/*
 * Copyright ConsenSys AG.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
package org.hyperledger.besu.ethereum.mainnet;

import org.hyperledger.besu.ethereum.chain.Blockchain;
import org.hyperledger.besu.ethereum.core.Address;
import org.hyperledger.besu.ethereum.core.BlockHeader;
import org.hyperledger.besu.ethereum.core.MutableWorldState;
import org.hyperledger.besu.ethereum.core.Transaction;
import org.hyperledger.besu.ethereum.core.TransactionReceipt;
import org.hyperledger.besu.ethereum.core.Wei;
import org.hyperledger.besu.ethereum.core.WorldState;
import org.hyperledger.besu.ethereum.core.WorldUpdater;
import org.hyperledger.besu.ethereum.core.fees.TransactionGasBudgetCalculator;
import org.hyperledger.besu.ethereum.privacy.storage.PrivateMetadataUpdater;
import org.hyperledger.besu.ethereum.processing.TransactionProcessingResult;
import org.hyperledger.besu.ethereum.vm.BlockHashLookup;
import org.hyperledger.besu.ethereum.vm.OperationTracer;
import org.hyperledger.besu.plugin.data.TransactionType;

import java.util.ArrayList;
import java.util.List;

import com.google.common.collect.ImmutableList;
import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.Tracer;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public abstract class AbstractBlockProcessor implements BlockProcessor {

  @FunctionalInterface
  public interface TransactionReceiptFactory {

    TransactionReceipt create(
        TransactionType transactionType,
        TransactionProcessingResult result,
        WorldState worldState,
        long gasUsed);
  }

  private static final Logger LOG = LogManager.getLogger();

  private static final Tracer tracer =
      OpenTelemetry.getGlobalTracer("org.hyperledger.besu.block", "1.0.0");

  static final int MAX_GENERATION = 6;

  public static class Result implements BlockProcessor.Result {

    private static final AbstractBlockProcessor.Result FAILED =
        new AbstractBlockProcessor.Result(false, null);

    private final boolean successful;

    private final List<TransactionReceipt> receipts;

    public static AbstractBlockProcessor.Result successful(
        final List<TransactionReceipt> receipts) {
      return new AbstractBlockProcessor.Result(true, ImmutableList.copyOf(receipts));
    }

    public static AbstractBlockProcessor.Result failed() {
      return FAILED;
    }

    Result(final boolean successful, final List<TransactionReceipt> receipts) {
      this.successful = successful;
      this.receipts = receipts;
    }

    @Override
    public List<TransactionReceipt> getReceipts() {
      return receipts;
    }

    @Override
    public boolean isSuccessful() {
      return successful;
    }
  }

  protected final MainnetTransactionProcessor transactionProcessor;

  protected final AbstractBlockProcessor.TransactionReceiptFactory transactionReceiptFactory;

  final Wei blockReward;

  protected final boolean skipZeroBlockRewards;

  protected final MiningBeneficiaryCalculator miningBeneficiaryCalculator;

  protected final TransactionGasBudgetCalculator gasBudgetCalculator;

  protected AbstractBlockProcessor(
      final MainnetTransactionProcessor transactionProcessor,
      final TransactionReceiptFactory transactionReceiptFactory,
      final Wei blockReward,
      final MiningBeneficiaryCalculator miningBeneficiaryCalculator,
      final boolean skipZeroBlockRewards,
      final TransactionGasBudgetCalculator gasBudgetCalculator) {
    this.transactionProcessor = transactionProcessor;
    this.transactionReceiptFactory = transactionReceiptFactory;
    this.blockReward = blockReward;
    this.miningBeneficiaryCalculator = miningBeneficiaryCalculator;
    this.skipZeroBlockRewards = skipZeroBlockRewards;
    this.gasBudgetCalculator = gasBudgetCalculator;
  }

  @Override
  public AbstractBlockProcessor.Result processBlock(
      final Blockchain blockchain,
      final MutableWorldState worldState,
      final BlockHeader blockHeader,
      final List<Transaction> transactions,
      final List<BlockHeader> ommers,
      final PrivateMetadataUpdater privateMetadataUpdater) {
    final Span globalProcessBlock =
        tracer.spanBuilder("processBlock").setSpanKind(Span.Kind.INTERNAL).startSpan();
    try {
      final List<TransactionReceipt> receipts = new ArrayList<>();
      long currentGasUsed = 0;
      for (final Transaction transaction : transactions) {
        if (!hasAvailableBlockBudget(blockHeader, transaction, currentGasUsed)) {
          return AbstractBlockProcessor.Result.failed();
        }

        final WorldUpdater worldStateUpdater = worldState.updater();
        final BlockHashLookup blockHashLookup = new BlockHashLookup(blockHeader, blockchain);
        final Address miningBeneficiary =
            miningBeneficiaryCalculator.calculateBeneficiary(blockHeader);

        final TransactionProcessingResult result =
            transactionProcessor.processTransaction(
                blockchain,
                worldStateUpdater,
                blockHeader,
                transaction,
                miningBeneficiary,
                OperationTracer.NO_TRACING,
                blockHashLookup,
                true,
                TransactionValidationParams.processingBlock(),
                privateMetadataUpdater);
        if (result.isInvalid()) {
          LOG.info(
              "Block processing error: transaction invalid '{}'. Block {} Transaction {}",
              result.getValidationResult().getInvalidReason(),
              blockHeader.getHash().toHexString(),
              transaction.getHash().toHexString());
          return AbstractBlockProcessor.Result.failed();
        }

        worldStateUpdater.commit();

        currentGasUsed += transaction.getGasLimit() - result.getGasRemaining();

        final TransactionReceipt transactionReceipt =
            transactionReceiptFactory.create(
                transaction.getType(), result, worldState, currentGasUsed);
        receipts.add(transactionReceipt);
      }

      if (!rewardCoinbase(worldState, blockHeader, ommers, skipZeroBlockRewards)) {
        // no need to log, rewardCoinbase logs the error.
        return AbstractBlockProcessor.Result.failed();
      }

      worldState.persist(blockHeader);
      return AbstractBlockProcessor.Result.successful(receipts);
    } finally {
      globalProcessBlock.end();
    }
  }

  protected boolean hasAvailableBlockBudget(
      final BlockHeader blockHeader, final Transaction transaction, final long currentGasUsed) {
    if (!gasBudgetCalculator.hasBudget(
        transaction, blockHeader.getNumber(), blockHeader.getGasLimit(), currentGasUsed)) {
      final long remainingGasBudget = blockHeader.getGasLimit() - currentGasUsed;
      LOG.info(
          "Block processing error: transaction gas limit {} exceeds available block budget"
              + " remaining {}. Block {} Transaction {}",
          transaction.getGasLimit(),
          remainingGasBudget,
          blockHeader.getHash().toHexString(),
          transaction.getHash().toHexString());
      return false;
    }

    return true;
  }

  protected MiningBeneficiaryCalculator getMiningBeneficiaryCalculator() {
    return miningBeneficiaryCalculator;
  }

  abstract boolean rewardCoinbase(
      final MutableWorldState worldState,
      final BlockHeader header,
      final List<BlockHeader> ommers,
      final boolean skipZeroBlockRewards);
}
