oglimmer/lunchy

package de.oglimmer.lunchy.security;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

import javax.servlet.http.HttpServletRequest;

import lombok.extern.slf4j.Slf4j;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;

import de.oglimmer.lunchy.database.dao.LocationDao;
import de.oglimmer.lunchy.database.dao.UserDao;
import de.oglimmer.lunchy.database.generated.tables.records.LocationRecord;
import de.oglimmer.lunchy.rest.SessionProvider;
import de.oglimmer.lunchy.rest.UserRightException;
import de.oglimmer.lunchy.services.CommunityService;

@Slf4j
public enum SecurityProvider {
    INSTANCE;

    private LoadingCache<Integer, Permission> cb;

    private SecurityProvider() {
        cb = CacheBuilder.newBuilder().expireAfterAccess(1, TimeUnit.HOURS).build(new CacheLoader<Integer, Permission>() {
            public Permission load(Integer key) {
                return Permission.fromVal(UserDao.INSTANCE.getById(key).getPermissions());
            }
        });
    }

    public void checkAdmin(HttpServletRequest request) {
        checkRight(request, Permission.ADMIN);
    }

    public void checkConfirmedUser(HttpServletRequest request) {
        checkRight(request, Permission.CONFIRMED_USER);
    }
    
    public boolean isAllowedToDeleteLocation(int locationId, HttpServletRequest request) {
        Integer userId = SessionProvider.INSTANCE.getLoggedInUserId(request);
        if (userId != null) {
            LocationRecord locRec = LocationDao.INSTANCE.getById(locationId, CommunityService.get(request));
            if (locRec.getFkUser() == userId
                    || SecurityProvider.INSTANCE.checkRightOnSession(request, Permission.ADMIN)) {
                return true;
            }
        }
        return false;
    }

    private void checkRight(HttpServletRequest request, Permission permissionToCheck) {
        if (!checkRightOnSession(request, permissionToCheck)) {
            throw new UserRightException();
        }
    }

    public boolean checkRightOnSession(HttpServletRequest request, Permission permissionToCheck) {
        Integer userId = SessionProvider.INSTANCE.getLoggedInUserId(request);
        if (userId != null) {
            return checkRightOnUser(permissionToCheck, userId);
        }
        return false;
    }

    private boolean checkRightOnUser(Permission permissionToCheck, Integer userId) {
        try {
            Permission permission = cb.get(userId);
            if (permission.getVal() >= permissionToCheck.getVal()) {
                return true;
            }
        } catch (ExecutionException e) {
            log.error("Failed to ret permission from cache", e);
        }
        return false;
    }

    public void updateCache(Integer id) {
        cb.refresh(id);
    }

    public void reset() {
        cb.invalidateAll();
    }

}