feat: Added TopicRepository to search topics and topic messages

hiero-enterprise-base/src/main/java/com/openelements/hiero/base/data/ChunkInfo.java

@@ -0,0 +1,18 @@
+package com.openelements.hiero.base.data;
+
+import com.hedera.hashgraph.sdk.TransactionId;
+import org.jspecify.annotations.NonNull;
+
+import java.util.Objects;
+
+public record ChunkInfo(
+        @NonNull TransactionId initialTransactionId,
+        int nonce,
+        int number,
+        int total,
+        boolean scheduled
+) {
+    public ChunkInfo {
+        Objects.requireNonNull(initialTransactionId, "initialTransactionId must not be null");
+    }
+}

hiero-enterprise-base/src/main/java/com/openelements/hiero/base/data/Topic.java

@@ -0,0 +1,35 @@
+package com.openelements.hiero.base.data;
+
+import com.hedera.hashgraph.sdk.AccountId;
+import com.hedera.hashgraph.sdk.PublicKey;
+import com.hedera.hashgraph.sdk.TopicId;
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
+
+import java.time.Instant;
+import java.util.List;
+import java.util.Objects;
+
+public record Topic(
+        @NonNull  TopicId topicId,
+        @Nullable PublicKey adminKey,
+        @Nullable AccountId autoRenewAccount,
+        int autoRenewPeriod,
+        @NonNull Instant createdTimestamp,
+        @NonNull List<FixedFee> fixedFees,
+        @Nullable List<PublicKey> feeExemptKeyList,
+        @Nullable PublicKey feeScheduleKey,
+        @Nullable PublicKey submitKey,
+        boolean deleted,
+        String memo,
+        @NonNull Instant fromTimestamp,
+        @NonNull Instant toTimestamp
+) {
+    public Topic {
+        Objects.requireNonNull(topicId, "topicId must not be null");
+        Objects.requireNonNull(createdTimestamp, "createdTimestamp must not be null");
+        Objects.requireNonNull(fixedFees, "fixedFees must not be null");
+        Objects.requireNonNull(fromTimestamp, "fromTimestamp must not be null");
+        Objects.requireNonNull(toTimestamp, "toTimestamp must not be null");
+    }
+}

hiero-enterprise-base/src/main/java/com/openelements/hiero/base/data/TopicMessage.java

@@ -0,0 +1,27 @@
+package com.openelements.hiero.base.data;
+
+import com.hedera.hashgraph.sdk.AccountId;
+import com.hedera.hashgraph.sdk.TopicId;
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
+
+import java.time.Instant;
+import java.util.Objects;
+
+public record TopicMessage(
+        @Nullable ChunkInfo chunkInfo,
+        @NonNull Instant consensusTimestamp,
+        @NonNull String message,
+        @NonNull AccountId payerAccountId,
+        byte[] runningHash,
+        int runningHashVersion,
+        long sequenceNumber,
+        @NonNull TopicId topicId
+) {
+    public TopicMessage {
+        Objects.requireNonNull(consensusTimestamp, "consensusTimestamp must not be null");
+        Objects.requireNonNull(message, "message must not be null");
+        Objects.requireNonNull(payerAccountId, "payerAccountId must not be null");
+        Objects.requireNonNull(topicId, "topicId must not be null");
+    }
+}

hiero-enterprise-base/src/main/java/com/openelements/hiero/base/implementation/AbstractMirrorNodeClient.java

@@ -2,6 +2,7 @@
 
 import com.hedera.hashgraph.sdk.AccountId;
 import com.hedera.hashgraph.sdk.TokenId;
+import com.hedera.hashgraph.sdk.TopicId;
 import com.openelements.hiero.base.HieroException;
 import com.openelements.hiero.base.data.AccountInfo;
 import com.openelements.hiero.base.data.ExchangeRates;
@@ -12,6 +13,8 @@
 import com.openelements.hiero.base.data.NftMetadata;
 import com.openelements.hiero.base.data.TokenInfo;
 import com.openelements.hiero.base.data.TransactionInfo;
+import com.openelements.hiero.base.data.Topic;
+import com.openelements.hiero.base.data.TopicMessage;
 import com.openelements.hiero.base.mirrornode.MirrorNodeClient;
 import java.util.List;
 import java.util.Objects;
@@ -83,6 +86,20 @@ public final Optional<TransactionInfo> queryTransaction(@NonNull String transact
         return getJsonConverter().toTransactionInfo(json);
     }
 
