/*
 * Copyright 2016 Red Hat, Inc. and/or its affiliates
 * and other contributors as indicated by the @author tags.
 *
 * 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.protocol.oidc;

import org.jboss.logging.Logger;
import org.keycloak.OAuth2Constants;
import org.keycloak.OAuthErrorException;
import org.keycloak.common.util.Time;
import org.keycloak.events.Details;
import org.keycloak.events.EventBuilder;
import org.keycloak.events.EventType;
import org.keycloak.models.AuthenticatedClientSessionModel;
import org.keycloak.models.ClientModel;
import org.keycloak.models.KeycloakSession;
import org.keycloak.models.RealmModel;
import org.keycloak.models.UserSessionModel;
import org.keycloak.protocol.LoginProtocol;
import org.keycloak.protocol.oidc.utils.OIDCRedirectUriBuilder;
import org.keycloak.protocol.oidc.utils.OIDCResponseMode;
import org.keycloak.protocol.oidc.utils.OIDCResponseType;
import org.keycloak.representations.AccessTokenResponse;
import org.keycloak.services.ServicesLogger;
import org.keycloak.services.managers.AuthenticationManager;
import org.keycloak.services.managers.AuthenticationSessionManager;
import org.keycloak.services.managers.ClientSessionCode;
import org.keycloak.services.managers.ResourceAdminManager;
import org.keycloak.sessions.AuthenticationSessionModel;
import org.keycloak.util.TokenUtil;

import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.UriBuilder;
import javax.ws.rs.core.UriInfo;

/**
 * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
 * @author <a href="mailto:sthorger@redhat.com">Stian Thorgersen</a>
 */
public class OIDCLoginProtocol implements LoginProtocol {

    public static final String LOGIN_PROTOCOL = "openid-connect";
    public static final String STATE_PARAM = "state";
    public static final String LOGOUT_STATE_PARAM = "OIDC_LOGOUT_STATE_PARAM";
    public static final String SCOPE_PARAM = "scope";
    public static final String CODE_PARAM = "code";
    public static final String RESPONSE_TYPE_PARAM = "response_type";
    public static final String GRANT_TYPE_PARAM = "grant_type";
    public static final String REDIRECT_URI_PARAM = "redirect_uri";
    public static final String CLIENT_ID_PARAM = "client_id";
    public static final String NONCE_PARAM = "nonce";
    public static final String MAX_AGE_PARAM = OAuth2Constants.MAX_AGE;
    public static final String PROMPT_PARAM = OAuth2Constants.PROMPT;
    public static final String LOGIN_HINT_PARAM = "login_hint";
    public static final String REQUEST_PARAM = "request";
    public static final String REQUEST_URI_PARAM = "request_uri";
    public static final String UI_LOCALES_PARAM = OAuth2Constants.UI_LOCALES_PARAM;
    public static final String CLAIMS_PARAM = "claims";

    public static final String LOGOUT_REDIRECT_URI = "OIDC_LOGOUT_REDIRECT_URI";
    public static final String ISSUER = "iss";

    public static final String RESPONSE_MODE_PARAM = "response_mode";

    public static final String PROMPT_VALUE_NONE = "none";
    public static final String PROMPT_VALUE_LOGIN = "login";
    public static final String PROMPT_VALUE_CONSENT = "consent";
    public static final String PROMPT_VALUE_SELECT_ACCOUNT = "select_account";

    // Client authentication methods
    public static final String CLIENT_SECRET_BASIC = "client_secret_basic";
    public static final String CLIENT_SECRET_POST = "client_secret_post";
    public static final String CLIENT_SECRET_JWT = "client_secret_jwt";
    public static final String PRIVATE_KEY_JWT = "private_key_jwt";

    // https://tools.ietf.org/html/rfc7636#section-4.3
    public static final String CODE_CHALLENGE_PARAM = "code_challenge";
    public static final String CODE_CHALLENGE_METHOD_PARAM = "code_challenge_method";

    // https://tools.ietf.org/html/rfc7636#section-4.2
    public static final int PKCE_CODE_CHALLENGE_MIN_LENGTH = 43;
    public static final int PKCE_CODE_CHALLENGE_MAX_LENGTH = 128;

    // https://tools.ietf.org/html/rfc7636#section-4.1
    public static final int PKCE_CODE_VERIFIER_MIN_LENGTH = 43;
    public static final int PKCE_CODE_VERIFIER_MAX_LENGTH = 128;    
    
