COSC311Project1

/**
 *  This is a menu based program which creates and utilizes RandomAccessFiles to store, look up and modify
 *  "student" data including first and last names, student ID and GPA
 *
 * Sam Orosz
 * 1/17/2018
 */

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

public class Main {

	public static Scanner keyboard = new Scanner(System.in);

	public static void main (String args[]) throws IOException
	{
		try {
			printMenu();
			menuSelect();
		}
		catch(IOException e) { //handle all thrown exceptions
			System.out.println("specified file does not exist, returning to menu");
			printMenu();
			menuSelect();
		}

	}

	public static void printMenu()
	{
		//print menu
		System.out.println("1- Create a random-access file");
		System.out.println("2- Display a random-access file");
		System.out.println("3- Retrieve a record");
		System.out.println("4- Modify a record");
		System.out.println("5- Add a new record");
		System.out.println("6- Delete a record");
		System.out.println("7- Exit");

	}

	public static void menuSelect() throws IOException
	{
		int num = 0;
		try
		{
			System.out.println("Please select an action you wish to perform."); //prompt user
			num = keyboard.nextInt();
			keyboard.nextLine();
		}
		catch(InputMismatchException e)
		{
			System.out.println("Please use a number 1-7 to select your action."); //make sure inputs are ints
			keyboard.next();
			menuSelect();
			return;

		}

		if(num == 1)
		{
			Create();
		}
		else if(num == 2)
		{
			Display();
		}
		else if(num == 3)
		{
			System.out.println("What is the name of the file you would like to access?");
			String file = keyboard.nextLine();
			RandomAccessFile File = new RandomAccessFile(file + ".txt", "r" );
			Retrieve(File);
		}
		else if(num == 4)
		{
			System.out.println("What is the name of the file you would like to access?");
			String file = keyboard.nextLine();
			RandomAccessFile File = new RandomAccessFile(file + ".txt", "rw" );

			Modify(File);
		}
		else if(num == 5)
		{
			System.out.println("What is the name of the file you would like to access?");
			String file = keyboard.nextLine();
			RandomAccessFile File = new RandomAccessFile(file + ".txt", "rw" );
			Add(File);
		}
		else if(num == 6)
		{
			System.out.println("What is the name of the file you would like to access?");
			String file = keyboard.nextLine();
			RandomAccessFile File = new RandomAccessFile(file + ".txt", "rw" );
			Delete(File);
		}
		else if(num == 7)
		{
			System.out.println("Exiting Program.");
			System.exit(0);
		}
		else
		{
			System.out.println("Please use a number 1-7 to select your action."); //make sure input is a supported number
		}
	}

	public static void Create() throws IOException
	{
		//prompt user for name of input file
		System.out.println("Please give the name of the text file you would like to create the file from");
		String firstName = keyboard.nextLine();
		//prompt user for name of file they wish to create
		System.out.println("Please give the desired output file name");
		String secondName = keyboard.nextLine();

		//delete output file if it already exists
		File f = new File(secondName + ".txt");
		if(f.exists() && !f.isDirectory()) {
		    f.delete();
		}

		//create input and output files
		Reader originalFile = new FileReader(firstName + ".txt");
		RandomAccessFile newFile = new RandomAccessFile(secondName + ".txt", "rw" );

		//write data to RAF
		newFile.seek(0);
		boolean done = false;
		do {
			//first name
			  	char newCharTest = (char) originalFile.read();
		        while (!Character.isLetter(newCharTest))
		        {
		        		newCharTest = (char) originalFile.read();
		        }
		    		newFile.writeChar(newCharTest);
	        for(int i = 0; i < 19; i++)
	        {
		        	char newChar = (char) originalFile.read();
		        	if (Character.isLetter(newChar))
		        	{
		            	newFile.writeChar(newChar);
		        	}
		        	else
		        	{
		        		for( ; i < 19; i++)
		        		{
		        			newFile.writeChar(' ');
		        		}
		        	}

	        }
	        //last name
	        newCharTest = (char) originalFile.read();
	        while (!Character.isLetter(newCharTest))
	        {
	        		newCharTest = (char) originalFile.read();
	        }
	    		newFile.writeChar(newCharTest);
	        for(int i = 0; i < 19; i++)
	        {
		        	char newChar = (char) originalFile.read();
		        	if (Character.isLetter(newChar))
		        	{
		            	newFile.writeChar(newChar);
		        	}
		        	else
		        	{
		        		for( ; i < 19; i++)
		        		{
		        			newFile.writeChar(' ');
		        		}
		        	}