+    @Override
+    @NonNull
+    public final Optional<Topic> queryTopicById(TopicId topicId) throws HieroException {
+        final JSON json = getRestClient().queryTopicById(topicId);
+        return getJsonConverter().toTopic(json);
+    }
+
+    @Override
+    @NonNull
+    public final Optional<TopicMessage> queryTopicMessageBySequenceNumber(TopicId topicId, long sequenceNumber) throws HieroException {
+        final JSON json = getRestClient().queryTopicMessageBySequenceNumber(topicId, sequenceNumber);
+        return getJsonConverter().toTopicMessage(json);
+    }
+
     @Override
     public @NonNull Optional<NftMetadata> getNftMetadata(TokenId tokenId) throws HieroException {
         throw new UnsupportedOperationException("Not yet implemented");

hiero-enterprise-base/src/main/java/com/openelements/hiero/base/implementation/MirrorNodeJsonConverter.java

@@ -10,6 +10,8 @@
 import com.openelements.hiero.base.data.Token;
 import com.openelements.hiero.base.data.TokenInfo;
 import com.openelements.hiero.base.data.Balance;
+import com.openelements.hiero.base.data.Topic;
+import com.openelements.hiero.base.data.TopicMessage;
 
 import java.util.List;
 import java.util.Optional;
@@ -48,4 +50,13 @@ public interface MirrorNodeJsonConverter<JSON> {
     List<Balance> toBalances(JSON node);
 
     List<Token> toTokens(JSON node);
+
+    @NonNull
+    Optional<Topic> toTopic(JSON json);
+
+    @NonNull
+    Optional<TopicMessage> toTopicMessage(JSON json);
+
+    @NonNull
+    List<TopicMessage> toTopicMessages(JSON json);
 }

hiero-enterprise-base/src/main/java/com/openelements/hiero/base/implementation/MirrorNodeRestClient.java

@@ -2,6 +2,7 @@
 
 import com.hedera.hashgraph.sdk.AccountId;
 import com.hedera.hashgraph.sdk.TokenId;
+import com.hedera.hashgraph.sdk.TopicId;
 import com.openelements.hiero.base.HieroException;
 import java.util.Objects;
 import org.jspecify.annotations.NonNull;
@@ -55,6 +56,16 @@ default  JSON queryTokenById(TokenId tokenId) throws HieroException {
         return doGetCall("/api/v1/tokens/" + tokenId);
     }
 
+    @NonNull
+    default JSON queryTopicById(TopicId topicId) throws HieroException {
+        return doGetCall("/api/v1/topics/" + topicId);
+    }
+
+    @NonNull
+    default JSON queryTopicMessageBySequenceNumber(TopicId topicId, long sequenceNumber) throws HieroException {
+        return doGetCall("/api/v1/topics/" + topicId + "/messages/" + sequenceNumber);
+    }
+
     @NonNull
     JSON doGetCall(@NonNull String path) throws HieroException;
 }

hiero-enterprise-base/src/main/java/com/openelements/hiero/base/implementation/TopicRepositoryImpl.java