    // https://tools.ietf.org/html/rfc7636#section-6.2.2
    public static final String PKCE_METHOD_PLAIN = "plain";
    public static final String PKCE_METHOD_S256 = "S256";

    private static final Logger logger = Logger.getLogger(OIDCLoginProtocol.class);

    protected KeycloakSession session;

    protected RealmModel realm;

    protected UriInfo uriInfo;

    protected HttpHeaders headers;

    protected EventBuilder event;

    protected OIDCResponseType responseType;
    protected OIDCResponseMode responseMode;

    public OIDCLoginProtocol(KeycloakSession session, RealmModel realm, UriInfo uriInfo, HttpHeaders headers, EventBuilder event) {
        this.session = session;
        this.realm = realm;
        this.uriInfo = uriInfo;
        this.headers = headers;
        this.event = event;
    }

    public OIDCLoginProtocol() {

    }

    private void setupResponseTypeAndMode(String responseType, String responseMode) {
        this.responseType = OIDCResponseType.parse(responseType);
        this.responseMode = OIDCResponseMode.parse(responseMode, this.responseType);
        this.event.detail(Details.RESPONSE_TYPE, responseType);
        this.event.detail(Details.RESPONSE_MODE, this.responseMode.toString().toLowerCase());
    }

    @Override
    public OIDCLoginProtocol setSession(KeycloakSession session) {
        this.session = session;
        return this;
    }

    @Override
    public OIDCLoginProtocol setRealm(RealmModel realm) {
        this.realm = realm;
        return this;
    }

    @Override
    public OIDCLoginProtocol setUriInfo(UriInfo uriInfo) {
        this.uriInfo = uriInfo;
        return this;
    }

    @Override
    public OIDCLoginProtocol setHttpHeaders(HttpHeaders headers) {
        this.headers = headers;
        return this;
    }

    @Override
    public OIDCLoginProtocol setEventBuilder(EventBuilder event) {
        this.event = event;
        return this;
    }


    @Override
    public Response authenticated(UserSessionModel userSession, AuthenticatedClientSessionModel clientSession) {
        ClientSessionCode<AuthenticatedClientSessionModel> accessCode = new ClientSessionCode<>(session, realm, clientSession);

        String responseTypeParam = clientSession.getNote(OIDCLoginProtocol.RESPONSE_TYPE_PARAM);
        String responseModeParam = clientSession.getNote(OIDCLoginProtocol.RESPONSE_MODE_PARAM);
        setupResponseTypeAndMode(responseTypeParam, responseModeParam);

        String redirect = clientSession.getRedirectUri();
        OIDCRedirectUriBuilder redirectUri = OIDCRedirectUriBuilder.fromUri(redirect, responseMode);
        String state = clientSession.getNote(OIDCLoginProtocol.STATE_PARAM);
        logger.debugv("redirectAccessCode: state: {0}", state);
        if (state != null)
            redirectUri.addParam(OAuth2Constants.STATE, state);

        // Standard or hybrid flow
        String code = null;
        if (responseType.hasResponseType(OIDCResponseType.CODE)) {
            code = accessCode.getOrGenerateCode();
            redirectUri.addParam(OAuth2Constants.CODE, code);
        }

        // Implicit or hybrid flow
        if (responseType.isImplicitOrHybridFlow()) {
            TokenManager tokenManager = new TokenManager();
            TokenManager.AccessTokenResponseBuilder responseBuilder = tokenManager.responseBuilder(realm, clientSession.getClient(), event, session, userSession, clientSession)
                    .generateAccessToken();

            if (responseType.hasResponseType(OIDCResponseType.ID_TOKEN)) {

                responseBuilder.generateIDToken();

                if (responseType.hasResponseType(OIDCResponseType.TOKEN)) {
                    responseBuilder.generateAccessTokenHash();
                }

                if (responseType.hasResponseType(OIDCResponseType.CODE)) {
                    responseBuilder.generateCodeHash(code);
                }

