import posgtres from "postgres";
import fs from "fs";
import { Readable, Transform } from "stream";

const sql = posgtres({
  host: "localhost",
  user: "postgres",
  password: "1234",
  port: 5432,
});

async function dbtofile() {
  console.time();
  const readable = await sql`copy mytemp (id, content) to stdout`.readable();

  const write = fs.createWriteStream("output.csv");

  const transform = new Transform({
    transform(chunk, endonding, callback) {
      const [id, ...fields] = chunk.toString().trim().split(/\s+/);
      const newData = `${id}, ${fields.join(" ")}\n`;
      callback(null, newData);
    },
    highWaterMark: 1024, // Limit chunk size to 1KB
  });

  transform.pipe(write);
  readable.pipe(transform);

  await new Promise((resolve, reject) => {
    write.on("finish", () => {
      console.log("Escrita concluída.");
      resolve(null);
    });

    write.on("error", (err) => {
      console.error(err);
      resolve(null);
    });
  });

  transform.destroy();
  readable.destroy();
  write.destroy();
  sql.end();

  console.timeEnd();
}

async function filetodb() {
  await sql`delete from mytemp_copy`;
  const write = await sql`copy mytemp_copy (id, content) from stdin`.writable();
  const readable = fs.createReadStream("output.csv", {
    encoding: "utf8",
    highWaterMark: 1024,
  });

  const transform = new Transform({
    transform(chunk, encoding, callback) {
      const lines = ((this.partialLine || "") + chunk).split("\n");

      lines.forEach((line, index) => {
        // Ignora a última linha se não estiver completa (não terminada com uma quebra de linha)
        if (index === lines.length - 1 && !line.endsWith("\n")) {
          this.partialLine = line; // Salva a parte da linha para o próximo chunk
        } else {
          const [id, content] = line.split(", ");
          this.push(`${+id}\t${content.trim()}\n`);
        }
      });

      callback();
    },
  });

  readable.pipe(transform);
  transform.pipe(write);

  try {
    await new Promise((resolve, reject) => {
      readable.on("end", resolve);
      readable.on("error", reject);
      write.on("finish", resolve);
      write.on("error", reject);
    });
    console.log(await sql`select count(*) from mytemp_copy`);
  } finally {
    readable.destroy();
    sql.end();
  }
}

await filetodb();