'use strict';

exports = module.exports = {
    start,
    stop,
    revokeByUserId,
    clients: {
        add: clientsAdd,
        get: clientsGet,
        del: clientsDel,
        update: clientsUpdate,
        list: clientsList
    }
};

const assert = require('assert'),
    BoxError = require('./boxerror.js'),
    blobs = require('./blobs.js'),
    constants = require('./constants.js'),
    database = require('./database.js'),
    debug = require('debug')('box:oidc'),
    ejs = require('ejs'),
    express = require('express'),
    fs = require('fs'),
    middleware = require('./middleware'),
    path = require('path'),
    paths = require('./paths.js'),
    http = require('http'),
    HttpError = require('connect-lastmile').HttpError,
    jose = require('jose'),
    safe = require('safetydance'),
    settings = require('./settings.js'),
    users = require('./users.js'),
    util = require('util');

const OIDC_CLIENTS_TABLE_NAME = 'oidcClients';
const OIDC_CLIENTS_FIELDS = [ 'id', 'secret', 'name', 'appId', 'loginRedirectUri', 'logoutRedirectUri', 'tokenSignatureAlgorithm' ];

const ROUTE_PREFIX = '/openid';
const DEFAULT_TOKEN_SIGNATURE_ALGORITHM='RS256';

let gHttpServer = null;

// -----------------------------
// Database model
// -----------------------------
function postProcess(result) {
    assert.strictEqual(typeof result, 'object');

    result.tokenSignatureAlgorithm = result.tokenSignatureAlgorithm || DEFAULT_TOKEN_SIGNATURE_ALGORITHM;

    return result;
}

async function clientsAdd(id, data) {
    assert.strictEqual(typeof id, 'string');
    assert.strictEqual(typeof data.secret, 'string');
    assert.strictEqual(typeof data.loginRedirectUri, 'string');
    assert.strictEqual(typeof data.logoutRedirectUri, 'string');
    assert.strictEqual(typeof data.name, 'string');
    assert.strictEqual(typeof data.appId, 'string');
    assert(data.tokenSignatureAlgorithm === 'RS256' || data.tokenSignatureAlgorithm === 'EdDSA');

    debug(`clientsAdd: id:${id} secret:${data.secret} name:${data.name} appId:${data.appId} loginRedirectUri:${data.loginRedirectUri} logoutRedirectUri:${data.logoutRedirectUri} tokenSignatureAlgorithm:${data.tokenSignatureAlgorithm}`);

    const query = `INSERT INTO ${OIDC_CLIENTS_TABLE_NAME} (id, secret, name, appId, loginRedirectUri, logoutRedirectUri, tokenSignatureAlgorithm) VALUES (?, ?, ?, ?, ?, ?, ?)`;
    const args = [ id, data.secret, data.name, data.appId, data.loginRedirectUri, data.logoutRedirectUri, data.tokenSignatureAlgorithm ];

    const [error] = await safe(database.query(query, args));
    if (error && error.code === 'ER_DUP_ENTRY') throw new BoxError(BoxError.ALREADY_EXISTS, 'client already exists');
    if (error) throw error;
}

async function clientsGet(id) {
    assert.strictEqual(typeof id, 'string');

    debug(`clientsGet: id:${id}`);

    const result = await database.query(`SELECT ${OIDC_CLIENTS_FIELDS} FROM ${OIDC_CLIENTS_TABLE_NAME} WHERE id = ?`, [ id ]);
    if (result.length === 0) return null;

    return postProcess(result[0]);
}

async function clientsUpdate(id, data) {
    assert.strictEqual(typeof id, 'string');
    assert.strictEqual(typeof data.secret, 'string');
    assert.strictEqual(typeof data.loginRedirectUri, 'string');
    assert.strictEqual(typeof data.logoutRedirectUri, 'string');
    assert.strictEqual(typeof data.name, 'string');
    assert.strictEqual(typeof data.appId, 'string');
    assert(data.tokenSignatureAlgorithm === 'RS256' || data.tokenSignatureAlgorithm === 'EdDSA');

    debug(`clientsUpdate: id:${id} secret:${data.secret} name:${data.name} appId:${data.appId} loginRedirectUri:${data.loginRedirectUri} logoutRedirectUri:${data.logoutRedirectUri} tokenSignatureAlgorithm:${data.tokenSignatureAlgorithm}`);

