package yyx.hadoop.study;

import java.io.IOException;
import java.util.StringTokenizer;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;



public class WordCount {
	//inner class Mapper
	public static class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable> 
	{
		//map job value,Text type
		private Text word = new Text();
		private final static IntWritable one = new IntWritable(1);
		//map input type,Object and Text,output type,Text and IntWritable
		public void map(Object key, Text value, Context context ) throws IOException, InterruptedException {
			StringTokenizer itr = new StringTokenizer(value.toString());
			while(itr.hasMoreTokens()) {
				//get the word, store in Text
				word.set(itr.nextToken());
				context.write(word, one);
			}
		}
	}
	//inner class Reducer
	public static class IntSumReducer extends Reducer<Text, IntWritable, Text, IntWritable> 
	{
		private IntWritable result = new IntWritable();
		public void reduce(Text key, Iterable<IntWritable> values, Context context ) throws IOException, InterruptedException {
			int sum = 0;
			for(IntWritable val : values) {
				sum += val.get();
			}
			result.set(sum);
			context.write(key, result);
		}
	}
	
	public static void main(String[] args) throws Exception {
		Configuration conf = new Configuration();
		String[] otherArgs = new GenericOptionsParser(conf,args).getRemainingArgs();
//		System.out.println(otherArgs);
		if(otherArgs.length != 2) {
			System.out.println("Usage:wordcount <in> <out>");
			System.exit(2);
		}
//		if(args.length != 2) {
//			System.out.println("param error!");
//			System.exit(-1);
//		}
		
		Job job = new Job(conf, "word count");
		job.setJarByClass(WordCount.class);
		job.setMapperClass(TokenizerMapper.class);
		job.setCombinerClass(IntSumReducer.class);
		job.setReducerClass(IntSumReducer.class);
		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(IntWritable.class);
		FileInputFormat.addInputPath(job, new Path(args[0]));
		FileOutputFormat.setOutputPath(job, new Path(args[1]));
		System.exit(job.waitForCompletion(true) ? 0 : 1);
		
	}
}