            }

            AccessTokenResponse res = responseBuilder.build();

            if (responseType.hasResponseType(OIDCResponseType.ID_TOKEN)) {
                redirectUri.addParam(OAuth2Constants.ID_TOKEN, res.getIdToken());
            }

            if (responseType.hasResponseType(OIDCResponseType.TOKEN)) {
                redirectUri.addParam(OAuth2Constants.ACCESS_TOKEN, res.getToken());
                redirectUri.addParam("token_type", res.getTokenType());
                redirectUri.addParam("session_state", res.getSessionState());
                redirectUri.addParam("expires_in", String.valueOf(res.getExpiresIn()));
            }

            redirectUri.addParam("not-before-policy", String.valueOf(res.getNotBeforePolicy()));
        }

        return redirectUri.build();
    }


    @Override
    public Response sendError(AuthenticationSessionModel authSession, Error error) {
        String responseTypeParam = authSession.getClientNote(OIDCLoginProtocol.RESPONSE_TYPE_PARAM);
        String responseModeParam = authSession.getClientNote(OIDCLoginProtocol.RESPONSE_MODE_PARAM);
        setupResponseTypeAndMode(responseTypeParam, responseModeParam);

        String redirect = authSession.getRedirectUri();
        String state = authSession.getClientNote(OIDCLoginProtocol.STATE_PARAM);
        OIDCRedirectUriBuilder redirectUri = OIDCRedirectUriBuilder.fromUri(redirect, responseMode).addParam(OAuth2Constants.ERROR, translateError(error));
        if (state != null)
            redirectUri.addParam(OAuth2Constants.STATE, state);
        new AuthenticationSessionManager(session).removeAuthenticationSession(realm, authSession, true);
        return redirectUri.build();
    }

    private String translateError(Error error) {
        switch (error) {
            case CANCELLED_BY_USER:
            case CONSENT_DENIED:
                return OAuthErrorException.ACCESS_DENIED;
            case PASSIVE_INTERACTION_REQUIRED:
                return OAuthErrorException.INTERACTION_REQUIRED;
            case PASSIVE_LOGIN_REQUIRED:
                return OAuthErrorException.LOGIN_REQUIRED;
            default:
                ServicesLogger.LOGGER.untranslatedProtocol(error.name());
                return OAuthErrorException.SERVER_ERROR;
        }
    }

    @Override
    public void backchannelLogout(UserSessionModel userSession, AuthenticatedClientSessionModel clientSession) {
        ClientModel client = clientSession.getClient();
        new ResourceAdminManager(session).logoutClientSession(uriInfo.getRequestUri(), realm, client, clientSession);
    }

    @Override
    public Response frontchannelLogout(UserSessionModel userSession, AuthenticatedClientSessionModel clientSession) {
        // todo oidc redirect support
        throw new RuntimeException("NOT IMPLEMENTED");
    }

    @Override
    public Response finishLogout(UserSessionModel userSession) {
        String redirectUri = userSession.getNote(OIDCLoginProtocol.LOGOUT_REDIRECT_URI);
        String state = userSession.getNote(OIDCLoginProtocol.LOGOUT_STATE_PARAM);
        event.event(EventType.LOGOUT);
        if (redirectUri != null) {
            event.detail(Details.REDIRECT_URI, redirectUri);
        }
        event.user(userSession.getUser()).session(userSession).success();

        if (redirectUri != null) {
            UriBuilder uriBuilder = UriBuilder.fromUri(redirectUri);
            if (state != null)
                uriBuilder.queryParam(STATE_PARAM, state);
            return Response.status(302).location(uriBuilder.build()).build();
        } else {
            return Response.ok().build();
        }
    }


    @Override
    public boolean requireReauthentication(UserSessionModel userSession, AuthenticationSessionModel authSession) {
        return isPromptLogin(authSession) || isAuthTimeExpired(userSession, authSession);
    }

    protected boolean isPromptLogin(AuthenticationSessionModel authSession) {
        String prompt = authSession.getClientNote(OIDCLoginProtocol.PROMPT_PARAM);
        return TokenUtil.hasPrompt(prompt, OIDCLoginProtocol.PROMPT_VALUE_LOGIN);
    }

    protected boolean isAuthTimeExpired(UserSessionModel userSession, AuthenticationSessionModel authSession) {
        String authTime = userSession.getNote(AuthenticationManager.AUTH_TIME);
        String maxAge = authSession.getClientNote(OIDCLoginProtocol.MAX_AGE_PARAM);
        if (maxAge == null) {
            return false;
        }

        int authTimeInt = authTime==null ? 0 : Integer.parseInt(authTime);
        int maxAgeInt = Integer.parseInt(maxAge);

        if (authTimeInt + maxAgeInt < Time.currentTime()) {
            logger.debugf("Authentication time is expired, needs to reauthenticate. userSession=%s, clientId=%s, maxAge=%d, authTime=%d", userSession.getId(),
                    authSession.getClient().getId(), maxAgeInt, authTimeInt);
            return true;
        }

        return false;
    }

    @Override
    public void close() {

    }
}