    const result = await database.query(`UPDATE ${OIDC_CLIENTS_TABLE_NAME} SET secret=?, name=?, appId=?, loginRedirectUri=?, logoutRedirectUri=?, tokenSignatureAlgorithm=? WHERE id = ?`, [ data.secret, data.name, data.appId, data.loginRedirectUri, data.logoutRedirectUri, data.tokenSignatureAlgorithm, id]);
    if (result.affectedRows !== 1) throw new BoxError(BoxError.NOT_FOUND, 'client not found');
}

async function clientsDel(id) {
    assert.strictEqual(typeof id, 'string');

    const result = await database.query(`DELETE FROM ${OIDC_CLIENTS_TABLE_NAME} WHERE id = ?`, [ id ]);
    if (result.affectedRows !== 1) throw new BoxError(BoxError.NOT_FOUND, 'client not found');
}

async function clientsList() {
    const results = await database.query(`SELECT * FROM ${OIDC_CLIENTS_TABLE_NAME} ORDER BY id ASC`, []);

    results.forEach(postProcess);

    return results;
}

// -----------------------------
// Basic in-memory json file backed based data store
// -----------------------------
const DATA_STORE = {};

function load(modelName) {
    assert.strictEqual(typeof modelName, 'string');

    if (DATA_STORE[modelName]) return;

    const filePath = path.join(paths.OIDC_STORE_DIR, `${modelName}.json`);
    debug(`load: model ${modelName} based on ${filePath}.`);

    let data = {};
    try {
        data = JSON.parse(fs.readFileSync(filePath), 'utf8');
    } catch (e) {
        debug(`load: failed to read ${filePath}, start with new one.`, e);
    }

    DATA_STORE[modelName] = data;
}

function save(modelName) {
    assert.strictEqual(typeof modelName, 'string');

    if (!DATA_STORE[modelName]) return;

    const filePath = path.join(paths.OIDC_STORE_DIR, `${modelName}.json`);
    debug(`save: model ${modelName} to ${filePath}.`);

    try {
        fs.writeFileSync(filePath, JSON.stringify(DATA_STORE[modelName]), 'utf8');
    } catch (e) {
        debug(`revokeByUserId: failed to write ${filePath}`, e);
    }
}

// -----------------------------
// Session, Grant and Token management
// -----------------------------
// This is based on the same storage as the below CloudronAdapter
async function revokeByUserId(userId) {
    assert.strictEqual(typeof userId, 'string');

    debug(`revokeByUserId: userId:${userId}`);

    function revokeObjects(modelName) {
        load(modelName);

        for (let id in DATA_STORE[modelName]) {
            if (DATA_STORE[modelName][id].payload?.accountId === userId) delete DATA_STORE[modelName][id];
        }

        save(modelName);
    }

    revokeObjects('Session');
    revokeObjects('Grant');
    revokeObjects('AuthorizationCode');
    revokeObjects('AccessToken');
}

// -----------------------------
// Generic oidc node module data store model
// -----------------------------
class CloudronAdapter {
    /**
     *
     * Creates an instance of MyAdapter for an oidc-provider model.
     *
     * @constructor
     * @param {string} name Name of the oidc-provider model. One of "Grant, "Session", "AccessToken",
     * "AuthorizationCode", "RefreshToken", "ClientCredentials", "Client", "InitialAccessToken",
     * "RegistrationAccessToken", "DeviceCode", "Interaction", "ReplayDetection",
     * "BackchannelAuthenticationRequest", or "PushedAuthorizationRequest"
     *
     */
    constructor(name) {
        this.name = name;

        debug(`Creating storage adapter for ${name}`);

        if (this.name !== 'Client') {
            load(name);
        }
    }

    /**
     *
     * Update or Create an instance of an oidc-provider model.
     *
     * @return {Promise} Promise fulfilled when the operation succeeded. Rejected with error when
     * encountered.
     * @param {string} id Identifier that oidc-provider will use to reference this model instance for
     * future operations.
     * @param {object} payload Object with all properties intended for storage.
     * @param {integer} expiresIn Number of seconds intended for this model to be stored.
     *
     */
    async upsert(id, payload, expiresIn) {
        debug(`[${this.name}] upsert id:${id} expiresIn:${expiresIn}`, payload);

        if (this.name === 'Client') {
            console.log('WARNING!! this should not happen as it is stored in our db');
        } else {
            DATA_STORE[this.name][id] = { id, expiresIn, payload, consumed: false };
            save(this.name);
        }
    }

