const crypto = require("crypto");

class AssistantRequestJobs {
  constructor({ ttlMs = 15 * 60 * 1000, maxJobs = 200 } = {}) {
    this.ttlMs = ttlMs;
    this.maxJobs = maxJobs;
    this.jobs = new Map();
  }

  create({ userId, execute, metadata = {} }) {
    this.prune();
    const id = crypto.randomUUID();
    const controller = new AbortController();
    const job = {
      id,
      user_id: String(userId),
      state: "queued",
      stage: "queued",
      created_at: Date.now(),
      updated_at: Date.now(),
      result: null,
      error: null,
      retry_after_seconds: null,
      details: sanitizeDetails(metadata),
      controller,
      frontend_soft_timeout_at: null
    };
    this.jobs.set(id, job);
    setImmediate(async () => {
      try {
        const result = await execute(
          (stage, details = {}) => this.update(id, stage, details),
          controller.signal
        );
        if (job.state === "cancelled") return;
        Object.assign(job, {
          state: "complete",
          stage: "done",
          result,
          updated_at: Date.now()
        });
      } catch (error) {
        if (job.state === "cancelled") return;
        const cancelled = error.code === "REQUEST_CANCELLED" || error.name === "AbortError";
        Object.assign(job, {
          state: cancelled ? "cancelled" : "error",
          stage: cancelled ? "cancelled" : "error",
          error: cancelled ? "Assistant request was cancelled." : error.message || "Lumi Assistant could not complete the request.",
          retry_after_seconds: error.retry_after_seconds || null,
          details: sanitizeDetails({ ...job.details, error_code: error.code }),
          updated_at: Date.now()
        });
      }
    });
    return this.publicJob(job);
  }

  update(id, stage, details = {}) {
    const job = this.jobs.get(id);
    if (!job || ["complete", "error", "cancelled"].includes(job.state)) return null;
    job.state = stage === "queued" ? "queued" : "running";
    job.stage = stage;
    job.updated_at = Date.now();
    job.details = sanitizeDetails({ ...job.details, ...details });
    return this.publicJob(job);
  }

  get(id, userId) {
    this.prune();
    const job = this.jobs.get(id);
    if (!job || job.user_id !== String(userId)) return null;
    return this.publicJob(job);
  }

  cancel(id, userId, { admin = false } = {}) {
    this.prune();
    const job = this.jobs.get(id);
    if (!job || (!admin && job.user_id !== String(userId))) return null;
    if (["complete", "error", "cancelled"].includes(job.state)) return this.publicJob(job);
    job.state = "cancelled";
    job.stage = "cancelled";
    job.error = "Assistant request was cancelled.";
    job.updated_at = Date.now();
    job.controller.abort();
    return this.publicJob(job);
  }

  markSoftTimeout(id, userId) {
    const job = this.jobs.get(id);
    if (!job || job.user_id !== String(userId)) return null;
    job.frontend_soft_timeout_at = Date.now();
    job.details = sanitizeDetails({ ...job.details, frontend_soft_timeout: true });
    job.updated_at = Date.now();
    return this.publicJob(job);
  }

  diagnostics(limit = 25) {
    this.prune();
    return [...this.jobs.values()]
      .sort((left, right) => right.created_at - left.created_at)
      .slice(0, limit)
      .map((job) => ({ ...this.publicJob(job), user_id: job.user_id }));
  }

  publicJob(job) {
    return {
      id: job.id,
      state: job.state,
      stage: job.stage,
      created_at: job.created_at,
      updated_at: job.updated_at,
      elapsed_ms: Math.max(0, (["complete", "error", "cancelled"].includes(job.state) ? job.updated_at : Date.now()) - job.created_at),
      still_running: ["queued", "running"].includes(job.state),
      frontend_soft_timeout_at: job.frontend_soft_timeout_at,
      details: job.details || {},
      result: job.state === "complete" ? job.result : null,
      error: ["error", "cancelled"].includes(job.state) ? job.error : null,
      retry_after_seconds: job.retry_after_seconds
    };
  }

  prune(now = Date.now()) {
    for (const [id, job] of this.jobs) {
      if (
        ["complete", "error", "cancelled"].includes(job.state) &&
        now - job.updated_at > this.ttlMs
      ) this.jobs.delete(id);
    }
    if (this.jobs.size <= this.maxJobs) return;
    const oldest = [...this.jobs.values()]
      .filter((job) => ["complete", "error", "cancelled"].includes(job.state))
      .sort((left, right) => left.updated_at - right.updated_at)
      .slice(0, this.jobs.size - this.maxJobs);
    for (const job of oldest) this.jobs.delete(job.id);
  }
}

function sanitizeDetails(details) {
  const output = {};
  for (const key of [
    "queue_position", "gate_ms", "queue_ms", "prompt_eval_ms", "generation_ms", "total_ms",
    "prompt_tokens", "generated_tokens", "prompt_tps", "generation_tps", "gpu_layers",
    "context_size", "batch_size", "ubatch_size", "threads", "max_output_tokens",
    "max_output_tokens_used"
  ]) {
    if (Number.isFinite(Number(details[key]))) output[key] = Number(details[key]);
  }
  for (const key of ["route", "route_class", "reason_code", "backend", "error_code"]) {
    if (details[key] != null) output[key] = String(details[key]).slice(0, 120);
  }
  if (details.frontend_soft_timeout != null) output.frontend_soft_timeout = Boolean(details.frontend_soft_timeout);
  return output;
}

module.exports = { AssistantRequestJobs };