/**
 * Query-side embedding for the historical intelligence memory (#5694).
 *
 * Split out of intel-history-client.ts: turning free text into a vector is a
 * different upstream (a paid embeddings provider), a different failure mode,
 * and a different budget than reading the Convex store — and it is the half
 * that grows when the embedding model is versioned (#5742).
 *
 * EDGE-RUNTIME CONSTRAINT — the embedding call is reimplemented here rather
 * than reusing `embedBatch` from scripts/lib/brief-embedding.mjs. That module
 * imports `node:crypto` for its cache keys, and the intelligence gateway
 * (api/intelligence/v1/[rpc].ts) runs on the Vercel Edge runtime, which
 * rejects node: built-ins at runtime. Only the pure, dependency-free modules
 * are imported: the tunables that must not drift from the seed writer's, and
 * the outlet-suffix stripper that is half the normalization contract. The
 * other half (`normalizeQueryText`) is re-derived, and
 * tests/intel-history-endpoints.test.mts asserts it against the real
 * `normalizeForEmbedding` so the copy cannot drift silently.
 */

import {
  EMBED_DIMS,
  EMBED_MODEL,
  OPENROUTER_EMBEDDINGS_URL,
} from '../../scripts/lib/brief-dedup-consts.mjs';
import { stripSourceSuffix } from '../../scripts/lib/brief-dedup-jaccard.mjs';
import { getCachedJson, setCachedJson } from './redis';
// @ts-expect-error — JS module, no declaration file
import { captureSilentError } from '../../api/_sentry-edge.js';

/**
 * One embeddings call on a user-facing read path. Shorter than the seed
 * writer's 45s batch budget: this is a single input on an interactive
 * request, and a slow provider should degrade to `upstream_unavailable`
 * well inside the edge function's own limit.
 */
const EMBED_TIMEOUT_MS = 4_000;

/**
 * Query-vector cache. Every miss spends one paid OpenRouter call on an
 * interactive request, and repeat traffic here is real: agents re-issue the
 * same MCP query, and dashboard phrases repeat verbatim.
 *
 * The seed writer's 14-day TTL is sized for a corpus that never changes once
 * written; a query vector only has to outlive a burst of repeats, so hours
 * are enough and a shorter window bounds how long a model change could serve
 * mismatched vectors. The key carries the model and dimension for that
 * reason — a model swap lands on a cold namespace instead of silently mixing
 * vector spaces.
 *
 * The query itself is HASHED into the key, never embedded verbatim. What
 * users search for is their business: a raw-text key would expose every
 * analyst's query to anything that can list Redis keys (dashboards, key
 * dumps, support tooling) and would let an unbounded input become an
 * unbounded key.
 */
const EMBED_CACHE_TTL_SECONDS = 6 * 60 * 60;
const EMBED_CACHE_PREFIX = `intel-history:embed:v1:${EMBED_MODEL}:${EMBED_DIMS}:`;

/**
 * SHA-256 via Web Crypto — available on the Edge runtime, unlike the
 * node:crypto hashing the seed-side cache uses.
 */
async function hashCacheInput(input: string): Promise<string> {
  const digest = await crypto.subtle.digest('SHA-256', new TextEncoder().encode(input));
  return Array.from(new Uint8Array(digest))
    .map((b) => b.toString(16).padStart(2, '0'))
    .join('');
}

let _didWarnMissingOpenRouterKey = false;

/**
 * The query-side half of the normalization contract shared with
 * scripts/lib/brief-embedding.mjs:normalizeForEmbedding. The seed writer
 * embeds normalized text; a query normalized any differently ranks against a
 * subtly different vector space and degrades recall with nothing to point at.
 *
 * Kept byte-equivalent to that function — outlet-suffix strip (imported, so
 * the outlet list stays single-sourced), trim, whitespace collapse, lowercase.
 */
export function normalizeQueryText(text: string): string {
  if (typeof text !== 'string') return '';
  return stripSourceSuffix(text).trim().replace(/\s+/g, ' ').toLowerCase();
}