    /**
     *
     * Return previously stored instance of an oidc-provider model.
     *
     * @return {Promise} Promise fulfilled with what was previously stored for the id (when found and
     * not dropped yet due to expiration) or falsy value when not found anymore. Rejected with error
     * when encountered.
     * @param {string} id Identifier of oidc-provider model
     *
     */
    async find(id) {
        debug(`[${this.name}] find id:${id}`);

        if (this.name === 'Client') {
            const [error, client] = await safe(clientsGet(id));
            if (error) {
                console.log('Error getting client', error);
                return null;
            }
            if (!client) return null;

            debug(`[${this.name}] find id:${id}`, client);

            const tmp = {
                client_id: id,
                client_secret: client.secret,
                application_type: 'native',  // default is web but we want more flexible redirectUris and this is only used in https://github.com/panva/node-oidc-provider/blob/03c9bc513860e68ee7be84f99bfc9dc930b224e8/lib/helpers/client_schema.js#L536
                redirect_uris: client.loginRedirectUri.split(',').map(s => s.trim()),
                id_token_signed_response_alg: client.tokenSignatureAlgorithm || 'RS256'
            };

            if (client.logoutRedirectUri) tmp.post_logout_redirect_uris = [ client.logoutRedirectUri ];

            return tmp;
        } else {
            if (!DATA_STORE[this.name][id]) return null;

            debug(`[${this.name}] find id:${id}`, DATA_STORE[this.name][id]);

            return DATA_STORE[this.name][id].payload;
        }
    }

    /**
     *
     * Return previously stored instance of DeviceCode by the end-user entered user code. You only
     * need this method for the deviceFlow feature
     *
     * @return {Promise} Promise fulfilled with the stored device code object (when found and not
     * dropped yet due to expiration) or falsy value when not found anymore. Rejected with error
     * when encountered.
     * @param {string} userCode the user_code value associated with a DeviceCode instance
     *
     */
    async findByUserCode(userCode) {
        debug(`[${this.name}] FIXME findByUserCode userCode:${userCode}`);
    }

    /**
     *
     * Return previously stored instance of Session by its uid reference property.
     *
     * @return {Promise} Promise fulfilled with the stored session object (when found and not
     * dropped yet due to expiration) or falsy value when not found anymore. Rejected with error
     * when encountered.
     * @param {string} uid the uid value associated with a Session instance
     *
     */
    async findByUid(uid) {
        debug(`[${this.name}] findByUid uid:${uid}`);

        if (this.name === 'Client') {
            console.log('WARNING!! this should not happen as it is stored in our db');
        } else {
            for (let d in DATA_STORE[this.name]) {
                if (DATA_STORE[this.name][d].payload.uid === uid) return DATA_STORE[this.name][d].payload;
            }

            return false;
        }
    }

    /**
     *
     * Mark a stored oidc-provider model as consumed (not yet expired though!). Future finds for this
     * id should be fulfilled with an object containing additional property named "consumed" with a
     * truthy value (timestamp, date, boolean, etc).
     *
     * @return {Promise} Promise fulfilled when the operation succeeded. Rejected with error when
     * encountered.
     * @param {string} id Identifier of oidc-provider model
     *
     */
    async consume(id) {
        debug(`[${this.name}] consume id:${id}`);

        if (this.name === 'Client') {
            console.log('WARNING!! this should not happen as it is stored in our db');
        } else {
            if (DATA_STORE[this.name][id]) DATA_STORE[this.name][id].consumed = true;
            save(this.name);
        }
    }

    /**
     *
     * Destroy/Drop/Remove a stored oidc-provider model. Future finds for this id should be fulfilled
     * with falsy values.
     *
     * @return {Promise} Promise fulfilled when the operation succeeded. Rejected with error when
     * encountered.
     * @param {string} id Identifier of oidc-provider model
     *
     */
    async destroy(id) {
        debug(`[${this.name}] destroy id:${id}`);

        if (this.name === 'Client') {
            console.log('WARNING!! this should not happen as it is stored in our db');
        } else {
            delete DATA_STORE[this.name][id];
            save(this.name);
        }
    }

