/*This has been created by Mohammad Hammoud- Nov. 3, 2011.
 *CMUQ.
 * */

import java.util.*;
import java.io.*;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapred.*;
import org.apache.hadoop.util.*;

public class WordCount{
	
	public static class Map extends MapReduceBase implements Mapper<LongWritable,Text, Text, IntWritable>{
		
		Text word = new Text();
		IntWritable count = new IntWritable(1);
		
		public void map(LongWritable key, Text value, OutputCollector<Text, IntWritable> output, Reporter report) throws IOException{
			
			String line = value.toString();
			
			StringTokenizer tokenizer = new StringTokenizer(line);
			
			while(tokenizer.hasMoreTokens()){
				word.set(tokenizer.nextToken());
				output.collect(word, count);
			}
		}
		
	}
	public static class Reduce extends MapReduceBase implements Reducer<Text, IntWritable, Text, IntWritable>{
		
		public void reduce(Text key, Iterator<IntWritable> values, OutputCollector<Text, IntWritable> output, Reporter report) throws IOException{
			
			int sum = 0;
			
			while(values.hasNext()){
				sum += values.next().get();
			}
			
			output.collect(key, new IntWritable(sum));
			
		}
	}
	public static void main(String args[]) throws Exception{
		
		JobConf conf = new JobConf(WordCount.class);
		conf.setJobName("wordcount");
		conf.setOutputKeyClass(Text.class);
		conf.setOutputValueClass(IntWritable.class);
		conf.setMapperClass(Map.class);
		conf.setReducerClass(Reduce.class);
		conf.setInputFormat(TextInputFormat.class);
		conf.setOutputFormat(TextOutputFormat.class);
		conf.setNumReduceTasks(1);
		FileInputFormat.setInputPaths(conf, new Path(args[0]));
		FileOutputFormat.setOutputPath(conf, new Path(args[1]));
		
		JobClient.runJob(conf);
	}

}