import { parse } from 'csv-parse';
import fs from 'node:fs';
import zlib from 'zlib';
import mysql from 'mysql2';
import dotenv from 'dotenv';

dotenv.config();

if (process.argv.length != 3) {
    throw new Error('You should give a project dir');
}
const file = process.argv[2];

// csv parser
const delimiter = (file.match(/\.gz$/)) ? ',' : '|';
const parser = parse({
    delimiter,
    columns: true,
});

// mysql to escape string
const connectionString = process.env.MYSQL;
if (!connectionString) {
    throw new Error('MYSQL environment variable not set');
}

const connection = mysql.createConnection(process.env.MYSQL);

// generate sql
let columns = [];
const flushBatch = (batch) => {
    if (batch.length === 0) return;

    const values = batch.map(row => `(${row.map(val => connection.escape(val)).join(', ')})`).join(', ');
    const sql = `INSERT INTO dvf (${columns.join(', ')}) VALUES ${values};`;

    console.log(sql);

    // connection.query(sql, (error, results) => {
    //     if (error) throw error;
    //     console.log('Inserted rows:', results.affectedRows);
    // });
};

// quand quelques ligne de csv sont parsées on les assemble puis on genere le sql
parser.on('readable', function(){
    let record;
    const batch = []; 
    
    while ((record = parser.read()) !== null) {
        // console.log(record);

        // get columns and values to insert and escape them for sql
        if (columns.length === 0) {
            columns = Object.keys(record).map(col => connection.escapeId(col));
        }
        const values = Object.values(record);
        batch.push(values);
    }

    flushBatch(batch);
});
parser.on('error', function(err){
    console.error(err.message);
});
parser.on('end', function(){
    connection.end();
});

// ouvre le fichier, et le décompresse si besoin
if (file.match(/\.gz$/)) fs.createReadStream(file).pipe(zlib.createGunzip()).pipe(parser);
else fs.createReadStream(file).pipe(parser);