/*
 * Copyright (C) 2008-2019, Juick
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.juick.server.api;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.github.scribejava.apis.AppleClientSecretGenerator;
import com.github.scribejava.apis.AppleSignInApi;
import com.github.scribejava.apis.FacebookApi;
import com.github.scribejava.apis.VkontakteApi;
import com.github.scribejava.core.builder.ServiceBuilder;
import com.github.scribejava.core.model.OAuth2AccessToken;
import com.github.scribejava.core.model.OAuthRequest;
import com.github.scribejava.core.model.Verb;
import com.github.scribejava.core.oauth.OAuth20Service;
import com.google.api.client.googleapis.auth.oauth2.GoogleIdToken;
import com.google.api.client.googleapis.auth.oauth2.GoogleIdTokenVerifier;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.juick.model.Auth;
import com.juick.model.facebook.User;
import com.juick.server.util.HttpBadRequestException;
import com.juick.service.CrosspostService;
import com.juick.service.EmailService;
import com.juick.service.UserService;
import com.juick.model.vk.UsersResponse;
import com.nimbusds.jose.JOSEException;
import com.nimbusds.jose.JWSAlgorithm;
import com.nimbusds.jose.jwk.source.JWKSource;
import com.nimbusds.jose.jwk.source.RemoteJWKSet;
import com.nimbusds.jose.proc.BadJOSEException;
import com.nimbusds.jose.proc.JWSKeySelector;
import com.nimbusds.jose.proc.JWSVerificationKeySelector;
import com.nimbusds.jose.proc.SecurityContext;
import com.nimbusds.jwt.proc.ConfigurableJWTProcessor;
import com.nimbusds.jwt.proc.DefaultJWTClaimsVerifier;
import com.nimbusds.jwt.proc.DefaultJWTProcessor;
import net.minidev.json.JSONObject;
import org.apache.commons.lang3.RandomStringUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.math.NumberUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.util.UriComponentsBuilder;

import javax.annotation.PostConstruct;
import javax.inject.Inject;
import java.io.IOException;
import java.net.URL;
import java.security.GeneralSecurityException;
import java.text.ParseException;
import java.util.Collections;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ExecutionException;

/**
 *
 * @author Ugnich Anton
 */
@Controller
public class ApiSocialLogin {

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

    @Value("${facebook_appid:appid}")
    private String FACEBOOK_APPID;
    @Value("${facebook_secret:secret}")
    private String FACEBOOK_SECRET;
    private static final String FACEBOOK_REDIRECT = "https://api.juick.com/_fblogin";
    private static final String VK_REDIRECT = "https://api.juick.com/_vklogin";
    private static final String TWITTER_VERIFY_URL = "https://api.twitter.com/1.1/account/verify_credentials.json";
    @Inject
    private ObjectMapper jsonMapper;
    private OAuth20Service facebookAuthService, vkAuthService, appleSignInService;

    @Value("${twitter_consumer_key:appid}")
    private String twitterConsumerKey;
    @Value("${twitter_consumer_secret:secret}")
    private String twitterConsumerSecret;
    @Value("${vk_appid:appid}")
    private String VK_APPID;
    @Value("${vk_secret:secret}")
    private String VK_SECRET;
    @Value("${google_client_id:}")
    private String googleClientId;
    @Value("${apple_app_id:appid}")
    private String appleApplicationId;
    @Value("${ap_base_uri:http://localhost:8080/}")
    private String baseUri;

    @Inject
    private CrosspostService crosspostService;
    @Inject
    private UserService userService;
    @Inject
    private EmailService emailService;
    @Inject
    private AppleClientSecretGenerator clientSecretGenerator;

    private final HttpTransport transport = new NetHttpTransport();
    private final JsonFactory jsonFactory = new JacksonFactory();
    private GoogleIdTokenVerifier verifier;

    @PostConstruct
    public void init() {
        ServiceBuilder facebookBuilder = new ServiceBuilder(FACEBOOK_APPID);
        ServiceBuilder twitterBuilder = new ServiceBuilder(twitterConsumerKey);
        ServiceBuilder vkBuilder = new ServiceBuilder(VK_APPID);
        verifier = new GoogleIdTokenVerifier.Builder(transport, jsonFactory)
                .setAudience(Collections.singletonList(googleClientId))
                .build();
        facebookAuthService = facebookBuilder
                .apiSecret(FACEBOOK_SECRET)
                .callback(FACEBOOK_REDIRECT)
                .defaultScope("email")
                .build(FacebookApi.instance());
        vkAuthService = vkBuilder
                .apiSecret(VK_SECRET)
                .defaultScope("friends,wall,offline")
                .callback(VK_REDIRECT)
                .build(VkontakteApi.instance());
        ServiceBuilder appleSignInBuilder = new ServiceBuilder(appleApplicationId);
        UriComponentsBuilder redirectBuilder = UriComponentsBuilder.fromUriString(baseUri);
        String appleSignInRedirectUri = redirectBuilder.replacePath("/_apple").build().toUriString();
        appleSignInService = appleSignInBuilder
                .callback(appleSignInRedirectUri)
                .defaultScope("email")
                .build(new AppleSignInApi(clientSecretGenerator));
    }

