#!/usr/bin/env node
import { mkdir, readFile, writeFile } from "node:fs/promises";
import { dirname, resolve } from "node:path";
import { exportRecord } from "./export.js";
import type { DpoExample, SftExample } from "./export.js";
import type { PreferenceRecord } from "./types.js";

const inputPath = resolve(process.argv[2] ?? "data/preferences.jsonl");
const outputPrefix = resolve(process.argv[3] ?? "data/training");

try {
  const records = (await readFile(inputPath, "utf8"))
    .split("\n")
    .filter(Boolean)
    .map((line) => JSON.parse(line) as PreferenceRecord);
  const sft: SftExample[] = [];
  const dpo: DpoExample[] = [];
  for (const record of records) {
    const examples = exportRecord(record);
    sft.push(examples.sft);
    dpo.push(...examples.dpo);
  }

  const sftPath = `${outputPrefix}.sft.jsonl`;
  const dpoPath = `${outputPrefix}.dpo.jsonl`;
  await mkdir(dirname(outputPrefix), { recursive: true });
  await Promise.all([
    writeFile(sftPath, lines(sft), { encoding: "utf8", mode: 0o600 }),
    writeFile(dpoPath, lines(dpo), { encoding: "utf8", mode: 0o600 }),
  ]);
  process.stdout.write(`Exported ${sft.length} SFT examples to ${sftPath}\n`);
  process.stdout.write(`Exported ${dpo.length} preference pairs to ${dpoPath}\n`);
} catch (error) {
  process.stderr.write(`${error instanceof Error ? error.message : String(error)}\n`);
  process.exitCode = 1;
}

function lines(values: unknown[]): string {
  return values.map((value) => JSON.stringify(value)).join("\n") + (values.length ? "\n" : "");
}