package chocopy.common;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
import java.util.stream.Collectors;

/** Utility functions for general use. */
public class Utils {

    /**
     * Return resource file FILENAME's contents as a string. FILENAME can refer to a file within the
     * class hierarchy, so that a text resource in file resource.txt in the chocopy.common.codegen
     * package, for example, could be referred to with FILENAME chocopy/common/codegen/resource.txt.
     *
     * <p>Credit: Lucio Paiva.
     */
    public static String getResourceFileAsString(String fileName) {
        InputStream is = Utils.class.getClassLoader().getResourceAsStream(fileName);
        if (is != null) {
            BufferedReader reader =
                    new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
            return reader.lines().collect(Collectors.joining(System.lineSeparator()));
        }
        return null;
    }

    /**
     * Return an exception signalling a fatal error having a message formed from MSGFORMAT and ARGS,
     * as for String.format.
     */
    public static Error fatal(String msgFormat, Object... args) {
        return new Error(String.format(msgFormat, args));
    }

    /**
     * Return the string S padded with FILL to TOLEN characters. Padding is on the left if
     * PADONLEFT, and otherwise on the right. If S is already at least TOLEN characters, returns S.
     */
    public static String pad(String s, Character fill, int toLen, boolean padOnLeft) {
        StringBuilder result = new StringBuilder(toLen);
        if (!padOnLeft) {
            result.append(s);
        }
        for (int n = s.length(); n < toLen; n += 1) {
            result.append(fill);
        }
        if (padOnLeft) {
            result.append(s);
        }
        return result.toString();
    }
}