import { TextLineStream } from "jsr:@std/streams@1/text-line-stream";
import { ExportEntry } from "./directory-tailer.ts";
import { tailer } from "./main.ts";

export const catchUp = async () => {
  using exports = await Deno.open("./data/exports.jsonl", { read: true });
  await exports.seek(-4096, Deno.SeekMode.End); // grab last 4kib

  const lineStream = exports.readable
    .pipeThrough(new TextDecoderStream())
    .pipeThrough(new TextLineStream());

  // discard one partial line
  {
    const lineReader = lineStream.getReader();
    const _line = await lineReader.read();
    lineReader.releaseLock();
  }

  let lastLine: string | undefined;
  for await (const line of lineStream.values()) {
    lastLine = line;
  }

  if (lastLine) {
    const entry = JSON.parse(lastLine) as unknown as ExportEntry;
    tailer.latestDate = entry.createdAt;
  }
};

try {
  await catchUp();
} catch (err) {
  console.warn(err);
}

await tailer.fetchExports();