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const mssql = require('mssql');
const { deepEncode, deepDecode } = require('./deepMap');
/**
* @typedef {object} State
* @prop {string} senderId
* @prop {string} pageId
* @prop {object} state
*/
/**
* @typedef {object} StateCondition
* @prop {string} [search]
*/
/**
* Storage for chat states
*
* @class
*/
class StateStorage {
/**
* @param {Promise<mssql.ConnectionPool>} pool
*/
constructor (pool) {
this._pool = pool;
}
/**
*
* @param {string} senderId
* @param {string} pageId
* @returns {Promise<State|null>}
*/
async getState (senderId, pageId) {
const cp = await this._pool;
const { recordset } = await cp.request()
.input('senderId', mssql.VarChar, senderId)
.input('pageId', mssql.VarChar, pageId)
.query('SELECT TOP 1 * FROM states WHERE senderId=@senderId AND pageId=@pageId');
const [res] = recordset;
if (!res) {
return null;
}
return {
...res,
state: this._decodeState(res.state)
};
}
/**
* Load state from database and lock it to prevent another reads
*
* @param {string} senderId - sender identifier
* @param {string} pageId - page identifier
* @param {object} [defaultState] - default state of the conversation
* @param {number} [timeout=300] - given default state
* @returns {Promise<object>} - conversation state
*/
async getOrCreateAndLock (senderId, pageId, defaultState = {}, timeout = 300) {
const now = Date.now();
const threshold = now - timeout;
const cp = await this._pool;
const res = await cp.request()
.input('senderId', mssql.VarChar, senderId)
.input('pageId', mssql.VarChar, pageId)
.input('lock', mssql.BigInt, now)
.input('threshold', mssql.BigInt, threshold)
.query('UPDATE states SET lock = @lock WHERE senderId = @senderId AND pageId = @pageId AND lock < @threshold');
if (res.rowsAffected[0] === 1) {
// successfully locked
return this.getState(senderId, pageId);
}
try {
// not exists or conflict
await this._insertState(cp, senderId, pageId, defaultState, now);
return {
senderId,
pageId,
lock: now,
state: { ...defaultState }
};
} catch (e) {
// 2627 is unique constraint (includes primary key), 2601 is unique index
if (e.number === 2601 || e.number === 2627) {
// for compatibility with MongDB connnector sending same error code
e.code = 11000;
}
throw e;
}
}
/**
* Save the state to database
*
* @param {object} state - conversation state
* @returns {Promise<object>}
*/
async saveState (state) {
const {
senderId, pageId, lastSendError, off = false, lastInteraction
} = state;
const cp = await this._pool;
const res = await cp.request()
.input('senderId', mssql.VarChar, senderId)
.input('pageId', mssql.VarChar, pageId)
.input('lastSendError', mssql.NVarChar, lastSendError)
.input('state', mssql.NVarChar, this._encodeState(state.state))
.input('itsOff', mssql.VarChar, off ? 'true' : 'false')
.input('lastInteraction', mssql.BigInt, lastInteraction)
.query('UPDATE states SET lock = 0, state = @state, itsOff = @itsOff, lastInteraction = @lastInteraction WHERE senderId = @senderId AND pageId = @pageId');
if (res.rowsAffected[0] === 0) {
// nothing was updated so let's insert it
await this._insertState(cp, senderId, pageId, state.state, 0, lastInteraction, off);
}
return state;
}
_decodeState (state) {
return deepDecode(JSON.parse(state));
}
_encodeState (state) {
return JSON.stringify(deepEncode(state));
}
async _insertState (cp, senderId, pageId, state, lock = 0, lastInt = null, off = false) {
return cp.request()
.input('senderId', mssql.VarChar, senderId)
.input('pageId', mssql.VarChar, pageId)
.input('lock', mssql.BigInt, lock)
.input('state', mssql.NVarChar, this._encodeState(state))
.input('itsOff', mssql.VarChar, off ? 'true' : 'false')
.input('lastInteraction', mssql.BigInt, lastInt)
.query('INSERT INTO states (senderId, pageId, lock, state, itsOff, lastInteraction) VALUES (@senderId, @pageId, @lock, @state, @itsOff, @lastInteraction)');
}
// @TODO Davide, getStates jsem uz nestihl.
// našel jsem že MS SQL má taky metodu SKIP a LIMIT které se tu používají v MongoDB
// https://docs.microsoft.com/en-us/dotnet/framework/data/adonet/ef/language-reference/skip-entity-sql
// https://docs.microsoft.com/en-us/dotnet/framework/data/adonet/ef/language-reference/limit-entity-sql
/**
*
* @param {StateCondition} condition
* @param {number} limit
* @param {string} lastKey
* @returns {Promise<{data:State[],lastKey:string}>}
*/
async getStates (condition = {}, limit = 20, lastKey = null) {
const cp = await this._pool;
let lastInteraction = 0;
let skip = 0;
if (lastKey !== null) {
const key = JSON.parse(Buffer.from(lastKey, 'base64').toString('utf8'));
if (key.skip) {
({ skip } = key);
} else {
({ lastInteraction } = key);
// Object.assign(useCondition, {
// lastInteraction: {
// $lte: new Date(key.lastInteraction)
// }
// });
}
}
const searchStates = typeof condition.search === 'string';
let where = '';
if (lastInteraction) {
where = 'WITH (INDEX(lastInteraction)) WHERE lastInteraction BETWEEN 0 AND @lastInteraction';
} else if (searchStates) {
where = 'WHERE';
}
if (searchStates && lastInteraction) {
where += ' AND';
}
if (searchStates) {
where += ' senderId LIKE @search';
}
const res = await cp.request()
.input('offset', mssql.BigInt, skip)
.input('limit', mssql.BigInt, limit + 1)
.input('lastInteraction', mssql.BigInt, lastInteraction)
.input('search', mssql.VarChar, `${condition.search}%`)
.query(`SELECT * FROM states ${where} ORDER BY lastInteraction DESC OFFSET @offset ROWS FETCH NEXT @limit ROWS ONLY`);
let { recordset: data } = res;
let nextLastKey = null;
if (limit !== null && data.length > limit) {
if (searchStates) {
nextLastKey = Buffer.from(JSON.stringify({
skip: skip + limit
})).toString('base64');
} else {
const last = data[data.length - 1];
nextLastKey = Buffer.from(JSON.stringify({
lastInteraction: last.lastInteraction
})).toString('base64');
}
// @ts-ignore
data = data.slice(0, limit);
}
return {
data: data.map((camp) => this._mapState(camp)),
lastKey: nextLastKey
};
}
_mapState (state) {
if (!state) {
return null;
}
// eslint-disable-next-line no-param-reassign
state.state = this._decodeState(state.state);
// eslint-disable-next-line no-param-reassign
state.itsOff = state.itsOff === 'true' || state.itsOff === true;
// eslint-disable-next-line no-param-reassign
state.lastInteraction = new Date(typeof state.lastInteraction === 'string'
? parseInt(state.lastInteraction, 10)
: state.lastInteraction);
delete state._id; // eslint-disable-line
delete state.lock; // eslint-disable-line
delete state.off; // eslint-disable-line
delete state.lastSendError // eslint-disable-line
delete state.score // eslint-disable-line
return state;
}
}
module.exports = StateStorage;
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