/*
 * Copyright 2023 Daniel Raper (me@danr.uk)
 *
 * 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.traccar.database;

import org.traccar.config.Config;
import org.traccar.config.Keys;
import org.traccar.api.resource.SessionResource;
import org.traccar.api.security.LoginService;
import org.traccar.model.User;
import org.traccar.storage.StorageException;
import org.traccar.helper.LogAction;
import org.traccar.helper.ServletHelper;

import java.net.URI;
import java.net.URISyntaxException;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse.BodyHandlers;
import java.security.GeneralSecurityException;
import java.util.Map;
import java.io.IOException;
import javax.servlet.http.HttpServletRequest;

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.inject.Inject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.nimbusds.oauth2.sdk.http.HTTPResponse;
import com.nimbusds.oauth2.sdk.AuthorizationCode;
import com.nimbusds.oauth2.sdk.ResponseType;
import com.nimbusds.oauth2.sdk.Scope;
import com.nimbusds.oauth2.sdk.AuthorizationGrant;
import com.nimbusds.oauth2.sdk.TokenRequest;
import com.nimbusds.oauth2.sdk.TokenResponse;
import com.nimbusds.oauth2.sdk.AuthorizationCodeGrant;
import com.nimbusds.oauth2.sdk.ParseException;
import com.nimbusds.oauth2.sdk.AuthorizationResponse;
import com.nimbusds.oauth2.sdk.auth.Secret;
import com.nimbusds.oauth2.sdk.auth.ClientSecretBasic;
import com.nimbusds.oauth2.sdk.auth.ClientAuthentication;
import com.nimbusds.oauth2.sdk.token.BearerAccessToken;
import com.nimbusds.oauth2.sdk.id.State;
import com.nimbusds.oauth2.sdk.id.ClientID;
import com.nimbusds.openid.connect.sdk.OIDCTokenResponse;
import com.nimbusds.openid.connect.sdk.OIDCTokenResponseParser;
import com.nimbusds.openid.connect.sdk.UserInfoResponse;
import com.nimbusds.openid.connect.sdk.UserInfoRequest;
import com.nimbusds.openid.connect.sdk.AuthenticationRequest;

import com.nimbusds.openid.connect.sdk.claims.UserInfo;

public class OpenIdProvider {
    private static final Logger LOGGER = LoggerFactory.getLogger(OpenIdProvider.class);

    private final Boolean force;
    private final ClientID clientId;
    private final ClientAuthentication clientAuth;
    private URI callbackUrl;
    private URI authUrl;
    private URI tokenUrl;
    private URI userInfoUrl;
    private URI baseUrl;
    private final String adminGroup;

    private LoginService loginService;

    @Inject
    public OpenIdProvider(Config config, LoginService loginService) {
        this.loginService = loginService;

        force = config.getBoolean(Keys.OPENID_FORCE);
        clientId = new ClientID(config.getString(Keys.OPENID_CLIENTID));
        clientAuth = new ClientSecretBasic(clientId, new Secret(config.getString(Keys.OPENID_CLIENTSECRET)));

        try {
            callbackUrl = new URI(config.getString(Keys.WEB_URL, "") + "/api/session/openid/callback");
            baseUrl = new URI(config.getString(Keys.WEB_URL, ""));

            if (
                config.hasKey(Keys.OPENID_ISSUERURL)
                && (
                    !config.hasKey(Keys.OPENID_AUTHURL)
                    || !config.hasKey(Keys.OPENID_TOKENURL)
                    || !config.hasKey(Keys.OPENID_USERINFOURL))
                ) {
                    HttpClient httpClient = HttpClient.newHttpClient();

                    HttpRequest httpRequest = HttpRequest.newBuilder(
                        URI.create(
                            config.getString(Keys.OPENID_ISSUERURL) + "/.well-known/openid-configuration")
                            )
                        .header("accept", "application/json")
                        .build();

                    String httpResponse = httpClient.send(httpRequest, BodyHandlers.ofString()).body();