/**
 * A vector is only usable at exactly the index's dimension, all components
 * finite. Applied to cache hits as well as provider responses: a stale or
 * corrupt entry must be re-embedded, never forwarded — Convex would reject
 * it and the caller would report an outage that isn't one.
 */
function isUsableVector(value: unknown): value is number[] {
  return (
    Array.isArray(value) &&
    value.length === EMBED_DIMS &&
    value.every((n) => typeof n === 'number' && Number.isFinite(n))
  );
}

/**
 * Embed one free-text query with the model and dimensions the stored vectors
 * were produced under. Returns null on any failure — missing key, provider
 * error, timeout, or a vector the store would reject anyway.
 *
 * A wrong-dimension or non-finite vector is treated as failure rather than
 * passed through: convex/intelHistory.ts would reject it, and a silently
 * substituted vector would return arbitrary rows presented as real matches.
 *
 * Results are cached on the normalized query text, so a repeated query costs
 * a Redis read instead of a paid provider call. Cache failures are never
 * fatal: a miss or a write error just means the provider is asked again.
 */
export async function embedQueryText(text: string): Promise<number[] | null> {
  const apiKey = process.env.OPENROUTER_API_KEY ?? '';
  if (!apiKey) {
    if (!_didWarnMissingOpenRouterKey) {
      _didWarnMissingOpenRouterKey = true;
      console.warn('[intel-history] OPENROUTER_API_KEY not set; semantic history search disabled');
    }
    return null;
  }

  const input = normalizeQueryText(text);
  if (!input) return null;

  const cacheKey = `${EMBED_CACHE_PREFIX}${await hashCacheInput(input)}`;
  const cached = await getCachedJson(cacheKey);
  if (isUsableVector(cached)) return cached;

  try {
    const resp = await fetch(OPENROUTER_EMBEDDINGS_URL, {
      method: 'POST',
      headers: {
        Authorization: `Bearer ${apiKey}`,
        'Content-Type': 'application/json',
        'HTTP-Referer': 'https://worldmonitor.app',
        'X-Title': 'World Monitor',
        'User-Agent': 'worldmonitor-gateway/1.0',
      },
      body: JSON.stringify({ model: EMBED_MODEL, input: [input], dimensions: EMBED_DIMS }),
      signal: AbortSignal.timeout(EMBED_TIMEOUT_MS),
    });
    if (!resp.ok) {
      console.warn(`[intel-history] embeddings provider returned HTTP ${resp.status}`);
      return null;
    }
    const body = (await resp.json()) as { data?: Array<{ embedding?: unknown }> };
    const vector = body?.data?.[0]?.embedding;
    if (!Array.isArray(vector) || vector.length !== EMBED_DIMS) {
      console.warn(
        `[intel-history] embeddings provider returned ${
          Array.isArray(vector) ? `${vector.length} dims` : 'no vector'
        }, expected ${EMBED_DIMS}`,
      );
      return null;
    }
    if (!vector.every((n) => typeof n === 'number' && Number.isFinite(n))) {
      console.warn('[intel-history] embeddings provider returned a non-finite component');
      return null;
    }
    await setCachedJson(cacheKey, vector, EMBED_CACHE_TTL_SECONDS);
    return vector as number[];
  } catch (err) {
    // Degrades to upstreamUnavailable rather than a 5xx, so the caller sees a
    // 200 with no records — report it, or a provider outage is indistinguishable
    // from an empty history in every dashboard we have.
    const msg = err instanceof Error ? err.message : String(err);
    console.warn(`[intel-history] embeddings call failed: ${msg}`);
    captureSilentError(err, {
      tags: { surface: 'server', component: 'intel-history', stage: 'embed' },
      fingerprint: ['intel-history', 'embed-error'],
    });
    return null;
  }
}