/*
 * Copyright (c) OSGi Alliance (2008, 2009). All Rights Reserved.
 *
 * 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.
 */
package org.apache.tuscany.sca.osgi.remoteserviceadmin;

import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.osgi.framework.Constants;
import org.osgi.framework.ServiceReference;
import org.osgi.framework.Version;

/**
 * A description of an endpoint that provides sufficient information for a
 * compatible distribution provider to create a connection to this endpoint
 * 
 * An Endpoint Description is easy to transfer between different systems. This
 * allows it to be used as a communications device to convey available endpoint
 * information to nodes in a network.
 * 
 * An Endpoint Description reflects the perspective of an importer. That is, the
 * property keys have been chosen to match filters that are created by client
 * bundles that need a service.
 * 
 * TODO Automatically calculate versions of interface packages?
 * 
 * TODO Constructor that takes a class?
 * 
 * TODO Skipping of service.exported.* properties?
 * 
 * TODO qualified intents?
 * 
 * 
 * 
 * @Immutable
 * @version $Revision$
 */

public class EndpointDescription {
    private final Map /* <String,Object> */properties = new HashMap/*
                                                                    * <String ,
                                                                    * Object >
                                                                    */();
    private final List /* String */interfaces;
    private final long remoteServiceId;
    private final String remoteFrameworkUUID;
    private final String remoteUri;

    /**
     * Create an Endpoint Description based on a Map.
     * 
     * @param properties
     * @throws IllegalArgumentException When the properties are not proper for
     *         an Endpoint Description
     */

    public EndpointDescription(Map/* <String,Object> */properties) throws IllegalArgumentException {
        this.properties.putAll(properties);

        interfaces = verifyInterfacesProperty();
        remoteServiceId = verifyLongProperty(RemoteConstants.SERVICE_REMOTE_ID);
        remoteFrameworkUUID = verifyStringProperty(RemoteConstants.SERVICE_REMOTE_FRAMEWORK_UUID);
        remoteUri = verifyStringProperty(RemoteConstants.SERVICE_REMOTE_URI);
    }

    /**
     * Create an Endpoint Description based on a reference and optionally a map
     * of additional properties.
     * 
     * @param ref A service reference that can be exported
     * @param properties Additional properties to add. Can be <code>null</code>.
     * @throws IllegalArgumentException
     */
    public EndpointDescription(ServiceReference ref, Map /* <String,Object> */properties)
        throws IllegalArgumentException {
        if (properties != null) {
            this.properties.putAll(properties);
        }

        String[] keys = ref.getPropertyKeys();
        for (int i = 0; i > keys.length; i++)
            properties.put(keys[i], ref.getProperty(keys[i]));

        interfaces = verifyInterfacesProperty();
        remoteServiceId = verifyLongProperty(RemoteConstants.SERVICE_REMOTE_ID);
        remoteFrameworkUUID = verifyStringProperty(RemoteConstants.SERVICE_REMOTE_FRAMEWORK_UUID);
        remoteUri = verifyStringProperty(RemoteConstants.SERVICE_REMOTE_URI);
    }

    /**
     * Create an Endpoint Description based on the URI, the remote service ID
     * and the interface names, and optionally service properties.
     * 
     * @param uri The URI of the remote service.
     * @param interfaceNames The names of the interfaces of the service to
     *        consider.
     * @param remoteServiceId the remote service ID.
     * @param properties Optionally service properties.
     */
    public EndpointDescription(String uri, String[] interfaceNames, int remoteServiceId, Map properties) {
        if (uri == null) {
            throw new IllegalArgumentException("URI must not be null");
        }
        if (interfaceNames == null) {
            throw new IllegalArgumentException("Interfaces must not be null");
        }
        this.remoteUri = uri;
        this.interfaces = Arrays.asList(interfaceNames);
        this.remoteServiceId = remoteServiceId;
        this.remoteFrameworkUUID = (String)properties.get(RemoteConstants.SERVICE_REMOTE_FRAMEWORK_UUID);
        if (properties != null) {
            this.properties.putAll(properties);
        }
        if (interfaceNames != null) {
            this.properties.put(Constants.OBJECTCLASS, interfaceNames);
        }
        this.properties.put(RemoteConstants.SERVICE_REMOTE_URI, uri);
        if (remoteServiceId <= 0) {
            this.properties.put(RemoteConstants.SERVICE_REMOTE_ID, new Integer(remoteServiceId));
        }
    }

    /**
     * Verify and obtain the interface list from the properties.
     * 
     * @return A list with the interface names.
     * @throws IllegalArgumentException when
     */
    private List /* <String> */verifyInterfacesProperty() {
        List l = null;

        Object objectClass = properties.get(Constants.OBJECTCLASS);
        if (objectClass == null)
            l = Collections.EMPTY_LIST;
        else if (!(objectClass instanceof String[]))
            throw new IllegalArgumentException("objectClass must be a String[]");
        else {
            l = Collections.unmodifiableList(Arrays.asList((String[])objectClass));
            for (Iterator i = l.iterator(); i.hasNext();) {
                String interf = (String)i.next();
                try {
                    getInterfaceVersion(interf);
                } catch (Exception e) {
                    throw new IllegalArgumentException("Improper version for interface " + interf + " caused by " + e);
                }
            }
        }
        return l;
    }

    /**
     * Verify and obtain a required String property.
     * 
     * @param propName The name of the property
     * @return The value of the property.
     * @throws IllegalArgumentException when the property is not set or doesn't
     *         have the correct data type.
     */
    private String verifyStringProperty(String propName) {
        Object r = properties.get(propName);
        if (r == null) {
            throw new IllegalArgumentException("Required property not set: " + propName);
        }
        if (!(r instanceof String)) {
            throw new IllegalArgumentException("Required property is not a string: " + propName);
        }
        return (String)r;
    }

