package com.github.scribejava.core.extractors;
import java.util.Map;
import com.github.scribejava.core.exceptions.OAuthParametersMissingException;
import com.github.scribejava.core.model.OAuthConstants;
import com.github.scribejava.core.model.OAuthRequest;
import com.github.scribejava.core.utils.OAuthEncoder;
import com.github.scribejava.core.utils.Preconditions;
/**
* Default implementation of {@link HeaderExtractor}. Conforms to OAuth 1.0a
*/
public class HeaderExtractorImpl implements HeaderExtractor {
public static final int ESTIMATED_PARAM_LENGTH = 20;
private static final String PARAM_SEPARATOR = ", ";
private static final String PREAMBLE = "OAuth ";
/**
* {@inheritDoc}
*/
@Override
public String extract(OAuthRequest request) {
checkPreconditions(request);
final Map<String, String> parameters = request.getOauthParameters();
final StringBuilder header = new StringBuilder(parameters.size() * ESTIMATED_PARAM_LENGTH);
header.append(PREAMBLE);
for (Map.Entry<String, String> entry : parameters.entrySet()) {
if (header.length() > PREAMBLE.length()) {
header.append(PARAM_SEPARATOR);
}
header.append(String.format("%s=\"%s\"", entry.getKey(), OAuthEncoder.encode(entry.getValue())));
}
if (request.getRealm() != null && !request.getRealm().isEmpty()) {
header.append(PARAM_SEPARATOR);
header.append(String.format("%s=\"%s\"", OAuthConstants.REALM, request.getRealm()));
}
return header.toString();
}
private void checkPreconditions(OAuthRequest request) {
Preconditions.checkNotNull(request, "Cannot extract a header from a null object");
if (request.getOauthParameters() == null || request.getOauthParameters().size() <= 0) {
throw new OAuthParametersMissingException(request);
}
}
}