import { promises as fs } from "node:fs";
import path from "node:path";
import { getAgentDir } from "@earendil-works/pi-coding-agent";
import { LABEL_KINDS, type LabelRun } from "./types.ts";

function runDir(sessionId: string): string {
  return path.join(getAgentDir(), "pi-tree-labeler", "runs", sessionId.replace(/[^A-Za-z0-9._-]/g, "_"));
}

function isRun(value: unknown, sessionId: string): value is LabelRun {
  if (!value || typeof value !== "object") return false;
  const run = value as Partial<LabelRun>;
  if (run.version !== 1 || run.sessionId !== sessionId || typeof run.id !== "string" || typeof run.createdAt !== "string") return false;
  if (!["proposed", "applied", "discarded", "failed"].includes(String(run.status)) || !Array.isArray(run.proposals) || !Array.isArray(run.conflicts)) return false;
  return run.proposals.every((proposal) => Boolean(proposal)
    && typeof proposal.entryId === "string"
    && typeof proposal.label === "string"
    && LABEL_KINDS.includes(proposal.kind));
}

export async function saveRun(run: LabelRun): Promise<void> {
  const dir = runDir(run.sessionId);
  await fs.mkdir(dir, { recursive: true, mode: 0o700 });
  const target = path.join(dir, `${run.id}.json`);
  const temporary = `${target}.${process.pid}.${Date.now()}.tmp`;
  await fs.writeFile(temporary, `${JSON.stringify(run, null, 2)}\n`, { mode: 0o600 });
  await fs.rename(temporary, target);
}

export async function loadRuns(sessionId: string, limit = 20): Promise<LabelRun[]> {
  const dir = runDir(sessionId);
  let names: string[];
  try { names = await fs.readdir(dir); } catch { return []; }
  const runs: LabelRun[] = [];
  for (const name of names.filter((item) => item.endsWith(".json"))) {
    try {
      const run: unknown = JSON.parse(await fs.readFile(path.join(dir, name), "utf8"));
      if (isRun(run, sessionId) && name === `${run.id}.json`) runs.push(run);
    } catch { /* Ignore corrupt individual history records. */ }
  }
  return runs.sort((a, b) => b.createdAt.localeCompare(a.createdAt)).slice(0, limit);
}

export async function latestPendingRun(sessionId: string): Promise<LabelRun | undefined> {
  return (await loadRuns(sessionId, Number.MAX_SAFE_INTEGER)).find((run) => run.status === "proposed" && run.proposals.length > 0);
}