// Streams an input through the engine in fixed-size chunks and reports peak memory.buffer.byteLength.
// Usage: TYPESTRIP_ERASE_WASM=build/erase.wasm node bench/profile/stream-memory.mjs [file|--concat=50] [chunkBytes]
// --concat=N builds an N MB input by concatenating corpus files (the streaming proof: memory must stay flat).
import fs from "node:fs";
import { engine, transformSync } from "../../src/index.js";
import { cases } from "../../test/corpus.mjs";
const exports = engine();

const arg = process.argv[2] ?? new URL("../../node_modules/typescript/lib/lib.dom.d.ts", import.meta.url).pathname;
const chunk = Number(process.argv[3] ?? 65536);
let src;
if (arg.startsWith("--concat=")) {
  const target = Number(arg.slice(9)) * 1e6;
  const parts = [];
  let total = 0;
  while (total < target) {
    for (const { src: s } of cases()) {
      parts.push(s.endsWith("\n") ? s : s + "\n");
      total += s.length + 1;
      if (total >= target) break;
    }
  }
  src = parts.join("");
} else {
  src = fs.readFileSync(arg, "utf8");
}

function* parts(s) {
  for (let i = 0; i < s.length; i += chunk) yield s.slice(i, i + chunk);
}

const before = exports.memory.buffer.byteLength;
let peak = before;
let outLen = 0;
let errors = 0;
const t0 = performance.now();
for (const piece of transformSync(parts(src), { onError: () => errors++ })) {
  outLen += piece.length;
  peak = Math.max(peak, exports.memory.buffer.byteLength);
}
const ms = performance.now() - t0;
console.log(`input ${(src.length / 1e6).toFixed(2)}M chars in ${chunk}-char chunks: output ${outLen} chars, ${errors} errors, ${ms.toFixed(0)}ms, memory before ${(before / 1e6).toFixed(1)}MB peak ${(peak / 1e6).toFixed(1)}MB`);