	        }
	        //student id
	        char newDigit = (char) originalFile.read();
	        while (!Character.isDigit(newDigit))
	        {
	        		newDigit = (char) originalFile.read();
	        }

	        int ID = Character.getNumericValue(newDigit);
	        for(int i = 0; i < 3; i++)
	        {
	        	newDigit = (char) originalFile.read();
	            ID = (ID * 10) + Character.getNumericValue(newDigit);
	        }

	        newFile.writeInt(ID);
	        //GPA
	        newDigit = (char) originalFile.read();
	        while (!Character.isDigit(newDigit))
	        {
	        		newDigit = (char) originalFile.read();
	        }
	        double GPA = Character.getNumericValue(newDigit);

	        originalFile.read();
	        for(int i = -1; i > -3; i--)
	        {
	        	newDigit = (char) originalFile.read();
	            GPA = GPA + (Character.getNumericValue(newDigit) * java.lang.Math.pow(10,i));
	        }
	        newFile.writeDouble(GPA);
	        //ends loop if the end of the input file is reached
	        if( originalFile.read() == -1)
	        {
	        	done = true;
	        }

		} while(!done);
		originalFile.close();
        newFile.close();

        printMenu();
		menuSelect();
	}
	public static void Display() throws IOException
	{
		System.out.println("What is the name of the file you would like to access?");
		String file = keyboard.nextLine();
		RandomAccessFile File = new RandomAccessFile(file + ".txt", "r" );

		while(File.getFilePointer() < (File.length() - 91))
		{
			System.out.println("First Name            Last Name            Student ID          GPA");

			for (int i = 0; i < 5; i++)
			{
				if (File.getFilePointer() < (File.length() - 91)) //make sure file won't end before data has been printed
				{
					char D = File.readChar();  //make sure to not display deleted students
					char L = File.readChar();
					char T = File.readChar();
					char D2 = File.readChar();
					if ( D == 'D' && L == 'L' && T == 'T' && D2 == 'D')
					{
						i--;
						File.seek(File.getFilePointer() + 84); //skip forward if deleted
						continue;

					}
					else
					{
						File.seek(File.getFilePointer() - 8); // skip back to beginning if not
					}

					for (int j = 0; j < 20; j++) {		//first name
					System.out.print(File.readChar());
					}
					System.out.print("  ");
					for (int j = 0; j < 20; j++) {		//last name
						System.out.print(File.readChar());
					}
					System.out.print(" ");
					System.out.print(File.readInt());  //ID
					System.out.print("                ");
					System.out.println(String.format("%.3g%n",File.readDouble()));  //formatted GPA (only displays 2 decimal places
				}
				else
				{
					//since the end of the file was reached, users are given a choice
					//of returning to the menu or repeating Display()
					System.out.println("End of File.");
					System.out.println("Enter any letter to return to menu, or any non-letter character to display a new file");
					if (Character.isLetter(keyboard.next().charAt(0)))
					{
						keyboard.nextLine();
						printMenu();
						menuSelect();
						return;
					}
					 else
					 {
						Display();
					 	return;
					 }
				}
			}

			//display and ask user for choice of options
			System.out.println("M- Return to menu.");
			System.out.println("N- Display next page.");
			System.out.println("A- Display all remaining students.");
			System.out.println("Please choose an action to continue");
			char option = ' ';
			boolean success = false;
			while (success == false)   //repeat selection process until one of the correct chars is selected
			{
				option = keyboard.next().charAt(0);
				keyboard.nextLine();
				if(option == 'M' || option == 'm' || option == 'N' || option == 'n' || option == 'A' || option == 'a' )
				{
					success = true;
				}
				else
				{
					System.out.println("Please input M, N, or A."); //prompt user
				}

			}
			if (option == 'M' || option == 'm' ) //selection goes back to menu
			{
				printMenu();
				menuSelect();
				File.close();
				return;
			}
			//an actual n is redundant as the loop automatically does it if neither other option is selected

			else if (option == 'A' || option == 'a' ) //selection displays the rest of the file
			{

