/*
 * JBoss, Home of Professional Open Source
 *
 * Copyright 2013 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.keycloak.services.resources;

import org.jboss.logging.Logger;
import org.jboss.resteasy.spi.HttpRequest;
import org.keycloak.ClientConnection;
import org.keycloak.broker.provider.AuthenticationRequest;
import org.keycloak.broker.provider.AuthenticationResponse;
import org.keycloak.broker.provider.FederatedIdentity;
import org.keycloak.broker.provider.IdentityBrokerException;
import org.keycloak.broker.provider.IdentityProvider;
import org.keycloak.broker.provider.IdentityProviderFactory;
import org.keycloak.events.Details;
import org.keycloak.events.Errors;
import org.keycloak.events.EventBuilder;
import org.keycloak.events.EventType;
import org.keycloak.models.ClientModel;
import org.keycloak.models.ClientSessionModel;
import org.keycloak.models.FederatedIdentityModel;
import org.keycloak.models.IdentityProviderModel;
import org.keycloak.models.KeycloakSession;
import org.keycloak.models.OAuthClientModel;
import org.keycloak.models.RealmModel;
import org.keycloak.models.UserModel;
import org.keycloak.models.UserSessionModel;
import org.keycloak.protocol.oidc.TokenManager;
import org.keycloak.provider.ProviderFactory;
import org.keycloak.services.managers.AppAuthManager;
import org.keycloak.services.managers.AuthenticationManager;
import org.keycloak.services.managers.AuthenticationManager.AuthResult;
import org.keycloak.services.managers.ClientSessionCode;
import org.keycloak.services.managers.EventsManager;
import org.keycloak.services.resources.flows.Flows;
import org.keycloak.services.resources.flows.Urls;
import org.keycloak.social.SocialIdentityProvider;

import javax.ws.rs.Consumes;
import javax.ws.rs.GET;
import javax.ws.rs.OPTIONS;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.Status;
import javax.ws.rs.core.UriBuilder;
import javax.ws.rs.core.UriInfo;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import static org.keycloak.models.AccountRoles.MANAGE_ACCOUNT;
import static org.keycloak.models.ClientSessionModel.Action.AUTHENTICATE;
import static org.keycloak.models.Constants.ACCOUNT_MANAGEMENT_APP;
import static org.keycloak.models.UserModel.RequiredAction.UPDATE_PROFILE;

/**
 * <p></p>
 *
 * @author Pedro Igor
 */
@Path("/broker")
public class IdentityBrokerService {

    private static final Logger LOGGER = Logger.getLogger(IdentityBrokerService.class);

    private final RealmModel realmModel;

    @Context
    private UriInfo uriInfo;

    @Context
    private KeycloakSession session;

    @Context
    private ClientConnection clientConnection;

    @Context
    private HttpRequest request;
    private EventBuilder event;

    public IdentityBrokerService(RealmModel realmModel) {
        if (realmModel == null) {
            throw new IllegalArgumentException("Realm can not be null.");
        }

        this.realmModel = realmModel;
    }

    public void init() {
        this.event = new EventsManager(this.realmModel, this.session, this.clientConnection).createEventBuilder().event(EventType.IDENTITY_PROVIDER_LOGIN);
    }

    @GET
    @Path("/{provider_id}/login")
    public Response performLogin(@PathParam("provider_id") String providerId, @QueryParam("code") String code) {
        this.event.detail(Details.IDENTITY_PROVIDER, providerId);

        if (isDebugEnabled()) {
            LOGGER.debugf("Sending authentication request to identity provider [%s].", providerId);
        }

        try {
            ClientSessionCode clientSessionCode = parseClientSessionCode(code, providerId);
            IdentityProvider identityProvider = getIdentityProvider(providerId);
            AuthenticationResponse authenticationResponse = identityProvider.handleRequest(createAuthenticationRequest(providerId, clientSessionCode));