                    Map<String, Object> discoveryMap = new ObjectMapper().readValue(
                        httpResponse, new TypeReference<Map<String, Object>>() { });

                    authUrl = new URI(discoveryMap.get("authorization_endpoint").toString());
                    tokenUrl = new URI(discoveryMap.get("token_endpoint").toString());
                    userInfoUrl = new URI(discoveryMap.get("userinfo_endpoint").toString());

                    LOGGER.info("OpenID Connect auto discovery successful");
            } else {
                authUrl = new URI(config.getString(Keys.OPENID_AUTHURL));
                tokenUrl = new URI(config.getString(Keys.OPENID_TOKENURL));
                userInfoUrl = new URI(config.getString(Keys.OPENID_USERINFOURL));
            }
        } catch (URISyntaxException error) {
            LOGGER.error("Invalid URIs provided in OpenID configuration");
        } catch (InterruptedException | IOException error) {
            LOGGER.error("OpenID Connect auto discovery failed");
        }

        adminGroup = config.getString(Keys.OPENID_ADMINGROUP);
    }

    public URI createAuthUri() {
        Scope scope = new Scope("openid", "profile", "email");

        if (adminGroup != null) {
            scope.add("groups");
        }

        AuthenticationRequest.Builder request = new AuthenticationRequest.Builder(
                new ResponseType("code"),
                scope,
                clientId,
                callbackUrl);

        return request.endpointURI(authUrl)
                .state(new State())
                .build()
                .toURI();
    }

    private OIDCTokenResponse getToken(
        AuthorizationCode code) throws IOException, ParseException, GeneralSecurityException {
            AuthorizationGrant codeGrant = new AuthorizationCodeGrant(code, callbackUrl);
            TokenRequest tokenRequest = new TokenRequest(tokenUrl, clientAuth, codeGrant);

            HTTPResponse tokenResponse = tokenRequest.toHTTPRequest().send();
            TokenResponse token = OIDCTokenResponseParser.parse(tokenResponse);
            if (!token.indicatesSuccess()) {
                throw new GeneralSecurityException("Unable to authenticate with the OpenID Connect provider.");
            }

            return (OIDCTokenResponse) token.toSuccessResponse();
    }

    private UserInfo getUserInfo(BearerAccessToken token) throws IOException, ParseException, GeneralSecurityException {
        HTTPResponse httpResponse = new UserInfoRequest(userInfoUrl, token)
                .toHTTPRequest()
                .send();

        UserInfoResponse userInfoResponse = UserInfoResponse.parse(httpResponse);

        if (!userInfoResponse.indicatesSuccess()) {
            throw new GeneralSecurityException(
                "Failed to access OpenID Connect user info endpoint. Please contact your administrator.");
        }

        return userInfoResponse.toSuccessResponse().getUserInfo();
    }

    public URI handleCallback(
            URI requestUri, HttpServletRequest request
        ) throws StorageException, ParseException, IOException, GeneralSecurityException {
            AuthorizationResponse response = AuthorizationResponse.parse(requestUri);

            if (!response.indicatesSuccess()) {
                throw new GeneralSecurityException(response.toErrorResponse().getErrorObject().getDescription());
            }

            AuthorizationCode authCode = response.toSuccessResponse().getAuthorizationCode();

            if (authCode == null) {
                throw new GeneralSecurityException("Malformed OpenID callback.");
            }

            OIDCTokenResponse tokens = getToken(authCode);

            BearerAccessToken bearerToken = tokens.getOIDCTokens().getBearerAccessToken();

            UserInfo userInfo = getUserInfo(bearerToken);

            Boolean administrator = adminGroup != null && userInfo.getStringListClaim("groups").contains(adminGroup);

            User user = loginService.login(userInfo.getEmailAddress(), userInfo.getName(), administrator);

            request.getSession().setAttribute(SessionResource.USER_ID_KEY, user.getId());
            LogAction.login(user.getId(), ServletHelper.retrieveRemoteAddress(request));

            return baseUrl;
    }

    public boolean getForce() {
        return force;
    }
}