    /**
     *
     * Destroy/Drop/Remove a stored oidc-provider model by its grantId property reference. Future
     * finds for all tokens having this grantId value should be fulfilled with falsy values.
     *
     * @return {Promise} Promise fulfilled when the operation succeeded. Rejected with error when
     * encountered.
     * @param {string} grantId the grantId value associated with a this model's instance
     *
     */
    async revokeByGrantId(grantId) {
        debug(`[${this.name}] revokeByGrantId grantId:${grantId}`);

        if (this.name === 'Client') {
            console.log('WARNING!! this should not happen as it is stored in our db');
        } else {
            for (let d in DATA_STORE[this.name]) {
                if (DATA_STORE[this.name][d].grantId === grantId) {
                    delete DATA_STORE[this.name][d];
                    return save(this.name);
                }
            }
        }
    }
}

// -----------------------------
// Route handler
// -----------------------------
function renderInteractionPage(provider) {
    assert.strictEqual(typeof provider, 'object');

    return async function (req, res, next) {
        try {
            const { uid, prompt, params, session } = await provider.interactionDetails(req, res);
            console.log('details', await provider.interactionDetails(req, res));

            debug(`route interaction get uid:${uid} prompt.name:${prompt.name} client_id:${params.client_id} session:${session}`);

            const [error, client] = await safe(clientsGet(params.client_id));
            if (error) return next(error);

            switch (prompt.name) {
            case 'login': {
                return res.render('login', {
                    submitUrl: `${ROUTE_PREFIX}/interaction/${uid}/login`,
                    name: client?.name || 'Cloudron'
                });
            }
            case 'consent': {
                return res.render('interaction', {
                    submitUrl: `${ROUTE_PREFIX}/interaction/${uid}/confirm`,
                    name: client?.name || 'Cloudron'
                });
            }
            default:
                return undefined;
            }
        } catch (error) {
            debug('route interaction get error');
            console.log(error);

            return next(error);
        }
    };
}

function interactionLogin(provider) {
    assert.strictEqual(typeof provider, 'object');

    return async function(req, res, next) {
        const [detailsError, details] = await safe(provider.interactionDetails(req, res));
        if (detailsError) return next(new HttpError(500, detailsError));

        const uid = details.uid;
        const prompt = details.prompt;
        const name = prompt.name;

        debug(`route interaction login post uid:${uid} prompt.name:${name}`, req.body);

        assert.equal(name, 'login');

        if (!req.body.username || typeof req.body.username !== 'string') return next(new HttpError(400, 'A username must be non-empty string'));
        if (!req.body.password || typeof req.body.password !== 'string') return next(new HttpError(400, 'A password must be non-empty string'));
        if ('totpToken' in req.body && typeof req.body.totpToken !== 'string') return next(new HttpError(400, 'totpToken must be a string' ));

        const { username, password, totpToken } = req.body;

        const verifyFunc = username.indexOf('@') === -1 ? users.verifyWithUsername : users.verifyWithEmail;

        const [verifyError, user] =  await safe(verifyFunc(username, password, users.AP_WEBADMIN, { totpToken }));
        if (verifyError && verifyError.reason === BoxError.INVALID_CREDENTIALS) return next(new HttpError(401, verifyError.message));
        if (verifyError && verifyError.reason === BoxError.NOT_FOUND) return next(new HttpError(401, 'Unauthorized'));
        if (verifyError) return next(new HttpError(500, verifyError));
        if (!user) return next(new HttpError(401, 'Unauthorized'));

        // TODO we may have to check what else the Account class provides, in which case we have to map those things
        const result = {
            login: {
                accountId: user.id,
            },
        };

        const [interactionFinishError, redirectTo] = await safe(provider.interactionResult(req, res, result));
        if (interactionFinishError) return next(new HttpError(500, interactionFinishError));

        debug(`route interaction login post result redirectTo:${redirectTo}`);

        res.status(200).send({ redirectTo });
    };
}

function interactionConfirm(provider) {
    assert.strictEqual(typeof provider, 'object');

    return async function (req, res, next) {
        try {
            const interactionDetails = await provider.interactionDetails(req, res);
            const { uid, prompt: { name, details }, params, session: { accountId } } = interactionDetails;

