/*
 * 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.felix.ipojo.handler.temporal;

import org.apache.felix.ipojo.ConfigurationException;
import org.apache.felix.ipojo.PrimitiveHandler;
import org.apache.felix.ipojo.metadata.Element;
import org.apache.felix.ipojo.parser.FieldMetadata;
import org.apache.felix.ipojo.parser.MethodMetadata;
import org.apache.felix.ipojo.parser.PojoMetadata;
import org.apache.felix.ipojo.util.DependencyMetadataHelper;
import org.apache.felix.ipojo.util.DependencyModel;
import org.apache.felix.ipojo.util.DependencyStateListener;
import org.osgi.framework.Filter;
import org.osgi.framework.InvalidSyntaxException;

import java.util.*;

/**
 * Temporal dependency handler.
 * A temporal dependency waits (block) for the availability of the service.
 * If no provider arrives in the specified among of time, a runtime exception is thrown.
 *
 * @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a>
 */
public class TemporalHandler extends PrimitiveHandler implements DependencyStateListener {

    /**
     * Default timeout if not specified.
     */
    public static final int DEFAULT_TIMEOUT = 3000;
    /**
     * No policy.
     */
    public static final int NO_POLICY = 0;
    /**
     * Uses a nullable object.
     */
    public static final int NULLABLE = 1;
    /**
     * Uses a default-implementation object.
     */
    public static final int DEFAULT_IMPLEMENTATION = 2;
    /**
     * Uses an empty array.
     */
    public static final int EMPTY = 3;
    /**
     * Uses {@code null}.
     */
    public static final int NULL = 4;
    /**
     * The handler namespace.
     */
    public static final String NAMESPACE = "org.apache.felix.ipojo.handler.temporal";
    /**
     * The list of managed dependencies.
     */
    private List/*<deps>*/ m_dependencies = new ArrayList(1);

    /**
     * Start method. Starts managed dependencies.
     *
     * @see org.apache.felix.ipojo.Handler#start()
     */
    public void start() {
        for (int i = 0; i < m_dependencies.size(); i++) {
            ((TemporalDependency) m_dependencies.get(i)).start();
        }
    }

    /**
     * Stop method. Stops managed dependencies.
     *
     * @see org.apache.felix.ipojo.Handler#stop()
     */
    public void stop() {
        for (int i = 0; i < m_dependencies.size(); i++) {
            ((TemporalDependency) m_dependencies.get(i)).stop();
        }
        m_dependencies.clear();
    }

    /**
     * Configure method. Creates managed dependencies.
     *
     * @param meta       the component type metadata.
     * @param dictionary the instance configuration.
     * @throws ConfigurationException if the dependency is not configured correctly
     * @see org.apache.felix.ipojo.Handler#configure(org.apache.felix.ipojo.metadata.Element, java.util.Dictionary)
     */
    public void configure(Element meta, Dictionary dictionary) throws ConfigurationException {
        PojoMetadata manipulation = getFactory().getPojoMetadata();
        Element[] deps = meta.getElements("requires", NAMESPACE);

        // Also check with temporal is no requires.
        if (deps == null || deps.length == 0) {
            deps = meta.getElements("temporal", NAMESPACE);
        }

        // Get instance filters.
        Dictionary filtersConfiguration = getRequiresFilters(dictionary.get("temporal.filters"));
        if (filtersConfiguration == null || filtersConfiguration.isEmpty()) {
            // Fall back on the Requires handler configuration, if any
            filtersConfiguration = getRequiresFilters(dictionary.get("requires.filters"));
        }
        // Get from filters if any.
        Dictionary fromConfiguration = getRequiresFilters(dictionary.get("temporal.from"));
        if (fromConfiguration == null || fromConfiguration.isEmpty()) {
            // Fall back on the Requires handler configuration, if any
            fromConfiguration = getRequiresFilters(dictionary.get("requires.from"));
        }


        for (int i = 0; i < deps.length; i++) {
            if (!deps[i].containsAttribute("field") || m_dependencies.contains(deps[i].getAttribute("field"))) {
                error("One temporal dependency must be attached to a field or the field is already used");
                return;
            }
            String field = deps[i].getAttribute("field");

            String id = field;
            if (deps[i].containsAttribute("id")) {
                id = deps[i].getAttribute("id");
            }

            FieldMetadata fieldmeta = manipulation.getField(field);
            if (fieldmeta == null) {
                error("The field " + field + " does not exist in the class " + getInstanceManager().getClassName());
                return;
            }

            boolean agg = false;
            boolean collection = false;
            String spec = fieldmeta.getFieldType();
            if (spec.endsWith("[]")) {
                agg = true;
                spec = spec.substring(0, spec.length() - 2);
            } else if (Collection.class.getName().equals(spec)) {
                agg = true;
                collection = true;
                // Collection detected. Check for the specification attribute
                spec = deps[i].getAttribute("specification");
                if (spec == null) {
                    error("A dependency injected inside a Collection must contain the 'specification' attribute");
                }
            }

            // Determine the filter
            String fil = deps[i].getAttribute("filter");
            // Override the filter if filter configuration if available in the instance configuration
            if (filtersConfiguration != null && id != null && filtersConfiguration.get(id) != null) {
                fil = (String) filtersConfiguration.get(id);
            }

