package goodjava.util;

import java.io.UnsupportedEncodingException;
import java.util.Base64;
import java.util.ArrayList;


public final class GoodUtils {

	public static byte[] getBytes(String s,String charsetName) {
		try {
			return s.getBytes(charsetName);
		} catch(UnsupportedEncodingException e) {
			throw new RuntimeException(e);
		}
	}

	public static String base64Encode(String s) {
		return Base64.getEncoder().encodeToString(getBytes(s,"UTF-8"));
	}

	public static String[] split(String s,String splitter) {
		return split(s,splitter,-1);
	}

	// modified from String.java
	public static String[] split(String s,String splitter,int limit) {
		int len = s.length();
		int n = splitter.length();
		int off = 0;
		int next = 0;
		boolean limited = limit > 0;
		ArrayList<String> list = new ArrayList<>();
		if( n==0 ) {
			limit = limited ? Math.min(limit,len) : len;
			for( int i=0; i<limit; i++ ) {
				list.add(s.substring(i, i+1));
			}
			String[] result = new String[limit];
			return list.toArray(result);
		}
		while ((next = s.indexOf(splitter, off)) != -1) {
			if (!limited || list.size() < limit - 1) {
				list.add(s.substring(off, next));
				off = next + n;
			} else {    // last one
				//assert (list.size() == limit - 1);
				list.add(s.substring(off, len));
				off = len;
				break;
			}
		}
		// If no match was found, return s
		if (off == 0)
			return new String[]{s};

		// Add remaining segment
		if (!limited || list.size() < limit)
			list.add(s.substring(off, len));

		// Construct result
		int resultSize = list.size();
		if (limit == 0) {
			while (resultSize > 0 && list.get(resultSize - 1).length() == 0) {
				resultSize--;
			}
		}
		String[] result = new String[resultSize];
		return list.subList(0, resultSize).toArray(result);
	}

	// faster than String.replace()
	public static String replace(String s,String target,String replacement) {
		int i = s.indexOf(target);
		if( i == -1 )
			return s;
		int starting = 0;
		int n = target.length();
		StringBuilder sb = new StringBuilder();
		do {
			sb.append(s,starting,i);
			sb.append(replacement);
			starting = i + n;
			i = s.indexOf(target,starting);
		} while( i != -1 );
		sb.append(s,starting,s.length());
		return sb.toString();
	}

}