import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.conf.Configured;

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.input.TextInputFormat;

import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import org.apache.hadoop.util.Tool;

import org.apache.hadoop.util.ToolRunner;

import java.io.IOException;

import java.util.Iterator;

import java.util.Objects;

public class STjoin extends Configured implements Tool {

    public static int time = 0;

　　//map将输入分割成child和parent,然后正序输出一次作为右表，反序输出一次作为左表
　　//需要注意的是在输出的value中必须加上左右表区别标志

    public static class Map extends Mapper<Object,Text,Text,Text>{

        public void map(Object key,Text value,Context context) throws IOException,

                InterruptedException{

            String childname = new String();

            String parentname = new String();

            String relationtype = new String();

            String line = value.toString();

            int i = 0;
　　　　　　　//文件以空格分隔

            while(line.charAt(i) != ' '){

                i++;

            }
　　　　　　　//拆分child 和 parent

            String[] values = {line.substring(0,i),line.substring(i+1)};

            if(values[0].compareTo("child") != 0){

                childname = values[0];

                parentname = values[1];
　　　　　　　　　//左右表区分标志

                relationtype = "1";

                context.write(new Text(values[1]),new Text(relationtype + "+" + childname + "+" + parentname));

                relationtype = "2";

                context.write(new Text(values[0]),new Text(relationtype + "+" + childname + "+" + parentname));

            }

        }

    }

    public static class Reduce extends Reducer<Text,Text,Text,Text>{

        public void reduce(Text key,Iterable<Text> values,Context context) throws IOException,InterruptedException{
　　　　　　　　//输出表头

            if(time == 0){

                context.write(new Text("grandchild"),new Text("grandparent"));

                time++;

            }

            int grandchildnum = 0;

            String grandchild[] = new String[10];

            int grandparentnum = 0;

            String grandparent[] = new String[10];

            Iterator ite = values.iterator();

            while(ite.hasNext()){

                String record = ite.next().toString();

                int len = record.length();

                int i = 2;

                if(len == 0){

                    continue;

                }

                char relationtype = record.charAt(0);

                String childname = new String();

                String parentname = new String();

                while(record.charAt(i) != '+'){

                    childname = childname + record.charAt(i);

                    i++;

                }

                i = i+1;

                while(i<len){

                    parentname = parentname + record.charAt(i);

                    i++;

                }

                if(relationtype == '1') {

                    grandchild[grandchildnum] = childname;

                    ;

                    grandchildnum++;

                }else{

                    grandparent[grandparentnum] = parentname;

                    grandparentnum++;

                }

            }

            if(grandparentnum != 0 && grandchildnum != 0){

                    for(int m = 0;m<grandchildnum;m++){

                        for(int n = 0;n<grandparentnum;n++){

                            System.out.println(grandchild[m] + "  " + grandparent[n]);

                            context.write(new Text(grandchild[m]),new Text(grandparent[n]));

                        }

                    }

            }

        }

    }

    public  int run(String[] args) throws Exception{

        Configuration aaa = new Configuration();

        Job job = Job.getInstance(aaa);

        String InputPaths = "/usr/local/idea-IC-139.1117.1/Hadoop/out/datainput/child-parent.txt";

        String OutputPath = "/usr/local/idea-IC-139.1117.1/Hadoop/out/dataout/";

        job.setJarByClass(Sort.class);

        job.setJobName("Sort");

        job.setMapperClass(Map.class);

        job.setReducerClass(Reduce.class);

        FileInputFormat.setInputPaths(job, new Path(InputPaths));

        FileOutputFormat.setOutputPath(job, new Path(OutputPath));

        job.setOutputKeyClass(Text.class);

        job.setOutputValueClass(Text.class);

        job.setInputFormatClass(TextInputFormat.class);

        job.setOutputFormatClass(org.apache.hadoop.mapreduce.lib.output.TextOutputFormat.class);

        boolean success = job.waitForCompletion(true);

        return success ? 0 : 1;

    }

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

            int ret = ToolRunner.run(new STjoin(), args);

            System.exit(ret);

    }

}