/**
 * tools/observer-self-assessment-api.mjs
 *
 * Phase 3 deferred follow-up #5: real LLM self-assessment API call.
 *
 * Exports:
 *   buildSelfAssessmentPrompt({ prompt, recommendedNode, actualNode, chainExecuted })
 *   callSelfAssessmentApi({ prompt, recommendedNode, actualNode, chainExecuted,
 *                           apiKey, baseUrl, model, fetchImpl, timeoutMs, abortSignal })
 *   readRuntimeFlag(name, { homedir, fsImpl })
 *
 * All functions are pure / fail-quiet — they never throw in production.
 * callSelfAssessmentApi always returns string | null (null = skip self-assessment).
 */

import { join } from 'path';
import { existsSync, readFileSync } from 'fs';
import { homedir as osHomedir } from 'os';

// ---------------------------------------------------------------------------
// Prompt builder (pure)
// ---------------------------------------------------------------------------

/**
 * Build the self-assessment prompt for Sonnet.
 *
 * System: Russian instruction asking Claude to evaluate its own routing choice
 * and return a JSON object with 4 fields.
 *
 * User: interpolates the 4 context fields.
 *
 * @param {object} opts
 * @param {string|null|undefined} opts.prompt             — the user's original prompt text
 * @param {string|null|undefined} opts.recommendedNode    — node recommended by router
 * @param {string|null|undefined} opts.actualNode         — node actually chosen / 'direct'
 * @param {string[]|null|undefined} opts.chainExecuted    — list of chain steps executed
 * @returns {{ system: string, user: string }}
 */
export function buildSelfAssessmentPrompt({ prompt, recommendedNode, actualNode, chainExecuted } = {}) {
  const safePrompt = prompt ?? '';
  const safeRecommended = recommendedNode ?? 'не определён';
  const safeActual = actualNode ?? 'direct';
  const safeChain = Array.isArray(chainExecuted) && chainExecuted.length > 0
    ? chainExecuted.join(' → ')
    : '[]';

  const system = [
    'Ты — внутренний наблюдатель роутинговой системы Claude Code.',
    'Твоя задача — честно оценить качество роутингового решения, принятого в этой сессии.',
    'Отвечай ТОЛЬКО валидным JSON-объектом без markdown-обёрток, ровно 4 поля:',
    '  "summary": строка — краткое описание принятого решения (до 120 символов)',
    '  "confidence_in_choice": число от 0.0 до 1.0 — насколько оптимальным был выбор',
    '  "what_could_be_better": строка или null — что можно было сделать иначе',
    '  "lesson_learned": строка или null — чему учит этот эпизод для будущих сессий',
    'Не добавляй лишних полей. Не используй markdown. Только JSON.',
  ].join('\n');

  const user = [
    'Контекст роутингового решения:',
    '',
    `Запрос пользователя: ${safePrompt || '(пусто)'}`,
    `Рекомендованный узел роутером: ${safeRecommended}`,
    `Фактически выбранный узел: ${safeActual}`,
    `Выполненная цепочка: ${safeChain}`,
    '',
    'Оцени это решение. Верни JSON с 4 полями.',
  ].join('\n');

  return { system, user };
}

// ---------------------------------------------------------------------------
// Runtime flag reader
// ---------------------------------------------------------------------------

/**
 * Read a runtime flag from ~/.claude/runtime/<name>.json.
 * Returns the "value" field from the file, or 'off' on any error.
 *
 * @param {string} name — flag file basename without .json
 * @param {object} opts
 * @param {string} [opts.homedir] — override home dir (for tests)
 * @param {{ existsSync: Function, readFileSync: Function }} [opts.fsImpl] — override fs (for tests)
 * @returns {string}
 */
export function readRuntimeFlag(name, { homedir, fsImpl } = {}) {
  const home = homedir ?? osHomedir();
  const fs = fsImpl ?? { existsSync, readFileSync };

  try {
    const filePath = join(home, '.claude', 'runtime', `${name}.json`);
    if (!fs.existsSync(filePath)) return 'off';
    const raw = fs.readFileSync(filePath, 'utf-8');
    const parsed = JSON.parse(raw);
    // Runtime flag files use `mode` (canonical, see all ~/.claude/runtime/*-mode.json);
    // `value` retained as legacy alias to keep existing test fixtures working.
    const val = parsed.mode ?? parsed.value;
    if (typeof val !== 'string') return 'off';
    return val;
  } catch {
    return 'off';
  }
}

