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

/**
 * Parses the temperature and date from a file given as a string to the file
 * @author Isaac Shoebottom (3429069)
 */

public class TemperatureParser {
    private Scanner sc;
    private int counterDateTime = -1;
    private int counterTemperature = -1;
    private double temperature;
    private String date;

    /**
     * Constructor for the parser
     * Measures the index of the date/time and temperature in the csv file
     * @param filename The filename of the csv file to be parsed.
     */
    TemperatureParser(String filename) {
        try {
            sc = new Scanner(new File(filename), "UTF-8").useDelimiter("\",\"");
        } catch (FileNotFoundException exception) {
            System.out.println("File not found, the file might have been typed incorrectly");
            System.out.print("Use tab to autocomplete a filename when in the same directory as the program");
            System.exit(1);
        }
        int counter = 1;
        String field;
        while (sc.hasNext() && counterTemperature == -1 | counterDateTime == -1) {
            field = sc.next();
            if (field.equals("Date/Time (LST)"))
                counterDateTime = counter;
            if (field.equals("Temp (°C)"))
                counterTemperature = counter;
            counter++;
        }
        sc.nextLine();

    }


    /**
     * Parses a line of a csv and gets the date/time and temperature
     * @throws NoSuchElementException When a line is incomplete or a field is empty in the csv spreadsheet this error is thrown
     */
    void parseLine() throws NoSuchElementException {
        String line = sc.nextLine();
        Scanner scanDate = new Scanner(line).useDelimiter("\",\"");
        Scanner scanTemp = new Scanner(line).useDelimiter("\",\"");
        try {
            for (int i = 1; i < counterDateTime; i++) {
                scanDate.next();
            }
            date = scanDate.next();
            for (int i = 1; i < counterTemperature; i++) {
                scanTemp.next();
            }
            temperature = scanTemp.nextDouble();
        }
        catch (NoSuchElementException exception) {
            System.out.println("Invalid entry at: " + date);
        }
    }

    /**
     * Checks if there is a value next
     * @return boolean if there is a next value true if not false
     */
    boolean parseHasNext() {
        return sc.hasNext();
    }

    /**
     * Gets there temperature that was most recently parsed
     * @return The temperature that was most recently parsed as a double
     */
    public double getTemperature() {
        return temperature;
    }

    /**
     * Gets the date that was most recently parsed
     * @return The date/time that was most recently parsed
     */
    public String getDate() {
        return date;
    }
}