// detection-schedule.mjs — Spor C / C1: opt-in session-anchored detection.
//
// The DETECTION layer (poll → report → discover → detect-skill-lifecycle) is
// pure node: it polls Microsoft Learn sitemaps and writes JSON reports, and
// NEVER contacts Anthropic/Claude. It is therefore OUTSIDE the ToS surface —
// Consumer Terms §3.7 restricts automated access to "our Services" (Anthropic),
// not running local scripts. The APPLY layer (which invokes Claude) stays
// manual, in-session, and gated. This module is the pure decision core for the
// SessionStart hook + the run-detection.mjs executor.
//
// parseScheduleConfig is pure (text in, config out). loadScheduleConfig resolves
// paths via lib/user-data.mjs (which itself depends only on node:os/path), so
// the user-owned config dir is the single source of truth shared with the hook.

import { readFileSync, existsSync } from 'node:fs';
import { join } from 'node:path';
import { homedir } from 'node:os';
import { resolveConfigPath, CONFIG_FILENAME } from './user-data.mjs';

// Opt-in: detection is OFF until the user sets enabled:true. "Frivillig å sette
// opp — men gjøres det, skal det virke." (operator 2026-06-20)
export const DEFAULT_SCHEDULE_CONFIG = Object.freeze({
  enabled: false,
  interval_days: 7,
  include_skill_lifecycle: true,
  // C3.4: opt-in inside opt-in. Course detection (Learn Platform API) needs Entra
  // Keychain creds almost nobody has, so default false — a default-true would
  // give every user a red/"skipped" step. (spec §5, §8 d)
  include_course_detection: false,
  // Tier 2 (launchd) cadence. 'daily' = poll on every (daily) fire; 'interval'
  // = throttle to interval_days via the same staleness gate Tier 1 uses. Read
  // ONLY by the Tier-2 entrypoint (scheduler.mjs run); the Tier-1 hook ignores
  // it, so existing behavior is unchanged. Operator default: daily.
  os_scheduler_cadence: 'daily',
});

// The ordered, Claude-FREE detection pipeline. Every step is a local node
// script that produces a JSON report; none invoke Claude. run-detection.mjs
// resolves each as `node <pluginRoot>/scripts/<dir>/<script> <args>`.
export const DETECTION_STEPS = Object.freeze([
  { name: 'poll-sitemaps', dir: 'kb-update', script: 'poll-sitemaps.mjs', args: ['--force'] },
  { name: 'report-changes', dir: 'kb-update', script: 'report-changes.mjs', args: [] },
  { name: 'discover-new-urls', dir: 'kb-update', script: 'discover-new-urls.mjs', args: ['--limit', '500'] },
  { name: 'detect-skill-lifecycle', dir: 'kb-eval', script: 'detect-skill-lifecycle.mjs', args: ['--write'], skillLifecycle: true },
  // C3.4: parallel spore on the Learn Platform API. Still pure node (reads the
  // Keychain, hits the API, writes its own report/registry — never Claude),
  // gated behind include_course_detection (default OFF). (spec §5)
  { name: 'detect-courses', dir: 'kb-update', script: 'detect-courses.mjs', args: [], courseDetection: true },
]);

/**
 * Apply the opt-in content gates to the detection pipeline. Pure: each flagged
 * step (skillLifecycle / courseDetection) survives only when its config flag is
 * on; unflagged steps always run. run-detection.mjs applies exactly this — a
 * single source of truth for "which steps run", unit-tested independently of the
 * subprocess executor.
 * @param {{include_skill_lifecycle?: boolean, include_course_detection?: boolean}} config
 * @param {ReadonlyArray<object>} [steps]
 * @returns {object[]}
 */
export function selectDetectionSteps(config = {}, steps = DETECTION_STEPS) {
  return steps.filter(
    (s) =>
      (!s.skillLifecycle || config.include_skill_lifecycle) &&
      (!s.courseDetection || config.include_course_detection),
  );
}

/** Coerce a YAML-ish scalar to bool/number/string. Unknown booleans => false. */
function coerce(key, raw) {
  const v = raw.trim();
  if (key === 'enabled' || key === 'include_skill_lifecycle' || key === 'include_course_detection') {
    if (v === 'true') return true;
    if (v === 'false') return false;
    return undefined; // non-boolean => caller keeps default (or OFF for enabled)
  }
  if (key === 'interval_days') {
    const n = Number.parseInt(v, 10);
    return Number.isFinite(n) && n > 0 ? n : undefined;
  }
  if (key === 'os_scheduler_cadence') {
    // Only 'interval' opts out of daily; any other/garbage value => default daily.
    return v === 'interval' ? 'interval' : 'daily';
  }
  return undefined;
}