    @GetMapping("/api/_fblogin")
    protected String doFacebookLogin(@RequestParam(required = false) String code,
                         @RequestParam(required = false) String state) throws IOException, ExecutionException, InterruptedException {
        if (StringUtils.isBlank(code)) {
            String fbstate = UUID.randomUUID().toString();
            crosspostService.addFacebookState(fbstate, state);
            return "redirect:" + facebookAuthService.getAuthorizationUrl(fbstate);
        }

        String redirectUrl = crosspostService.verifyFacebookState(state);

        if (StringUtils.isEmpty(redirectUrl)) {
            logger.error("state is missing");
            throw new HttpBadRequestException();
        }
        OAuth2AccessToken token = facebookAuthService.getAccessToken(code);
        final OAuthRequest meRequest = new OAuthRequest(Verb.GET, "https://graph.facebook.com/v3.2/me?fields=id,name,email");
        facebookAuthService.signRequest(token, meRequest);
        String graph = facebookAuthService.execute(meRequest).getBody();
        if (StringUtils.isBlank(graph)) {
            logger.error("FACEBOOK GRAPH ERROR");
            throw new HttpBadRequestException();
        }
        User fb = jsonMapper.readValue(graph, User.class);
        long fbID = NumberUtils.toLong(fb.getId(), 0);
        if (fbID == 0 || StringUtils.isBlank(fb.getName())) {
            logger.error("Missing required fields, id: {}, name: {}", fbID, fb.getName());
            throw new HttpBadRequestException();
        }

        int uid = crosspostService.getUIDbyFBID(fbID);
        if (uid > 0) {
            if (!crosspostService.updateFacebookUser(fbID, token.getAccessToken(), fb.getName())) {
                logger.error("error updating facebook user, id: {}, token: {}", fbID, token.getAccessToken());
                throw new HttpBadRequestException();
            }
            UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromUriString(redirectUrl);
            uriComponentsBuilder.queryParam("hash", userService.getHashByUID(uid));
            return "redirect:" + uriComponentsBuilder.build().toUriString();
        } else {
            if (!crosspostService.createFacebookUser(fbID, state, token.getAccessToken(), fb.getName())) {
                if (StringUtils.isNotEmpty(fb.getEmail())) {
                    logger.info("found {} for facebook user {}", fb.getEmail(), fb.getName());
                    Integer userId = crosspostService.getUIDbyFBID(fbID);
                    if (!emailService.getEmails(userId, false).contains(fb.getEmail())) {
                        emailService.addEmail(userId, fb.getEmail());
                    }
                }
                logger.info("email not found for facebook user {}", fb.getName());
                throw new HttpBadRequestException();
            }
            return "redirect:/signup?type=fb&hash=" + state;
        }
    }
    @GetMapping("/api/_vklogin")
    protected String doVKLogin(@RequestParam(required = false) String code,
                           @RequestParam String state) throws IOException, ExecutionException, InterruptedException {
        if (StringUtils.isBlank(code)) {
            String vkstate = UUID.randomUUID().toString();
            crosspostService.addVKState(vkstate, state);
            return "redirect:" + vkAuthService.getAuthorizationUrl(vkstate);
        }

        String redirectUrl = crosspostService.verifyVKState(state);
        if (StringUtils.isBlank(redirectUrl)) {
            logger.error("state is missing");
            throw new HttpBadRequestException();
        }
        OAuth2AccessToken token = vkAuthService.getAccessToken(code);

        OAuthRequest meRequest = new OAuthRequest(Verb.GET, "https://api.vk.com/method/users.get?fields=screen_name&v=5.73");
        vkAuthService.signRequest(token, meRequest);
        String graph = vkAuthService.execute(meRequest).getBody();

        com.juick.model.vk.User jsonUser = jsonMapper.readValue(graph, UsersResponse.class).getUsers().get(0);
        String vkName = jsonUser.getFirstName() + " " + jsonUser.getLastName();
        String vkLink = jsonUser.getScreenName();

        if (vkName.length() == 1 || StringUtils.isBlank(vkLink)) {
            logger.error("vk user error");
            throw new HttpBadRequestException();
        }

