/*
 * Copyright 2009-2013 by The Regents of the University of California
 * 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 from
 * 
 *     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 edu.uci.ics.pregelix.api.util;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.util.ReflectionUtils;

import edu.uci.ics.pregelix.api.graph.GlobalAggregator;
import edu.uci.ics.pregelix.api.graph.MessageCombiner;
import edu.uci.ics.pregelix.api.graph.MsgList;
import edu.uci.ics.pregelix.api.graph.NormalizedKeyComputer;
import edu.uci.ics.pregelix.api.graph.Vertex;
import edu.uci.ics.pregelix.api.io.VertexInputFormat;
import edu.uci.ics.pregelix.api.io.VertexOutputFormat;
import edu.uci.ics.pregelix.api.job.PregelixJob;

/**
 * Help to use the configuration to get the appropriate classes or instantiate
 * them.
 */
public class BspUtils {
    private static Configuration defaultConf = null;

    public static void setDefaultConfiguration(Configuration conf) {
        defaultConf = conf;
    }

    /**
     * Get the user's subclassed {@link VertexInputFormat}.
     * 
     * @param conf
     *            Configuration to check
     * @return User's vertex input format class
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static <I extends WritableComparable, V extends Writable, E extends Writable, M extends Writable> Class<? extends VertexInputFormat<I, V, E, M>> getVertexInputFormatClass(
            Configuration conf) {
        return (Class<? extends VertexInputFormat<I, V, E, M>>) conf.getClass(PregelixJob.VERTEX_INPUT_FORMAT_CLASS,
                null, VertexInputFormat.class);
    }

    /**
     * Create a user vertex input format class
     * 
     * @param conf
     *            Configuration to check
     * @return Instantiated user vertex input format class
     */
    @SuppressWarnings("rawtypes")
    public static <I extends WritableComparable, V extends Writable, E extends Writable, M extends Writable> VertexInputFormat<I, V, E, M> createVertexInputFormat(
            Configuration conf) {
        Class<? extends VertexInputFormat<I, V, E, M>> vertexInputFormatClass = getVertexInputFormatClass(conf);
        VertexInputFormat<I, V, E, M> inputFormat = ReflectionUtils.newInstance(vertexInputFormatClass, conf);
        return inputFormat;
    }

    /**
     * Get the user's subclassed {@link VertexOutputFormat}.
     * 
     * @param conf
     *            Configuration to check
     * @return User's vertex output format class
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static <I extends WritableComparable, V extends Writable, E extends Writable> Class<? extends VertexOutputFormat<I, V, E>> getVertexOutputFormatClass(
            Configuration conf) {
        return (Class<? extends VertexOutputFormat<I, V, E>>) conf.getClass(PregelixJob.VERTEX_OUTPUT_FORMAT_CLASS,
                null, VertexOutputFormat.class);
    }

    /**
     * Create a user vertex output format class
     * 
     * @param conf
     *            Configuration to check
     * @return Instantiated user vertex output format class
     */
    @SuppressWarnings("rawtypes")
    public static <I extends WritableComparable, V extends Writable, E extends Writable> VertexOutputFormat<I, V, E> createVertexOutputFormat(
            Configuration conf) {
        Class<? extends VertexOutputFormat<I, V, E>> vertexOutputFormatClass = getVertexOutputFormatClass(conf);
        return ReflectionUtils.newInstance(vertexOutputFormatClass, conf);
    }

    /**
     * Get the user's subclassed {@link MessageCombiner}.
     * 
     * @param conf
     *            Configuration to check
     * @return User's vertex combiner class
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static <I extends WritableComparable, M extends Writable, P extends Writable> Class<? extends MessageCombiner<I, M, P>> getMessageCombinerClass(
            Configuration conf) {
        return (Class<? extends MessageCombiner<I, M, P>>) conf.getClass(PregelixJob.Message_COMBINER_CLASS,
                DefaultMessageCombiner.class, MessageCombiner.class);
    }

