/*
 * 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.sling.resourceresolver.impl.helper;

import org.apache.sling.adapter.annotations.Adaptable;
import org.apache.sling.adapter.annotations.Adapter;
import org.apache.sling.api.SlingException;
import org.apache.sling.api.resource.Resource;
import org.apache.sling.api.resource.ResourceMetadata;
import org.apache.sling.api.resource.ResourceResolver;
import org.apache.sling.api.resource.SyntheticResource;

/**
 * Used to provide the equivalent of an empty Node for GET requests to
 * *.something (SLING-344)
 */
@Adaptable(adaptableClass = Resource.class, adapters = @Adapter(value = { String.class }))
public class StarResource extends SyntheticResource {

    final static String SLASH_STAR = "/*";
    public final static String DEFAULT_RESOURCE_TYPE = "sling:syntheticStarResource";

    private static final String UNSET_RESOURCE_SUPER_TYPE = "<unset>";

    private String resourceSuperType;

    @SuppressWarnings("serial")
    static class SyntheticStarResourceException extends SlingException {
        SyntheticStarResourceException(String reason, Throwable cause) {
            super(reason, cause);
        }
    }

    /**
     * True if a StarResource should be used for the given request, if a real
     * Resource was not found
     */
    public static boolean appliesTo(String path) {
        return path.contains(SLASH_STAR) || path.endsWith(SLASH_STAR);
    }

    /**
     * Returns true if the path of the resource ends with the
     * {@link #SLASH_STAR} and therefore should be considered a star resource.
     */
    public static boolean isStarResource(Resource res) {
        return res.getPath().endsWith(SLASH_STAR);
    }

    public StarResource(ResourceResolver resourceResolver, String path) {
        super(resourceResolver, getResourceMetadata(path),
                DEFAULT_RESOURCE_TYPE);
        resourceSuperType = UNSET_RESOURCE_SUPER_TYPE;
    }

    /**
     * Calls {@link ResourceUtil#getResourceSuperType(ResourceResolver, String)}
     * method to dynamically resolve the resource super type of this star
     * resource.
     */
    @Override
    public String getResourceSuperType() {
        // Yes, this isn't how you're supposed to compare Strings, but this is
        // intentional.
        if (resourceSuperType == UNSET_RESOURCE_SUPER_TYPE) {
            resourceSuperType = this.getResourceResolver().getParentResourceType(this.getResourceType());
        }
        return resourceSuperType;
    }

    @Override
    @SuppressWarnings("unchecked")
    public <Type> Type adaptTo(Class<Type> type) {
        if (type == String.class) {
            return (Type) "";
        }
        return super.adaptTo(type);
    }

    /** Get our ResourceMetadata for given path */
    static ResourceMetadata getResourceMetadata(String path) {
        ResourceMetadata result = new ResourceMetadata();

        // The path is up to /*, what follows is pathInfo
        final int index = path.indexOf(SLASH_STAR);
        if (index >= 0) {
            result.setResolutionPath(path.substring(0, index) + SLASH_STAR);
            result.setResolutionPathInfo(path.substring(index
                    + SLASH_STAR.length()));
        } else {
            result.setResolutionPath(path);
        }
        return result;
    }
}