package de.vanitasvitae.imi.codes;

import java.io.File;
import java.util.regex.Pattern;

public class InputValidator {

    // Allowed characters
    public static final String REGEX_ALPHABET = "[a-zA-Z0-9]";
    public static final String ALPHABET = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

    /*
    REGEX pattern for study numbers. Allowed are all 3-letter numbers from the alphabet [a-zA-Z0-9].
     */
    private static final Pattern STUDY_NUMBER_MATCHER = Pattern.compile(REGEX_ALPHABET +"{3}");

    /*
    REGEX pattern for sample numbers. Allowed are four-letter numbers from the alphabet [a-zA-Z0-9].
     */
    private static final Pattern SAMPLE_NUMBER_MATCHER = Pattern.compile(REGEX_ALPHABET +"{4}");

    /**
     * Validate a given study number. Valid study numbers are 3-letter codes from the alphabet [a-zA-Z0-9].
     *
     * @param in input String
     * @return unmodified input String if it matches.
     *
     * @throws InvalidOptionException if the input String doesn't match the regex.
     */
    public static String validateStudyNumber(String in) throws InvalidOptionException {
        if (!STUDY_NUMBER_MATCHER.matcher(in).matches()) {
            throw new InvalidOptionException("Study number must be a three digit number from the alphabet [a-zA-Z0-9].");
        }

        return in;
    }

    /**
     * Validate a given sample type. Valid types are found in {@link SampleType}.#
     *
     * @param in input String
     * @return parsed {@link SampleType}.
     *
     * @throws InvalidOptionException if the given String doesn't match a {@link SampleType}.
     * @throws NullPointerException in case the given String is {@code null}.
     */
    public static SampleType validateSampleType(String in) throws InvalidOptionException {
        try {
            return SampleType.getEnum(in);
        } catch (IllegalArgumentException e) {
            String message = "Invalid sample type \"" + in + "\".";
            throw new InvalidOptionException(message, e);
        }
    }

    /**
     * Validate, that the user provided number of codes to be generated is an integer greater than 0.
     *
     * @param in input String
     * @return number of codes to be generated.
     *
     * @throws InvalidOptionException in case the input string is
     */
    public static int validateNumberOfCodes(String in) throws InvalidOptionException {
        int i;
        try {
            i = Integer.parseInt(in);
        } catch (NumberFormatException e) {
            throw new InvalidOptionException("Invalid input \"" + in + "\". Please enter a positive number.", e);
        }

        if (i <= 0) {
            throw new InvalidOptionException("Number of generated codes must be greater than 0.");
        }

        return i;
    }

    /**
     * Validate, that the user-provided path is writable and that any parent folders exist.
     * Otherwise throw a {@link InvalidOptionException}.
     *
     * @param path file path (absolut or relative) as a string.
     * @return file
     *
     * @throws InvalidOptionException in case any parent folder does not exist, the path points to a directory or the
     * destination is not writable.
     */
    public static File validateOutputPath(String path) throws InvalidOptionException {
        // TODO
        return null;
    }
}