package at.gv.egovernment.moa.id.protocols.oauth20.json;

import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Signature;

import org.apache.commons.lang.StringUtils;

/**
 * Enum of the signature algorithms supported by this package.
 */
public enum OAuthSignatureAlgorithm {
	ECDSA256("SHA256withECDSA", "ECDSA256", null), RS256("SHA256withRSA", "RS256", null), ECDSA256_IAKIK("SHA1withECDSA", "ECDSA256",
			"IAIK_ECC");
	
	private final String signatureName;
	private final String algorithm;
	private final String providerName;
	
	private OAuthSignatureAlgorithm(final String signatureName, final String hashAlg, final String providerName) {
		this.signatureName = signatureName;
		this.algorithm = hashAlg;
		this.providerName = providerName;
	}
	
	/**
	 * What the signature algorithm is named in the "alg" parameter in a JSON Token's envelope.
	 */
	public String getAlgorithm() {
		return this.algorithm;
	}
	
	/**
	 * 
	 * @return the signature name like SHA256withECDSA or SHA256withRSA
	 */
	public String getSignatureName() {
		return this.signatureName;
	}
	
	/**
	 * Calls {@link Signature#getInstance(String)} with the defined signature name
	 * 
	 * @return
	 * @throws NoSuchAlgorithmException
	 * @throws NoSuchProviderException
	 */
	public Signature getSignatureInstance() throws NoSuchAlgorithmException, NoSuchProviderException {
		if (!StringUtils.isEmpty(this.providerName)) {
			//return Signature.getInstance(this.signatureName, this.providerName);
			return Signature.getInstance(this.signatureName, this.providerName);
		} else {
			return Signature.getInstance(this.signatureName);
		}
	}
	
	/**
	 * Given the name of the algorithm in the envelope, returns the corresponding enum instance.
	 */
	public static OAuthSignatureAlgorithm getFromJsonName(String name) {
		return OAuthSignatureAlgorithm.valueOf(name);
	}
}