// Shared structured log for the goodies package (~/.pi/agent/goodies.log).
//
// Why not console: pi's TUI owns the terminal and, in interactive mode,
// intercepts neither stdout nor stderr — anything an extension prints lands
// raw on the current frame and is wiped by the next repaint. That reads as
// an error message flashing too fast to read or screenshot, and it leaves no
// trace anywhere. So everything durable goes here instead: JSONL, one event
// per line, filterable with jq (`select(.type == "summary_request")`), and
// console output is reserved for headless modes, where there is no TUI to
// corrupt.

import { appendFileSync, renameSync, statSync } from "node:fs";
import { homedir } from "node:os";
import { join } from "node:path";

export const GOODIES_LOG_DEFAULT_PATH = join(
  homedir(),
  ".pi",
  "agent",
  "goodies.log",
);

const MAX_BYTES = 256 * 1024;

let logPath = GOODIES_LOG_DEFAULT_PATH;

/** Redirect the log (tests point this at scratch storage). */
export function setGoodiesLogPathForTesting(path?: string): void {
  logPath = path ?? GOODIES_LOG_DEFAULT_PATH;
}

/** Append one event as a timestamped JSONL line; never throws. */
export function logGoodiesEvent(event: Record<string, unknown>): void {
  const stamped = { ts: new Date().toISOString(), pid: process.pid, ...event };
  let line: string;
  try {
    line = JSON.stringify(stamped);
  } catch {
    // Non-serializable payload — degrade to a marker instead of throwing.
    line = JSON.stringify({
      ts: stamped.ts,
      pid: process.pid,
      type: "unserializable",
    });
  }
  try {
    if (statSync(logPath).size > MAX_BYTES) {
      // Size cap without timers or rotation daemons: rotate by rename —
      // atomic on POSIX, so a crash mid-rotation can't truncate the log and
      // lines appended between the size check and the rename land in the
      // .old file instead of being destroyed by a read-then-overwrite. The
      // single .old slot is replaced on each rotation; the append below
      // recreates the live file.
      renameSync(logPath, `${logPath}.old`);
    }
  } catch {
    // Missing/unreadable file — the append below (re)creates it.
  }
  try {
    appendFileSync(logPath, `${line}\n`);
  } catch {
    // Unwritable destination — nothing else to do.
  }
}

/**
 * Report a failure durably: appended to the goodies log always, printed to
 * stderr only when headless (stdout is not a TTY). In TUI mode console
 * output is the unreadable flash described above; the file is the record.
 */
export function reportFailure(type: string, message: string): void {
  logGoodiesEvent({ type, message });
  if (!process.stdout.isTTY) {
    console.error(message);
  }
}