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

import "./write-compacted.ts";
import "./write-live.ts";

const addOperations = async (
  stream: ReadableStream<Uint8Array>,
  did: string,
  operations: ExportEntry[]
) => {
  const lines = stream
    .pipeThrough(new TextDecoderStream())
    .pipeThrough(new TextLineStream());

  for await (const line of lines.values()) {
    if (!line.startsWith(did)) continue;
    const [_did, _createdAt, _cid, rawEntry] = line.split("\u001f", 4);
    const entry = JSON.parse(rawEntry) as unknown as ExportEntry;
    operations.push(entry);
  }
};

export const getOperations = async (did: string) => {
  const operations: ExportEntry[] = [];

  const didplc = "did:plc:".length;
  const prefix = did.substring(didplc, didplc + 2);

  const compactedEntries = await Array.fromAsync(
    Deno.readDir("./data/plc/compacted")
  );
  compactedEntries.sort((a, b) =>
    a.name < b.name ? -1 : a.name > b.name ? 1 : 0
  );
  for (const entry of compactedEntries) {
    // TODO: if we assume that compacted files are *sorted*, we get ordering by did and createdAt,
    // which gives us a complete op log for each did. we can store a little size prefix for a block
    // and seek over dids we don't care about, giving us whole contiguous op logs in a compacted file.
    // but for now we just un-zstd it and skip individual lines we don't care about the same as a live file

    const process = new Deno.Command("zstd", {
      args: [
        "-d",
        `./data/plc/compacted/${entry.name}/${prefix}.zst`,
        "--stdout",
      ],
      cwd: Deno.cwd(),
      stdout: "piped",
      stdin: "null",
      stderr: "piped",
    }).spawn();

    await addOperations(process.stdout, did, operations);
    await process.status;
  }

  for (const dir of ["compacting", "live"]) {
    try {
      const f = await Deno.open(`./data/plc/${dir}/${prefix}`, { read: true });
      await addOperations(f.readable, did, operations);
    } catch (_err) {
      // ignore
    }
  }

  return operations;
};

if (import.meta.main) {
  await getOperations(Deno.args[0]);

  const then = performance.now();
  console.log(await getOperations(Deno.args[0]));
  console.log(performance.now() - then);
}