/*
 * 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.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Dictionary;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;

import org.osgi.framework.Constants;
import org.osgi.framework.Filter;
import org.osgi.framework.FrameworkUtil;
import org.osgi.framework.InvalidSyntaxException;
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. Therefore the map must not contain any
 * service.exported.* property and must contain the service.imported.* ones.
 * 
 * The service.intents property contains the intents provided by the service
 * itself combined with the intents added by the exporting distribution
 * provider. Qualified intents appear expanded on this property.
 * 
 * @Immutable
 * @version $Revision$
 */

public class EndpointDescription {
    private final Map<String, Object> properties;
    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 The map to create the Endpoint Description from.
     * @throws IllegalArgumentException When the properties are not proper for
     *         an Endpoint Description
     */

    public EndpointDescription(Map<String, Object> properties) {
        this(properties, null);
    }

    /**
     * Create an Endpoint Description based on a reference and optionally a map
     * of additional properties. The properties on the original service take
     * precedence over the ones in the map.
     * 
     * @param reference A service reference that can be exported
     * @param properties Additional properties to add. Can be <code>null</code>.
     * @throws IllegalArgumentException When the properties are not proper for
     *         an Endpoint Description
     */
    public EndpointDescription(ServiceReference reference, Map<String, Object> properties) {
        this(properties, reference);
        if (reference == null) {
            throw new NullPointerException("reference must not be null");
        }
    }

    private EndpointDescription(Map<String, Object> map, ServiceReference reference) {
        Map<String, Object> props = new TreeMap<String, Object>(String.CASE_INSENSITIVE_ORDER);

        if (map != null) {
            try {
                props.putAll(map);
            } catch (ClassCastException e) {
                IllegalArgumentException iae = new IllegalArgumentException("non-String key in properties");
                iae.initCause(e);
                throw iae;
            }
            if (props.size() < map.size()) {
                throw new IllegalArgumentException("duplicate keys with different cases in properties");
            }
        }

        if (reference != null) {
            for (String key : reference.getPropertyKeys()) {
                if (!props.containsKey(key)) {
                    props.put(key, reference.getProperty(key));
                }
            }
        }

        properties = Collections.unmodifiableMap(props);
        /* properties must be initialized before calling the following methods */
        interfaces = verifyInterfacesProperty();
        remoteServiceId = verifyLongProperty(RemoteConstants.SERVICE_REMOTE_ID);
        remoteFrameworkUUID = verifyStringProperty(RemoteConstants.SERVICE_REMOTE_FRAMEWORK_UUID);
        remoteUri = verifyStringProperty(RemoteConstants.SERVICE_REMOTE_URI);
    }

    /**
     * Verify and obtain the interface list from the properties.
     * 
     * @return A list with the interface names.
     * @throws IllegalArgumentException When the properties do not contain the
     *         right values for and interface list.
     * 
     */
    private List<String> verifyInterfacesProperty() {
        Object o = properties.get(Constants.OBJECTCLASS);
        if (o == null) {
            return Collections.EMPTY_LIST;
        }
        if (!(o instanceof String[])) {
            throw new IllegalArgumentException("objectClass must be a String[]");
        }
        String[] objectClass = (String[])o;
        for (String interf : objectClass) {
            try {
                getInterfaceVersion(interf);
            } catch (IllegalArgumentException e) {
                IllegalArgumentException iae = new IllegalArgumentException("Improper version for interface " + interf);
                iae.initCause(e);
                throw iae;
            }
        }
        return Collections.unmodifiableList(Arrays.asList(objectClass));
    }

    /**
     * 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);
        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 {
            return Long.parseLong((String)r);
        } catch (NumberFormatException e) {
            IllegalArgumentException iae =
                new IllegalArgumentException("Required property cannot be parsed as a long: " + propName);
            iae.initCause(e);
            throw iae;
        }
    }

    /**
     * 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;
    }

    /**
     * Provide 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;
    }

    /**
     * Provide 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.
     * For example:
     * 
     * <pre>
     * endpoint.version.com.acme.Foo
     * </pre>
     * 
     * The value of this property is in String format and will be converted to a
     * <code>Version</code> object by this method.
     * 
     * @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 version = (String)properties.get("endpoint.version." + name);
        return Version.parseVersion(version);
    }

    /**
     * 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 An unmodifiable list of the configuration types used for the
     *         associated endpoint and optionally synonyms.
     */
    public List<String> getConfigurationTypes() {
        return getStringPlusProperty(RemoteConstants.SERVICE_IMPORTED_CONFIGS);
    }

    /**
     * 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 An unmodifiable list of expanded intents that are provided by
     *         this endpoint.
     */
    public List<String> getIntents() {
        return getStringPlusProperty(RemoteConstants.SERVICE_INTENTS);
    }

    /**
     * Reads a 'String+' property from the properties map, which may be of type
     * String, String[] or Collection<String> and returns it as an unmodifiable
     * List.
     * 
     * @param key The property
     * @return An unmodifiable list
     * @throws Illegal
     */
    private List<String> getStringPlusProperty(String key) {
        Object value = properties.get(key);
        if (value == null) {
            return Collections.EMPTY_LIST;
        }

        if (value instanceof String) {
            return Collections.singletonList((String)value);
        }

        if (value instanceof String[]) {
            String[] values = (String[])value;
            List<String> result = new ArrayList<String>(values.length);
            for (String v : values) {
                if (v != null) {
                    result.add(v);
                }
            }
            return result;
        }

        if (value instanceof Collection<?>) {
            Collection<?> values = (Collection<?>)value;
            List<String> result = new ArrayList<String>(values.size());
            for (Iterator<?> iter = values.iterator(); iter.hasNext();) {
                Object v = iter.next();
                if ((v != null) && (v instanceof String)) {
                    result.add((String)v);
                }
            }
            return result;
        }

        return Collections.EMPTY_LIST;
    }

    /**
     * Return the framework UUID for the remote service, if present.
     * 
     * The property the framework UUID comes 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() {
        return 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.
     * 
     * @return The hashcode of this endpoint.
     */
    public int hashCode() {
        return getRemoteURI().hashCode();
    }

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

    /**
     * TODO
     * 
     * @param filter
     * @return
     * @throws InvalidSyntaxException
     */
    public boolean match(String filter) throws InvalidSyntaxException {
        Filter f = FrameworkUtil.createFilter(filter);
        Dictionary<String, Object> d = new UnmodifiableDictionary<String, Object>(properties);
        return f.matchCase(d);
    }

    /**
     * Unmodifiable wrapper for Dictionary.
     */
    private static class UnmodifiableDictionary<K, V> extends Dictionary<K, V> {
        private final Map<? extends K, ? extends V> wrapped;

        UnmodifiableDictionary(Map<? extends K, ? extends V> wrapped) {
            this.wrapped = wrapped;
        }

        public Enumeration<V> elements() {
            return (Enumeration<V>)Collections.enumeration(wrapped.values());
        }

        public V get(Object key) {
            return wrapped.get(key);
        }

        public boolean isEmpty() {
            return wrapped.isEmpty();
        }

        public Enumeration<K> keys() {
            return (Enumeration<K>)Collections.enumeration(wrapped.keySet());
        }

        public V put(K key, V value) {
            throw new UnsupportedOperationException();
        }

        public V remove(Object key) {
            throw new UnsupportedOperationException();
        }

        public int size() {
            return wrapped.size();
        }
    }
}