    /**
     * Get the user's subclassed {@link GlobalAggregator}.
     * 
     * @param conf
     *            Configuration to check
     * @return User's vertex combiner class
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static <I extends WritableComparable, V extends Writable, E extends Writable, M extends Writable, P extends Writable, F extends Writable> Class<? extends GlobalAggregator<I, V, E, M, P, F>> getGlobalAggregatorClass(
            Configuration conf) {
        return (Class<? extends GlobalAggregator<I, V, E, M, P, F>>) conf.getClass(PregelixJob.GLOBAL_AGGREGATOR_CLASS,
                GlobalCountAggregator.class, GlobalAggregator.class);
    }

    public static String getJobId(Configuration conf) {
        return conf.get(PregelixJob.JOB_ID);
    }

    /**
     * Create a user vertex combiner class
     * 
     * @param conf
     *            Configuration to check
     * @return Instantiated user vertex combiner class
     */
    @SuppressWarnings("rawtypes")
    public static <I extends WritableComparable, M extends Writable, P extends Writable> MessageCombiner<I, M, P> createMessageCombiner(
            Configuration conf) {
        Class<? extends MessageCombiner<I, M, P>> vertexCombinerClass = getMessageCombinerClass(conf);
        return ReflectionUtils.newInstance(vertexCombinerClass, conf);
    }

    /**
     * Create a user-defined normalized key computer class
     * 
     * @param conf
     *            Configuration to check
     * @return Instantiated user-defined normalized key computer
     */
    public static NormalizedKeyComputer createNormalizedKeyComputer(Configuration conf) {
        Class<? extends NormalizedKeyComputer> nmkClass = getNormalizedKeyComputerClass(conf);
        return ReflectionUtils.newInstance(nmkClass, conf);
    }

    /**
     * Create a global aggregator class
     * 
     * @param conf
     *            Configuration to check
     * @return Instantiated user vertex combiner class
     */
    @SuppressWarnings("rawtypes")
    public static <I extends WritableComparable, V extends Writable, E extends Writable, M extends Writable, P extends Writable, F extends Writable> GlobalAggregator<I, V, E, M, P, F> createGlobalAggregator(
            Configuration conf) {
        Class<? extends GlobalAggregator<I, V, E, M, P, F>> globalAggregatorClass = getGlobalAggregatorClass(conf);
        return ReflectionUtils.newInstance(globalAggregatorClass, conf);
    }

    /**
     * Get the user's subclassed Vertex.
     * 
     * @param conf
     *            Configuration to check
     * @return User's vertex class
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static <I extends WritableComparable, V extends Writable, E extends Writable, M extends Writable> Class<? extends Vertex<I, V, E, M>> getVertexClass(
            Configuration conf) {
        return (Class<? extends Vertex<I, V, E, M>>) conf.getClass(PregelixJob.VERTEX_CLASS, null, Vertex.class);
    }

    /**
     * Create a user vertex
     * 
     * @param conf
     *            Configuration to check
     * @return Instantiated user vertex
     */
    @SuppressWarnings("rawtypes")
    public static <I extends WritableComparable, V extends Writable, E extends Writable, M extends Writable> Vertex<I, V, E, M> createVertex(
            Configuration conf) {
        Class<? extends Vertex<I, V, E, M>> vertexClass = getVertexClass(conf);
        Vertex<I, V, E, M> vertex = ReflectionUtils.newInstance(vertexClass, conf);
        return vertex;
    }

    /**
     * Get the user's subclassed vertex index class.
     * 
     * @param conf
     *            Configuration to check
     * @return User's vertex index class
     */
    @SuppressWarnings("unchecked")
    public static <I extends Writable> Class<I> getVertexIndexClass(Configuration conf) {
        if (conf == null)
            conf = defaultConf;
        return (Class<I>) conf.getClass(PregelixJob.VERTEX_INDEX_CLASS, WritableComparable.class);
    }

