import { createReadStream } from "node:fs";

const filePath = process.argv[2] ?? "events.log";
const stream = createReadStream(filePath, {
  encoding: "utf8",
  highWaterMark: 32,
});

let chunks = 0;
let bytes = 0;
let lines = 0;
let errorLines = 0;
let carry = "";

function countRecord(record) {
  if (record === "") return;

  lines += 1;
  if (record.includes("ERROR")) {
    errorLines += 1;
  }
}

try {
  for await (const chunk of stream) {
    chunks += 1;
    bytes += Buffer.byteLength(chunk, "utf8");

    const records = (carry + chunk).split("\n");
    carry = records.pop() ?? "";

    for (const record of records) {
      countRecord(record);
    }
  }

  countRecord(carry);

  console.log(`file=${filePath}`);
  console.log(`chunks=${chunks}`);
  console.log(`bytes=${bytes}`);
  console.log(`lines=${lines}`);
  console.log(`errorLines=${errorLines}`);
} catch (error) {
  console.error(`Failed to read ${filePath}: ${error.code ?? error.message}`);
  process.exitCode = 1;
}