/* ====================================================================
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You 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 org.apache.poi.openxml4j.opc;

import java.net.URI;
import java.net.URISyntaxException;
import java.util.Objects;

/**
 * A part relationship.
 * @version 1.0
 */
public final class PackageRelationship {

    private static URI containerRelationshipPart;

    static {
        try {
            containerRelationshipPart = new URI("/_rels/.rels");
        } catch (URISyntaxException e) {
            // Do nothing
        }
    }

    /* XML markup */

    public static final String ID_ATTRIBUTE_NAME = "Id";

    public static final String RELATIONSHIPS_TAG_NAME = "Relationships";

    public static final String RELATIONSHIP_TAG_NAME = "Relationship";

    public static final String TARGET_ATTRIBUTE_NAME = "Target";

    public static final String TARGET_MODE_ATTRIBUTE_NAME = "TargetMode";

    public static final String TYPE_ATTRIBUTE_NAME = "Type";

    /* End XML markup */

    /**
     * Relation id.
     */
    private final String id;

    /**
     * Reference to the package.
     */
    private final OPCPackage container;

    /**
     * Relationship type
     */
    private final String relationshipType;

    /**
     * Part of this relationship source
     */
    private final PackagePart source;

    /**
     * Targeting mode [Internal|External]
     */
    private final TargetMode targetMode;

    /**
     * Target URI
     */
    private final URI targetUri;

    /**
     * Constructor.
     *
     * @throws NullPointerException if inputs are null
     */
    public PackageRelationship(OPCPackage pkg, PackagePart sourcePart,
            URI targetUri, TargetMode targetMode, String relationshipType,
            String id) {
        if (pkg == null)
            throw new NullPointerException("pkg cannot be null");
        if (targetUri == null)
            throw new NullPointerException("targetUri cannot be null");
        if (relationshipType == null)
            throw new NullPointerException("relationshipType cannot be null");
        if (id == null)
            throw new NullPointerException("id cannot be null");

        this.container = pkg;
        this.source = sourcePart;
        this.targetUri = targetUri;
        this.targetMode = targetMode;
        this.relationshipType = relationshipType;
        this.id = id;
    }

    @Override
    public boolean equals(Object obj) {
        if (!(obj instanceof PackageRelationship)) {
            return false;
        }
        PackageRelationship rel = (PackageRelationship) obj;
        return (this.id.equals(rel.id)
                && this.relationshipType.equals(rel.relationshipType)
                && (rel.source == null || rel.source.equals(this.source))
                && this.targetMode == rel.targetMode && this.targetUri
                .equals(rel.targetUri));
    }

    @Override
    public int hashCode() {
        return Objects.hash(id,relationshipType,source,targetMode,targetUri);
    }

    /* Getters */

    public static URI getContainerPartRelationship() {
        return containerRelationshipPart;
    }

    /**
     * @return the container
     */
    public OPCPackage getPackage() {
        return container;
    }

    /**
     * @return the id
     */
    public String getId() {
        return id;
    }

    /**
     * @return the relationshipType
     */
    public String getRelationshipType() {
        return relationshipType;
    }

    /**
     * @return the source
     */
    public PackagePart getSource() {
        return source;
    }

    /**
     *
     * @return URL of the source part of this relationship
     */
    public URI getSourceURI() {
        if (source == null) {
            return PackagingURIHelper.PACKAGE_ROOT_URI;
        }
        return source._partName.getURI();
    }

    /**
     * @return the targetMode
     */
    public TargetMode getTargetMode() {
        return targetMode;
    }

    /**
     * @return the targetUri
     */
    public URI getTargetURI() {
        // If it's an external target, we don't
        //  need to apply our normal validation rules
        if(targetMode == TargetMode.EXTERNAL) {
            return targetUri;
        }

        // If it's an internal hyperlink target, we don't
        //  need to apply our normal validation rules
        if (PackageRelationshipTypes.HYPERLINK_PART.equals(relationshipType)) {
            return targetUri;
        }

        // Internal target
        // If it isn't absolute, resolve it relative
        //  to ourselves
        if (!targetUri.toASCIIString().startsWith("/")) {
            // So it's a relative part name, try to resolve it
            return PackagingURIHelper.resolvePartUri(getSourceURI(), targetUri);
        }
        return targetUri;
    }

    @Override
    public String toString() {
        return "id=" + id +
                " - container=" + container +
                " - relationshipType=" + relationshipType +
                (source == null ? " - source=null" : " - source=" + getSourceURI().toASCIIString()) +
                " - target=" + getTargetURI().toASCIIString() +
                (targetMode == null ? ",targetMode=null" : ",targetMode=" + targetMode);
    }
}
