/*
* Copyright @ 2013 CurisTEC, S.A.S. All Rights Reserved.
*/
package net.curisit.securis.ioc;

import java.io.IOException;
import java.lang.reflect.Method;
import java.util.List;
import java.util.Set;

import jakarta.annotation.Priority;
import jakarta.inject.Inject;
import jakarta.persistence.EntityManager;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.ws.rs.Priorities;
import jakarta.ws.rs.WebApplicationException;
import jakarta.ws.rs.container.ContainerRequestContext;
import jakarta.ws.rs.container.ContainerRequestFilter;
import jakarta.ws.rs.container.ResourceInfo;
import jakarta.ws.rs.core.Context;
import jakarta.ws.rs.core.Response;
import jakarta.ws.rs.core.Response.Status;
import jakarta.ws.rs.ext.Provider;
import jakarta.ws.rs.ext.WriterInterceptor;
import jakarta.ws.rs.ext.WriterInterceptorContext;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import net.curisit.securis.db.User;
import net.curisit.securis.security.BasicSecurityContext;
import net.curisit.securis.security.Securable;
import net.curisit.securis.utils.CacheTTL;
import net.curisit.securis.utils.TokenHelper;

/**
* RequestsInterceptor
* <p>
* Authentication/authorization interceptor that:
* <ul>
*   <li>Loads and stores the {@link EntityManager} in the request context.</li>
*   <li>Validates tokens for methods annotated with {@link Securable}.</li>
*   <li>Builds a {@link BasicSecurityContext} with roles and scoped organization/application IDs.</li>
*   <li>Manages transactions when {@code @EnsureTransaction} is present.</li>
* </ul>
*
* <p><b>Cache usage:</b> Uses {@link CacheTTL} to cache roles and scope sets.
* The new {@link CacheTTL#getSet(String, Class)} helper removes unchecked
* conversion warnings when retrieving {@code Set<Integer>} from the cache.
* 
* @author JRA
* Last reviewed by JRA on Oct 5, 2025.
*/
@Provider
@Priority(Priorities.AUTHENTICATION)
public class RequestsInterceptor implements ContainerRequestFilter, WriterInterceptor {

    private static final Logger LOG = LogManager.getLogger(RequestsInterceptor.class);

    @Inject private CacheTTL cache;
    @Inject private TokenHelper tokenHelper;
    @Inject private EntityManagerProvider emProvider;

    @Context private HttpServletResponse servletResponse;
    @Context private HttpServletRequest servletRequest;
    @Context private ResourceInfo resourceInfo;

    private static final String EM_CONTEXT_PROPERTY = "curisit.entitymanager";

    // -------------------------------------------------------------
    // Request filter (authN/authZ + EM handling)
    // -------------------------------------------------------------

    /** 
     * filter<p>
     * Entry point before resource method invocation. 
     * 
     * @param requestContext
     * @throws IOException
     */
    @Override
    public void filter(ContainerRequestContext requestContext) throws IOException {
        EntityManager em = emProvider.getEntityManager();
        LOG.debug("GETTING EM: {}", em);

        // Store EntityManager for later retrieval (writer interceptor)
        requestContext.setProperty(EM_CONTEXT_PROPERTY, em);

        Method method = resourceInfo.getResourceMethod();

        if (checkSecurableMethods(requestContext, method)) {
            if (method.isAnnotationPresent(EnsureTransaction.class)) {
                LOG.debug("Beginning transaction");
                em.getTransaction().begin();
            }
        }
    }

    /**
    * checkSecurableMethods<p>
    * Enforce security checks for methods annotated with {@link Securable}.
    * Builds {@link BasicSecurityContext} when authorized.
    *
    * @param ctx
    * @param method
    * @return true if request can proceed; false when aborted
    */
    private boolean checkSecurableMethods(ContainerRequestContext ctx, Method method) {
        if (!method.isAnnotationPresent(Securable.class)) return true;

