93 lines
3.4 KiB
Dart
93 lines
3.4 KiB
Dart
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import 'dart:async';
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import 'remote_client.dart';
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import 'transport.dart';
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abstract class Server {
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final RemoteClient client;
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final Completer _done = Completer();
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StreamSubscription<OperationMessage> _sub;
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bool _init = false;
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Future get done => _done.future;
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Server(this.client) {
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_sub = client.stream.listen((msg) async {
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if (msg.type == OperationMessage.gqlConnectionInit && !_init) {
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try {
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Map connectionParams = null;
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if (msg.payload is Map)
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connectionParams = msg.payload as Map;
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else if (msg.payload != null)
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throw FormatException(
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'${msg.type} payload must be a map (object).');
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var connect = await onConnect(client, connectionParams);
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if (!connect) throw false;
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_init = true;
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client.sink.add(OperationMessage(OperationMessage.gqlConnectionAck));
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} catch (e) {
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if (e == false)
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_reportError('The connection was rejected.');
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else
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_reportError(e.toString());
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}
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} else if (_init) {
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if (msg.type == OperationMessage.gqlStart) {
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if (msg.id == null)
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throw FormatException('${msg.type} id is required.');
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if (msg.payload == null)
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throw FormatException('${msg.type} payload is required.');
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else if (msg.payload is! Map)
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throw FormatException(
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'${msg.type} payload must be a map (object).');
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var payload = msg.payload as Map;
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var query = payload['query'];
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var variables = payload['variables'];
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var operationName = payload['operationName'];
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if (query == null || query is! String)
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throw FormatException(
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'${msg.type} payload must contain a string named "query".');
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if (variables != null && variables is! Map)
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throw FormatException(
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'${msg.type} payload\'s "variables" field must be a map (object).');
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if (operationName != null && operationName is! String)
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throw FormatException(
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'${msg.type} payload\'s "operationName" field must be a string.');
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var result = await onOperation(
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msg.id,
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query as String,
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(variables as Map).cast<String, dynamic>(),
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operationName as String);
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var data = result.data;
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if (data is Stream) {
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await for (var event in data) {
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client.sink.add(OperationMessage(OperationMessage.gqlData,
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id: msg.id,
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payload: {'data': event, 'errors': result.errors}));
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}
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} else {
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client.sink.add(OperationMessage(OperationMessage.gqlData,
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id: msg.id, payload: {'data': data, 'errors': result.errors}));
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}
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client.sink
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.add(OperationMessage(OperationMessage.gqlComplete, id: msg.id));
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} else if (msg.type == OperationMessage.gqlConnectionTerminate) {
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await _sub?.cancel();
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}
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}
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}, onError: _done.completeError, onDone: _done.complete);
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}
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void _reportError(String message) {
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client.sink.add(OperationMessage(OperationMessage.gqlConnectionError,
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payload: {'message': message}));
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}
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FutureOr<bool> onConnect(RemoteClient client, [Map connectionParams]);
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FutureOr<GraphQLResult> onOperation(String id, String query,
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[Map<String, dynamic> variables, String operationName]);
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}
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