CSVFile.java

package creek;

import java.io.*;
import java.util.*;
import java.nio.file.*;
import java.nio.charset.*;

public class CSVFile implements TableFile {

	private File file;
	private CSV csv;
	
	private static String removeBOM ( String raw ) {
		// remove Byte Order Mark (BOM)
		if (
			raw != null &&
			raw.length() > 3 &&
			raw.charAt(0) == 0xEF &&
			raw.charAt(1) == 0xBB &&
			raw.charAt(2) == 0xBF
		) return raw.substring(3);
		return raw;
	}
	
	
	// constructors

	public CSVFile ( String path ) throws Exception {
		this( new File(path), true, null, "," );
	}

	public CSVFile ( String path, boolean append ) throws Exception {
		this( new File(path), append, null, "," );
	}

	public CSVFile ( String path, boolean append, Table table ) throws Exception {
		this( new File(path), append, table, "," );
	}

	public CSVFile ( File file ) throws Exception {
		this( file, true, null, "," );
	}

	public CSVFile ( File file, boolean append ) throws Exception {
		this( file, append, null, "," );
	}

	public CSVFile ( File file, boolean append, Table table, String comma ) throws Exception {
		this.file = file;
		csv = new CSV( comma, "\\", "\"" ); // create blank CSV object
		if (append) {
			read();
			if (table!=null) append( new CSV( table ) ); // append table data to both file and CSV
		} else {
			write( table );
		}
	}
	

	// TableFile interface
	
	public TableFile create ( File file ) throws Exception {
		return new CSVFile( file, false, null, "," );
	}
	
	public File file () {
		return file;
	}
	
	public Table table () {
		return csv;
	}

	public TableFile clear () throws Exception {
		if (file.exists()) file.delete();
		file.createNewFile(); // empty file
		csv = new CSV( csv.comma(), csv.escape(), csv.quote() );
		return this;
	}

	public TableFile read () throws Exception {
		if (file.exists()) {
			csv = new CSV (
				removeBOM(
					new String(
						Files.readAllBytes( file.toPath() ),
						Charset.defaultCharset()
					)
				), csv.comma()
			);
		} else {
			clear();
		}
		return this;
	}

	public TableFile append ( Table table ) throws Exception {
		return write( table, true );
	}
	
	
	public TableFile write ( Table table ) throws Exception {
		return write( table, false );
	}
	
	public TableFile write () throws Exception {
		return write( csv, false );
	}
	
	public TableFile write ( Table table, boolean append ) throws Exception {
		if (! append) clear(); // write operation
		if (table == null) return this;
		CSV newCsv = new CSV( csv.comma(), csv.escape(), csv.quote() );
		newCsv.append( table );
		if (!file.exists()) file.createNewFile();
		Files.write(
			file.toPath(),
			newCsv.serial().getBytes(),
			( append ? StandardOpenOption.APPEND : StandardOpenOption.WRITE )
		);
		if (append) csv.append( newCsv ); // append operation
		else csv = newCsv; // write operation
		//System.out.println( "CSVFile: "+csv.data() );
		return this;
	}
	
	public String toString () {
		return csv.toString();
	}
	
	
	public static void main ( String[] args ) {
	
		try {
			CSVFile f0 = new CSVFile( args[0], false );
			System.out.println( "********\nf0 empty:\n"+f0 );
			f0.append( SimpleTable.test() );
			System.out.println( "********\nf0 with test() data:\n"+f0 );
			f0.write(
				new CSV(
					"1,2,3\n"+
					"A,B,C\n"
				)
			);
			System.out.println( "********\nf0 overwritten:\n"+f0 );
			
			Thread.sleep(500);
			
			CSVFile f1 = new CSVFile( args[0]+"_2.csv", true );
			System.out.println( "********\nf1 as-is:\n"+f1 );
			f1.append( f0.table() );
			System.out.println( "********\nf1 with f0 appended:\n"+f1 );
			
			Thread.sleep(1000);
			
			f1.append(
				new CSV(
					"a,b,c\n"+
					"d,e,f\n"
				)
			);
			System.out.println( "********\nf1 with more data...\n"+f1 );
			
			Thread.sleep(500);
			
			CSVFile f2 = new CSVFile( args[0]+"_2.csv", true, new CSV( "|", "\\", "'" ) );
			System.out.println( "********\nf2 read from f1 file...\n"+f2.table() );

			(new CSVFile( args[0]+"_3.csv" ))
				.append( f2.table() )
				.append( f0.table() );
			
		} catch (Exception e) {
			e.printStackTrace();
		}
		
	}
	
}