plugins/org.eclipse.sirius.services.graphql.workspace/src/org/eclipse/sirius/services/graphql/workspace/internal/schema/ResourcePathField.java

/*******************************************************************************
 * Copyright (c) 2019 Obeo.
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *    Obeo - initial API and implementation
 *******************************************************************************/
package org.eclipse.sirius.services.graphql.workspace.internal.schema;

import java.util.Optional;

import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.IPath;

import graphql.Scalars;
import graphql.schema.DataFetcher;
import graphql.schema.GraphQLFieldDefinition;
import graphql.schema.GraphQLNonNull;

/**
 * The path field of the resources.
 *
 * @author sbegaudeau
 */
public final class ResourcePathField {

    /**
     * The name of the path field.
     */
    private static final String PATH_FIELD = "path"; //$NON-NLS-1$

    /**
     * The constructor.
     */
    private ResourcePathField() {
        // Prevent instantiation
    }

    /**
     * Returns the path field.
     *
     * @return The path field
     */
    public static GraphQLFieldDefinition build() {
        // @formatter:off
        return GraphQLFieldDefinition.newFieldDefinition()
                .name(PATH_FIELD)
                .type(new GraphQLNonNull(Scalars.GraphQLString))
                .dataFetcher(ResourcePathField.getPathDataFetcher())
                .build();
        // @formatter:on
    }

    /**
     * Returns the path data fetcher.
     *
     * @return The path data fetcher
     */
    private static DataFetcher<String> getPathDataFetcher() {
        // @formatter:off
        return environment -> Optional.of(environment.getSource())
                .filter(IResource.class::isInstance)
                .map(IResource.class::cast)
                .map(IResource::getProjectRelativePath)
                .map(IPath::toString)
                .orElse(null);
        // @formatter:on
    }
}