/*
 * Copyright Consensys Software Inc., 2022
 *
 * 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.
 */

package tech.pegasys.teku.spec.logic.common.util;

import tech.pegasys.teku.infrastructure.ssz.collections.SszBytes32Vector;
import tech.pegasys.teku.infrastructure.unsigned.UInt64;
import tech.pegasys.teku.spec.datastructures.blocks.BeaconBlockHeader;
import tech.pegasys.teku.spec.datastructures.lightclient.LightClientBootstrap;
import tech.pegasys.teku.spec.datastructures.lightclient.LightClientHeader;
import tech.pegasys.teku.spec.datastructures.state.SyncCommittee;
import tech.pegasys.teku.spec.datastructures.state.beaconstate.BeaconState;
import tech.pegasys.teku.spec.datastructures.state.beaconstate.versions.altair.BeaconStateAltair;
import tech.pegasys.teku.spec.logic.versions.altair.helpers.BeaconStateAccessorsAltair;
import tech.pegasys.teku.spec.schemas.SchemaDefinitionsAltair;

public class LightClientUtil {

  private final BeaconStateAccessorsAltair beaconStateAccessors;
  private final SyncCommitteeUtil syncCommitteeUtil;
  private final SchemaDefinitionsAltair schemaDefinitionsAltair;

  public LightClientUtil(
      final BeaconStateAccessorsAltair beaconStateAccessors,
      final SyncCommitteeUtil syncCommitteeUtil,
      final SchemaDefinitionsAltair schemaDefinitionsAltair) {
    this.beaconStateAccessors = beaconStateAccessors;
    this.syncCommitteeUtil = syncCommitteeUtil;
    this.schemaDefinitionsAltair = schemaDefinitionsAltair;
  }

  public LightClientBootstrap getLightClientBootstrap(final BeaconState state) {
    final UInt64 currentEpoch = beaconStateAccessors.getCurrentEpoch(state);

    // Requires rehashing the state. See
    // https://github.com/ethereum/consensus-specs/blob/dev/specs/altair/light-client/full-node.md#create_light_client_bootstrap
    final LightClientHeader lightClientHeader =
        schemaDefinitionsAltair
            .getLightClientHeaderSchema()
            .create(BeaconBlockHeader.fromState(state));

    final SyncCommittee currentSyncCommittee =
        syncCommitteeUtil.getSyncCommittee(state, currentEpoch);

    final SszBytes32Vector currentSyncCommitteeProof =
        BeaconStateAltair.required(state).createCurrentSyncCommitteeProof();

    return schemaDefinitionsAltair
        .getLightClientBootstrapSchema()
        .create(lightClientHeader, currentSyncCommittee, currentSyncCommitteeProof);
  }
}
