import { appendFileSync, mkdirSync } from "node:fs";
import { dirname, join } from "node:path";
import type { ModelCost } from "@earendil-works/pi-ai";
import type { ProbeOutcome } from "./types.ts";

type WarmLogValue =
  | string
  | number
  | boolean
  | null
  | undefined
  | ModelCost
  | WarmLogValue[]
  | { [key: string]: WarmLogValue };

export type WarmLogEvent = {
  ts: string;
  sessionId?: string;
  event: string;
  source?: "real_turn" | "warm_probe" | "system";
  probeOutcome?: ProbeOutcome;
  detail?: string;
  ok?: boolean;
  reason?: string;
  [key: string]: WarmLogValue;
};

/**
 * Append one JSONL diagnostic line.
 * Never write to stdout/stderr from timer paths - that can corrupt pi-tui frames.
 */
export function appendWarmLog(cwd: string | null | undefined, event: WarmLogEvent): string | null {
  try {
    const root = cwd && cwd.length > 0 ? cwd : process.cwd();
    const filePath = join(root, ".pi", "warm-cache.jsonl");
    mkdirSync(dirname(filePath), { recursive: true });
    appendFileSync(filePath, `${JSON.stringify(event)}\n`, "utf8");
    return filePath;
  } catch {
    return null;
  }
}

export function warmLogPath(cwd: string | null | undefined): string {
  const root = cwd && cwd.length > 0 ? cwd : process.cwd();
  return join(root, ".pi", "warm-cache.jsonl");
}