import java.io.EOFException;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.*;
public class Main {
	// This variable represents the users input in the selected() function
	public static Scanner scanner = new Scanner(System.in);		 // Setting a scanner variable

	// This function will present the user with various selections to choose from.
	public static void main(String[] args) throws IOException
	{
		int userinput;
		boolean cont = true;
		boolean flag = false;
		final int recsize = 92;
		String inputFile = ("");
		String outputFile = ("");

		RandomAccessFile raf = null;
		Student rec = null;
		Scanner keyIn = new Scanner(System.in);
		FileWriter writer = new FileWriter("students.txt", true);

		while(cont)
		{
			System.out.println("1- Create a random-access file "
					+ "\n2- Display a random-access file "
					+ "\n3- Retrieve a record "
					+ "\n4- Modify a record "
					+ "\n5- Add a new record "
					+ "\n6- Delete a record "
					+ "\n7- Exit"
					+ "\nChoose a selection:");

			userinput = scanner.nextInt();					// Asking the user for an input between 1 and 7
			switch(userinput)
			{

				default: 							//If userinput is less than 1, than the program will present an error
					System.out.println("Please enter a valid input");
				break;
				case 1:					//COMPLETE.


					System.out.println("Please enter an input file name: ");
					Scanner inputScanner = new Scanner(System.in);
							inputFile = inputScanner.nextLine();

					System.out.println("Please enter an output file name: ");
					Scanner outputScanner = new Scanner(System.in);
					outputFile = outputScanner.nextLine();

					File file = new File(inputFile + ".txt");
					File file2 = new File(outputFile + ".txt");

					if (file.createNewFile()){
						System.out.println("File is created!");
						}else{
						System.out.println("File already exists. ");
						writer.flush();
						new RandomAccessFile(inputFile,"rw").setLength(0);
						System.out.println("File has been cleared. ");
						}

					if (file2.createNewFile()){
						System.out.println("File is created!");
						}else{
						System.out.println("File already exists. ");
						writer = new FileWriter(outputFile + ".txt");
						System.out.println("File has been cleared. ");
						}

		        	// Create input and output file streams
		    		Scanner fin = new Scanner (new FileInputStream(outputFile + ".txt"));
		    		raf = new RandomAccessFile(inputFile, "rw");
		    		rec = new Student();

		    		// Read data from the input file and write them to the random access file
		    		while (fin.hasNext()){
		    			rec.readFromTextFile(fin);
		    			rec.writeToFile(raf);
		    		}
		    		flag = true;
		        	break;
				case 2:				 //NEEDS WORK (Menu almost finished.)

					Scanner scanner = new Scanner(System.in);
					String filename = ("");
			    	System.out.println("\nWhich file would you like to display?");
			    	rec = new Student();
			    	filename = scanner.nextLine();
			    	raf = new RandomAccessFile(filename, "rw");
			    	print (raf, rec, -2);
			    	flag = true;
		        	break;

				case 3:				//COMPLETE
					if(flag)
					{
						System.out.println("Please choose a record number:");
						int user = keyIn.nextInt();
						print(raf, rec, user);
					}
					else
						System.out.println("faggot");
		        	break;
				case 4:				//COMPLETE - Make it also work with the txt
					if(flag)
					{
						System.out.println("Please choose a record number:");
						int user = keyIn.nextInt();
						print(raf, rec, user);
						System.out.println("What would you like to change? 1(Name) 2(LastName) 3(ID) 4(GPA)");
						int inp = keyIn.nextInt();
						Scanner tester = new Scanner(System.in);
						switch(inp)
						{
							default:
								break;
							case 1:
								raf.seek(92*(user-1));
								System.out.println("Enter a First Name: ");
								raf.writeChars(Student.pad(keyIn.next(), 20));

								print (raf, rec, -1);
							case 2:
								raf.seek(92*(user-1));
								System.out.println("Enter a Last Name: ");
								raf.writeChars(Student.pad(keyIn.next(), 20));

								print (raf, rec, -1);
								break;
							case 3:
								raf.seek(92*(user-1));
								System.out.println("Enter an ID: ");
								raf.writeChars(Student.pad(keyIn.next(), 10));

								print (raf, rec, -1);
								break;
							case 4:
								raf.seek(92*(user-1));
								System.out.println("Enter a GPA: ");
								raf.writeChars(Student.pad(keyIn.next(), 10));

								print (raf, rec, -1);
								break;
						}
					}
					else
						System.out.println("faggot");
		        	break;
				case 5:				//COMPLETE
					if(flag)
					{
			        	System.out.println("");
			        	// Write a new record to the end of the random access file
			    		System.out.print("\nEnter your first name, last name, student ID, and GPA: ");
			    		rec.readFromTextFile(keyIn);
			    		raf.seek(raf.length());

			    		System.out.print("\nHere is your updated record: ");
			    		writer.write("\n" + rec.toString());
			    		writer.close();

		    			rec.writeToFile(raf);
			    		print (raf, rec, -1);

					}
					else
						System.out.println("faggot");
		        	break;
				case 6:				//NEEDS WORK
					if(flag)
					{
						int number = keyIn.nextInt();
						try{
						raf.seek(number*recsize);



						}catch (EOFException e){


						}

					}
					else
						System.out.println("faggot");
		        	break;
				case 7:				//COMPLETE
					cont = false;
					//output exit statement
					break;
			}
		}
		keyIn.close();

	}

	public static void print (RandomAccessFile raf, Student rec, int user) throws IOException
	{
		raf.seek(0);
		int incr = 0;
		int count = 0;

		boolean meme = false;

		if(user == -1) meme = true;
		try {
			while (true){
				if(meme)
				{
					rec.readFromFile(raf);
					System.out.println(++incr + ": " + rec);
				}
				else if(user == -2)
				{
					while(count<5)
					{
						raf.seek(count*92);
						rec.readFromFile(raf);
						System.out.println(rec);
						count ++;
					}
					if(count == 5)
					{
						int list = count + 5;
						System.out.println("(M)for main menu (N)for next screen (A)to display all");
						String minimenu = scanner.next().toLowerCase();
						switch(minimenu)
						{
						case "m":
							System.out.println("Mainmenu"); //break to main menu. Wont go back....
							break;

						case "n":
							try
							{
								while(count<list)
								{
									raf.seek(count*92);
									rec.readFromFile(raf);
									System.out.println(rec);
									count ++;
								}
							}
							catch(EOFException e)
							{
								System.out.println("Out of records.\n");
							}
							break;


						case "a": print(raf, rec, -1);// print all (Works)
							break;

						default:
							System.out.println("Please enter a valid option");
							break;


						}
					}
				}
				else
				{
					rec.readFromFile(raf);
					if(++incr == user)
					{
						System.out.println(incr + ": " + rec);
					}
				}
			}
		}
		catch (EOFException e){

		}
	}
}