            debug(`route interaction confirm post uid:${uid} prompt.name:${name} accountId:${accountId}`);

            assert.equal(name, 'consent');

            let { grantId } = interactionDetails;
            let grant;

            if (grantId) {
                // we'll be modifying existing grant in existing session
                grant = await provider.Grant.find(grantId);
            } else {
                // we're establishing a new grant
                grant = new provider.Grant({
                    accountId,
                    clientId: params.client_id,
                });
            }

            if (details.missingOIDCScope) {
                grant.addOIDCScope(details.missingOIDCScope.join(' '));
            }
            if (details.missingOIDCClaims) {
                grant.addOIDCClaims(details.missingOIDCClaims);
            }
            if (details.missingResourceScopes) {
                // eslint-disable-next-line no-restricted-syntax
                for (const [indicator, scopes] of Object.entries(details.missingResourceScopes)) {
                    grant.addResourceScope(indicator, scopes.join(' '));
                }
            }

            grantId = await grant.save();

            const consent = {};
            if (!interactionDetails.grantId) {
                // we don't have to pass grantId to consent, we're just modifying existing one
                consent.grantId = grantId;
            }

            const result = { consent };
            await provider.interactionFinished(req, res, result, { mergeWithLastSubmission: true });
        } catch (err) {
            next(err);
        }
    };
}

function interactionAbort(provider) {
    assert.strictEqual(typeof provider, 'object');

    return async function (req, res, next) {
        debug('route interaction abort');

        try {
            const result = {
                error: 'access_denied',
                error_description: 'End-User aborted interaction',
            };
            await provider.interactionFinished(req, res, result, { mergeWithLastSubmission: false });
        } catch (err) {
            next(err);
        }
    };
}

/**
   * @param use - can either be "id_token" or "userinfo", depending on
   *   where the specific claims are intended to be put in.
   * @param scope - the intended scope, while oidc-provider will mask
   *   claims depending on the scope automatically you might want to skip
   *   loading some claims from external resources etc. based on this detail
   *   or not return them in id tokens but only userinfo and so on.
   */
async function claims(userId, use, scope) {
    debug(`claims: userId:${userId} use:${use} scope:${scope}`);

    const [error, user] = await safe(users.get(userId));
    if (error) return { error: 'user not found' };

    const displayName = user.displayName || user.username || ''; // displayName can be empty and username can be null
    const nameParts = displayName.split(' ');
    const firstName = nameParts[0];
    const lastName = nameParts.length > 1  ? nameParts[nameParts.length - 1] : ''; // choose last part, if it exists

    const claims = {
        sub: user.username, // it is essential to always return a sub claim
        email: user.email,
        email_verified: true,
        family_name: lastName,
        given_name: firstName,
        locale: 'en-US',
        name: user.displayName,
        preferred_username: user.username
    };

    debug(`claims: userId:${userId} result`, claims);

    return claims;
}

// @param form - form source (id="op.logoutForm") to be embedded in the page and submitted by the End-User
async function logoutSource(ctx, form) {
    const data = {
        host: settings.dashboardFqdn(),
        form
    };

    ctx.body = ejs.render(fs.readFileSync(path.join(__dirname, 'oidc_templates/logout.ejs'), 'utf8'), data, {});
}

async function postLogoutSuccessSource(ctx) {
    // const client = ctx.oidc.client || {}; // client is defined if the user chose to stay logged in with the OP
    const data = {
        dashboardOrigin: settings.dashboardOrigin()
    };

    ctx.body = ejs.render(fs.readFileSync(path.join(__dirname, 'oidc_templates/post_logout.ejs'), 'utf8'), data, {});
}

async function findAccount(ctx, id) {
    debug(`findAccount id:${id}`);

    return {
        accountId: id,
        async claims(use, scope) { return await claims(id, use, scope); },
    };
}

async function renderError(ctx, out, error) {
    const data = {
        dashboardOrigin: settings.dashboardOrigin(),
        errorMessage: error.error_description || error.error_detail || 'Unknown error'
    };

    debug('renderError:', error);

    ctx.type = 'html';
    ctx.body = ejs.render(fs.readFileSync(path.join(__dirname, 'oidc_templates/error.ejs'), 'utf8'), data, {});
}

async function start() {
    const app = express();

    gHttpServer = http.createServer(app);

    const { Provider } = await import('oidc-provider');

