import java.io.*;
import java.util.*;

 /**
	 Generates a synthetic database for use in CSE 444 mini-project 3,
	 outputting the generated tables into CSV files that can be inserted into
	 a database using the DBMS's bulk import command.
	 @author Michael Ratanapintha
  */
public class DatabaseGenerator {
	/*  See importDatabase.sql for the database schema */

	/** 
		Scales the number of rows in each table 
		(see sizeR, sizeS, etc. to see how the scaling is done). 
	 */
	private static int tableSizeScale = 100;
	
	private static int sizeR() { return 1000 * tableSizeScale; };
	private static int sizeS() { return 1000 * tableSizeScale; }; 
	private static int sizeT() { return 1000 * tableSizeScale; };
	private static int sizeU() { return 1000 * tableSizeScale; }; 

	public static void main (String[] args) {
		Random r = new Random();
		if (args.length != 0 && args.length != 1) {
			System.out.println ("Usage: java DatabaseGenerator tableSizeScale");
			System.exit (1);
		}
		
		if (args.length == 1) {
			tableSizeScale = Integer.parseInt(args[0]);
		}

		MakeR ("tableR.txt", r);
		MakeS ("tableS.txt", r);
		MakeT ("tableT.txt", r);
		MakeU ("tableU.txt", r);
	}

	private static void MakeR (String filename, Random prng) {
		PrintStream Rstream = null;
		try {
			Rstream = new PrintStream (filename);
			for (int key = 1; key <= sizeR(); key++) {
				Rstream.print (key + "\t");
				// write fields A, B, C
				Rstream.printf("%d\t%d\t%d\t", 
					prng.nextInt(), 
					prng.nextInt(), 
					prng.nextInt());
				// Generate the varchar field by string-izing a byte array
				// (there is slightly less randomness here because while the individual bytes
				// are random, the array is always printed in the format [1, 2, 3,...],
				// with max 6 chars per byte (4 chars for value plus ", ", plus "[]" and less ", " for last byte value))
				byte arr_bytes[] = new byte[100];
				prng.nextBytes (arr_bytes);
				Rstream.println(Arrays.toString(arr_bytes));
			}
		} catch (Throwable ex) {
			System.err.println ("Cannot open or write to table R output file: \"" + filename + "\"");
			System.err.println ("Error info:");
			System.err.println (ex);
		} finally {
			if (null != Rstream) Rstream.close();
		}
	}

	private static void MakeS (String filename, Random prng) {
		PrintStream Sstream = null;
		try {
			Sstream = new PrintStream (filename);
			for (int key = 1; key <= sizeS(); key++) {
				Sstream.print (key + "\t");
				// write fields A, B, C
				int a = prng.nextInt();
				int b = prng.nextInt();
				if (b < 0) b = -b;
                                b = (b % sizeT())+1;  /* foreign key into T */
				int c = prng.nextInt();
  			        Sstream.printf("%d\t%d\t%d", a,b,c);
				Sstream.println();
			}
		} catch (Throwable ex) {
			System.err.println ("Cannot open or write to table S output file: \"" + filename + "\"");
			System.err.println ("Error info:");
			System.err.println (ex);
		} finally {
			if (null != Sstream) Sstream.close();
		}
	}

	private static void MakeT (String filename, Random prng) {
		PrintStream Tstream = null;
		try {
			Tstream = new PrintStream (filename);
			for (int key = 1; key <= sizeT(); key++) {
				Tstream.print (key + "\t");
				// write fields D, E
				Tstream.printf("%d\t%d", 
					prng.nextInt(), 
					prng.nextInt());
				Tstream.println();
			}
		} catch (Throwable ex) {
			System.err.println ("Cannot open or write to table T output file: \"" + filename + "\"");
			System.err.println ("Error info:");
			System.err.println (ex);
		} finally {
			if (null != Tstream) Tstream.close();
		}
	}

	private static void MakeU (String filename, Random prng) {
		PrintStream Ustream = null;
		try {
			Ustream = new PrintStream (filename);
			for (int key = 1; key <= sizeU(); key++) {
				Ustream.print (key + "\t");
				// write field A
				int a = prng.nextInt();
				if (a % 1000 == 0) a = 0;
				Ustream.print (a + "\t");
				// write field B
				Ustream.println(prng.nextInt());
			}
		} catch (Throwable ex) {
			System.err.println ("Cannot open or write to table T output file: \"" + filename + "\"");
			System.err.println ("Error info:");
			System.err.println (ex);
		} finally {
			if (null != Ustream) Ustream.close();
		}
	}
}