import mysql from 'mysql2/promise'
import { loadP42Secrets } from './secretsLoader.js'

export class MySQLClient {

    constructor(db, kal = 0) {
        this.db = db
        this.lastInsertedId = -1
        this.kalIntervalId = null
        if(kal > 0) {
            this.kalIntervalId = setInterval(() => {
                this.db.query('SELECT 1')
            }, 1000 * kal)
        }
    }

    static #assertValidDbName(name) {
        if(typeof(name) !== 'string' || !/^[A-Za-z0-9_]+$/.test(name)) {
            throw(new Error(`Invalid MySQL database name: ${name}`))
        }
    }

    static resolveDatabases(config = {}) {
        loadP42Secrets()
        const guiDatabase = process.env.mysql_guiDb || config.guiDatabase || config.database || 'p42GUI'
        const simDatabase = process.env.mysql_simDb || config.simDatabase || 'p42SIM'
        MySQLClient.#assertValidDbName(guiDatabase)
        MySQLClient.#assertValidDbName(simDatabase)
        return({ guiDatabase, simDatabase })
    }

    static resolveCredentials(config = {}) {
        loadP42Secrets()
        const user = process.env.mysql_user
        const password = process.env.mysql_pass
        if(!user || !password) {
            throw(new Error('Missing MySQL credentials: set mysql_user and mysql_pass in environment'))
        }
        const { guiDatabase } = MySQLClient.resolveDatabases(config)
        return({
            socketPath: config.socketPath,
            host: config.host,
            port: config.port,
            user,
            password,
            database: guiDatabase,
            waitForConnections: true,
            connectionLimit: config.connectionLimit ?? 5,
            queueLimit: 0,
        })
    }

    static async createPool(config) {
        return(await mysql.createPool(MySQLClient.resolveCredentials(config)))
    }

    static async poolExecute(pool, query, values = []) {
        const [rows] = await pool.execute(query, values)
        return(rows)
    }

    async close() {
        if(this.db) await this.db.end()
        if(this.kalIntervalId) clearInterval(this.kalIntervalId)
        this.db = null
    }

    escape(x) {
        return(mysql.escape(x))
    }

    async execute(query, values = []) {
        if(!this.db) return([])
        if(query.search(RegExp('(^|;) *(INSERT|REPLACE) +INTO', 'i')) > -1) this.lastInsertedId = -1
        const [result] = await this.db.execute(query, values)

        if('insertId' in result) {
            this.lastInsertedId = result.insertId
        }
        return(result)
    }

    async InsertObjectsStatement(table, rows) {
        this.lastInsertedId = -1
        if((!this.db) || (rows.length == 0)) return([])
        const keys = Object.keys(rows[0]).map((key) => `\`${key}\``).join(', ')
        const valuesArr = []
        for(const row of rows) {
            valuesArr.push(Object.values(row))
        }
        const query = `INSERT INTO ${table} (${keys}) VALUES ?`
        const [result] = await this.db.query(query, [valuesArr])
        if('insertId' in result) {
            this.lastInsertedId = result.insertId
        }
        return(result)
    }

    async ReplaceObjectsStatement(table, rows) {
        this.lastInsertedId = -1
        if((!this.db) || (rows.length == 0)) return([])
        const keys = Object.keys(rows[0]).map((key) => `\`${key}\``).join(', ')
        const valuesArr = []
        for(const row of rows) {
            valuesArr.push(Object.values(row))
        }
        const query = `REPLACE INTO ${table} (${keys}) VALUES ?`
        const [result] = await this.db.query(query, [valuesArr])
        if('insertId' in result) {
            this.lastInsertedId = result.insertId
        }
        return(result)
    }

}