    /**
     * Create a user vertex index
     * 
     * @param conf
     *            Configuration to check
     * @return Instantiated user vertex index
     */
    @SuppressWarnings("rawtypes")
    public static <I extends WritableComparable> I createVertexIndex(Configuration conf) {
        Class<I> vertexClass = getVertexIndexClass(conf);
        try {
            return vertexClass.newInstance();
        } catch (InstantiationException e) {
            throw new IllegalArgumentException("createVertexIndex: Failed to instantiate", e);
        } catch (IllegalAccessException e) {
            throw new IllegalArgumentException("createVertexIndex: Illegally accessed", e);
        }
    }

    /**
     * Get the user's subclassed vertex value class.
     * 
     * @param conf
     *            Configuration to check
     * @return User's vertex value class
     */
    @SuppressWarnings("unchecked")
    public static <V extends Writable> Class<V> getVertexValueClass(Configuration conf) {
        return (Class<V>) conf.getClass(PregelixJob.VERTEX_VALUE_CLASS, Writable.class);
    }

    /**
     * Create a user vertex value
     * 
     * @param conf
     *            Configuration to check
     * @return Instantiated user vertex value
     */
    public static <V extends Writable> V createVertexValue(Configuration conf) {
        Class<V> vertexValueClass = getVertexValueClass(conf);
        try {
            return vertexValueClass.newInstance();
        } catch (InstantiationException e) {
            throw new IllegalArgumentException("createVertexValue: Failed to instantiate", e);
        } catch (IllegalAccessException e) {
            throw new IllegalArgumentException("createVertexValue: Illegally accessed", e);
        }
    }

    /**
     * Get the user's subclassed edge value class.
     * 
     * @param conf
     *            Configuration to check
     * @return User's vertex edge value class
     */
    @SuppressWarnings("unchecked")
    public static <E extends Writable> Class<E> getEdgeValueClass(Configuration conf) {
        return (Class<E>) conf.getClass(PregelixJob.EDGE_VALUE_CLASS, Writable.class);
    }

    /**
     * Create a user edge value
     * 
     * @param conf
     *            Configuration to check
     * @return Instantiated user edge value
     */
    public static <E extends Writable> E createEdgeValue(Configuration conf) {
        Class<E> edgeValueClass = getEdgeValueClass(conf);
        try {
            return edgeValueClass.newInstance();
        } catch (InstantiationException e) {
            throw new IllegalArgumentException("createEdgeValue: Failed to instantiate", e);
        } catch (IllegalAccessException e) {
            throw new IllegalArgumentException("createEdgeValue: Illegally accessed", e);
        }
    }

    /**
     * Get the user's subclassed vertex message value class.
     * 
     * @param conf
     *            Configuration to check
     * @return User's vertex message value class
     */
    @SuppressWarnings("unchecked")
    public static <M extends Writable> Class<M> getMessageValueClass(Configuration conf) {
        if (conf == null)
            conf = defaultConf;
        return (Class<M>) conf.getClass(PregelixJob.MESSAGE_VALUE_CLASS, Writable.class);
    }

    /**
     * Get the user's subclassed global aggregator's partial aggregate value class.
     * 
     * @param conf
     *            Configuration to check
     * @return User's global aggregate value class
     */
    @SuppressWarnings("unchecked")
    public static <M extends Writable> Class<M> getPartialAggregateValueClass(Configuration conf) {
        if (conf == null)
            conf = defaultConf;
        return (Class<M>) conf.getClass(PregelixJob.PARTIAL_AGGREGATE_VALUE_CLASS, Writable.class);
    }

    /**
     * Get the user's subclassed combiner's partial combine value class.
     * 
     * @param conf
     *            Configuration to check
     * @return User's global aggregate value class
     */
    @SuppressWarnings("unchecked")
    public static <M extends Writable> Class<M> getPartialCombineValueClass(Configuration conf) {
        if (conf == null)
            conf = defaultConf;
        return (Class<M>) conf.getClass(PregelixJob.PARTIAL_COMBINE_VALUE_CLASS, Writable.class);
    }

