package android.service.autofill;
import static android.view.autofill.Helper.sDebug;
import android.annotation.NonNull;
import android.annotation.TestApi;
import android.os.Parcel;
import android.os.Parcelable;
import android.util.Log;
import android.view.autofill.AutofillId;
import com.android.internal.util.Preconditions;
import java.util.Arrays;
public final class LuhnChecksumValidator extends InternalValidator implements Validator,
Parcelable {
private static final String TAG = "LuhnChecksumValidator";
private final AutofillId[] mIds;
public LuhnChecksumValidator(@NonNull AutofillId... ids) {
mIds = Preconditions.checkArrayElementsNotNull(ids, "ids");
}
private static boolean isLuhnChecksumValid(@NonNull String number) {
int sum = 0;
boolean isDoubled = false;
for (int i = number.length() - 1; i >= 0; i--) {
final int digit = number.charAt(i) - '0';
if (digit < 0 || digit > 9) {
continue;
}
int addend;
if (isDoubled) {
addend = digit * 2;
if (addend > 9) {
addend -= 9;
}
} else {
addend = digit;
}
sum += addend;
isDoubled = !isDoubled;
}
return sum % 10 == 0;
}
@Override
@TestApi
public boolean isValid(@NonNull ValueFinder finder) {
if (mIds == null || mIds.length == 0) return false;
final StringBuilder builder = new StringBuilder();
for (AutofillId id : mIds) {
final String partialNumber = finder.findByAutofillId(id);
if (partialNumber == null) {
if (sDebug) Log.d(TAG, "No partial number for id " + id);
return false;
}
builder.append(partialNumber);
}
final String number = builder.toString();
boolean valid = isLuhnChecksumValid(number);
if (sDebug) Log.d(TAG, "isValid(" + number.length() + " chars): " + valid);
return valid;
}
@Override
public String toString() {
if (!sDebug) return super.toString();
return "LuhnChecksumValidator: [ids=" + Arrays.toString(mIds) + "]";
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel parcel, int flags) {
parcel.writeParcelableArray(mIds, flags);
}
public static final Parcelable.Creator<LuhnChecksumValidator> CREATOR =
new Parcelable.Creator<LuhnChecksumValidator>() {
@Override
public LuhnChecksumValidator createFromParcel(Parcel parcel) {
return new LuhnChecksumValidator(parcel.readParcelableArray(null, AutofillId.class));
}
@Override
public LuhnChecksumValidator[] newArray(int size) {
return new LuhnChecksumValidator[size];
}
};
}