// ---------------------------------------------------------------------------
// API caller (async, fail-quiet)
// ---------------------------------------------------------------------------

const DEFAULT_BASE_URL = 'https://api.proxyapi.ru/anthropic';
const DEFAULT_MODEL = 'claude-sonnet-4-6';
// A2 (2026-05-26): raised 10000 → 30000. On Windows, first ProxyAPI fetch
// triggers TLS handshake которое часто занимает 20+ секунд; 10с убивал каждый
// первый вызов → 85% no_self_assessment в brain-retro #6. Stop-hook outer
// timeout в .claude/settings.json поднят до 60с параллельно.
// brain-retro #7 C3 (2026-05-27): bumped 30s → 50s. Self_assessment coverage
// fell to 22% (18/23 episodes self_assessment_pending) because Windows TLS
// handshake (20-25s first call, see memory feedback_windows_tls_handshake.md)
// + Sonnet latency (3-10s) routinely exceeded the 30s budget. Stop-hook has
// a 60s budget; self-assessment can safely use 50s within it.
// Exported for tests + observability.
export const DEFAULT_TIMEOUT_MS = 50000;
const MAX_TOKENS = 512;

/**
 * Call the Anthropic /v1/messages endpoint with the self-assessment prompt.
 * Returns the text content from the first content block, or null on any failure.
 *
 * Fail-quiet contract: any error (missing key, network error, non-2xx, JSON
 * parse error, timeout) → return null. Never throws.
 *
 * @param {object} opts
 * @param {string|null|undefined} opts.prompt
 * @param {string|null|undefined} opts.recommendedNode
 * @param {string|null|undefined} opts.actualNode
 * @param {string[]|null|undefined} opts.chainExecuted
 * @param {string|null|undefined} opts.apiKey         — ROUTER_LLM_KEY value
 * @param {string} [opts.baseUrl]                     — API base URL
 * @param {string} [opts.model]                       — model alias
 * @param {Function} [opts.fetchImpl]                 — override fetch (for tests)
 * @param {number} [opts.timeoutMs]                   — abort timeout in ms
 * @param {AbortSignal} [opts.abortSignal]            — external abort signal
 * @returns {Promise<string|null>}
 */
export async function callSelfAssessmentApi({
  prompt,
  recommendedNode,
  actualNode,
  chainExecuted,
  apiKey,
  // Смена оператора 2026-06-12: env-переключатель в дефолте (зеркало callAnthropicAPI).
  baseUrl = process.env.ROUTER_LLM_BASE_URL || DEFAULT_BASE_URL,
  model = DEFAULT_MODEL,
  fetchImpl,
  timeoutMs = DEFAULT_TIMEOUT_MS,
  abortSignal,
} = {}) {
  // Guard: no key → skip silently
  if (!apiKey) return null;

  const fetchFn = fetchImpl ?? globalThis.fetch;

  const { system, user } = buildSelfAssessmentPrompt({ prompt, recommendedNode, actualNode, chainExecuted });

  const url = `${baseUrl}/v1/messages`;
  const body = JSON.stringify({
    model,
    max_tokens: MAX_TOKENS,
    system,
    messages: [{ role: 'user', content: user }],
  });

  // Build abort signal — wire to caller's signal if provided
  let timeoutId;
  let controller;
  let signal = abortSignal;

  if (!signal) {
    controller = new AbortController();
    signal = controller.signal;
  }

  // Build a timeout promise that resolves to null after timeoutMs.
  // We always race the fetch against the timeout so that even when the
  // fetchImpl ignores the AbortSignal (e.g. in tests) the timeout still wins.
  const timeoutPromise = new Promise((resolve) => {
    timeoutId = setTimeout(() => resolve(null), timeoutMs);
    if (controller) {
      // Also abort the controller so real fetch() implementations cancel early.
      setTimeout(() => controller.abort(), timeoutMs);
    }
  });

  try {
    const fetchPromise = fetchFn(url, {
      method: 'POST',
      headers: {
        'content-type': 'application/json',
        'x-api-key': apiKey,
        'authorization': `Bearer ${apiKey}`,
        'anthropic-version': '2023-06-01',
      },
      body,
      signal,
    }).then(async (response) => {
      if (!response.ok) return null;
      const data = await response.json();
      const text = data?.content?.[0]?.text;
      if (typeof text !== 'string') return null;
      return text;
    }).catch(() => null);

    // Race: first settlement wins.
    const result = await Promise.race([fetchPromise, timeoutPromise]);
    return result ?? null;
  } catch {
    // Unexpected outer error → fail-quiet
    return null;
  } finally {
    if (timeoutId !== undefined) clearTimeout(timeoutId);
  }
}