import android.app.Activity;
import android.content.Context;
import android.support.v4.app.Fragment;
import com.facebook.FacebookRequestError;
import com.facebook.Request;
import com.facebook.Response;
import com.facebook.Session;
import com.facebook.SessionState;
import com.facebook.model.GraphUser;
import java.util.List;

public class Facebook {

  private Context context;
  private Session session;
  private Session.OpenRequest request;

  private List<String> permissions;

  private Callback callback;

  public Facebook(Context context) {
    this.context = context;
  }

  public Facebook permissions(List<String> permissions) {
    this.permissions = permissions;
    return this;
  }

  public Facebook login(Callback callback, Activity activity) {
    this.callback = callback;
    request = new Session.OpenRequest(activity);
    config();
    return this;
  }

  public Facebook login(Callback callback, Fragment fragment) {
    this.callback = callback;
    request = new Session.OpenRequest(fragment);
    config();
    return this;
  }

  private void config() {
    request.setPermissions(permissions);
    request.setCallback(callbackFacebook);
    session = new Session(context);
    Session.setActiveSession(session);
    session.openForRead(request);
  }

  private Session.StatusCallback callbackFacebook = new Session.StatusCallback() {
    @Override public void call(Session session, SessionState state, Exception exception) {
      if(exception != null) {
        exception.printStackTrace();
        return;
      }
      if (session.isOpened()) {
        Request request = Request.newMeRequest(session, new Request.GraphUserCallback() {
          @Override public void onCompleted(GraphUser user, Response response) {
            if(response != null &&
                response.getError() != null &&
                response.getError().getErrorCode() ==
                    FacebookRequestError.INVALID_ERROR_CODE) {
              callback.onFail();
              return;
            }
            if (response != null && response.getGraphObject() == null) {
              callback.onFail();
              return;
            }
            if (user != null) {
              try {
                callback.onSuccess(user);
              } catch (Exception e) {
                if(DebugUtil.DEBUG) {
                  e.printStackTrace();
                }
                callback.onFail();
              }
            } else {
              callback.onFail();
            }
          }
        });
        request.executeAsync();
      } else {
        callback.onFail();
      }
    }
  };

  public interface Callback {
    void onSuccess(GraphUser graphUser);
    void onFail();
  }

}