    // TODO we may want to rotate those in the future
    const jwksKeys = [];

    let keyEdDsa = await blobs.getString(blobs.OIDC_KEY_EDDSA);
    if (!keyEdDsa) {
        debug('Generating new OIDC EdDSA key');
        const { privateKey } = await jose.generateKeyPair('EdDSA');
        keyEdDsa = await jose.exportJWK(privateKey);
        await blobs.setString(blobs.OIDC_KEY_EDDSA, JSON.stringify(keyEdDsa));
        jwksKeys.push(keyEdDsa);
    } else {
        debug('Using existing OIDC EdDSA key');
        jwksKeys.push(JSON.parse(keyEdDsa));
    }

    let keyRs256 = await blobs.getString(blobs.OIDC_KEY_RS256);
    if (!keyRs256) {
        debug('Generating new OIDC RS256 key');
        const { privateKey } = await jose.generateKeyPair('RS256');
        keyRs256 = await jose.exportJWK(privateKey);
        await blobs.setString(blobs.OIDC_KEY_RS256, JSON.stringify(keyRs256));
        jwksKeys.push(keyRs256);
    } else {
        debug('Using existing OIDC RS256 key');
        jwksKeys.push(JSON.parse(keyRs256));
    }

    const configuration = {
        findAccount,
        renderError,
        adapter: CloudronAdapter,
        interactions: {
            url: async function(ctx, interaction) {
                return `${ROUTE_PREFIX}/interaction/${interaction.uid}`;
            }
        },
        jwks: {
            jwksKeys
        },
        claims: {
            email: ['email', 'email_verified'],
            profile: [ 'family_name', 'given_name', 'locale', 'name', 'preferred_username' ]
        },
        features: {
            devInteractions: { enabled: false },
            rpInitiatedLogout: {
                enabled: true,
                logoutSource,
                postLogoutSuccessSource
            },
        },
        // if a client only has one redirect uri specified, the client does not have to provide it in the request
        allowOmittingSingleRegisteredRedirectUri: true,
        clients: [],
        cookies: {
            // FIXME https://github.com/panva/node-oidc-provider/blob/b1c1a9318036c2d3793cc9e668f99937c5c36bc6/lib/helpers/defaults.js#L770
            keys: [ 'cookiesecret1', 'cookiesecret2' ]
        },
        pkce: {
            required: function pkceRequired(ctx, client) {
                return false;
            }
        },
        ttl: {
            // in seconds, can also be a function returning the seconds https://github.com/panva/node-oidc-provider/blob/b1c1a9318036c2d3793cc9e668f99937c5c36bc6/docs/README.md#ttl
            AccessToken: 3600, // 1 hour
            IdToken: 3600, // 1 hour
            Grant: 1209600, // 14 days
            Session: 1209600, // 14 days
            Interaction: 3600 // 1 hour
        }
    };

    debug(`start: create provider for ${settings.dashboardFqdn()} at ${ROUTE_PREFIX}`);
    const provider = new Provider(`https://${settings.dashboardFqdn()}${ROUTE_PREFIX}`, configuration);

    app.enable('trust proxy');
    provider.proxy = true;

    app.set('views', path.join(__dirname, 'oidc_templates'));
    app.set('view engine', 'ejs');

    const json = middleware.json({ strict: true, limit: '2mb' });
    function setNoCache(req, res, next) {
        res.set('cache-control', 'no-store');
        next();
    }

    app.get (`${ROUTE_PREFIX}/interaction/:uid`,          setNoCache,       renderInteractionPage(provider));
    app.post(`${ROUTE_PREFIX}/interaction/:uid/login`,    setNoCache, json, interactionLogin(provider));
    app.post(`${ROUTE_PREFIX}/interaction/:uid/confirm`,  setNoCache, json, interactionConfirm(provider));
    app.get (`${ROUTE_PREFIX}/interaction/:uid/abort`,    setNoCache,       interactionAbort(provider));

    app.use(ROUTE_PREFIX, provider.callback());

    await util.promisify(gHttpServer.listen.bind(gHttpServer))(constants.OIDC_PORT, '127.0.0.1');
}

async function stop() {
    if (!gHttpServer) return;

    await util.promisify(gHttpServer.close.bind(gHttpServer))();

    gHttpServer = null;
}