				System.out.println("First Name            Last Name            Student ID          GPA");
				while (File.getFilePointer() < (File.length() - 91)) {
					for (int j = 0; j < 20; j++) {
					System.out.print(File.readChar());
					}
					System.out.print("  ");
					for (int j = 0; j < 20; j++) {
						System.out.print(File.readChar());
					}
					System.out.print(" ");
					System.out.print(File.readInt());
					System.out.print("                ");
					System.out.println(String.format("%.3g%n",File.readDouble()));
				}
				//since the end of the file was reached, users are given a choice
				//of returning to the menu or repeating Display()
				System.out.println("Enter any letter to return to menu, or any non-letter character to display a new file");
				if (Character.isLetter(keyboard.next().charAt(0)))
				{
					keyboard.nextLine();
					printMenu();
					menuSelect();
					File.close();
					return;
				}
				 else
				 {
					keyboard.nextLine();
					Display();
				 	return;
				 }
			}
		}

	}
	public static void Retrieve(RandomAccessFile File)  throws IOException
	{
		//prompt user
		System.out.println("Which student file would you like to retrieve? (1 - 1st, 2 - 2nd, etc...)");
		int number = keyboard.nextInt();
		keyboard.nextLine();

		File.seek((number - 1) * 92); //find student
		if (File.getFilePointer() < (File.length() - 91)) //check if student number exists
		{
			char D = File.readChar(); //make sure the student is not deleted
			char L = File.readChar();
			char T = File.readChar();
			char D2 = File.readChar();
			if ( D != 'D' || L != 'L' || T != 'T' || D2 != 'D')
			{
				//print student data + labels
				File.seek((number - 1) * 92);
				System.out.println("First Name            Last Name            Student ID          GPA");
				for (int j = 0; j < 20; j++) {
					System.out.print(File.readChar());
					}
					System.out.print("  ");
					for (int j = 0; j < 20; j++) {
						System.out.print(File.readChar());
					}
					System.out.print(" ");
					System.out.print(File.readInt());
					System.out.print("                ");
					System.out.println(String.format("%.3g%n",File.readDouble()));
			}
			else
			{
				System.out.println("Student does not exist: Deleted");
			}
		}
		else
		{
			System.out.println("Student does not exist: Past end of file");
		}
		//since the end of the task was reached, users are given a choice
		//of returning to the menu or repeating Retrieve()
		System.out.println("Enter any letter to return to menu, or any non-letter character to retrieve another student");
		if (Character.isLetter(keyboard.next().charAt(0)))
		{
			keyboard.nextLine();
			printMenu();
			menuSelect();
			return;
		}
		 else
		 {
			keyboard.nextLine();
			Retrieve(File);
		 	return;
		 }


	}
	public static void Modify(RandomAccessFile File)  throws IOException
	{
		System.out.println("Which student file would you like to modify? (1 - 1st, 2 - 2nd, etc...)");
		int number = keyboard.nextInt();
		keyboard.nextLine();

		File.seek((number - 1) * 92); //find student
		if (File.getFilePointer() < (File.length() - 91)) //check if student number exists
		{
			char D = File.readChar();  //make sure the student is not deleted
			char L = File.readChar();
			char T = File.readChar();
			char D2 = File.readChar();
			if ( D != 'D' || L != 'L' || T != 'T' || D2 != 'D')
			{
				//print student data for reference by user
				File.seek((number - 1) * 92);
				for (int j = 0; j < 20; j++) {
					System.out.print(File.readChar());
				}
				System.out.print("  ");
				for (int j = 0; j < 20; j++) {
					System.out.print(File.readChar());
				}
				System.out.print(" ");
				System.out.print(File.readInt());
				System.out.print("                ");
				System.out.println(String.format("%.3g%n",File.readDouble()));

				System.out.println("What do you wish to modify?");
				System.out.println("F - First Name");
				System.out.println("L - Last Name");		//user options for modification
				System.out.println("I - Student ID");
				System.out.println("G - GPA");

				char option = ' ';
				boolean success = false;
				while (success == false) //make sure a correct char is selected
				{
					option = keyboard.next().charAt(0);
					keyboard.nextLine();
					if(option == 'F' || option == 'f' || option == 'L' || option == 'l' || option == 'I' || option == 'i' || option == 'G' || option == 'g' )
					{
						success = true;
					}
					else
					{
						System.out.println("Please input F, L, I, or G.");
					}

