package org.springframework.security.web.authentication.preauth;

import java.util.*;

import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.GrantedAuthoritiesContainer;
import org.springframework.security.core.userdetails.AuthenticationUserDetailsService;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;

import org.springframework.util.Assert;

/**
 * <p>
 * This AuthenticationUserDetailsService implementation creates a UserDetails
 * object based solely on the information contained in the given
 * PreAuthenticatedAuthenticationToken. The user name is set to the name as
 * returned by PreAuthenticatedAuthenticationToken.getName(), the password is
 * set to a fixed dummy value (it will not be used by the
 * PreAuthenticatedAuthenticationProvider anyway), and the Granted Authorities
 * are retrieved from the details object as returned by
 * PreAuthenticatedAuthenticationToken.getDetails().
 *
 * <p>
 * The details object as returned by PreAuthenticatedAuthenticationToken.getDetails() must implement the
 * {@link GrantedAuthoritiesContainer} interface for this implementation to work.
 *
 * @author Ruud Senden
 * @since 2.0
 */
public class PreAuthenticatedGrantedAuthoritiesUserDetailsService
        implements AuthenticationUserDetailsService<PreAuthenticatedAuthenticationToken> {
    /**
     * Get a UserDetails object based on the user name contained in the given
     * token, and the GrantedAuthorities as returned by the
     * GrantedAuthoritiesContainer implementation as returned by
     * the token.getDetails() method.
     */
    public final UserDetails loadUserDetails(PreAuthenticatedAuthenticationToken token) throws AuthenticationException {
        Assert.notNull(token.getDetails());
        Assert.isInstanceOf(GrantedAuthoritiesContainer.class, token.getDetails());
        Collection<? extends GrantedAuthority> authorities = ((GrantedAuthoritiesContainer) token.getDetails()).getGrantedAuthorities();
        return createUserDetails(token, authorities);
    }

    /**
     * Creates the final <tt>UserDetails</tt> object. Can be overridden to customize the contents.
     *
     * @param token the authentication request token
     * @param authorities the pre-authenticated authorities.
     */
    protected UserDetails createUserDetails(Authentication token, Collection<? extends GrantedAuthority> authorities) {
        return new User(token.getName(), "N/A", true, true, true, true, authorities);
    }
}
