import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;

/* GPA_App.java
** Java application that, given an input file containing raw data (in the
** form of CSV-Strings) about students, the courses that they took, and the
** grades they earned in those courses, produces a report showing each 
** student's GPA.  (See the processStudent() method for a description of
** the assumed format of the lines/records in the input file and what
** each line of the report includes.
**
** CMPS 134 Fall 2025 Prog. Assg. #5
** Author: R. McCloskey and < STUDENT's NAME >
** October 2025
** Collaborated with: ...
** Known Defects: ...
*/

public class GPA_App {

   public static void main(String[] args) throws FileNotFoundException {

      // Establish the Scanner that will read from an input file
      Scanner input = getScanner(args);

      System.out.println();
      printHeading();

      while (input.hasNextLine()) {
         String line = input.nextLine();        // read next line/record from input file
         CSV_String csv = new CSV_String(line); // use it to create a CSV_String object
         processStudent(csv);
      }

      System.out.println("\nGoodbye!");
   }


   /* Processes the given CSV_String object, culminating in a line of output
   ** being produced.  The assumed format of the CSV_String is exemplified by 
   **
   ** Richard.Sharkface@rpi.edu,20020502,MUSIC432 3 C+,ART114 3 A,HIST257 3 A-
   **
   ** That is:
   ** -- Field-0 is the student's e-mail address, assumed to be of the
   **    form <firstName>.<lastName>@<school>,
   ** -- Field-1 is the student's birthdate (in yyyymmdd format), and 
   ** -- each subsequent field includes three items of data, separated
   **    by spaces: course ID, # of credits, and letter grade earned by
   **    the student.
   ** 
   ** The line of output that should be produced as a result of processing
   ** the CSV_String shown above is 
   **
   ** Sharkface, Richard             02-May-2002    3.33
   **
   ** In general, each such line of output includes the student's name
   ** (which can be inferred from the e-mail address), date of birth (in
   ** dd-Mon-yyyy format), and GPA (with two digits after the decimal point).
   */
   private static void processStudent(CSV_String csv) {

      // Extract the email-address field from 'csv' and then 
      // translate it into a name in <lastName>, <firstName> format:

      //  < MISSING CODE >


      // Extract the calendar date field from 'csv' and then
      // translate it into the dd-Mon-yyyy format:

      //  < MISSING CODE >


      // Use the remaining fields of 'csv' to compute the student's GPA:

      //  < MISSING CODE >


      // Produce a line of output:

      //  < MISSING CODE >

   }


   /* Given an e-mail address assumed to be in the form 
   ** <firstName>.<lastName>@<...>, returns the person's
   ** name in <lastName>, <firstName> format.
   ** Example: "Mary.Smith@psu.edu" maps to "Smith, Mary".
   */
   private static String emailAddrToName(String emailAddr) {
      return "Lincoln, Abraham";   // STUB
   }


   // Methods in support of converting a calendar date 
   // in yyyymmdd format into dd-Mon-yyyy format.
   // ------------------------------------------------

   /* Given a calendar date expressed in yyyymmdd format, returns the
   ** same date expressed in dd-Mon-yyyy format.
   ** Examples: 
   **   "20191016" maps to "16-Oct-2019"
   **   "19870309" maps to "09-Mar-1987"
   */
   private static String yyyymmdd_to_ddMONyyyy(String yyyymmdd) {
      return "1809-Feb-12";   // STUB!
   }

   /* Given a month number, returns the corresponding 3-character abbreviation.
   ** Each month's abbreviation is the first three letters of its name, with
   ** only the first letter capitalized.
   ** Examples: 3 maps to "Mar", 8 maps to "Aug"
   */
   private static String monthAbbreviation(int monthNumber) {
      return "GLORP";   // STUB!
   }

   // End of methods in support of calendar date conversion.


   // Methods in support of computing GPA
   // -----------------------------------

   /* Given a CSV-String each of whose fields identifies a course, its number
   ** of credits, and the letter grade earned in the course, computes the GPA.
   ** Example: "PHIL120 3 B,MATH114 4 A-,CHEM141 3 C+" maps to 3.07.
   */
   private static double computeGPA(CSV_String csv) {
      return -1.0;    // STUB
   }

   /* Returns the number of quality points associated to the given letter grade.
   ** Exhaustive mapping:
   **  "A"  maps to 4.0      "C+" maps to 2.33     "F" maps to 0.0
   **  "A-" maps to 3.67     "C"  maps to 2.0
   **  "B+" maps to 3.33     "C-" maps to 1.67
   **  "B"  maps to 3.0      "D+" maps to 1.33
   **  "B-" maps to 2.67     "D"  maps to 1.0
   */
   private static double gradeToQualityPoints(String grade) {
      if (grade.equals("A")) { return 4.0; }
      else if (grade.equals("A-")) { return 3.67; }
      else if (grade.equals("B+")) { return 3.33; }
      else if (grade.equals("B")) { return 3.0; }
      else if (grade.equals("B-")) { return 2.67; }
      else if (grade.equals("C+")) { return 2.33; }
      else if (grade.equals("C")) { return 2.0; }
      else if (grade.equals("C-")) { return 1.67; }
      else if (grade.equals("D+")) { return 1.33; }
      else if (grade.equals("D")) { return 1.0; }
      else if (grade.equals("F")) { return 0.0; }
      else { return 0.0; }  // should never get here
   }



   // Methods in support of printing the heading and the output records.
   // ------------------------------------------------------------------

   /* Given a student's name, birthdate, and GPA, prints a properly
   ** formatted output record.
   */
   private static void printStudent(String name, String birthDate, double gpa) {  
      System.out.printf("%-30s %11s    %4.2f\n", name, birthDate, gpa);
   }

   /* Prints the column headings of the report.
   */
   private static void printHeading() {

      System.out.printf("       %-22s %13s   %3s\n", 
                        "Name", "Date of Birth", "GPA");
      printChars('-', 50);
      System.out.println();
   }


   /* Prints the specified character the specified number of times.
   */
   private static void printChars(char ch, int numTimes) {
      for (int i=0; i != numTimes; i++) {
         System.out.print(ch);
      }
   }



   // Methods in support of establishing a Scanner
   // to be used for reading input data from a file.
   // -----------------------------------------------

   /* Returns a Scanner object that can read from the file named by either
   ** args[0] or, if args[] has no elements, from a file named by the user
   ** in response to a prompt.
   */
   private static Scanner getScanner(String[] args) {
      Scanner result = null;
      String fileName;
      if (args.length == 0) {
         fileName = getStringFromUser("Enter name of input file: ");
      }
      else {
         fileName = args[0];
      }
      System.out.println("Program to read from file " + fileName);

      try {
         // Establish a Scanner to read from the file with the specified name.
         result = new Scanner(new File(fileName));  
      }
      catch (FileNotFoundException e) {
         System.out.println("No such file exists; program aborting.");
         System.exit(0);
      }
      return result;
   }

   /* Prints the given prompt and reads/returns a line of data read
   ** from standard input (the keyboard).
   */
   private static String getStringFromUser(String prompt) {
      Scanner keyboard = new Scanner(System.in);
      System.out.print(prompt);
      return keyboard.nextLine();
   }

}