/**
 * Parse the `scheduled_detection:` block out of a config file's text. Pure;
 * tolerant: any parse failure or missing block yields the OFF default. Reads a
 * minimal indented key: value sub-block (no YAML dependency — the format is
 * documented + controlled).
 * @param {string} text
 * @returns {{enabled: boolean, interval_days: number, include_skill_lifecycle: boolean}}
 */
export function parseScheduleConfig(text) {
  const cfg = { ...DEFAULT_SCHEDULE_CONFIG };
  if (typeof text !== 'string' || !text.includes('scheduled_detection:')) return cfg;
  const lines = text.split('\n');
  let inBlock = false;
  for (const line of lines) {
    if (/^\s*scheduled_detection:\s*$/.test(line)) { inBlock = true; continue; }
    if (!inBlock) continue;
    // Block ends at the first non-indented, non-blank line (e.g. `---` or next key).
    if (line.trim() === '') continue;
    if (!/^\s+\S/.test(line)) break;
    const m = line.match(/^\s+([A-Za-z_]+):\s*(.*)$/);
    if (!m) continue;
    const [, key, raw] = m;
    if (!(key in DEFAULT_SCHEDULE_CONFIG)) continue;
    const val = coerce(key, raw);
    if (val !== undefined) cfg[key] = val;
  }
  return cfg;
}

/**
 * Serialize a schedule config to a full config-file text: a `---`-fenced
 * frontmatter with the `scheduled_detection:` block (all four known keys) plus a
 * short human header. The inverse of parseScheduleConfig — C2.3's onboarding
 * write-path uses THIS (no second format definition): values are normalized
 * exactly as coerce() would read them, so
 *   parseScheduleConfig(serializeScheduleConfig(c))
 * yields a DEFAULT-merged, normalized c (round-trip, acceptance K5). Pure.
 * @param {Partial<typeof DEFAULT_SCHEDULE_CONFIG>} [config]
 * @returns {string}
 */
export function serializeScheduleConfig(config = {}) {
  const c = { ...DEFAULT_SCHEDULE_CONFIG, ...config };
  const interval =
    Number.isInteger(c.interval_days) && c.interval_days > 0
      ? c.interval_days
      : DEFAULT_SCHEDULE_CONFIG.interval_days;
  return [
    '---',
    'scheduled_detection:',
    `  enabled: ${c.enabled === true}`,
    `  interval_days: ${interval}`,
    `  include_skill_lifecycle: ${c.include_skill_lifecycle !== false}`,
    `  include_course_detection: ${c.include_course_detection === true}`,
    `  os_scheduler_cadence: ${c.os_scheduler_cadence === 'interval' ? 'interval' : 'daily'}`,
    '---',
    '',
    '# ms-ai-architect — planlagt deteksjon',
    '',
    'Skrevet av `/architect:onboard`. Styrer den opt-in, Claude-frie deteksjonen',
    '(poll → rapport → discovery → skill-livssyklus). Endre `scheduled_detection`-',
    'blokka over, eller kjør `/architect:onboard` på nytt.',
    '',
  ].join('\n');
}

/**
 * Load the opt-in schedule config. C2.1: the user-owned path
 * (~/.claude/ms-ai-architect/ms-ai-architect.local.md) takes precedence so the
 * config survives a plugin reinstall (acceptance K2); the legacy
 * <pluginRoot>/ms-ai-architect.local.md remains as a backward-compat fallback
 * for setups that already wrote it there. Absent/unreadable => OFF default.
 * @param {string} pluginRoot
 * @param {string} [home]  injectable home dir (defaults to os.homedir())
 * @returns {{enabled: boolean, interval_days: number, include_skill_lifecycle: boolean}}
 */
export function loadScheduleConfig(pluginRoot, home = homedir()) {
  const candidates = [resolveConfigPath(home), join(pluginRoot, CONFIG_FILENAME)];
  for (const path of candidates) {
    if (!existsSync(path)) continue;
    try {
      return parseScheduleConfig(readFileSync(path, 'utf8'));
    } catch {
      return { ...DEFAULT_SCHEDULE_CONFIG };
    }
  }
  return { ...DEFAULT_SCHEDULE_CONFIG };
}