            Response response = authenticationResponse.getResponse();

            if (response != null) {
                this.event.success();
                if (isDebugEnabled()) {
                    LOGGER.debugf("Identity provider [%s] is going to send a request [%s].", identityProvider, response);
                }
                return response;
            }
        } catch (IdentityBrokerException e) {
            return redirectToErrorPage("Could not send authentication request to identity provider [" + providerId + "].", e);
        } catch (Exception e) {
            return redirectToErrorPage("Unexpected error when handling authentication request to identity provider [" + providerId + "].", e);
        }

        return redirectToErrorPage("Could not proceed with authentication request to identity provider.");
    }

    @GET
    @Path("{provider_id}")
    public Response handleResponseGet(@PathParam("provider_id") String providerId) {
        return handleResponse(providerId);
    }

    @POST
    @Path("{provider_id}")
    public Response handleResponsePost(@PathParam("provider_id") String providerId) {
        return handleResponse(providerId);
    }

    @Path("{provider_id}/token")
    @OPTIONS
    public Response retrieveTokenPreflight() {
        return Cors.add(this.request, Response.ok()).auth().preflight().build();
    }

    @GET
    @Path("{provider_id}/token")
    public Response retrieveToken(@PathParam("provider_id") String providerId) {
        return getToken(providerId, false);
    }

    private Response getToken(String providerId, boolean forceRetrieval) {
        this.event.event(EventType.IDENTITY_PROVIDER_RETRIEVE_TOKEN);

        try {
            AppAuthManager authManager = new AppAuthManager();
            AuthResult authResult = authManager.authenticateBearerToken(this.session, this.realmModel, this.uriInfo, this.clientConnection, this.request.getHttpHeaders());

            if (authResult != null) {
                String audience = authResult.getToken().getAudience();
                ClientModel clientModel = this.realmModel.findClient(audience);

                if (clientModel == null) {
                    return badRequest("Invalid client.");
                }

                if (!clientModel.hasIdentityProvider(providerId)) {
                    return corsResponse(badRequest("Client [" + audience + "] not authorized."), clientModel);
                }

                if (!clientModel.isAllowedRetrieveTokenFromIdentityProvider(providerId)) {
                    return corsResponse(badRequest("Client [" + audience + "] not authorized to retrieve tokens from identity provider [" + providerId + "]."), clientModel);
                }

                if (OAuthClientModel.class.isInstance(clientModel) && !forceRetrieval) {
                    return corsResponse(Flows.forms(this.session, this.realmModel, clientModel, this.uriInfo)
                            .setClientSessionCode(authManager.extractAuthorizationHeaderToken(this.request.getHttpHeaders()))
                            .setAccessRequest("Your information from " + providerId + " identity provider.")
                            .setClient(clientModel)
                            .setUriInfo(this.uriInfo)
                            .setActionUri(this.uriInfo.getRequestUri())
                            .createOAuthGrant(null), clientModel);
                }

                IdentityProvider identityProvider = getIdentityProvider(providerId);
                IdentityProviderModel identityProviderConfig = getIdentityProviderConfig(providerId);

                if (identityProviderConfig.isStoreToken()) {
                    FederatedIdentityModel identity = this.session.users().getFederatedIdentity(authResult.getUser(), providerId, this.realmModel);

                    if (identity == null) {
                        return corsResponse(badRequest("User [" + authResult.getUser().getId() + "] is not associated with identity provider [" + providerId + "]."), clientModel);
                    }

                    this.event.success();

                    return corsResponse(identityProvider.retrieveToken(identity), clientModel);
                }

                return corsResponse(badRequest("Identity Provider [" + providerId + "] does not support this operation."), clientModel);
            }

            return badRequest("Invalid token.");
        } catch (IdentityBrokerException e) {
            return redirectToErrorPage("Could not obtain token fron identity provider [" + providerId + "].", e);
        }  catch (Exception e) {
            return redirectToErrorPage("Unexpected error when retrieving token from identity provider [" + providerId + "].", e);
        }
    }

