import java.io.*;
import com.google.common.hash.*;
import com.google.common.io.Files;
import org.marc4j.*;
import org.marc4j.marc.Record;

public class split {

	public static void main(String[] args) throws Exception
	{
		long StartTime = System.currentTimeMillis();
		//Default values for arguments
		int NRecords = 250;
		String OutputPath = "./out/";

		//Incorrect number of arguments supplied
		if(args.length!=5)
		{
			System.err.println("USAGE: java split [-n records_per_file] [-o output_path] input.xml");
			System.err.println("DEFAULT: [-n 200] [-o ./out/]");
			return;
		}
		//read arguments	
		for(int i=0; i < args.length; i+=2)
		{
			if(args[i].equals("-n"))
				NRecords = Integer.parseInt(args[i+1]);
			else if(args[i].equals("-o"))
				OutputPath = args[i+1];
		}
		
		InputStream in;
		try{
			in = new FileInputStream(args[args.length-1]);
		}
		catch(Exception e){
			System.err.println("Input file doesn't exist");
			return;
		}

		MarcXmlReader reader = new MarcXmlReader(in);
		String TempFilename = OutputPath + "/temp.xml"; 
		File f;
		int RecordCount = 0;
		
		while(reader.hasNext())
		{		
			f = new File(TempFilename);
			MarcWriter writer = new MarcXmlWriter(new FileOutputStream(f),true);
			
			Record record;
			//Write segment of records to file
			for(int i=0; (i<NRecords && reader.hasNext()); i++)
			{
				record = reader.next();
				writer.write(record);
				RecordCount++;
			}
			writer.close();
			
			//Print update
			if(RecordCount%50000==0)
				System.err.println("Processed " + RecordCount + " records");
			
			//Calculate MD5
			HashCode hc = Files.hash(f, Hashing.md5());
			String s = hc.toString();
			
			//Ensure target folder exists, then rename file to hash string
			File target = new File(OutputPath+"/"+s.substring(0, 2)+"/"+s.substring(2)+".xml");
			File parent = target.getParentFile();
			if(!parent.exists() && !parent.mkdirs()){
				throw new IllegalStateException("Couldn't create dir " + parent);
			}
			f.renameTo(target);
		}		
		System.err.println("Processed " + RecordCount + " records");
		System.err.println("Time taken: " + (System.currentTimeMillis()-StartTime) + "ms");		
	}
}