroyed
  void _endCall() async {
    try {
      // Leave the call
      await CallsHelper.leave(convID);
    } catch (e, stack) {
      print("Could not end call properly! $e\n$stack");
    }
  }

  /// Make us leave the call
  void _leaveCall({bool needConfirm = true}) async {
    if (needConfirm &&
        !await showConfirmDialog(
            context: context,
            message: tr("Do you really want to leave this call ?"))) return;

    MainController.of(context).popPage();
  }

  /// Call this when a user started to stream media
  Future<void> _memberReady(int memberID) async {
    try {
      _membersList.getUser(memberID).status = MemberStatus.READY;
      setState(() {});

      // Create peer connection
      final peerConnection = await createPeerConnection(_conf.pluginConfig, {
        "mandatory": {
          "OfferToReceiveAudio": true,
          "OfferToReceiveVideo":
              _conversation.callCapabilities == CallCapabilities.VIDEO,
        },
        "optional": [],
      });

      _peersConnections[memberID] = peerConnection;

      // Request an offer to establish a peer connection
      await CallsHelper.requestOffer(convID, memberID);
    } catch (e, stack) {
      print("Could not connect to remote peer $e\n$stack!");
      showSimpleSnack(context, tr("Could not connect to a remote peer!"));
    }
  }

  /// Call this method each time we get a new signal
  void _newSignal(NewCallSignalEvent ev) async {
    try {
      // Check if we can process this message
      if (!_peersConnections.containsKey(ev.peerID)) {
        print(
            "Could not process a signal for the connection with peer ${ev.peerID}!");
        return;
      }

      // Check the kind of signal
      // SessionDescription
      if (ev.sessionDescription != null) {
        await _peersConnections[ev.peerID]
            .setRemoteDescription(ev.sessionDescription);

        // Send answer if required
        if (ev.sessionDescription.type == "offer") {
          final answer = await _peersConnections[ev.peerID].createAnswer({});

          //TODO : Send answer back to server
          print("ANSWER TO SEND ${answer.toMap()}");
        }
      }

      // Ice Candidate
      else {
        await _peersConnections[ev.peerID].addCandidate(ev.candidate);
      }
    } catch (e, stack) {
      print("Error while handling new signal ! $e\n$stack");
      showSimpleSnack(context, tr("Error while processing new signal!"));
    }
  }

  /// Call this when a user has interrupted streaming
  void _removeRemotePeerConnection(int memberID) {
    _membersList.getUser(memberID).status = MemberStatus.JOINED;
    setState(() {});
  }

  /// Call this when a members has completely left the call
  void _removeMember(int memberID) {
    _removeRemotePeerConnection(memberID);

    _membersList.removeUser(memberID);
    setState(() {});
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        leading: IconButton(
          icon: Icon(Icons.arrow_back),
          onPressed: () => _leaveCall(),
        ),
        title:
            _convName == null ? CircularProgressIndicator() : Text(_convName),
      ),
      body: _buildBody(),
    );
  }

  /// Build widget body
  Widget _buildBody() {
    // Handle errors
    if (_error)
      return buildErrorCard(tr("Could not initialize call!"), actions: [
        MaterialButton(
          onPressed: () => _initCall(),
          child: Text(tr("Try again").toUpperCase()),
        )
      ]);

    // Check if are not ready to show call UI
    if (_membersList == null) return buildCenteredProgressBar();

    return Column(
      children: <Widget>[_buildMembersArea(), Spacer(), _buildFooterArea()],
    );
  }

  /// Build members area
  Widget _buildMembersArea() {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(8.0),
        child: RichText(
            text: TextSpan(
                children: _membersList
                    .map((f) => TextSpan(
                        text: _usersList.getUser(f.userID).displayName + " ",
                        style: TextStyle(
                            color: f.status == MemberStatus.JOINED
                                ? null
                                : Colors.green)))
                    .toList())),
      ),
    );
  }

  /// Footer area
  Widget _buildFooterArea() {
    return Material(
      color: Colors.black,
      child: Row(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          // Hang up call
          IconButton(
            icon: Icon(Icons.phone, color: Colors.red),
            onPressed: () => _leaveCall(),
          ),
        ],
      ),
    );
  }
}