package iv3;



import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
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.Reducer.Context;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

public class TopValues extends Configured implements Tool{

	public static class TopValuesMapper extends Mapper<LongWritable,Text,Text,Text>	{	
		String column_delimiter;
		int column_to_rank;
		int rank_limit,rank_key;
		Boolean sort_ascending;

		@Override
		public void setup(Context context) 	{
			Configuration conf = context.getConfiguration();
			column_delimiter = conf.get("column.delimiter");
			column_to_rank = conf.getInt("column.to.rank", Integer.MIN_VALUE) - 1;
			rank_limit = conf.getInt("rank.limit", Integer.MIN_VALUE);
			rank_key = conf.getInt("rank.keys", Integer.MIN_VALUE)-1;
			sort_ascending = conf.getBoolean("sort.ascending", true);		
		}
		@Override
		protected void map(LongWritable key, Text value,Context context)throws IOException, InterruptedException 	{
			String column[]=value.toString().split(column_delimiter);			
			context.write(new Text(column[rank_key]),value);				
		}
	}	

	public static class TopValuesReducer extends Reducer<Text,Text,NullWritable,Text>{
		String column_delimiter;
		int column_to_rank;
		int rank_limit,rank_key;
		Boolean sort_ascending;
		@Override
		public void setup(Context context) 	{
			Configuration conf = context.getConfiguration();
			column_delimiter = conf.get("column.delimiter");
			column_to_rank = conf.getInt("column.to.rank", Integer.MIN_VALUE) - 1;
			rank_limit = conf.getInt("rank.limit", Integer.MIN_VALUE);
			sort_ascending = conf.getBoolean("sort.ascending", true);
			rank_key=conf.getInt("rank.keys", Integer.MIN_VALUE)-1;			
		}	

		@Override
		protected void reduce(Text key, Iterable<Text> value,Context context)throws IOException, InterruptedException 	{
			StringBuilder builder=new StringBuilder();	
			TreeMap<Integer, String> sortval = new TreeMap<Integer, String>();
			
			for(Text val:value)	{
				String column[]=val.toString().split(column_delimiter);		
				sortval.put(Integer.parseInt(column[column_to_rank]),val.toString());
				if (sortval.size() > rank_limit) {
					if (sort_ascending) 
					{
						sortval.remove(sortval.lastKey());
					}else 
					{
						sortval.remove(sortval.firstKey());
					}
				}
			}
			Set set = sortval.entrySet();		     
			Iterator i = set.iterator();		  
			while(i.hasNext()) {
				Map.Entry me = (Map.Entry)i.next();			
				context.write(NullWritable.get(),new Text( me.getValue().toString()));	
			}
		}
	}
	@Override
	public int run(String[] args) throws Exception {

		Configuration conf = new Configuration();
		String[] remaining_args = new GenericOptionsParser(conf, args).getRemainingArgs();
		if (remaining_args.length == 7) {
			conf.set("column.delimiter", remaining_args[2]);
			conf.set("rank.keys", remaining_args[3]);
			conf.set("column.to.rank", remaining_args[4]);
			conf.set("rank.limit", remaining_args[5]);
			conf.setBoolean("sort.ascending", Boolean.parseBoolean(remaining_args[6]));			
		}
		conf.set("hadoop.job.history.user.location", "none");
		Job job = new Job(conf, getClass().getSimpleName());
		job.setJarByClass(getClass());
		FileInputFormat.addInputPath(job, new Path(remaining_args[0]));
		FileOutputFormat.setOutputPath(job, new Path(remaining_args[1]));
		job.setInputFormatClass(TextInputFormat.class);
		job.setOutputFormatClass(TextOutputFormat.class);
		job.setMapperClass(TopValuesMapper.class);
		job.setReducerClass(TopValuesReducer.class);
		job.setMapOutputKeyClass(Text.class);
		job.setMapOutputValueClass(Text.class);
		job.setOutputKeyClass(NullWritable.class);
		job.setOutputValueClass(Text.class);
		return job.waitForCompletion(true) ? 0 : 1;
	}

	public static void main(String[] args) throws Exception {

		int exit_code = ToolRunner.run(new TopValues(), args);
		System.exit(exit_code);
	}
}