        long vkID = NumberUtils.toLong(jsonUser.getId(), 0);
        int uid = crosspostService.getUIDbyVKID(vkID);
        if (uid > 0) {
            UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromUriString(redirectUrl);
            uriComponentsBuilder.queryParam("hash", userService.getHashByUID(uid));
            return "redirect:" + uriComponentsBuilder.build().toUriString();
        } else {
            String loginhash = UUID.randomUUID().toString();
            if (!crosspostService.createVKUser(vkID, loginhash, token.getAccessToken(), vkName, vkLink)) {
                logger.error("create vk user error");
                throw new HttpBadRequestException();
            }
            return "redirect:/signup?type=vk&hash=" + loginhash;
        }
    }
    @ResponseBody
    @PostMapping("/api/_google")
    public ResponseEntity<Auth> googleSignIn(@RequestParam(name = "idToken") String idTokenString)
            throws GeneralSecurityException, IOException {
        logger.info("Token: {}", idTokenString);
        logger.info("Client: {}", googleClientId);
        GoogleIdToken idToken = verifier.verify(idTokenString);
        if (idToken != null) {
            String email = idToken.getPayload().getEmail();
            if (userService.getUserByEmail(email).isAnonymous()) {
                String verificationCode = RandomStringUtils.randomAlphanumeric(8).toUpperCase();
                emailService.addVerificationCode(null, email, verificationCode);
                return ResponseEntity.ok(new Auth(email, verificationCode));
            }
        }
        return ResponseEntity.status(HttpStatus.FORBIDDEN).body(null);
    }
    @ResponseBody
    @PostMapping("/api/signup")
    public ResponseEntity<com.juick.User> signupWithEmail(String username, String password, String verificationCode) {
        if (username.length() < 2 || username.length() > 16 || !username.matches("^[a-zA-Z0-9\\-]+$")
                || password.length() < 6 || password.length() > 32) {
            throw new HttpBadRequestException();
        }

        String verifiedEmail = emailService.getEmailByAuthCode(verificationCode);
        if (StringUtils.isNotEmpty(verifiedEmail)) {
            com.juick.User newUser = userService.createUser(username, password).orElseThrow(HttpBadRequestException::new);
            emailService.addEmail(newUser.getUid(), verifiedEmail);
            emailService.deleteAuthCode(verificationCode);
            return ResponseEntity.ok(newUser);
        } else {
            return ResponseEntity.status(HttpStatus.FORBIDDEN).body(null);
        }
    }
    @GetMapping("/_apple")
    public String doAppleLogin(@RequestParam(required = false) String code, @RequestParam String state) {
        if (StringUtils.isBlank(code)) {
            String astate = UUID.randomUUID().toString();
            crosspostService.addVKState(astate, state);
            return "redirect:" + appleSignInService.getAuthorizationUrl(astate);
        }
        throw new HttpBadRequestException();
    }
    @PostMapping("/_apple")
    public String doVerifyAppleResponse(@RequestParam Map<String, String> body) throws InterruptedException, ExecutionException, IOException, ParseException, JOSEException, BadJOSEException {
        OAuth2AccessToken token = appleSignInService.getAccessToken(body.get("code"));
        var jsonNode = jsonMapper.readTree(token.getRawResponse());
        var idToken = jsonNode.get("id_token").textValue();

// Create a JWT processor for the access tokens
        ConfigurableJWTProcessor<SecurityContext> jwtProcessor =
                new DefaultJWTProcessor<>();

// The public RSA keys to validate the signatures will be sourced from the
// OAuth 2.0 server's JWK set, published at a well-known URL. The RemoteJWKSet
// object caches the retrieved keys to speed up subsequent look-ups and can
// also handle key-rollover
        JWKSource<SecurityContext> keySource =
                new RemoteJWKSet<>(new URL("https://appleid.apple.com/auth/keys"));

// The expected JWS algorithm of the access tokens (agreed out-of-band)
        JWSAlgorithm expectedJWSAlg = JWSAlgorithm.RS256;

// Configure the JWT processor with a key selector to feed matching public
// RSA keys sourced from the JWK set URL
        JWSKeySelector<SecurityContext> keySelector =
                new JWSVerificationKeySelector<>(expectedJWSAlg, keySource);

        jwtProcessor.setJWSKeySelector(keySelector);

// Set the required JWT claims for access tokens issued by the Connect2id
// server, may differ with other servers
        jwtProcessor.setJWTClaimsSetVerifier(new DefaultJWTClaimsVerifier<>());

// Process the token
        JSONObject claimsSet = jwtProcessor.process(idToken, null).toJSONObject();

        var email = claimsSet.getAsString("email");
        var verified = claimsSet.getAsString("email_verified").equals("true");

        if (verified) {
            com.juick.User user = userService.getUserByEmail(email);
            if (!user.isAnonymous()) {
                String redirectUrl = crosspostService.verifyVKState(body.get("state"));
                if (StringUtils.isBlank(redirectUrl)) {
                    logger.error("state is missing");
                    throw new HttpBadRequestException();
                }
                UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromUriString(redirectUrl);
                uriComponentsBuilder.queryParam("hash", userService.getHashByUID(user.getUid()));
                return "redirect:" + uriComponentsBuilder.build().toUriString();
            } else {
                String verificationCode = RandomStringUtils.randomAlphanumeric(8).toUpperCase();
                emailService.addVerificationCode(null, email, verificationCode);
                return "redirect:/signup?type=email&hash=" + verificationCode;
            }
        }
        throw new HttpBadRequestException();
    }
}