    @POST
    @Path("{provider_id}/token")
    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
    public Response consentTokenRetrieval(@PathParam("provider_id") String providerId,
                                          MultivaluedMap<String, String> formData) {
        if (formData.containsKey("cancel")) {
            return redirectToErrorPage("Permission not approved.");
        }

        return getToken(providerId, true);
    }

    private Response handleResponse(String providerId) {
        if (isDebugEnabled()) {
            LOGGER.debugf("Handling authentication response from identity provider [%s].", providerId);
        }
        this.event.event(EventType.IDENTITY_PROVIDER_RESPONSE);
        this.event.detail(Details.IDENTITY_PROVIDER, providerId);
        IdentityProviderModel identityProviderConfig = getIdentityProviderConfig(providerId);

        try {
            IdentityProvider identityProvider = getIdentityProvider(providerId);
            String relayState = identityProvider.getRelayState(createAuthenticationRequest(providerId, null));

            if (relayState == null) {
                return redirectToErrorPage("No relay state in response from identity identity [" + providerId + ".");
            }

            if (isDebugEnabled()) {
                LOGGER.debugf("Relay state is valid: [%s].", relayState);
            }

            ClientSessionCode clientSessionCode = parseClientSessionCode(relayState, providerId);
            AuthenticationResponse authenticationResponse = identityProvider.handleResponse(createAuthenticationRequest(providerId, clientSessionCode));
            Response response = authenticationResponse.getResponse();

            if (response != null) {
                if (isDebugEnabled()) {
                    LOGGER.debugf("Identity provider [%s] is going to send a response [%s].", identityProvider, response);
                }
                return response;
            }

            FederatedIdentity identity = authenticationResponse.getUser();

            if (isDebugEnabled()) {
                LOGGER.debugf("Identity provider [%s] returned with identity [%s].", providerId, identity);
            }

            if (!identityProviderConfig.isStoreToken()) {
                if (isDebugEnabled()) {
                    LOGGER.debugf("Token will not be stored for identity provider [%s].", providerId);
                }
                identity.setToken(null);
            }

            identity.setIdentityProviderId(providerId);

            return performLocalAuthentication(identity, clientSessionCode);
        } catch (IdentityBrokerException e) {
            rollback();
            return redirectToErrorPage("Authentication failed. Could not authenticate with identity provider [" + providerId + "].", e);
        } catch (Exception e) {
            rollback();
            return redirectToErrorPage("Unexpected error when handling response from identity provider [" + providerId + "].", e);
        } finally {
            if (this.session.getTransaction().isActive()) {
                this.session.getTransaction().commit();
            }
        }
    }

    private Response performLocalAuthentication(FederatedIdentity updatedIdentity, ClientSessionCode clientCode) {
        ClientSessionModel clientSession = clientCode.getClientSession();
        IdentityProviderModel identityProviderConfig = getIdentityProviderConfig(updatedIdentity.getIdentityProviderId());
        String providerId = identityProviderConfig.getId();
        FederatedIdentityModel federatedIdentityModel = new FederatedIdentityModel(providerId, updatedIdentity.getId(),
                updatedIdentity.getUsername(), updatedIdentity.getToken());

        this.event.event(EventType.IDENTITY_PROVIDER_LOGIN)
                .detail(Details.REDIRECT_URI, clientSession.getRedirectUri())
                .detail(Details.IDENTITY_PROVIDER_IDENTITY, updatedIdentity.getUsername());

        UserModel federatedUser = this.session.users().getUserByFederatedIdentity(federatedIdentityModel, this.realmModel);