/**
 * Decide whether the SessionStart hook should background-spawn detection. Pure.
 * Opt-in: a disabled config never runs (the default). Enabled + stale (days
 * since last poll >= interval) runs; enabled + fresh does not. force overrides.
 * @param {{enabled: boolean, interval_days: number}} config
 * @param {number} lastPollDaysAgo  Infinity when never polled
 * @param {{force?: boolean}} [opts]
 * @returns {{run: boolean, reason: string}}
 */
export function shouldRunDetection(config, lastPollDaysAgo, opts = {}) {
  if (opts.force) return { run: true, reason: 'force' };
  if (!config || !config.enabled) return { run: false, reason: 'disabled (opt-in off)' };
  const interval = config.interval_days ?? DEFAULT_SCHEDULE_CONFIG.interval_days;
  if (lastPollDaysAgo >= interval) {
    return { run: true, reason: `stale (${Math.floor(lastPollDaysAgo)}d >= ${interval}d)` };
  }
  return { run: false, reason: 'fresh (within interval)' };
}

/**
 * Days since the last sitemap poll, read from a parsed change-report.json.
 * Pure; mirrors the SessionStart hook's computation. Missing/invalid
 * last_poll => Infinity ("infinitely stale" => the 'interval' cadence runs).
 * @param {object|null} report  parsed change-report.json ({ last_poll?: string })
 * @param {number} now  Date.now()
 * @returns {number}
 */
export function daysSinceLastPoll(report, now) {
  const DAY_MS = 24 * 60 * 60 * 1000;
  if (!report || !report.last_poll) return Infinity;
  const t = new Date(report.last_poll).getTime();
  if (!Number.isFinite(t)) return Infinity;
  return (now - t) / DAY_MS;
}

/**
 * Build a compact one-liner summarizing skill-lifecycle signals for the
 * SessionStart hook. Pure; tolerant of partial/missing reports. Returns null
 * when there is nothing worth surfacing.
 * @param {object|null} report  parsed skill-lifecycle-report.json
 * @param {{threshold?: number}} [opts]  K10 overlap threshold (default 7.0)
 * @returns {string|null}
 */
export function summarizeSkillLifecycle(report, opts = {}) {
  if (!report || typeof report !== 'object') return null;
  const threshold = opts.threshold ?? 7.0;
  const overlapFail = (report.overlap?.pairs ?? []).filter((p) => (p?.combined ?? 0) >= threshold).length;
  const gaps = report.coverage?.summary?.gaps ?? (report.coverage?.gaps ?? []).length;
  const thin = report.coverage?.summary?.thin ?? 0;
  const bloat = (report.bloat?.summary?.bloatCandidates ?? []).length;
  const stale = (report.bloat?.summary?.staleCandidates ?? []).length;

  const parts = [];
  if (overlapFail > 0) parts.push(`${overlapFail} overlapp-par`);
  if (gaps > 0) parts.push(`${gaps} gap`);
  if (thin > 0) parts.push(`${thin} tynne`);
  if (bloat > 0) parts.push(`${bloat} bloat`);
  if (stale > 0) parts.push(`${stale} stale`);
  return parts.length ? `Skill-signaler: ${parts.join(', ')}` : null;
}

/**
 * Build a compact one-liner summarizing course-detection leads (Spor C / C3.6)
 * for the SessionStart hook. Pure; tolerant of partial/missing reports. Mirrors
 * summarizeSkillLifecycle. Surfaces only NEW + UPDATED leads in covered
 * products; `removed` is an informational rapport-signal (spec §4.2), never a
 * surfaced lead. Returns null when there is nothing worth surfacing (0 new + 0
 * updated, a skipped/error report, or a malformed shape).
 * @param {object|null} report  parsed course-detection-report.json
 * @returns {string|null}
 */
export function summarizeCourses(report) {
  if (!report || typeof report !== 'object') return null;
  if (report.status && report.status !== 'ok') return null;
  const counts = report.counts ?? {};
  const fresh = Number(counts.new) || 0;
  const changed = Number(counts.updated) || 0;

  const parts = [];
  if (fresh > 0) parts.push(`${fresh} nye`);
  if (changed > 0) parts.push(`${changed} endrede`);
  return parts.length ? `Kurs-signaler: ${parts.join(' / ')} kurs i dekkede produkter` : null;
}

