package forma;

import java.io.IOException;
import org.apache.hadoop.mapred.FileSplit;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.mapred.RecordReader;

class WholeFileRecordReader implements RecordReader<Text, BytesWritable> {
  
    private FileSplit fileSplit;
    private Configuration conf;
    private boolean processed = false;
  
    public WholeFileRecordReader(FileSplit fileSplit, Configuration conf) throws IOException {
        this.fileSplit = fileSplit;
        this.conf = conf;
    }

    @Override
    public boolean next(Text key, BytesWritable value) throws IOException {
        if (!processed) {
            byte[] contents = new byte[(int) fileSplit.getLength()];
            Path file = fileSplit.getPath();

            String fileName = file.getName();
            key.set(fileName);

            FileSystem fs = file.getFileSystem(conf);
            FSDataInputStream in = null;
            try {
                in = fs.open(file);
                IOUtils.readFully(in, contents, 0, contents.length);                
                value.set(contents, 0, contents.length);
            } finally {
                IOUtils.closeStream(in);
            }
            processed = true;
            return true;
        }
        return false;
    }

    @Override
    public Text createKey() {
        return new Text();
    }

    @Override
    public BytesWritable createValue() {
        return new BytesWritable();
    }

    @Override
    public long getPos() throws IOException {
        return processed ? fileSplit.getLength() : 0;
    }

    @Override
    public float getProgress() throws IOException {
        return processed ? 1.0f : 0.0f;
    }

    @Override
    public void close() throws IOException {
        // do nothing
    }
}