// WordCountHBase 
//說明： 
//  此程式碼將輸入路徑的檔案內的字串取出做字數統計
//  再將結果塞回HTable內
//
//運算方法：
//  將此程式運作在hadoop 1.0.0 + hbase 0.90.5 平台上
//
//結果：
// ---------------------------
//  $ hbase shell
//  > scan 'wordcount'
//  ROW   COLUMN+CELL 
//  am    column=content:count, timestamp=1264406245488, value=1
//  chen  column=content:count, timestamp=1264406245488, value=1 
//  hi,   column=content:count, timestamp=1264406245488, value=2
//  ......(略)
// ---------------------------
//注意：
//1.  在hdfs 上來源檔案的路徑為 "/user/$YOUR_NAME/input"
//  請注意必須先放資料到此hdfs上的資料夾內，且此資料夾內只能放檔案，不可再放資料夾
//2.  運算完後，程式將執行結果放在hbase的wordcount資料表內
// 

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.ZooKeeperConnectionException;
import org.apache.hadoop.hbase.client.HBaseAdmin;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.mapreduce.TableOutputFormat;
import org.apache.hadoop.hbase.mapreduce.TableReducer;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;

public class WordCountHBase {
  
  public Configuration hbase_config ;
  public Configuration hadoop_config;
  public HBaseAdmin hbase_admin;
  public String input ,tablename;
  
  public WordCountHBase() throws MasterNotRunningException, ZooKeeperConnectionException{
    hbase_config = HBaseConfiguration.create();
    hadoop_config = new Configuration();
    hbase_admin = new HBaseAdmin(hbase_config);
  }
  
  public void createHBaseTable(String family)
      throws IOException {
    // HTableDescriptor contains the name of an HTable, and its column
    // families
    // HTableDescriptor 用來描述table的屬性
    HTableDescriptor htd = new HTableDescriptor(tablename);
    // HColumnDescriptor HColumnDescriptor contains information about a
    // column family such as the number of versions, compression settings,
    // etc.
    // HTableDescriptor 透過 add() 方法來加入Column family

    htd.addFamily(new HColumnDescriptor(family));

    // HBaseConfiguration 能接收 hbase-site.xml 的設定值
    // HBaseConfiguration config = new HBaseConfiguration();
    

    // 檔案的操作則使用 HBaseAdmin
    
    // 檢查
    if (hbase_admin.tableExists(tablename)) {
      System.out.println("Table: " + tablename + "Existed.");
    } else {
      System.out.println("create new table: " + tablename);
      // 建立
      hbase_admin.createTable(htd);
    }
  }

  public void drop() {
    // HBaseConfiguration conf = new HBaseConfiguration(); // deprecated ,
    // v0.90
    
    try {
      hbase_admin = new HBaseAdmin(hbase_config);
      if (hbase_admin.tableExists(tablename)) {
        hbase_admin.disableTable(tablename);
        hbase_admin.deleteTable(tablename);
        System.out.println("Droped the table [" + tablename + "]");
      } else {
        System.out.println("Table [" + tablename + "] was not found!");
      }

    } catch (IOException e) {
      e.printStackTrace();
    }
  }

  public static class HtMap extends
      Mapper<LongWritable, Text, Text, IntWritable> {
    private IntWritable one = new IntWritable(1);

    public void map(LongWritable key, Text value, Context context)
        throws IOException, InterruptedException {
      // 輸入的字串先轉換成小寫再用空白區隔
      String s[] = value.toString().toLowerCase().trim().split(" ");
      for (String m : s) {
        // 寫入到輸出串流
        context.write(new Text(m), one);
      }
    }
  }

  // TableReducer<KEYIN,VALUEIN,KEYOUT>
  // 原本為 TableReducer<Text, IntWritable, NullWritable >
  // 但在此改成 LongWritable 也可以
  // 因此證明在此的Class可以很多,org.apache.hadoop.io.* 內有write()的Writable class應該皆可
  public static class HtReduce extends
      TableReducer<Text, IntWritable, LongWritable> {

    public void reduce(Text key, Iterable<IntWritable> values,
        Context context) throws IOException, InterruptedException {
      int sum = 0;
      for (IntWritable i : values) {
        sum += i.get();
      }

      // org.apache.hadoop.hbase.client.Put
      // Used to perform Put operations for a single row.
      // new Put(byte[] row)
      Put put = new Put(Bytes.toBytes(key.toString()));

      // add(byte[] family, byte[] qualifier, byte[] value)
      // 在main設定output format class 為 TableOutputFormat
      // TableReducer 內有定義 output Key class 必須為 Put 或 Delete
      put.add(Bytes.toBytes("content"), Bytes.toBytes("word"),
          Bytes.toBytes(key.toString()));
      put.add(Bytes.toBytes("content"), Bytes.toBytes("count"),
          Bytes.toBytes(String.valueOf(sum)));

      // NullWritable.get(): Returns the single instance of this class.
      // NullWritable.write(): Serialize the fields of this object to out.
      context.write(new LongWritable(), put);
      // context.write(NullWritable.get(), put)
    }
  }
  public boolean run() throws IOException, InterruptedException, ClassNotFoundException{
    Job job = new Job(hadoop_config, "WordCount table with " + input);

    job.setJarByClass(WordCountHBase.class);

    job.setMapperClass(HtMap.class);
    job.setReducerClass(HtReduce.class);
    // 此範例的輸出為 <Text,IntWritable> 因此其實可以省略宣告
    // set{Map|Reduce}Output{Key|Value}Class()
    job.setMapOutputKeyClass(Text.class);
    job.setMapOutputValueClass(IntWritable.class);
    // InputFormat 只有一個子介面
    // FileInputFormat <-(SequenceFileInputFormat,TextInputFormat)
    // 其中TextInputFormat 最常用 ，預設輸入為 LongWritable,Text
    // 另外HBase 則設計了一個子類別 TableInputFormat
    job.setInputFormatClass(TextInputFormat.class);
    // TAbleOutputFormat
    // 宣告此行則可使 reduce 輸出為 HBase 的table
    job.setOutputFormatClass(TableOutputFormat.class);

    // 原本設定輸入檔案為 Config.setInputPath(Path) 卻改為
    // FileInputFormat.addInputPath(Job, Path()) 的設計，
    // 猜測應該是考慮某些檔案操作並不需要跑mapreduce的Job，因此提到外面
    FileInputFormat.addInputPath(job, new Path(input));

    return job.waitForCompletion(true) ? true : false;
  }
  public static void main(String argv[]) throws Exception {
    // debug
    String[] argc = { "/tmp/ProductEmp/input/" };
    argv = argc;
    
    WordCountHBase wchb = new WordCountHBase();
    

    if (argv.length < 1) {
      System.out.println("CountToHBaseReducer <inHdfsDir> ");
      return;
    }

    wchb.input = argv[0];

    wchb.tablename = "wordcounthbase";

    // OUTPUT_TABLE = "hbase.mapred.outputtable"
    // conf.set 用於設定 如 core-site.xml 的 name 與 value
    // 告訴程式 hbase.mapred.outputtable --> wordcount
    
    wchb.hadoop_config.set(TableOutputFormat.OUTPUT_TABLE, wchb.tablename);

    
    // 建立hbase 的table 否則沒先建立會出錯
    wchb.drop();
    wchb.createHBaseTable( "content");

    wchb.run();
  }
}