            // Check the from attribute
            String from = deps[i].getAttribute("from");
            if (fromConfiguration != null && id != null && fromConfiguration.get(id) != null) {
                from = (String) fromConfiguration.get(id);
            }

            if (from != null) {
                String fromFilter = "(|(instance.name=" + from + ")(service.pid=" + from + "))";
                if (agg) {
                    warn("The 'from' attribute is incompatible with aggregate requirements: only one provider will " +
                            "match : " + fromFilter);
                }
                if (fil != null) {
                    fil = "(&" + fromFilter + fil + ")"; // Append the two filters
                } else {
                    fil = fromFilter;
                }
            }

            Filter filter = null;
            if (fil != null) {
                try {
                    filter = getInstanceManager().getContext().createFilter(fil);
                } catch (InvalidSyntaxException e) {
                    throw new ConfigurationException("A requirement filter is invalid : " + filter, e);
                }
            }

            String prox = deps[i].getAttribute("proxy");
            // Use proxy by default except for array:
            boolean proxy = prox == null || prox.equals("true");

            if (prox == null && proxy) { // Proxy set because of the default.
                if (agg && !collection) { // Aggregate and array
                    proxy = false;
                }
            }

            if (proxy && agg) {
                if (!collection) {
                    error("Proxied aggregate temporal dependencies cannot be an array. Only collections are supported");
                }
            }

            long timeout = DEFAULT_TIMEOUT;
            if (deps[i].containsAttribute("timeout")) {
                String to = deps[i].getAttribute("timeout");
                if (to.equalsIgnoreCase("infinite") || to.equalsIgnoreCase("-1")) {
                    timeout = Long.MAX_VALUE; // Infinite wait time ...
                } else {
                    timeout = new Long(deps[i].getAttribute("timeout")).longValue();
                }
            }

            int policy = NO_POLICY;
            String di = null;
            String onTimeout = deps[i].getAttribute("onTimeout");
            if (onTimeout != null) {
                if (onTimeout.equalsIgnoreCase("nullable")) {
                    policy = NULLABLE;
                } else if (onTimeout.equalsIgnoreCase("empty-array") || onTimeout.equalsIgnoreCase("empty")) {
                    policy = EMPTY;
                    if (!agg) {
                        // The empty array policy can only be used on aggregate dependencies
                        error("Cannot use the empty array policy for " + field + " : non aggregate dependency.");
                    }
                } else if (onTimeout.equalsIgnoreCase("null")) {
                    policy = NULL;
                } else if (onTimeout.length() > 0) {
                    di = onTimeout;
                    policy = DEFAULT_IMPLEMENTATION;
                }
            }

            Class specification = DependencyMetadataHelper.loadSpecification(spec, getInstanceManager().getContext());
            TemporalDependency dep = new TemporalDependency(specification, agg, collection, proxy, filter, getInstanceManager().getContext(), timeout, policy, di, this);
            m_dependencies.add(dep);

            if (!proxy) { // Register method interceptor only if are not a proxy
                MethodMetadata[] methods = manipulation.getMethods();
                for (int k = 0; k < methods.length; k++) {
                    getInstanceManager().register(methods[k], dep);
                }
            }

            getInstanceManager().register(fieldmeta, dep);
        }
    }

    /**
     * Gets the requires filter configuration from the given object.
     * The given object must come from the instance configuration.
     * This method was made to fix FELIX-2688. It supports filter configuration using
     * an array:
     * <code>{"myFirstDep", "(property1=value1)", "mySecondDep", "(property2=value2)"});</code>
     * <p/>
     * Copied from DependencyHandler#getRequiresFilters(Object)
     *
     * @param requiresFiltersValue the value contained in the instance
     *                             configuration.
     * @return the dictionary. If the object in already a dictionary, just returns it,
     *         if it's an array, builds the dictionary.
     * @throws ConfigurationException the dictionary cannot be built
     */
    private Dictionary getRequiresFilters(Object requiresFiltersValue)
            throws ConfigurationException {
        if (requiresFiltersValue != null
                && requiresFiltersValue.getClass().isArray()) {
            String[] filtersArray = (String[]) requiresFiltersValue;
            if (filtersArray.length % 2 != 0) {
                throw new ConfigurationException(
                        "A requirement filter is invalid : "
                                + requiresFiltersValue);
            }
            Dictionary requiresFilters = new Hashtable();
            for (int i = 0; i < filtersArray.length; i += 2) {
                requiresFilters.put(filtersArray[i], filtersArray[i + 1]);
            }
            return requiresFilters;
        }

        return (Dictionary) requiresFiltersValue;
    }

    /**
     * Nothing to do.
     * A temporal dependency is always valid.
     *
     * @param dependencymodel dependency.
     * @see org.apache.felix.ipojo.util.DependencyStateListener#invalidate(org.apache.felix.ipojo.util.DependencyModel)
     */
    public void invalidate(DependencyModel dependencymodel) {
    }

    /**
     * Nothing to do.
     * A temporal dependency is always valid.
     *
     * @param dependencymodel dependency.
     * @see org.apache.felix.ipojo.util.DependencyStateListener#validate(org.apache.felix.ipojo.util.DependencyModel)
     */
    public void validate(DependencyModel dependencymodel) {
    }


}