				}

				if (option == 'F' || option == 'f') //change first name
				{
					System.out.println("What would you like to change the first name to?");
					File.seek((number - 1) * 92);
					String fName = keyboard.nextLine();

					for(int i = 0; i < fName.length(); i++)
					{
						File.writeChar(fName.charAt(i));
						if( i == 19)
							break;
					}
					for(int i = fName.length(); i < 20; i++)
					{
						File.writeChar(' ');
					}
				}
				if (option == 'L' || option == 'l') //change last name
				{
					System.out.println("What would you like to change the last name to?");
					File.seek(((number - 1) * 92) + 40);
					String lName = keyboard.nextLine();

					for(int i = 0; i < lName.length(); i++)
					{
						File.writeChar(lName.charAt(i));
						if( i == 19)
							break;
					}
					for(int i = lName.length(); i < 20; i++)
					{
						File.writeChar(' ');
					}
				}
				if (option == 'I' || option == 'i') //change ID
				{
					System.out.println("What would you like to change the student ID to?");
					File.seek(((number - 1) * 92) + 80);
					File.writeInt( keyboard.nextInt());
					keyboard.nextLine();

				}
				if (option == 'G' || option == 'g') //change GPA
				{
					System.out.println("What would you like to change the GPA to?");
					File.seek(((number - 1) * 92) + 84);
					File.writeDouble( keyboard.nextDouble());
					keyboard.nextLine();
				}
			}
			else
			{
				System.out.println("Student does not exist: Deleted");
			}
		}
		else
		{
			System.out.println("Student does not exist: Past end of file");
		}


		//since the end of the task was reached, users are given a choice
		//of returning to the menu or repeating Modify()
		System.out.println("Enter any letter to return to menu, or any non-letter character to modify another student");
		if (Character.isLetter(keyboard.next().charAt(0)))
		{
			keyboard.nextLine();
			printMenu();
			menuSelect();
			File.close();
			return;
		}
		 else
		 {
			keyboard.nextLine();
			Modify(File);
		 	return;
		 }

	}
	public static void Add(RandomAccessFile File)  throws IOException
	{
		File.seek(File.length());
		System.out.println("What is the first name of the new student?");
		String fName = keyboard.nextLine();

		for(int i = 0; i < fName.length(); i++)
		{
			File.writeChar(fName.charAt(i));
			if( i == 19)
				break;
		}
		for(int i = fName.length(); i < 20; i++)
		{
			File.writeChar(' ');
		}

		System.out.println("What is the last name?");
		String lName = keyboard.nextLine();

		for(int i = 0; i < lName.length(); i++)
		{
			File.writeChar(lName.charAt(i));
			if( i == 19)
				break;
		}
		for(int i = lName.length(); i < 20; i++)
		{
			File.writeChar(' ');
		}

		System.out.println("What is the student ID?");
		File.writeInt( keyboard.nextInt());
		keyboard.nextLine();

		System.out.println("What is their GPA?");
		File.writeDouble( keyboard.nextDouble());
		keyboard.nextLine();

		//since the end of the task was reached, users are given a choice
		//of returning to the menu or repeating Add()
		System.out.println("Enter any letter to return to menu, or any non-letter character to add a new student");
		if (Character.isLetter(keyboard.next().charAt(0)))
		{
			keyboard.nextLine();
			printMenu();
			menuSelect();
			File.close();
			return;
		}
		else
		{
			keyboard.nextLine();
			Add(File);
		 	return;
		}

	}
	public static void Delete(RandomAccessFile File)  throws IOException
	{
		System.out.println("Which student file would you like to delete? (1 - 1st, 2 - 2nd, etc...)");
		int number = keyboard.nextInt();
		keyboard.nextLine();

		File.seek((number - 1) * 92); //find student
		if (File.getFilePointer() < (File.length() - 92)) //check if student number exists
		{
			char D = File.readChar(); //check if already deleted
			char L = File.readChar();
			char T = File.readChar();
			char D2 = File.readChar();
			if ( D != 'D' || L != 'L' || T != 'T' || D2 != 'D')
			{
				File.seek((number - 1) * 92);
				File.writeChar('D');  //overwrite first four chars with deletion marker
				File.writeChar('L');
				File.writeChar('T');
				File.writeChar('D');
			}
			else
			{
				System.out.println("Student already deleted");
			}
		}

		else
		{
			System.out.println("Student does not exist: Past end of file");
		}
		//since the end of the task was reached, users are given a choice
		//of returning to the menu or repeating Delete()
		System.out.println("Enter any letter to return to menu, or any non-letter character to delete another new student");
		if (Character.isLetter(keyboard.next().charAt(0)))
		{
			keyboard.nextLine();
			printMenu();
			menuSelect();
			File.close();
			return;
		}
		else
		{
			keyboard.nextLine();
			Delete(File);
		 	return;
		}

	}
}