/*
Tibisay Movil

Copyright (C) 2013 Antonio Araujo (aaraujo@cenditel.gob.ve), Jose Ruiz 
(jruiz@cenditel.gob.ve), Fundacion Centro Nacional de Desarrollo e 
Investigacion en Tecnologias Libres - CENDITEL.

La Fundación CENDITEL concede permiso para usar, copiar, distribuir y/o 
modificar este programa, reconociendo el derecho que la humanidad posee al
libre acceso al conocimiento, bajo los términos de la licencia de software 
GPL versión 2.0 de la Free Software Foundation.

Este programa se distribuye con la esperanza de que sea util, pero SIN
NINGUNA GARANTIA; tampoco las implicitas garantias de MERCANTILIDAD o
ADECUACION A UN PROPOSITO PARTICULAR.

Para mayor información sobre los términos de la licencia ver el archivo 
llamado "gpl-2.0.txt" en ingles.
*/

package ve.gob.cenditel.tibisaymovil;

import java.io.Serializable;
import java.security.PrivateKey;
import java.security.cert.X509Certificate;

import android.os.Build;
import android.os.Build.VERSION_CODES;

/**
 * Accesses the KeyChain in a unified way both in Android versions post and pre 4.0. Android 4.0 and later has an
 * operating system level keychain. This keychain is shared across the operating system and all applications. In prior
 * versions a custom, application private keychain will be used.
 *
 * @author José M. Prieto (jmprieto@emergya.com)
 */
public abstract class KeyChainStrategy implements Serializable {

    private static final long serialVersionUID = -5156264665372692833L;
    protected static KeyChainStrategy theInstance = null;

    protected static KeyChainClientActivity activity;

    public static KeyChainStrategy getInstance() {

        if (theInstance == null) {
            if (Build.VERSION.SDK_INT < VERSION_CODES.ICE_CREAM_SANDWICH) {
                // < Android 4.0. Does not have KeyChain API
                return CustomKeyChain.getInstance();
            } else {
                // >= Android 4.0. KeyChain available!
                return AndroidKeyChain.getInstance();
            }
        }
        return theInstance;
    }

    /**
     * Set the KeyChainClientActivity that will be notified of the alias selected by the user. The notification is done
     * via the {@link KeyChainClientActivity#setAlias(String)} callback.
     *
     * @param activity the receiver of notifications
     */
    public void setClientActivity(KeyChainClientActivity activity) {
        KeyChainStrategy.activity = activity;
    }

    /**
     * Launches an Activity for the user to select the alias for a private key and certificate pair for authentication.
     * The selected alias or null will be returned to the {@link KeyChainClientActivity} passed to the previous call to
     * {@link #setClientActivity(KeyChainClientActivity)} via the
     * {@link KeyChainClientActivity#setAlias(String)} callback.
     */
    public abstract void choosePrivateKeyAlias();
    
    
    /**
     * Same as before, but only to modify alias list.
     */
    public abstract void choosePrivateKeyList();
    

    /**
     * Get a certificate chain from the keystore.
     * This method requires the caller to hold the permission USE_CREDENTIALS on Android >= 4.0.
     *
     * @param alias The alias of the desired certificate chain
     * @return the X509Certificate chain for the requested alias, or null if no there is no result
     * @throws InterruptedException if the operation has been interrupted before completion
     * @throws KeystoreException when there is some error accessing the keystore
     */
    public abstract X509Certificate[] getCertificateChain(String alias)
    throws InterruptedException, KeystoreException;

    /**
     * Get a private key from the keystore.
     *
     * @param alias the alias of the desired private key
     * @return the PrivateKey for the requested alias, or null if no there is no result
     * @throws InterruptedException if the operation has been interrupted before completion
     * @throws KeystoreException when there is some error accessing the keystore
     */
    public abstract PrivateKey getPrivateKey(String alias)
    throws InterruptedException, KeystoreException;
    
    
    
    
    /**
     * Delete a certificate from the keystore.
     *
     * @param alias the alias of the certificate chain to delete
     * @throws InterruptedException if the operation has been interrupted before completion
     * @throws KeystoreException when there is some error accessing the keystore
     */
    public abstract int deleteCertificate(String alias) 
    		throws InterruptedException, KeystoreException;
    
    
    
}