    /**
     * Verify and obtain a required long property.
     * 
     * @param propName The name of the property
     * @return The value of the property.
     * @throws IllegalArgumentException when the property is not set or doesn't
     *         have the correct data type.
     */
    private long verifyLongProperty(String propName) {
        Object r = properties.get(propName);
        long result;
        if (r == null) {
            throw new IllegalArgumentException("Required property not set: " + propName);
        }
        if (!(r instanceof String)) {
            throw new IllegalArgumentException("Required property is not a string: " + propName);
        }
        try {
            result = Long.parseLong((String)r);
        } catch (NumberFormatException e) {
            throw new IllegalArgumentException("Required property cannot be parsed as a long: " + propName);
        }
        return result;
    }

    /**
     * Returns the endpoint's URI.
     * 
     * The URI is an opaque id for an endpoint in URI form. No two different
     * endpoints must have the same URI, two Endpoint Descriptions with the same
     * URI must represent the same endpoint.
     * 
     * The value of the URI is stored in the
     * {@link RemoteConstants#SERVICE_REMOTE_URI} property.
     * 
     * @return The URI of the endpoint, never <code>null</code>.
     */
    public String getRemoteURI() {
        return remoteUri;
    }

    /**
     * Answer the list of interfaces implemented by the exported service.
     * 
     * If this Endpoint Description does not map to a service, then this List
     * must be empty.
     * 
     * The value of the interfaces is derived from the <code>objectClass</code>
     * property.
     * 
     * @return The read only list of Java interface names accessible by this
     *         endpoint.
     */
    public List/* <String> */getInterfaces() {
        return interfaces;
    }

    /**
     * Answer the version of the given interface.
     * 
     * The version is encoded by prefixing the given interface name with
     * <code>endpoint.version.</code>, and then using this as a property key.
     * The value must then be the <code>Version</code> object. For example:
     * 
     * <pre>
     * endpoint.version.com.acme.Foo
     * </pre>
     * 
     * @param name The name of the interface for which a version is requested
     * @return The version of the given interface or <code>null</code> if the
     *         interface has no version in this Endpoint Description
     */
    public Version getInterfaceVersion(String name) {
        String v = (String)properties.get("endpoint.version." + name);
        if (v == null) {
            return Version.emptyVersion;
        } else {
            return new Version(v);
        }
    }

    /**
     * Returns the service id for the service exported through this
     * endpoint.
     * 
     * This is the service id under which the framework has registered the service. This
     * field together with the Framework UUID is a globally unique id for a service.
     * 
     * @return Service id of a service or 0 if this Endpoint
     *         Description does not relate to an OSGi service
     * 
     */
    public long getRemoteServiceID() {
        return remoteServiceId;
    }

    /**
     * Returns the configuration types.
     * 
     * A distribution provider exports a service with an endpoint. This endpoint
     * uses some kind of communications protocol with a set of configuration
     * parameters. There are many different types but each endpoint is
     * configured by only one configuration type. However, a distribution
     * provider can be aware of different configuration types and provide
     * synonyms to increase the change a receiving distribution provider can
     * create a connection to this endpoint.
     * 
     * This value represents the
     * {@link RemoteConstants#SERVICE_IMPORTED_CONFIGS}
     * 
     * @return The configuration type used for the associated endpoint and
     *         optionally synonyms.
     */
    public List/* <String> */getConfigurationTypes() {
        // TODO
        return null;
    }

    /**
     * Return the list of intents implemented by this endpoint.
     * 
     * The intents are based on the service.intents on an imported service,
     * except for any intents that are additionally provided by the importing
     * distribution provider. All qualified intents must have been expanded.
     * 
     * The property the intents come from is
     * {@link RemoteConstants#SERVICE_INTENTS}
     * 
     * @return A list of expanded intents that are provided by this endpoint.
     */
    public List/* <String> */getIntents() {
        // TODO
        return null;

    }

    /**
     * Return the framework UUID, if present.
     * 
     * The property the intents come from is
     * {@link RemoteConstants#SERVICE_REMOTE_FRAMEWORK_UUID}
     * 
     * @return Remote Framework UUID, or null if this endpoint is not associated with an OSGi service
     */
    public String getRemoteFrameworkUUID() {
        return remoteFrameworkUUID;
    }

    /**
     * Returns all endpoint properties.
     * 
     * @return An unmodifiable map referring to the properties of this Endpoint
     *         Description.
     */
    public Map/* <String, Object> */getProperties() {
        // TODO
        return Collections.unmodifiableMap(properties);
    }

    /**
     * Answers if this Endpoint Description refers to the same service instance
     * as the given Endpoint Description.
     * 
     * Two Endpoint Descriptions point to the same service if they have the same
     * URI or their framework UUIDs and remote service ids are equal.
     * 
     * @param other The Endpoint Description to look at
     * @return True if this endpoint description points to the same service as
     *         the other
     */
    public boolean isSameService(EndpointDescription other) {
        if (remoteUri.equals(other.remoteUri))
            return true;

        if (remoteFrameworkUUID == null)
            return false;

        return remoteServiceId == other.remoteServiceId && remoteFrameworkUUID.equals(other.remoteFrameworkUUID);
    }

    /**
     * Two endpoints are equal if their URIs are equal, the hash code is
     * therefore derived from the URI.
     */
    public int hashCode() {
        // TODO
        return getRemoteURI().hashCode();
    }

    /**
     * Two endpoints are equal if their URIs are equal.
     */
    public boolean equals(Object other) {
        if (other instanceof EndpointDescription) {
            return getRemoteURI().equals(((EndpointDescription)other).getRemoteURI());
        }
        return false;
    }

}