@@ -0,0 +1,42 @@
+package com.openelements.hiero.base.implementation;
+
+import com.hedera.hashgraph.sdk.TopicId;
+import com.openelements.hiero.base.HieroException;
+import com.openelements.hiero.base.data.Page;
+import com.openelements.hiero.base.data.Topic;
+import com.openelements.hiero.base.data.TopicMessage;
+import com.openelements.hiero.base.mirrornode.MirrorNodeClient;
+import com.openelements.hiero.base.mirrornode.TopicRepository;
+import org.jspecify.annotations.NonNull;
+
+import java.util.Objects;
+import java.util.Optional;
+
+public class TopicRepositoryImpl implements TopicRepository {
+    private final MirrorNodeClient mirrorNodeClient;
+
+    public TopicRepositoryImpl(@NonNull final MirrorNodeClient mirrorNodeClient) {
+        this.mirrorNodeClient = Objects.requireNonNull(mirrorNodeClient, "mirrorNodeClient must not be null");
+    }
+
+    @Override
+    public @NonNull Optional<Topic> findTopicById(TopicId topicId) throws HieroException {
+        Objects.requireNonNull(topicId, "topicId must not be null");
+        return mirrorNodeClient.queryTopicById(topicId);
+    }
+
+    @Override
+    public @NonNull Page<TopicMessage> getMessages(TopicId topicId) throws HieroException {
+        Objects.requireNonNull(topicId, "topicId must not be null");
+        return mirrorNodeClient.queryTopicMessages(topicId);
+    }
+
+    @Override
+    public @NonNull Optional<TopicMessage> getMessageBySequenceNumber(TopicId topicId, long sequenceNumber) throws HieroException {
+        Objects.requireNonNull(topicId, "topicId must not be null");
+        if (sequenceNumber < 1) {
+            throw new IllegalArgumentException("sequenceNumber must be greater than 0");
+        }
+        return mirrorNodeClient.queryTopicMessageBySequenceNumber(topicId, sequenceNumber);
+    }
+}

hiero-enterprise-base/src/main/java/com/openelements/hiero/base/mirrornode/MirrorNodeClient.java

@@ -2,6 +2,7 @@
 
 import com.hedera.hashgraph.sdk.AccountId;
 import com.hedera.hashgraph.sdk.TokenId;
+import com.hedera.hashgraph.sdk.TopicId;
 import com.openelements.hiero.base.HieroException;
 import com.openelements.hiero.base.data.AccountInfo;
 import com.openelements.hiero.base.data.Balance;
@@ -15,6 +16,8 @@
 import com.openelements.hiero.base.data.Token;
 import com.openelements.hiero.base.data.TokenInfo;
 import com.openelements.hiero.base.data.TransactionInfo;
+import com.openelements.hiero.base.data.Topic;
+import com.openelements.hiero.base.data.TopicMessage;
 import com.openelements.hiero.base.data.Result;
 import com.openelements.hiero.base.data.BalanceModification;
 import java.util.List;
@@ -377,6 +380,77 @@ default Page<Balance> queryTokenBalancesForAccount(@NonNull String tokenId, @Non
         return queryTokenBalancesForAccount(TokenId.fromString(tokenId), AccountId.fromString(accountId));
     }
 
+    /**
+     * Return Topic for given topicId.
+     *
+     * @param topicId id of the topic
+     * @return Optional of Topic
+     * @throws HieroException if the search fails
+     */
+    @NonNull
+    Optional<Topic> queryTopicById(TopicId topicId) throws HieroException;
+
+    /**
+     * Return Topic for given topicId.
+     *
+     * @param topicId id of the topic
+     * @return Optional of Topic
+     * @throws HieroException if the search fails
+     */
+    @NonNull
+    default Optional<Topic> queryTopicById(String topicId) throws HieroException {
+        Objects.requireNonNull(topicId, "topicId must not be null");
+        return queryTopicById(TopicId.fromString(topicId));
+    }
+
+    /**
+     * Return TopicMessages for given topicId.
+     *
+     * @param topicId id of the topic
+     * @return Page of TopicMessage
+     * @throws HieroException if the search fails
+     */
+    @NonNull
+    Page<TopicMessage> queryTopicMessages(TopicId topicId) throws HieroException;
+
+    /**
+     * Return TopicMessages for given topicId.
+     *
+     * @param topicId id of the topic
+     * @return Page of TopicMessage
+     * @throws HieroException if the search fails
+     */
+    @NonNull
+    default Page<TopicMessage> queryTopicMessages(String topicId) throws HieroException {
+        Objects.requireNonNull(topicId, "topicId must not be null");
+        return queryTopicMessages(TopicId.fromString(topicId));
+    }
+
+    /**
+     * Return TopicMessage for given topicId.
+     *
+     * @param topicId id of the topic
+     * @param sequenceNumber sequenceNumber of the message
+     * @return Optional of TopicMessage
+     * @throws HieroException if the search fails
+     */
+    @NonNull
+    Optional<TopicMessage> queryTopicMessageBySequenceNumber(TopicId topicId, long sequenceNumber) throws HieroException;
+
+    /**
+     * Return TopicMessage for given topicId.
+     *
+     * @param topicId id of the topic
+     * @param sequenceNumber sequenceNumber of the message
+     * @return Optional of TopicMessage
+     * @throws HieroException if the search fails
+     */
+    @NonNull
+    default Optional<TopicMessage> queryTopicMessageBySequenceNumber(String topicId, long sequenceNumber) throws HieroException {
+        Objects.requireNonNull(topicId, "topicId must not be null");
+        return queryTopicMessageBySequenceNumber(TopicId.fromString(topicId), sequenceNumber);
+    }
+
     @NonNull
     Optional<NftMetadata> getNftMetadata(@NonNull TokenId tokenId) throws HieroException;
 