        // Check if federatedUser is already authenticated (this means linking social into existing federatedUser account)
        if (clientSession.getUserSession() != null) {
            return performAccountLinking(clientSession, providerId, federatedIdentityModel, federatedUser);
        }

        if (federatedUser == null) {
            try {
                federatedUser = createUser(updatedIdentity);

                if (identityProviderConfig.isUpdateProfileFirstLogin()) {
                    if (isDebugEnabled()) {
                        LOGGER.debugf("Identity provider requires update profile action.", federatedUser);
                    }
                    federatedUser.addRequiredAction(UPDATE_PROFILE);
                }
            } catch (Exception e) {
                return redirectToLoginPage(e, clientCode);
            }
        }

        updateFederatedIdentity(updatedIdentity, federatedUser);

        UserSessionModel userSession = this.session.sessions()
                .createUserSession(this.realmModel, federatedUser, federatedUser.getUsername(), this.clientConnection.getRemoteAddr(), "broker", false);

        this.event.user(federatedUser);
        this.event.session(userSession);

        TokenManager.attachClientSession(userSession, clientSession);

        if (isDebugEnabled()) {
            LOGGER.debugf("Performing local authentication for user [%s].", federatedUser);
        }

        return AuthenticationManager.nextActionAfterAuthentication(this.session, userSession, clientSession, this.clientConnection, this.request,
                this.uriInfo, event);
    }

    private Response performAccountLinking(ClientSessionModel clientSession, String providerId, FederatedIdentityModel federatedIdentityModel, UserModel federatedUser) {
        this.event.event(EventType.IDENTITY_PROVIDER_ACCCOUNT_LINKING);

        if (federatedUser != null) {
            return redirectToErrorPage("The identity returned by the identity provider [" + providerId + "] is already linked to other user.");
        }

        UserModel authenticatedUser = clientSession.getUserSession().getUser();

        if (isDebugEnabled()) {
            LOGGER.debugf("Linking account [%s] from identity provider [%s] to user [%s].", federatedIdentityModel, providerId, authenticatedUser);
        }

        if (!authenticatedUser.isEnabled()) {
            fireErrorEvent(Errors.USER_DISABLED);
            return redirectToErrorPage("User is disabled.");
        }

        if (!authenticatedUser.hasRole(this.realmModel.getApplicationByName(ACCOUNT_MANAGEMENT_APP).getRole(MANAGE_ACCOUNT))) {
            fireErrorEvent(Errors.NOT_ALLOWED);
            return redirectToErrorPage("Insufficient permissions to link identities.");
        }

        this.session.users().addFederatedIdentity(this.realmModel, authenticatedUser, federatedIdentityModel);

        this.event.success();

        return Response.status(302).location(UriBuilder.fromUri(clientSession.getRedirectUri()).build()).build();
    }

    private void updateFederatedIdentity(FederatedIdentity updatedIdentity, UserModel federatedUser) {
        FederatedIdentityModel federatedIdentityModel = this.session.users().getFederatedIdentity(federatedUser, updatedIdentity.getIdentityProviderId(), this.realmModel);

        federatedIdentityModel.setToken(updatedIdentity.getToken());

        this.session.users().updateFederatedIdentity(this.realmModel, federatedUser, federatedIdentityModel);

        if (isDebugEnabled()) {
            LOGGER.debugf("Identity [%s] update with response from identity provider [%s].", federatedUser, updatedIdentity.getIdentityProviderId());
        }
    }

    private ClientSessionCode parseClientSessionCode(String code, String providerId) {
        ClientSessionCode clientCode = ClientSessionCode.parse(code, this.session, this.realmModel);

        if (clientCode != null && clientCode.isValid(AUTHENTICATE)) {
            ClientSessionModel clientSession = clientCode.getClientSession();

            if (clientSession != null) {
                ClientModel client = clientSession.getClient();

                if (client != null) {
                    LOGGER.debugf("Got authorization code from client [%s].", client.getClientId());
                    this.event.client(client);
                }

                if (clientSession.getUserSession() != null) {
                    this.event.session(clientSession.getUserSession());
                }
            } else {
                validateClientPermissions(clientCode, providerId);
            }

            if (isDebugEnabled()) {
                LOGGER.debugf("Authorization code is valid.");
            }

