gRPC API for payments service

service/src/main/java/org/whispersystems/textsecuregcm/grpc/PaymentsGrpcService.java

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+/*
+ * Copyright 2023 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.grpc;
+
+import static java.util.Objects.requireNonNull;
+
+import io.grpc.Status;
+import java.math.BigDecimal;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+import javax.annotation.Nonnull;
+import org.apache.commons.lang3.tuple.Pair;
+import org.signal.chat.payments.GetCurrencyConversionsRequest;
+import org.signal.chat.payments.GetCurrencyConversionsResponse;
+import org.signal.chat.payments.ReactorPaymentsGrpc;
+import org.whispersystems.textsecuregcm.auth.grpc.AuthenticationUtil;
+import org.whispersystems.textsecuregcm.currency.CurrencyConversionManager;
+import org.whispersystems.textsecuregcm.entities.CurrencyConversionEntityList;
+import reactor.core.publisher.Mono;
+
+public class PaymentsGrpcService extends ReactorPaymentsGrpc.PaymentsImplBase {
+
+  private final CurrencyConversionManager currencyManager;
+
+
+  public PaymentsGrpcService(final CurrencyConversionManager currencyManager) {
+    this.currencyManager = requireNonNull(currencyManager);
+  }
+
+  @Override
+  public Mono<GetCurrencyConversionsResponse> getCurrencyConversions(final GetCurrencyConversionsRequest request) {
+    AuthenticationUtil.requireAuthenticatedDevice();
+
+    final CurrencyConversionEntityList currencyConversionEntityList = currencyManager
+        .getCurrencyConversions()
+        .orElseThrow(Status.UNAVAILABLE::asRuntimeException);
+
+    final List<GetCurrencyConversionsResponse.CurrencyConversionEntity> currencyConversionEntities = currencyConversionEntityList
+        .getCurrencies()
+        .stream()
+        .map(cce -> GetCurrencyConversionsResponse.CurrencyConversionEntity.newBuilder()
+            .setBase(cce.getBase())
+            .putAllConversions(transformBigDecimalsToStrings(cce.getConversions()))
+            .build())
+        .toList();
+
+    return Mono.just(GetCurrencyConversionsResponse.newBuilder()
+        .addAllCurrencies(currencyConversionEntities).setTimestamp(currencyConversionEntityList.getTimestamp())
+        .build());
+  }
+
+  @Nonnull
+  private static Map<String, String> transformBigDecimalsToStrings(final Map<String, BigDecimal> conversions) {
+    AuthenticationUtil.requireAuthenticatedDevice();
+    return conversions.entrySet().stream()
+        .map(e -> Pair.of(e.getKey(), e.getValue().toString()))
+        .collect(Collectors.toMap(Pair::getKey, Pair::getValue));
+  }
+}