io.gdcc.xoai.dataprovider.handlers.GetRecordHandler Maven / Gradle / Ivy

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/*
 * The contents of this file are subject to the license and copyright
 * detailed in the LICENSE and NOTICE files at the root of the source
 * tree and available online at
 *
 * http://www.dspace.org/license/
 */

package io.gdcc.xoai.dataprovider.handlers;

import io.gdcc.xoai.dataprovider.exceptions.handler.CannotDisseminateFormatException;
import io.gdcc.xoai.dataprovider.exceptions.handler.HandlerException;
import io.gdcc.xoai.dataprovider.exceptions.handler.IdDoesNotExistException;
import io.gdcc.xoai.dataprovider.handlers.helpers.MetadataHelper;
import io.gdcc.xoai.dataprovider.model.Context;
import io.gdcc.xoai.dataprovider.model.Item;
import io.gdcc.xoai.dataprovider.model.MetadataFormat;
import io.gdcc.xoai.dataprovider.model.Set;
import io.gdcc.xoai.dataprovider.repository.Repository;
import io.gdcc.xoai.model.oaipmh.Request;
import io.gdcc.xoai.model.oaipmh.results.Record;
import io.gdcc.xoai.model.oaipmh.results.record.About;
import io.gdcc.xoai.model.oaipmh.results.record.Header;
import io.gdcc.xoai.model.oaipmh.results.record.Metadata;
import io.gdcc.xoai.model.oaipmh.verbs.GetRecord;
import java.util.Optional;

public final class GetRecordHandler extends VerbHandler {
    public GetRecordHandler(Context context, Repository repository) {
        super(context, repository);
    }

    @Override
    public GetRecord handle(final Request request) throws HandlerException {
        // Get the metadata format or throw errors
        String requestedFormat =
                request.getMetadataPrefix()
                        .orElseThrow(
                                () ->
                                        new CannotDisseminateFormatException(
                                                "Missing required argument 'metadataPrefix'"));
        MetadataFormat format =
                Optional.ofNullable(getContext().formatForPrefix(requestedFormat))
                        .orElseThrow(
                                () ->
                                        new CannotDisseminateFormatException(
                                                "Format '"
                                                        + requestedFormat
                                                        + "' not applicable in this context"));

        // Retrieve the item from our source repository, indicating the metadata format to enable
        // prefilled metadata
        String identifier = request.getIdentifier().orElseThrow(IdDoesNotExistException::new);
        Item item = getRepository().getItemRepository().getItem(identifier, format);

        // Check the item for existence, filter with context and format conditions
        if (item == null) throw new IdDoesNotExistException();
        if (!getContext().isItemShown(item))
            throw new IdDoesNotExistException("This context does not include this item");
        if (!format.isItemShown(item))
            throw new CannotDisseminateFormatException(
                    "Format " + format.getPrefix() + " not applicable to this item");

        // Construct the OAI PMH  model to be filled with data from the repository
        Header header = new Header();
        Record record = new Record().withHeader(header);
        GetRecord result = new GetRecord(record);

        // Build the  part of the response
        header.withIdentifier(item.getIdentifier());
        header.withDatestamp(item.getDatestamp());

        // Add set specifications containing this item.
        // Start with the sets from the context by checking if they contain the item
        getContext().getSets().stream()
                .filter(set -> set.isItemShown(item))
                .forEach(set -> header.withSetSpec(set.getSpec()));

        for (Set set : item.getSets()) header.withSetSpec(set.getSpec());

        // No  or  may be present if this item is deleted
        if (item.isDeleted()) {
            header.withStatus(Header.Status.DELETED);
        } else {
            // Next up:  response part. Skip the pipeline on request by the source.
            // Skip the metadata transformation on request by the source repository.
            Metadata metadata = item.getMetadata();
            if (!metadata.needsProcessing()) record.withMetadata(metadata);
            else record.withMetadata(MetadataHelper.process(metadata, format, getContext()));

            // Last add the  section if present (protocol spec says: optional and repeatable)
            for (About about : item.getAbout()) record.withAbout(about);
        }
        return result;
    }
}