package mypackage;

/**
 * Utility class for reading (doubles) and writing to files.
 *
 * @author Jenny Orr
 * @version Fall2015
 */
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Scanner;

public class FileIO {

    public FileIO() {
    }

    /**
     * Reads doubles (one per line) from a file .
     *
     * @param fileName the name of the file to be read (list of doubles, one per
     * line)
     * @return an array containing the data
     */
    public static double[] readFile(String fileName) {
        double[] data = null;
        File file = new File(fileName);
        System.out.println("Reading data file: " + file.getAbsolutePath());

        try {
            ArrayList<Double> dataList = new ArrayList<Double>();
            Scanner reader = new Scanner(file);
            while (reader.hasNext()) {
                String d = reader.nextLine();
                double temp = Double.parseDouble(d);
                dataList.add(temp);
            }
            reader.close();
            data = new double[dataList.size()];
            System.out.println("Length of array: " + dataList.size());
            for (int i = 0; i < dataList.size(); i++) {
                data[i] = dataList.get(i);
            }
        } catch (FileNotFoundException e) {
            System.out.println(e + "\nFile not found:\n " + file.getAbsolutePath());
            System.exit(0);
        } catch (NullPointerException e) {
            System.out.println("No data found " + e);
            System.exit(0);
        } catch (NumberFormatException e) {
            System.out.println("String does not contain a number. " + e);
            System.exit(0);
        } catch (Exception e) {
            System.out.println("Problem reading file. " + e);
            System.exit(0);
        }
        System.out.println("Done reading file.");
        return data;
    }

    /**
     * Returns a PrintWriter object for a file to be named fileName. If the file
     * already exists, returns null.
     *
     * @param fileName the name of the file to write to
     * @param overwrite if true will overwrite an existing file of same name.
     * @return a PrintWriter object or null if the file already exists.
     */
    public static PrintWriter getPrintWriter(String fileName, boolean overwrite) {
        PrintWriter outputFile = null;
        try {
            File file = new File(fileName);
            if (!overwrite && file.exists()) {
                System.out.println("File already exists. Will not overwrite.");
            } else {
                if (file.exists()) {
                    System.out.println("Overwriting file " + file.getAbsolutePath());
                } else {
                    System.out.println("Writing to " + file.getAbsolutePath());
                }
                outputFile = new PrintWriter(file);
                return outputFile;
            }
        } catch (Exception e) {
            System.out.println(e + "\nProblem writing to file. " + fileName);
            System.exit(0);
        }
        return null;  // file already exists so return null
    }

}