// In-memory background-job tracker. Used by /relay/transcribe-url
// (and any future long-running endpoint) so the request that kicks
// off the work returns immediately with a job_id, and the client
// polls /relay/jobs/{id} to find out when it's done.
//
// Rationale: synchronous HTTP responses for multi-minute transcribes
// are fragile. Any intermediate proxy / load balancer / NAT in the
// path will drop the connection after some idle/total timeout (often
// 100s–10min), failing the whole job mid-flight even though the
// relay backend is working fine. Async jobs sidestep all of that:
// the long-running work happens off the request path and the client
// polls short, cheap requests until done.
//
// Storage is in-process memory. Restart-survivability is a known
// gap — a relay restart mid-job loses that job's state, and the
// client will re-poll forever until it gives up. Acceptable for v1
// at small relay scale; the audit log already captures every
// completed call so the operator has a paper trail either way.
// Migrate to SQLite if/when restart-resilience becomes important.
//
// Each job is { id, kind, install_id, status, started_at, updated_at,
//   completed_at?, progress?, result?, error? }
// status: "queued" | "running" | "complete" | "failed"

import { randomUUID } from "crypto";
import { sanitizeErrorForClient } from "./sanitize-error.js";

// All in-memory; lost on restart.
const jobs = new Map();

// Cap how long completed jobs hang around so the map doesn't grow
// unbounded. Once a client has polled and seen "complete", it'll
// stop polling — keeping the record 24h gives slow / retried clients
// a generous window without exhausting memory.
const RETENTION_MS = 24 * 60 * 60 * 1000;

export function createJob({ kind, installId, metadata = {} }) {
  pruneExpired();
  const id = randomUUID();
  const now = Date.now();
  const job = {
    id,
    kind,
    install_id: installId,
    status: "queued",
    started_at: now,
    updated_at: now,
    completed_at: null,
    progress: null,
    result: null,
    error: null,
    metadata,
    // Event log + live subscriber list. Used by jobs that stream
    // incremental results via SSE (e.g., /relay/summarize-url
    // dispatches transcribe_progress, transcribe_complete,
    // window_complete, done, error events). Each event is
    // { type, data, ts } and gets BOTH appended to the log (so a
    // late SSE-connecting client can replay missed events) and
    // pushed to any currently-subscribed callbacks. `subscribers`
    // is intentionally non-enumerable / non-serialized so it never
    // leaks into snapshotJobs() or HTTP responses.
    events: [],
  };
  Object.defineProperty(job, "subscribers", {
    value: new Set(),
    enumerable: false,
    writable: false,
  });
  jobs.set(id, job);
  return job;
}

// Append an event to a job's log AND notify any live SSE
// subscribers. Used by /relay/summarize-url's background worker to
// emit per-window progress as it streams in from runChunkedAnalysis.
// Event shape:
//   { type: "window_complete"|"transcribe_complete"|"done"|"error"|"progress",
//     data: <event payload>,
//     ts:   ms-epoch }
// Subscriber callbacks receive ONLY the new event (not the full log);
// new subscribers should replay the log themselves on connect.
export function appendEvent(jobId, type, data) {
  const job = jobs.get(jobId);
  if (!job) return;
  const event = { type, data, ts: Date.now() };
  job.events.push(event);
  job.updated_at = event.ts;
  // Cap the log so a runaway job doesn't blow memory. 1000 events
  // is far beyond any plausible window count (typical: 10-20).
  if (job.events.length > 1000) job.events.shift();
  for (const cb of job.subscribers) {
    try {
      cb(event);
    } catch (err) {
      console.warn(`[jobs] subscriber callback failed: ${err?.message || err}`);
    }
  }
}

