import java.io.IOException;
import java.util.*;
 
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.*;
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;
 
public class OneStepMatrixMultiplication {
 /*******************Mapper class**********************/
//key=Byteupset of line(LongWritable)
//value=Text line
    
	public static class Map extends Mapper<LongWritable, Text, Text, Text> {
 
	public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
            Configuration conf = context.getConfiguration();

            int m = Integer.parseInt(conf.get("m"));
            int p = Integer.parseInt(conf.get("p"));
            String line = value.toString();
            String[] indicesAndValue = line.split(",");
            Text outputKey = new Text();
            Text outputValue = new Text();
            if (indicesAndValue[0].equals("A")) {
                for (int k = 0; k < p; k++) {
                    outputKey.set(indicesAndValue[1] + "," + k);
                    outputValue.set("A," + indicesAndValue[2] + "," + indicesAndValue[3]);
                    context.write(outputKey, outputValue);
                }
            } else {
                for (int i = 0; i < m; i++) {
                    outputKey.set(i + "," + indicesAndValue[2]);
                    outputValue.set("B," + indicesAndValue[1] + "," + indicesAndValue[3]);
                    context.write(outputKey, outputValue);
                }
            }
        }
    }
 
/*************************Reducer Class*************************************/
    public static class Reduce extends Reducer<Text, Text, Text, Text> {
        public void reduce(Text key, Iterable<Text> values, Context context) throws IOException, InterruptedException {
           
		 String[] value;
            HashMap<Integer, Float> hashA = new HashMap<Integer, Float>();
            HashMap<Integer, Float> hashB = new HashMap<Integer, Float>();
            for (Text val : values) {
                
		value = val.toString().split(",");
                if (value[0].equals("A")) {
                    hashA.put(Integer.parseInt(value[1]), Float.parseFloat(value[2]));
                } else {
                    hashB.put(Integer.parseInt(value[1]), Float.parseFloat(value[2]));
                }
            }
 		   
		double[] myList = new double[10];
	    for (Float value1 : hashA.values()) {
            System.out.println("Value of A = " + value1);
            
	
	    }



	    int n = Integer.parseInt(context.getConfiguration().get("n"));
            float result = 0.0f;
            float a_ij;
            float b_jk;
            for (int j = 0; j < n; j++) {
                a_ij = hashA.containsKey(j) ? hashA.get(j) : 0.0f;
                System.out.println(a_ij);
		b_jk = hashB.containsKey(j) ? hashB.get(j) : 0.0f;
                System.out.println(b_jk);
		result += a_ij * b_jk;
            }
            if (result != 0.0f) {
                context.write(null, new Text(key.toString() + "," + Float.toString(result)));
            }
        }
    }
 
/***********************Driver(main) function***********************************/
    public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
 	// A is an m-by-n matrix; B is an n-by-p matrix.
	conf.set("m", "2");
        conf.set("n", "5");
        conf.set("p", "3");


        Job job = Job.getInstance(conf, "MatrixMatrixMultiplicationOneStep");
        job.setJarByClass(OneStepMatrixMultiplication.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(Text.class);
 
        job.setMapperClass(Map.class);
        job.setReducerClass(Reduce.class);
 
        job.setInputFormatClass(TextInputFormat.class);
        job.setOutputFormatClass(TextOutputFormat.class);
 
        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));
 
        job.submit();
    }
}