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/*
 * Copyright 2020 APICATALOG and HASMAC.
 *
 * 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 no.hasmac.jsonld.context;

import java.util.Collection;
import java.util.Map;

/**
 *
 * @see Term Selection
 *
 */
public final class TermSelector {

    // required
    private final ActiveContext activeContext;

    private final String variable;

    private final Collection containers;

    private final String typeLanguage;

    private TermSelector(final ActiveContext activeContext, final String variable, final Collection containers, final String typeLanguage) {
        this.activeContext = activeContext;
        this.variable = variable;
        this.containers = containers;
        this.typeLanguage = typeLanguage;
    }

    public static TermSelector with(final ActiveContext activeContext, final String variable, final Collection containers, final String typeLanguage) {
        return new TermSelector(activeContext, variable, containers, typeLanguage);
    }

    public String match(final Collection preferredValues) {

        // 1. If the active context has a null inverse context,
        //    set inverse context in active context to the result of calling
        //    the Inverse Context Creation algorithm using active context.
        if (activeContext.getInverseContext() == null) {
            activeContext.createInverseContext();
        }

        // 2. Initialize inverse context to the value of inverse context in active context.
        final InverseContext inverseContext = activeContext.getInverseContext();


        // 4.
        for (String container : containers) {
            Map map = inverseContext.getNullable(variable, container, typeLanguage);
            if (map != null) {
                for (String item : preferredValues) {
                    String result = map.get(item);
                    if (result != null) {
                        return result;
                    }
                }
            }
        }
        return null;
    }
}