package task3;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.Date;

/*
 * Helpdesk class, containing all file I/O functionality.
 */

public class Helpdesk {

    /*
     * Class fields -
     *      record -> array containing all other class fields, initialised in constructor
     *      recordID -> unique string used to identify individual questions
     *      question -> user-supplied question
     *      answer -> user-supplied answer
     *      status -> contains either "Pending" or "Answered" depending on state
     *      questionDate -> date that the question was posted
     *      answerDate -> date that the answer was posted
     *      delimiter -> delimiter used to convert Strings to String arrays
     */

    private String record[] = null; // null fields are initialised at a later time
    private String recordID = "0", question = "-", answer = "-", status = "Pending";
    private Date questionDate = null, answerDate = null;
    private char delimiter = '|'; // global delimiter

    /*
     * Helpdesk constructor -
     *      - Assigns questionDate to the time of object instantiation
     *      - Assigns recordID to the String value of the system time in milliseconds
     *          (the number of milliseconds since 00:00 on January 1st, 1970)
     *      - Assigns question to the contents of the string passed to the constructor
     *          as an argument
     *      - Calls the addQuestion() method
     */

    Helpdesk(String question) {
        questionDate = new Date();
        this.recordID = String.valueOf(questionDate.getTime()); // String.valueOf() converts
        this.question = question;                               // an Object to a String
        addQuestion();
    }

    /*
     * writeRecord() method -
     *      - Takes one string array argument
     *      - Instantiates a FileWriter object to write to a file named "archive.txt", and
     *          appends to that file.
     *      - Instantiates a PrintWriter object to be used in future references to the file
     *      - Contains a loop that iterates five times, writing the contents of each index to
     *          the file, followed by the delimiter. On the final iteration, the contents of
     *          the index plus one (the final element of the array) is also written, followed
     *          by two delimiters to signify the end of the record.
     *      - Closes the file
     *
     */

    public void writeRecord(String[] record) {
        try {
            FileWriter file = new FileWriter("archive.txt", true); // "true" here signifies appending
            PrintWriter fileOut = new PrintWriter(file);

            for (int index  = 0; index < 5; index++) {
                fileOut.print(record[index] + delimiter); // one delimiter for indexes 0 to 4
                if (index == 4) {
                    fileOut.println(record[index + 1] + delimiter + delimiter); // two delimiters for index 5
                }
            }

            fileOut.close();
        } catch (Exception exc) {
            exc.printStackTrace();
        }
    }

    /*
     * addQuestion() method -
     *      - Assigns the previously declared record field a 6-element String array
     *      - Assigns each element
     *      - Calls the writeRecord() method
     */

    public void addQuestion() {
        record = new String[6];

        record[0] = this.recordID;
        record[1] = questionDate.toString(); // Object.toString() returns String equivalent of Object
        record[2] = this.question;
        record[3] = status;
        record[4] = "-"; // record[4] and record[5] are initialised to meaningful values later
        record[5] = "-";

        writeRecord(record);
    }

    /*
     * addAnswer() method -
     *      - Takes two String arguments
     *      - Assigns answerDate to the time that the method is called
     *      - Assigns status to "Answered"
     *      - Assigns the previously declared record field to the return value of readRecord()
     *      - Assigns the last three elements of the record array
     *      - Calls the writeRecord() method
     */

    public void addAnswer(String answer, String recordID) {
        answerDate = new Date();
        this.answer = answer;

        status = "Answered"; // status is no longer "Pending"
        record = readRecord(recordID);
        if (record == null) { // checks to make sure the record exists, and takes appropriate
            System.out.println("Record does not exist."); // action if it does not
            return; // returns to caller
        }

        record[3] = status;
        record[4] = this.answer;
        record[5] = answerDate.toString();

        writeRecord(record);
    }

    /*
     * readRecord() method -
     *      - Declares a String array variable and assigns it to null
     *      - Instantiates a BufferedReader object used a reference to the file to be read
     *      - Declares a String object to hold a string of class fields
     *      - While there are lines to be read in the file, assigns the String array
     *          variable to the return value of the split String variable. If the first
     *          element matches the argument passed to the method, the array is returned to
     *          the caller
     *      - Closes the file
     *      - Returns null, if no recordArray[0] elements matched the argument passed
     */

    public String[] readRecord(String recordID) {
        String[] recordArray = null;

        try {
            BufferedReader fileIn = new BufferedReader(new FileReader("archive.txt")); // file name
            String record = null;
            while ((record = fileIn.readLine()) != null) {
                recordArray = record.split("[" + delimiter + "]"); // split string using delimiter
                if (recordID.equals(recordArray[0]))
                    return recordArray;
            }

            fileIn.close();
        } catch (Exception exc) {
            exc.printStackTrace();
        }

        return null;
    }

    public static void main(String[] args) {
        Helpdesk helpdesk = new Helpdesk("Question goes here.");
        helpdesk.addAnswer("Answer goes here.", "1328889314890");
    }
}