hiero-enterprise-base/src/main/java/com/openelements/hiero/base/mirrornode/TopicRepository.java

@@ -0,0 +1,88 @@
+package com.openelements.hiero.base.mirrornode;
+
+import com.hedera.hashgraph.sdk.TopicId;
+import com.openelements.hiero.base.HieroException;
+import com.openelements.hiero.base.data.Page;
+import com.openelements.hiero.base.data.Topic;
+import com.openelements.hiero.base.data.TopicMessage;
+import org.jspecify.annotations.NonNull;
+
+import java.util.Objects;
+import java.util.Optional;
+
+/**
+ * Interface for interacting with a Hiero network. This interface provides methods
+ * for searching Topic and TopicMessages.
+ */
+public interface TopicRepository {
+    /**
+     * Return Topic for given topicId.
+     *
+     * @param topicId id of the topic
+     * @return Optional of Topic
+     * @throws HieroException if the search fails
+     */
+    @NonNull
+    Optional<Topic> findTopicById(TopicId topicId) throws HieroException;
+
+    /**
+     * Return Topic for given topicId.
+     *
+     * @param topicId id of the topic
+     * @return Optional of Topic
+     * @throws HieroException if the search fails
+     */
+    @NonNull
+    default Optional<Topic> findTopicById(String topicId) throws HieroException {
+        Objects.requireNonNull(topicId, "topicId must not be null");
+        return findTopicById(TopicId.fromString(topicId));
+    }
+
+    /**
+     * Return TopicMessages for given topicId.
+     *
+     * @param topicId id of the topic
+     * @return Page of TopicMessage
+     * @throws HieroException if the search fails
+     */
+    @NonNull
+    Page<TopicMessage> getMessages(TopicId topicId) throws HieroException;
+
+    /**
+     * Return TopicMessages for given topicId.
+     *
+     * @param topicId id of the topic
+     * @return Page of TopicMessage
+     * @throws HieroException if the search fails
+     */
+    @NonNull
+    default Page<TopicMessage> getMessages(String topicId) throws HieroException {
+        Objects.requireNonNull(topicId, "topicId must not be null");
+        return getMessages(TopicId.fromString(topicId));
+    };
+
+    /**
+     * Return TopicMessage for given topicId.
+     *
+     * @param topicId id of the topic
+     * @param sequenceNumber sequenceNumber of the message
+     * @return Optional of TopicMessage
+     * @throws HieroException if the search fails
+     */
+    @NonNull
+    Optional<TopicMessage> getMessageBySequenceNumber(TopicId topicId, long sequenceNumber) throws HieroException;
+
+    /**
+     * Return TopicMessage for given topicId.
+     *
+     * @param topicId id of the topic
+     * @param sequenceNumber sequenceNumber of the message
+     * @return Optional of TopicMessage
+     * @throws HieroException if the search fails
+     */
+    @NonNull
+    default Optional<TopicMessage> getMessageBySequenceNumber(String topicId, long sequenceNumber) throws HieroException {
+        Objects.requireNonNull(topicId, "topicId must not be null");
+        return getMessageBySequenceNumber(TopicId.fromString(topicId), sequenceNumber);
+    };
+}