// Subscribe to live events from a job. Returns an unsubscribe
// function the caller MUST call (e.g., on SSE connection close)
// or the job state will leak the callback closure forever.
// Returns null when the job no longer exists.
export function subscribeToJob(jobId, callback) {
  const job = jobs.get(jobId);
  if (!job) return null;
  job.subscribers.add(callback);
  return () => {
    job.subscribers.delete(callback);
  };
}

export function getJob(jobId) {
  pruneExpired();
  return jobs.get(jobId) || null;
}

export function markRunning(jobId) {
  const job = jobs.get(jobId);
  if (!job) return;
  job.status = "running";
  job.updated_at = Date.now();
}

export function setProgress(jobId, message) {
  const job = jobs.get(jobId);
  if (!job) return;
  job.progress = String(message).slice(0, 200);
  job.updated_at = Date.now();
}

export function markComplete(jobId, envelope) {
  const job = jobs.get(jobId);
  if (!job) return;
  job.status = "complete";
  // Keep the full envelope shape on the job (caller decides what to
  // pass — typically { result: {...inner...}, credit_charged, tier }).
  // Internal consumers that read job.result directly still see the
  // wrapped form.
  job.result = envelope;
  job.completed_at = Date.now();
  job.updated_at = job.completed_at;
  // SSE "done" event: emit the INNER result directly so subscribers
  // can read fields off `data.result.title` (or `.transcript`,
  // `.analysis`, etc.) instead of a confusing `data.result.result.title`.
  // The wrapped form (envelope.result) is unwrapped here; if the
  // caller passed a flat result without an inner `.result` key we
  // just pass it through unchanged. credit_charged + tier travel
  // alongside as siblings so the SSE consumer can update its
  // balance display without digging into the result body.
  //
  // Why this matters: Recap-app's SSE handler does
  // `finalResult = data.result`, then reads `finalResult.title`.
  // Before this fix, that landed on the wrapping envelope and every
  // title came back undefined — library entries persisted as
  // "Untitled" despite the relay correctly extracting the real title
  // via yt-dlp. The audit log was unaffected (it reads the local
  // `title` variable directly) which made the bug look like a
  // Recap-side issue. It wasn't.
  const inner = envelope && typeof envelope === "object" && "result" in envelope
    ? envelope.result
    : envelope;
  appendEvent(jobId, "done", {
    result: inner,
    credit_charged: envelope?.credit_charged,
    tier: envelope?.tier,
  });
}

export function markFailed(jobId, errorMessage) {
  const job = jobs.get(jobId);
  if (!job) return;
  job.status = "failed";
  // Sanitize at the source so EVERY downstream surface that reads
  // job.error (SSE error event, the per-job GET endpoints, etc.)
  // gets the client-safe wording, without having to remember to
  // sanitize at every call site. The raw operator-internal message
  // stays available on job.error_internal for the admin dashboard +
  // audit log (snapshotJobs exposes both fields).
  const raw = String(errorMessage || "unknown error").slice(0, 500);
  job.error_internal = raw;
  job.error = sanitizeErrorForClient(raw).slice(0, 500);
  job.completed_at = Date.now();
  job.updated_at = job.completed_at;
  // Same terminal event for failures — SSE clients close on this
  // and surface the error to the user.
  appendEvent(jobId, "error", { error: job.error });
}

export function snapshotJobs() {
  pruneExpired();
  return Array.from(jobs.values()).map((j) => ({
    id: j.id,
    kind: j.kind,
    install_id: j.install_id,
    status: j.status,
    started_at: j.started_at,
    updated_at: j.updated_at,
    completed_at: j.completed_at,
    progress: j.progress,
    has_result: j.result != null,
    // Both error variants exposed — the admin dashboard consumes
    // snapshotJobs and can prefer error_internal for operator
    // diagnosis (full backend / spark-control wording intact).
    // External callers should always read `error` (sanitized).
    error: j.error,
    error_internal: j.error_internal || j.error,
  }));
}

function pruneExpired() {
  const cutoff = Date.now() - RETENTION_MS;
  for (const [id, job] of jobs) {
    const ref = job.completed_at || job.updated_at || job.started_at;
    if (ref && ref < cutoff) {
      jobs.delete(id);
    }
  }
}