package com.fsck.k9.mail;
import java.util.Random;
import android.support.annotation.VisibleForTesting;
public class BoundaryGenerator {
private static final BoundaryGenerator INSTANCE = new BoundaryGenerator(new Random());
private static final int BOUNDARY_CHARACTER_COUNT = 30;
private static final char[] BASE36_MAP = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
'U', 'V', 'W', 'X', 'Y', 'Z'
};
private final Random random;
public static BoundaryGenerator getInstance() {
return INSTANCE;
}
@VisibleForTesting
BoundaryGenerator(Random random) {
this.random = random;
}
public String generateBoundary() {
StringBuilder builder = new StringBuilder(4 + BOUNDARY_CHARACTER_COUNT);
builder.append("----");
for (int i = 0; i < BOUNDARY_CHARACTER_COUNT; i++) {
builder.append(BASE36_MAP[random.nextInt(36)]);
}
return builder.toString();
}
}