/**
 * Auto-naming via `pi -p` (S-09a).
 *
 * After a configurable number of user messages, spawn a cheap `pi -p` call
 * to generate a short session name from the conversation context.
 * The result is stored as the tmux session's @description.
 *
 * Gated by [autoname] enabled in config.toml (T-1.7 wires the config;
 * until then defaults are used).
 *
 * Owner: T-1.4
 */

import { execFile } from "node:child_process";
import { promisify } from "node:util";
import { setDescription } from "../tmux/manager.js";

const execFileAsync = promisify(execFile);

export interface AutonameConfig {
  enabled: boolean;
  triggerAfter: number; // number of user messages before naming
  model: string; // e.g. "claude-haiku-4-5"
}

export const DEFAULT_AUTONAME_CONFIG: AutonameConfig = {
  enabled: true,
  triggerAfter: 3,
  model: "claude-haiku-4-5",
};

/**
 * Attempt to auto-name a session using `pi -p`.
 * If pi is not on PATH or the call fails, silently no-ops.
 *
 * @param sessionId   tmux session name to set @description on
 * @param context     recent conversation context (short excerpt)
 * @param cfg         autoname configuration
 */
export async function autoname(
  sessionId: string,
  context: string,
  cfg: AutonameConfig = DEFAULT_AUTONAME_CONFIG,
): Promise<void> {
  if (!cfg.enabled) return;

  const prompt = `Give a 2-4 word title for this conversation. Reply with only the title, no punctuation.\n\n${context.slice(0, 800)}`;

  try {
    const { stdout } = await execFileAsync(
      "pi",
      [
        "-p",
        "--model",
        cfg.model,
        "--no-session",
        "--no-tools",
        "--no-extensions",
        "--no-skills",
        "--offline",
        prompt,
      ],
      { timeout: 15_000 },
    );

    const name = stdout.trim().slice(0, 60); // cap at 60 chars
    if (name) {
      await setDescription(sessionId, name);
    }
  } catch {
    // Autoname failures are non-fatal
  }
}