            return clientCode;
        }

        throw new IdentityBrokerException("Invalid code, please login again through your application.");
    }

    private AuthenticationRequest createAuthenticationRequest(String providerId, ClientSessionCode clientSessionCode) {
        ClientSessionModel clientSession = null;
        String relayState = null;

        if (clientSessionCode != null) {
            clientSession = clientSessionCode.getClientSession();
            relayState = clientSessionCode.getCode();
        }

        return new AuthenticationRequest(this.session, this.realmModel, clientSession, this.request, this.uriInfo, relayState, getRedirectUri(providerId));
    }

    private String getRedirectUri(String providerId) {
        return Urls.identityProviderAuthnResponse(this.uriInfo.getBaseUri(), providerId, this.realmModel.getName()).toString();
    }

    private Response redirectToErrorPage(String message) {
        return redirectToErrorPage(message, null);
    }

    private Response redirectToErrorPage(String message, Throwable throwable) {
        if (message == null) {
            message = "Unexpected error when authenticating with identity provider";
        }

        fireErrorEvent(message, throwable);
        return Flows.forwardToSecurityFailurePage(this.session, this.realmModel, this.uriInfo, message);
    }

    private Response redirectToLoginPage(Throwable t, ClientSessionCode clientCode) {
        String message = t.getMessage();

        if (message == null) {
            message = "Unexpected error when authenticating with identity provider";
        }

        fireErrorEvent(message);
        return Flows.forms(this.session, this.realmModel, clientCode.getClientSession().getClient(), this.uriInfo)
                .setClientSessionCode(clientCode.getCode())
                .setError(message)
                .createLogin();
    }

    private Response badRequest(String message) {
        fireErrorEvent(message);
        return Flows.errors().error(message, Status.BAD_REQUEST);
    }

    private IdentityProvider getIdentityProvider(String providerId) {
        IdentityProviderModel identityProviderModel = this.realmModel.getIdentityProviderById(providerId);

        if (identityProviderModel != null) {
            IdentityProviderFactory providerFactory = getIdentityProviderFactory(identityProviderModel);

            if (providerFactory == null) {
                throw new IdentityBrokerException("Could not find factory for identity provider [" + providerId + "].");
            }

            return providerFactory.create(identityProviderModel);
        }

        throw new IdentityBrokerException("Identity Provider [" + providerId + "] not found.");
    }

    private IdentityProviderFactory getIdentityProviderFactory(IdentityProviderModel model) {
        Map<String, IdentityProviderFactory> availableProviders = new HashMap<String, IdentityProviderFactory>();
        List<ProviderFactory> allProviders = new ArrayList<ProviderFactory>();

        allProviders.addAll(this.session.getKeycloakSessionFactory().getProviderFactories(IdentityProvider.class));
        allProviders.addAll(this.session.getKeycloakSessionFactory().getProviderFactories(SocialIdentityProvider.class));

        for (ProviderFactory providerFactory : allProviders) {
            availableProviders.put(providerFactory.getId(), (IdentityProviderFactory) providerFactory);
        }

        return availableProviders.get(model.getProviderId());
    }

    private IdentityProviderModel getIdentityProviderConfig(String providerId) {
        for (IdentityProviderModel model : this.realmModel.getIdentityProviders()) {
            if (model.getId().equals(providerId)) {
                return model;
            }
        }

        throw new IdentityBrokerException("Configuration for identity provider [" + providerId + "] not found.");
    }

    private void validateClientPermissions(ClientSessionCode clientSessionCode, String providerId) {
        ClientSessionModel clientSession = clientSessionCode.getClientSession();
        ClientModel clientModel = clientSession.getClient();

        if (clientModel == null) {
            throw new IdentityBrokerException("Invalid client.");
        }

        if (!clientModel.hasIdentityProvider(providerId)) {
            throw new IdentityBrokerException("Client [" + clientModel.getClientId() + "] not authorized to authenticate with identity provider [" + providerId + "].");
        }
    }