        String token = servletRequest.getHeader(TokenHelper.TOKEN_HEADER_PÀRAM);
        if (token == null || !tokenHelper.isTokenValid(token)) {
            LOG.warn("Access denied, invalid token");
            ctx.abortWith(Response.status(Status.UNAUTHORIZED).build());
            return false;
        }

        String username = tokenHelper.extractUserFromToken(token);
        int roles = getUserRoles(username);
        Securable securable = method.getAnnotation(Securable.class);

        if (securable.roles() != 0 && (securable.roles() & roles) == 0) {
            LOG.warn("User {} lacks required roles for method {}", username, method.getName());
            ctx.abortWith(Response.status(Status.UNAUTHORIZED).build());
            return false;
        }

        BasicSecurityContext sc = new BasicSecurityContext(username, roles, servletRequest.isSecure());
        sc.setOrganizationsIds(getUserOrganizations(username));
        sc.setApplicationsIds(getUserApplications(username));
        ctx.setSecurityContext(sc);
        return true;
    }

    // -------------------------------------------------------------
    // Cached lookups (roles/orgs/apps)
    // -------------------------------------------------------------

    /**
    * getUserRoles<p>
    * Retrieve roles bitmask for the given user (cached).
    * 
    * @param username
    * @return userRoles
    */
    private int getUserRoles(String username) {
        if (username == null) return 0;
        Integer cached = cache.get("roles_" + username, Integer.class);
        if (cached != null) return cached;

        EntityManager em = emProvider.getEntityManager();
        User user = em.find(User.class, username);
        int roles = 0;
        if (user != null) {
            List<Integer> r = user.getRoles();
            if (r != null) for (Integer role : r) roles += role;
            cache.set("roles_" + username, roles, 3600);
            // also warm some caches
            cache.set("orgs_" + username, user.getOrgsIds(), 3600);
        }
        return roles;
    }

    /**
    * getUserOrganizations<p>
    * Retrieve organization scope for the user as a typed {@code Set<Integer>}
    * using the cache helper that validates element types.
    * 
    * @param username
    * @return userOrganizations
    */
    private Set<Integer> getUserOrganizations(String username) {
        Set<Integer> cached = cache.getSet("orgs_" + username, Integer.class);
        if (cached != null) return cached;

        User user = emProvider.getEntityManager().find(User.class, username);
        if (user != null) {
            Set<Integer> result = user.getAllOrgsIds();
            cache.set("orgs_" + username, result, 3600);
            return result;
        }
        return Set.of();
    }

    /**
    * getUserApplications<p>
    * Retrieve application scope for the user as a typed {@code Set<Integer>}
    * using the cache helper that validates element types.
    * 
    * @param username
    * @return userApplications
    */
    private Set<Integer> getUserApplications(String username) {
        Set<Integer> cached = cache.getSet("apps_" + username, Integer.class);
        if (cached != null) return cached;

        User user = emProvider.getEntityManager().find(User.class, username);
        if (user != null) {
            Set<Integer> result = user.getAllAppsIds();
            cache.set("apps_" + username, result, 3600);
            return result;
        }
        return Set.of();
    }

    // -------------------------------------------------------------
    // Writer interceptor (transaction finalize)
    // -------------------------------------------------------------

    /** 
     * aroundWriteTo<p>
     * Commit/rollback and close EM after response writing. 
     * 
     * @param context
     * @throws IOException
     * @throws WebApplicationException
     */
    @Override
    public void aroundWriteTo(WriterInterceptorContext context) throws IOException, WebApplicationException {
        context.proceed();

        EntityManager em = (EntityManager) context.getProperty(EM_CONTEXT_PROPERTY);
        if (em == null) return;

        try {
            if (em.getTransaction().isActive()) {
                if (servletResponse.getStatus() == Status.OK.getStatusCode()) {
                    em.getTransaction().commit();
                    LOG.debug("Transaction committed");
                } else {
                    em.getTransaction().rollback();
                    LOG.debug("Transaction rolled back");
                }
            }
        } finally {
            if (em.isOpen()) {
                try {
                    em.close();
                } catch (Exception e) {
                    LOG.error("Error closing EntityManager", e);
                }
            }
        }
    }
}