[ANCHOR-916] Put Horizon behind interface

core/src/main/java/org/stellar/anchor/ledger/Horizon.java

@@ -0,0 +1,145 @@
+package org.stellar.anchor.ledger;
+
+import static org.stellar.anchor.api.asset.AssetInfo.NATIVE_ASSET_CODE;
+
+import java.util.List;
+import java.util.stream.Collectors;
+import lombok.Getter;
+import org.stellar.anchor.config.AppConfig;
+import org.stellar.anchor.ledger.LedgerTransaction.LedgerTransactionResponse;
+import org.stellar.anchor.util.AssetHelper;
+import org.stellar.sdk.*;
+import org.stellar.sdk.exception.NetworkException;
+import org.stellar.sdk.requests.PaymentsRequestBuilder;
+import org.stellar.sdk.responses.AccountResponse;
+import org.stellar.sdk.responses.TransactionResponse;
+import org.stellar.sdk.responses.operations.OperationResponse;
+import org.stellar.sdk.xdr.AssetType;
+
+/** The horizon-server. */
+public class Horizon implements LedgerApi {
+
+  @Getter private final String horizonUrl;
+  @Getter private final String stellarNetworkPassphrase;
+  private final Server horizonServer;
+
+  public Horizon(AppConfig appConfig) {
+    this.horizonUrl = appConfig.getHorizonUrl();
+    this.stellarNetworkPassphrase = appConfig.getStellarNetworkPassphrase();
+    this.horizonServer = new Server(appConfig.getHorizonUrl());
+  }
+
+  public Server getServer() {
+    return this.horizonServer;
+  }
+
+  public boolean hasTrustline(String account, String asset) throws NetworkException {
+    String assetCode = AssetHelper.getAssetCode(asset);
+    if (NATIVE_ASSET_CODE.equals(assetCode)) {
+      return true;
+    }
+    String assetIssuer = AssetHelper.getAssetIssuer(asset);
+
+    AccountResponse accountResponse = getServer().accounts().account(account);
+    return accountResponse.getBalances().stream()
+        .anyMatch(
+            balance -> {
+              TrustLineAsset trustLineAsset = balance.getTrustLineAsset();
+              if (trustLineAsset.getAssetType() == AssetType.ASSET_TYPE_CREDIT_ALPHANUM4
+                  || trustLineAsset.getAssetType() == AssetType.ASSET_TYPE_CREDIT_ALPHANUM12) {
+                AssetTypeCreditAlphaNum creditAsset =
+                    (AssetTypeCreditAlphaNum) trustLineAsset.getAsset();
+                assert creditAsset != null;
+                return creditAsset.getCode().equals(assetCode)
+                    && creditAsset.getIssuer().equals(assetIssuer);
+              }
+              return false;
+            });
+  }
+
+  @Override
+  public Account getAccount(String account) throws NetworkException {
+    AccountResponse response = getServer().accounts().account(account);
+    AccountResponse.Thresholds thresholds = response.getThresholds();
+
+    return Account.builder()
+        .accountId(response.getAccountId())
+        .sequenceNumber(response.getSequenceNumber())
+        .thresholds(
+            LedgerApi.Thresholds.builder()
+                .lowThreshold(thresholds.getLowThreshold())
+                .medThreshold(thresholds.getMedThreshold())
+                .highThreshold(thresholds.getHighThreshold())
+                .build())
+        .balances(
+            response.getBalances().stream()
+                .map(
+                    b ->
+                        Balance.builder()
+                            .assetType(b.getAssetType())
+                            .assetCode(b.getAssetCode())
+                            .assetIssuer(b.getAssetIssuer())
+                            .liquidityPoolId(b.getLiquidityPoolId())
+                            .limit(b.getLimit())
+                            .build())
+                .collect(Collectors.toList()))
+        .signers(
+            response.getSigners().stream()
+                .map(
+                    s ->
+                        Signer.builder()
+                            .key(s.getKey())
+                            .type(s.getType())
+                            .weight(s.getWeight())
+                            .sponsor(s.getSponsor())
+                            .build())
+                .collect(Collectors.toList()))
+        .build();
+  }
+
+  @Override
+  public LedgerTransaction getTransaction(String transactionId) throws NetworkException {
+    TransactionResponse response = getServer().transactions().transaction(transactionId);
+    return LedgerTransaction.builder()
+        .hash(response.getHash())
+        .sourceAccount(response.getSourceAccount())
+        .envelopeXdr(response.getEnvelopeXdr())
+        .metaXdr(response.getResultMetaXdr())
+        .sourceAccount(response.getSourceAccount())
+        .memo(response.getMemo())
+        .sequenceNumber(response.getSourceAccountSequence())
+        .createdAt(response.getCreatedAt())
+        .build();
+  }
+
+  @Override
+  public LedgerTransactionResponse submitTransaction(Transaction transaction)
+      throws NetworkException {
+    TransactionResponse txnR = getServer().submitTransaction(transaction, false);
+
+    return LedgerTransactionResponse.builder()
+        .hash(txnR.getHash())
+        .metaXdr(txnR.getEnvelopeXdr())
+        .envelopXdr(txnR.getEnvelopeXdr())
+        .sourceAccount(txnR.getSourceAccount())
+        .feeCharged(txnR.getFeeCharged().toString())
+        .createdAt(txnR.getCreatedAt())
+        .build();
+  }
+
+  /**
+   * Get payment operations for a transaction.
+   *
+   * @param stellarTxnId the transaction id
+   * @return the operations
+   * @throws NetworkException request failed, see {@link PaymentsRequestBuilder#execute()}
+   */
+  public List<OperationResponse> getStellarTxnOperations(String stellarTxnId) {
+    return getServer()
+        .payments()
+        .includeTransactions(true)
+        .forTransaction(stellarTxnId)
+        .execute()
+        .getRecords();
+  }
+}