    /**
     * Get the user's subclassed normalized key computer class.
     * 
     * @param conf
     *            Configuration to check
     * @return User's normalized key computer class
     */
    @SuppressWarnings("unchecked")
    public static Class<? extends NormalizedKeyComputer> getNormalizedKeyComputerClass(Configuration conf) {
        if (conf == null)
            conf = defaultConf;
        return (Class<? extends NormalizedKeyComputer>) conf.getClass(PregelixJob.NMK_COMPUTER_CLASS,
                NormalizedKeyComputer.class);
    }

    /**
     * Get the user's subclassed normalized key computer class.
     * 
     * @param conf
     *            Configuration to check
     * @return User's global aggregate value class
     */
    @SuppressWarnings("unchecked")
    public static <M extends Writable> Class<M> getFinalAggregateValueClass(Configuration conf) {
        if (conf == null)
            conf = defaultConf;
        return (Class<M>) conf.getClass(PregelixJob.FINAL_AGGREGATE_VALUE_CLASS, Writable.class);
    }

    /**
     * Create a user vertex message value
     * 
     * @param conf
     *            Configuration to check
     * @return Instantiated user vertex message value
     */
    public static <M extends Writable> M createMessageValue(Configuration conf) {
        Class<M> messageValueClass = getMessageValueClass(conf);
        try {
            return messageValueClass.newInstance();
        } catch (InstantiationException e) {
            throw new IllegalArgumentException("createMessageValue: Failed to instantiate", e);
        } catch (IllegalAccessException e) {
            throw new IllegalArgumentException("createMessageValue: Illegally accessed", e);
        }
    }

    /**
     * Create a user partial aggregate value
     * 
     * @param conf
     *            Configuration to check
     * @return Instantiated user aggregate value
     */
    public static <M extends Writable> M createPartialAggregateValue(Configuration conf) {
        Class<M> aggregateValueClass = getPartialAggregateValueClass(conf);
        try {
            return aggregateValueClass.newInstance();
        } catch (InstantiationException e) {
            throw new IllegalArgumentException("createMessageValue: Failed to instantiate", e);
        } catch (IllegalAccessException e) {
            throw new IllegalArgumentException("createMessageValue: Illegally accessed", e);
        }
    }

    /**
     * Create a user partial combine value
     * 
     * @param conf
     *            Configuration to check
     * @return Instantiated user aggregate value
     */
    @SuppressWarnings("rawtypes")
    public static <M extends Writable> M createPartialCombineValue(Configuration conf) {
        Class<M> aggregateValueClass = getPartialCombineValueClass(conf);
        try {
            M instance = aggregateValueClass.newInstance();
            if (instance instanceof MsgList) {
                // set conf for msg list, if the value type is msglist
                ((MsgList) instance).setConf(conf);
            }
            return instance;
        } catch (InstantiationException e) {
            throw new IllegalArgumentException("createMessageValue: Failed to instantiate", e);
        } catch (IllegalAccessException e) {
            throw new IllegalArgumentException("createMessageValue: Illegally accessed", e);
        }
    }

    /**
     * Create a user aggregate value
     * 
     * @param conf
     *            Configuration to check
     * @return Instantiated user aggregate value
     */
    public static <M extends Writable> M createFinalAggregateValue(Configuration conf) {
        Class<M> aggregateValueClass = getFinalAggregateValueClass(conf);
        try {
            return aggregateValueClass.newInstance();
        } catch (InstantiationException e) {
            throw new IllegalArgumentException("createMessageValue: Failed to instantiate", e);
        } catch (IllegalAccessException e) {
            throw new IllegalArgumentException("createMessageValue: Illegally accessed", e);
        }
    }

    /**
     * Get the job configuration parameter whether the vertex states will increase dynamically
     * 
     * @param conf
     *            the job configuration
     * @return the boolean setting of the parameter, by default it is false
     */
    public static boolean getDynamicVertexValueSize(Configuration conf) {
        return conf.getBoolean(PregelixJob.INCREASE_STATE_LENGTH, false);
    }

    /**
     * Get the specified frame size
     * 
     * @param conf
     *            the job configuration
     * @return the specified frame size; -1 if it is not set by users
     */
    public static int getFrameSize(Configuration conf) {
        return conf.getInt(PregelixJob.FRAME_SIZE, -1);
    }
}