    private UserModel createUser(FederatedIdentity updatedIdentity) {
        FederatedIdentityModel federatedIdentityModel = new FederatedIdentityModel(updatedIdentity.getIdentityProviderId(), updatedIdentity.getId(),
                updatedIdentity.getUsername(), updatedIdentity.getToken());
        // Check if no user already exists with this username or email
        UserModel existingUser = null;

        if (updatedIdentity.getEmail() != null) {
            existingUser = this.session.users().getUserByEmail(updatedIdentity.getEmail(), this.realmModel);
        }

        if (existingUser != null) {
            fireErrorEvent(Errors.FEDERATED_IDENTITY_EMAIL_EXISTS);
            throw new IdentityBrokerException("federatedIdentityEmailExists");
        }

        String username = updatedIdentity.getUsername();
        if (this.realmModel.isRegistrationEmailAsUsername()) {
            username = updatedIdentity.getEmail();
            if (username == null || username.trim().length() == 0) {
                fireErrorEvent(Errors.FEDERATED_IDENTITY_REGISTRATION_EMAIL_MISSING);
                throw new IdentityBrokerException("federatedIdentityRegistrationEmailMissing");
                // TODO KEYCLOAK-1053 (ask user to enter email address) should be implemented instead of plain exception as better solution for this case
            }
            username = username.trim();
        } else if (username != null) {
            username = username.trim();
        }

        existingUser = this.session.users().getUserByUsername(username, this.realmModel);

        if (existingUser != null) {
            fireErrorEvent(Errors.FEDERATED_IDENTITY_USERNAME_EXISTS);
            throw new IdentityBrokerException("federatedIdentityUsernameExists");
        }

        if (isDebugEnabled()) {
            LOGGER.debugf("Creating account from identity [%s].", federatedIdentityModel);
        }

        UserModel federatedUser = this.session.users().addUser(this.realmModel, username);

        if (isDebugEnabled()) {
            LOGGER.debugf("Account [%s] created.", federatedUser);
        }

        federatedUser.setEnabled(true);
        federatedUser.setFirstName(updatedIdentity.getFirstName());
        federatedUser.setLastName(updatedIdentity.getLastName());
        federatedUser.setEmail(updatedIdentity.getEmail());

        this.session.users().addFederatedIdentity(this.realmModel, federatedUser, federatedIdentityModel);

        this.event.clone().user(federatedUser).event(EventType.REGISTER)
                .detail(Details.IDENTITY_PROVIDER, federatedIdentityModel.getIdentityProvider())
                .detail(Details.IDENTITY_PROVIDER_IDENTITY, updatedIdentity.getUsername())
                .removeDetail("auth_method")
                .success();

        return federatedUser;
    }

    private Response corsResponse(Response response, ClientModel clientModel) {
        return Cors.add(this.request, Response.fromResponse(response)).auth().allowedOrigins(clientModel).build();
    }

    private void fireErrorEvent(String message, Throwable throwable) {
        if (!this.event.getEvent().getType().toString().endsWith("_ERROR")) {
            boolean newTransaction = !this.session.getTransaction().isActive();

            try {
                if (newTransaction) {
                    this.session.getTransaction().begin();
                }

                this.event.error(message);

                if (newTransaction) {
                    this.session.getTransaction().commit();
                }
            } catch (Exception e) {
                LOGGER.error("Could not fire event.", e);
                rollback();
            }
        }

        if (throwable != null) {
            LOGGER.error(message, throwable);
        } else {
            LOGGER.error(message);
        }
    }

    private void fireErrorEvent(String message) {
        fireErrorEvent(message, null);
    }

    private boolean isDebugEnabled() {
        return LOGGER.isDebugEnabled();
    }

    private void rollback() {
        if (this.session.getTransaction().isActive()) {
            this.session.getTransaction().rollback();
        }
    }
}