core/src/main/java/org/stellar/anchor/ledger/LedgerApi.java

@@ -0,0 +1,110 @@
+package org.stellar.anchor.ledger;
+
+import java.io.IOException;
+import java.util.List;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.Value;
+import org.stellar.sdk.KeyPair;
+import org.stellar.sdk.Transaction;
+import org.stellar.sdk.TransactionBuilderAccount;
+import org.stellar.sdk.exception.NetworkException;
+
+public interface LedgerApi {
+  /**
+   * Check if the account has a trustline for the given asset.
+   *
+   * @param account The account to check.
+   * @param asset The asset to check.
+   * @return True if the account has a trustline for the asset.
+   * @throws NetworkException If there was an error communicating with the network.
+   */
+  boolean hasTrustline(String account, String asset) throws NetworkException, IOException;
+
+  /**
+   * Get the account details for the given account.
+   *
+   * @param account The account to get.
+   * @return The account details.
+   * @throws NetworkException If there was an error communicating with the network.
+   */
+  Account getAccount(String account) throws NetworkException;
+
+  /**
+   * Get the operations for the given Stellar transaction.
+   *
+   * @param stellarTxnId The Stellar transaction ID.
+   * @return The operations for the transaction.
+   */
+  LedgerTransaction getTransaction(String stellarTxnId);
+
+  /**
+   * Submit a transaction to the network.
+   *
+   * @param transaction The transaction to submit.
+   * @return The transaction response.
+   * @throws NetworkException If there was an error communicating with the network.
+   */
+  LedgerTransaction.LedgerTransactionResponse submitTransaction(Transaction transaction)
+      throws NetworkException;
+
+  @Builder
+  @Getter
+  class Account implements TransactionBuilderAccount {
+    private String accountId;
+    private Long sequenceNumber;
+
+    private Thresholds thresholds;
+    private List<Balance> balances;
+    private List<Signer> signers;
+
+    @Override
+    public KeyPair getKeyPair() {
+      return KeyPair.fromAccountId(accountId);
+    }
+
+    @Override
+    public void setSequenceNumber(long seqNum) {
+      sequenceNumber = seqNum;
+    }
+
+    @Override
+    public Long getIncrementedSequenceNumber() {
+      return sequenceNumber + 1;
+    }
+
+    /** Increments sequence number in this object by one. */
+    public void incrementSequenceNumber() {
+      sequenceNumber++;
+    }
+  }
+
+  @Builder
+  @Getter
+  class Thresholds {
+    Integer lowThreshold;
+    Integer medThreshold;
+    Integer highThreshold;
+  }
+
+  @Builder
+  @Getter
+  class Balance {
+    String assetType;
+    String assetCode;
+    String assetIssuer;
+    String liquidityPoolId;
+    String limit;
+    String balance;
+  }
+
+  @Value
+  @Builder
+  @Getter
+  class Signer {
+    String key;
+    String type;
+    Integer weight;
+    String sponsor;
+  }
+}