import crypto from 'node:crypto';

function newId() {
  return crypto.randomUUID();
}

function nowMs() {
  return Date.now();
}

function slugEntityName(name) {
  return String(name).trim().slice(0, 128);
}

const MIN_TERM_COUNT = Number(process.env.UMS_CANDIDATE_MIN_TERM_COUNT ?? 3);

function isProjectLikeTerm(term) {
  if (/^[A-Z][a-zA-Z0-9]+$/.test(term)) return true;
  if (/meinput|memind|input|agent|rime|fcitx|tkmind|goosed|pgvector/i.test(term)) return true;
  return term.includes('Input') || term.includes('Mind');
}

/**
 * V0.1：从 term_frequency signals 推断 project/focus candidates
 * @param {import('mysql2/promise').Pool} pool
 * @param {string} userId
 */
export async function mergeCandidatesFromSignals(pool, userId) {
  const [rows] = await pool.query(
    `SELECT signal_id, dimension_key, value_json, evidence_ids, window_end
     FROM um_signals
     WHERE user_id = ? AND signal_type = 'term_frequency'
     ORDER BY window_end DESC
     LIMIT 500`,
    [userId],
  );

  const termCounts = new Map();
  for (const row of rows) {
    const term = row.dimension_key.replace(/^term:/, '');
    const value = typeof row.value_json === 'string' ? JSON.parse(row.value_json) : row.value_json;
    const evidenceIds =
      typeof row.evidence_ids === 'string' ? JSON.parse(row.evidence_ids) : row.evidence_ids;
    const prev = termCounts.get(term) ?? { count: 0, signal_ids: [], evidence_ids: [] };
    prev.count += Number(value.count ?? 0);
    prev.signal_ids.push(row.signal_id);
    prev.evidence_ids.push(...(evidenceIds ?? []));
    termCounts.set(term, prev);
  }

  let touched = 0;
  const ts = nowMs();
  for (const [term, stats] of termCounts) {
    if (stats.count < MIN_TERM_COUNT) continue;
    if (term.length < 2) continue;

    const isProjectLike = isProjectLikeTerm(term);
    const candidateType = isProjectLike ? 'project' : 'focus';
    const confidence = Math.min(0.99, 0.4 + stats.count * 0.05);
    const promotionScore = Math.min(0.99, 0.3 + stats.count * 0.1);
    const hypothesis = isProjectLike
      ? { type: 'project', name: term, status: 'active' }
      : { type: 'focus', topic: term };

    const [existing] = await pool.query(
      isProjectLike
        ? `SELECT candidate_id FROM um_candidates
           WHERE user_id = ? AND candidate_type = 'project'
             AND JSON_UNQUOTE(JSON_EXTRACT(hypothesis_json, '$.name')) = ?
           LIMIT 1`
        : `SELECT candidate_id FROM um_candidates
           WHERE user_id = ? AND candidate_type = 'focus'
             AND JSON_UNQUOTE(JSON_EXTRACT(hypothesis_json, '$.topic')) = ?
           LIMIT 1`,
      [userId, term],
    );

    const status = promotionScore >= 0.8 ? 'accepted' : promotionScore >= 0.55 ? 'open' : 'observed';
    const uniqueEvidence = [...new Set(stats.evidence_ids)].slice(0, 200);

    if (existing[0]) {
      await pool.query(
        `UPDATE um_candidates
         SET promotion_score = ?, confidence = ?, status = ?, signal_ids = ?, evidence_ids = ?,
             last_seen_at = NOW(3), updated_at = ?, version = version + 1
         WHERE candidate_id = ?`,
        [
          promotionScore,
          confidence,
          status,
          JSON.stringify(stats.signal_ids),
          JSON.stringify(uniqueEvidence),
          ts,
          existing[0].candidate_id,
        ],
      );
    } else {
      await pool.query(
        `INSERT INTO um_candidates
         (candidate_id, user_id, candidate_type, hypothesis_json, status, promotion_score, confidence,
          signal_ids, evidence_ids, first_seen_at, last_seen_at, version, created_at, updated_at)
         VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, NOW(3), NOW(3), 1, ?, ?)`,
        [
          newId(),
          userId,
          candidateType,
          JSON.stringify(hypothesis),
          status,
          promotionScore,
          confidence,
          JSON.stringify(stats.signal_ids),
          JSON.stringify(uniqueEvidence),
          ts,
          ts,
        ],
      );
    }
    touched += 1;

    if (status === 'accepted' && isProjectLike) {
      await upsertProjectGraph(pool, userId, term, confidence, uniqueEvidence, promotionScore);
    }
  }
  return touched;
}

async function upsertProjectGraph(pool, userId, name, confidence, evidenceIds, weight) {
  const ts = nowMs();
  const canonical = slugEntityName(name);
  const [entities] = await pool.query(
    `SELECT entity_id FROM um_entities WHERE user_id = ? AND entity_type = 'project' AND canonical_name = ? LIMIT 1`,
    [userId, canonical],
  );
  let entityId = entities[0]?.entity_id;
  if (!entityId) {
    entityId = newId();
    await pool.query(
      `INSERT INTO um_entities (entity_id, user_id, entity_type, canonical_name, status, created_at, updated_at)
       VALUES (?, ?, 'project', ?, 'active', ?, ?)`,
      [entityId, userId, canonical, ts, ts],
    );
  }

  const valueJson = { name: canonical, status: 'active' };
  const contentHash = crypto.createHash('sha256').update(JSON.stringify(valueJson)).digest('hex');
  const [attrs] = await pool.query(
    `SELECT attribute_id FROM um_attributes
     WHERE user_id = ? AND entity_id = ? AND attr_key = 'project.status' AND status = 'active'
     LIMIT 1`,
    [userId, entityId],
  );
  if (attrs[0]) {
    await pool.query(
      `UPDATE um_attributes SET confidence = ?, effective_weight = ?, evidence_ids = ?, last_seen_at = NOW(3)
       WHERE attribute_id = ?`,
      [confidence, weight, JSON.stringify(evidenceIds.slice(0, 50)), attrs[0].attribute_id],
    );
  } else {
    await pool.query(
      `INSERT INTO um_attributes
       (attribute_id, user_id, entity_id, attr_key, value_json, confidence, decay_halflife_days,
        effective_weight, evidence_ids, first_seen_at, last_seen_at, status, version, content_hash)
       VALUES (?, ?, ?, 'project.status', ?, ?, 90, ?, ?, NOW(3), NOW(3), 'active', 1, ?)`,
      [
        newId(),
        userId,
        entityId,
        JSON.stringify(valueJson),
        confidence,
        weight,
        JSON.stringify(evidenceIds.slice(0, 50)),
        contentHash,
      ],
    );
  }
}

export { isProjectLikeTerm, MIN_TERM_COUNT };