import fs from "node:fs";
import { RunsError } from "./errors.mjs";
import { RUNS_DIRNAME, isMissing, readJsonObject, resolveInside } from "./paths.mjs";

export const RUN_ID_PATTERN = /^r-[A-Za-z0-9][A-Za-z0-9._-]{0,63}$/;
export const RUN_DOCUMENTS = ["result.json", "task.json", "mission.json"];

export function isRunId(value) {
  return typeof value === "string" && RUN_ID_PATTERN.test(value);
}

function requireRunId(runId) {
  if (!isRunId(runId)) throw new RunsError(`invalid run id: ${JSON.stringify(runId)} (expected r-<id>)`);
}

// Every name under <dataRoot>/runs/ that starts with "r-", sorted. Run ids
// begin with a UTC stamp, so the order is oldest first. A missing data root
// or runs directory is an empty list.
export function listRunIds(dataRoot) {
  const root = resolveInside(dataRoot, RUNS_DIRNAME);
  if (root === null) return [];
  let names;
  try {
    names = fs.readdirSync(root);
  } catch (error) {
    if (isMissing(error)) return [];
    throw new RunsError(`cannot read ${root}: ${error.code ?? error.message}`);
  }
  return names.filter((name) => name.startsWith("r-")).sort();
}

// One of RUN_DOCUMENTS from a run, or null when it is missing, unreadable,
// not a JSON object or outside the data root.
export function readRunDocument(dataRoot, runId, name) {
  requireRunId(runId);
  if (!RUN_DOCUMENTS.includes(name)) throw new RunsError(`unknown run document: ${JSON.stringify(name)}`);
  return readJsonObject(dataRoot, RUNS_DIRNAME, runId, name);
}

// [{ runId, result }] for every listed run; result is null for an
// incomplete or unreadable record. Names come from listRunIds, so a name
// that starts with "r-" but isn't a valid run id is still listed.
export function listRunRecords(dataRoot) {
  return listRunIds(dataRoot).map((runId) => ({
    runId,
    result: readJsonObject(dataRoot, RUNS_DIRNAME, runId, "result.json"),
  }));
}

// One run's documents and artifact names, or null when the run directory
// doesn't exist or isn't a directory. Artifacts are in directory order.
export function readRunRecord(dataRoot, runId) {
  requireRunId(runId);
  // The runs directory first, so a refusal names the link that escapes.
  if (resolveInside(dataRoot, RUNS_DIRNAME) === null) return null;
  const dir = resolveInside(dataRoot, RUNS_DIRNAME, runId);
  if (dir === null) return null;
  let artifacts;
  try {
    artifacts = fs.readdirSync(dir);
  } catch (error) {
    if (isMissing(error)) return null;
    throw new RunsError(`cannot read ${dir}: ${error.code ?? error.message}`);
  }
  return {
    runId,
    result: readRunDocument(dataRoot, runId, "result.json"),
    task: readRunDocument(dataRoot, runId, "task.json"),
    mission: readRunDocument(dataRoot, runId, "mission.json"),
    artifacts,
  };
}