package cn.home1.oss.lib.security;
   
   import com.google.common.base.Preconditions;
   import com.google.common.collect.ImmutableList;
   
   import org.springframework.security.authentication.AuthenticationProvider;
   import org.springframework.security.core.Authentication;
   import org.springframework.security.core.AuthenticationException;
   
  import java.util.List;
  import java.util.Optional;
  
  /**
   * Created by zhanghaolun on 16/7/6.
   */
  public class CompositeAuthenticationProvider implements AuthenticationProvider {
  
    private List<AuthenticationProvider> delegates = ImmutableList.of();
  
    public void setDelegates(final List<AuthenticationProvider> delegates) {
      Preconditions.checkArgument(delegates != null, "delegates must not null");
      this.delegates = delegates;
    }
  
    AuthenticationProvider findAuthenticationProviderFor(final Authentication authentication) {
      return authentication != null ? this.findAuthenticationProviderFor(authentication.getClass()) : null;
    }
  
    AuthenticationProvider findAuthenticationProviderFor(final Class<?> authentication) {
      final AuthenticationProvider found;
      if (authentication != null) {
        final Optional<AuthenticationProvider> optional =
          this.delegates.stream().filter(provider -> provider.supports(authentication)).findFirst();
        found = optional.isPresent() ? optional.get() : null;
      } else {
        found = null;
      }
      return found;
    }
  
    @Override
    public Authentication authenticate(final Authentication authentication) throws AuthenticationException {
      final AuthenticationProvider authenticationProvider = this.findAuthenticationProviderFor(authentication);
      return authenticationProvider != null ? authenticationProvider.authenticate(authentication) : null;
    }
  
    @Override
    public boolean supports(final Class<?> authentication) {
      return this.findAuthenticationProviderFor(authentication) != null;
    }
  }