// Default skill-quality target (%). The score cache always carries its own
// `target` (buildScoreCache); this literal is only a defensive fallback for an
// older/partial cache. Mirrors TARGET in scripts/kb-eval/lib/skill-score.mjs —
// kept local so this Claude-free kb-update module never imports the kb-eval lib.
const SKILL_QUALITY_TARGET_DEFAULT = 90;

/**
 * Build a compact one-liner summarizing skill-quality scores (Spor D / Steg C)
 * for the SessionStart hook. Pure; tolerant of partial/missing caches. Mirrors
 * summarizeSkillLifecycle / summarizeCourses.
 *
 * Consumes the CACHED score report (scripts/kb-eval/data/skill-score-report.json,
 * produced by `score-skill.mjs --write`) — it NEVER scores live: buildReport
 * reads ~400 ref-files, far too expensive for a SessionStart hook. That cache is
 * gitignored (derived/regenerable), so it is ABSENT in a fresh clone — this MUST
 * tolerate a missing/malformed cache → null and never crash the hook. In
 * practice the one-liner therefore surfaces only for a maintainer who has run
 * `--write` locally, never for an end-user of a fresh checkout.
 *
 * Surfaces ONLY skills below target. Returns null when every skill meets target,
 * when the cache is missing/non-object, or when it carries no usable skill data.
 * @param {object|null} cache  parsed skill-score-report.json
 *   ({target, scored:[{name, meetsTarget}], below:[name]})
 * @returns {string|null}
 */
export function summarizeSkillQuality(cache) {
  if (!cache || typeof cache !== 'object') return null;
  const target = Number.isFinite(cache.target) ? cache.target : SKILL_QUALITY_TARGET_DEFAULT;
  // Trust the precomputed `below` name-list; fall back to deriving it from
  // `scored` (tolerant of an older/partial shape). Neither present => unusable.
  let below;
  if (Array.isArray(cache.below)) {
    below = cache.below;
  } else if (Array.isArray(cache.scored)) {
    below = cache.scored.filter((s) => s && s.meetsTarget === false).map((s) => s.name);
  } else {
    return null;
  }
  below = below.filter(Boolean);
  if (below.length === 0) return null;
  const noun = below.length === 1 ? 'skill' : 'skills';
  return `Skill-kvalitet: ${below.length} ${noun} < ${target} % (${below.join(', ')})`;
}

/**
 * Build the KB-trust reporting floor one-liner (Spor 3 Port 3, P3b) for the
 * SessionStart hook. Pure; tolerant of partial/missing reports. Mirrors
 * summarizeSkillQuality.
 *
 * Consumes the CACHED verified-staleness-report.json (produced by
 * report-verified-staleness.mjs on the KB-refresh cadence) — it NEVER judges
 * live. That cache is gitignored (derived/regenerable), so it is ABSENT in a
 * fresh clone — this MUST tolerate a missing/malformed report → null and never
 * crash the hook.
 *
 * A REPORTING FLOOR, not a gate (§4c — avoid alarm fatigue on an 84 % signal):
 * surfaces ONLY drift (stale-since-verified) + contract breaches (unverified),
 * the actionable "confirm against source" set. `unmigrated` (the Spor-1 backlog,
 * 306 today) is DELIBERATELY excluded: at that volume it would fire every
 * session and become noise; the migration census belongs to CT5 (P3c).
 *
 * @param {object|null} report  parsed verified-staleness-report.json
 *   ({counts: {stale, unverified, ...}})
 * @returns {string|null}
 */
export function summarizeTrustFreshness(report) {
  if (!report || typeof report !== 'object') return null;
  const counts = report.counts;
  if (!counts || typeof counts !== 'object') return null;
  const stale = Number(counts.stale) || 0;
  const unverified = Number(counts.unverified) || 0;
  if (stale === 0 && unverified === 0) return null;

  const parts = [];
  if (stale > 0) parts.push(`${stale} ${stale === 1 ? 'fil' : 'filer'} driftet siden verifisering`);
  if (unverified > 0) parts.push(`${unverified} uverifisert`);
  return `KB-tillit: ${parts.join(', ')} — bekreft mot kilde (aldri auto-fiks)`;
}