/**
 * rag.js — Wisdom Database v2.0
 *
 * PERUBAHAN DARI v1.0:
 * - Schema wisdom diperluas: domain, confidence, source tracking
 * - topicExists() untuk validasi session dari DB
 * - updateTopicTitle() untuk update title setelah pesan pertama
 * - Deduplication di layer DB (unique constraint)
 * - getWisdomByDomain() untuk inject yang relevan saja
 * - Statistik: hitungWisdom(), getDomainStats()
 */

'use strict';

const Database = require('better-sqlite3');
const path     = require('path');
const crypto   = require('crypto');

const dbPath = path.join(__dirname, 'reasoning_memory.db');
const db     = new Database(dbPath);

// WAL mode untuk concurrent reads lebih baik
db.pragma('journal_mode = WAL');
db.pragma('synchronous = NORMAL');

// ================================================================
// SCHEMA
// ================================================================
db.exec(`
  CREATE TABLE IF NOT EXISTS wisdom (
    id           INTEGER PRIMARY KEY AUTOINCREMENT,
    domain       TEXT    NOT NULL DEFAULT 'general',
    rule         TEXT    NOT NULL,
    source       TEXT    NOT NULL DEFAULT 'auto-extracted',
    confidence   INTEGER NOT NULL DEFAULT 70,
    use_count    INTEGER NOT NULL DEFAULT 0,
    created_at   DATETIME DEFAULT CURRENT_TIMESTAMP,
    last_used_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    UNIQUE(rule)
  );

  -- Legacy table compat (lessons → wisdom alias)
  CREATE TABLE IF NOT EXISTS lessons (
    id             INTEGER PRIMARY KEY AUTOINCREMENT,
    topic          TEXT    NOT NULL,
    reasoning_rule TEXT    NOT NULL,
    source         TEXT    DEFAULT 'auto',
    created_at     DATETIME DEFAULT CURRENT_TIMESTAMP
  );

  CREATE TABLE IF NOT EXISTS chat_topics (
    id         TEXT    PRIMARY KEY,
    title      TEXT    NOT NULL,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
  );

  CREATE TABLE IF NOT EXISTS chat_messages (
    id         INTEGER PRIMARY KEY AUTOINCREMENT,
    topic_id   TEXT    NOT NULL,
    role       TEXT    NOT NULL,
    content    TEXT    NOT NULL,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY(topic_id) REFERENCES chat_topics(id)
  );

  CREATE INDEX IF NOT EXISTS idx_messages_topic ON chat_messages(topic_id);
  CREATE INDEX IF NOT EXISTS idx_wisdom_domain   ON wisdom(domain);
  CREATE INDEX IF NOT EXISTS idx_wisdom_source   ON wisdom(source);
`);

// ================================================================
// PREPARED STATEMENTS
// ================================================================
const stmts = {
  // Wisdom
  insertWisdom: db.prepare(
    'INSERT OR IGNORE INTO wisdom (domain, rule, source, confidence) VALUES (?, ?, ?, ?)'
  ),
  getWisdom: db.prepare(
    'SELECT domain, rule, source, confidence, use_count FROM wisdom ORDER BY confidence DESC, use_count DESC, created_at DESC LIMIT 60'
  ),
  getWisdomByDomain: db.prepare(
    'SELECT domain, rule, source, confidence FROM wisdom WHERE domain LIKE ? ORDER BY confidence DESC LIMIT 10'
  ),
  getWisdomCount: db.prepare('SELECT COUNT(*) as count FROM wisdom'),
  updateUseCount: db.prepare(
    'UPDATE wisdom SET use_count = use_count + 1, last_used_at = CURRENT_TIMESTAMP WHERE id = ?'
  ),
  getDomainStats: db.prepare(
    'SELECT domain, COUNT(*) as count, AVG(confidence) as avg_confidence FROM wisdom GROUP BY domain ORDER BY count DESC'
  ),

  // Legacy lessons (backward compat)
  insertLesson: db.prepare(
    'INSERT INTO lessons (topic, reasoning_rule, source) VALUES (?, ?, ?)'
  ),

  // Topics
  createTopic: db.prepare('INSERT INTO chat_topics (id, title) VALUES (?, ?)'),
  topicExists: db.prepare('SELECT id FROM chat_topics WHERE id = ?'),
  updateTitle:  db.prepare('UPDATE chat_topics SET title = ? WHERE id = ?'),
  getTopics:   db.prepare(
    'SELECT id, title, created_at FROM chat_topics ORDER BY created_at DESC LIMIT 30'
  ),

  // Messages
  insertMessage: db.prepare(
    'INSERT INTO chat_messages (topic_id, role, content) VALUES (?, ?, ?)'
  ),
  getMessages: db.prepare(
    'SELECT role, content, created_at FROM chat_messages WHERE topic_id = ? ORDER BY created_at ASC'
  ),
  countMessages: db.prepare(
    'SELECT COUNT(*) as count FROM chat_messages WHERE topic_id = ?'
  )
};

// ================================================================
// EXPORTS
// ================================================================
module.exports = {

  // ── WISDOM LOOP ──────────────────────────────────────────────

  saveReasoning(topic, rule, source = 'auto') {
    // Simpan ke tabel wisdom baru (dengan dedup)
    const result = stmts.insertWisdom.run(
      topic.toLowerCase().replace(/\s+/g, '_').substring(0, 50),
      rule.trim().substring(0, 400),
      source,
      source === 'manual' ? 90 : 70
    );

    // Backward compat: juga simpan ke lessons
    if (result.changes > 0) {
      try {
        stmts.insertLesson.run(topic, rule, source);
      } catch (_) { /* tidak fatal */ }
      console.log(`[RAG] Wisdom (${source}): ${topic} → ${rule.substring(0, 60)}`);
    }

    return result.changes > 0;
  },

  getAllWisdom() {
    try { return stmts.getWisdom.all(); } catch { return []; }
  },

  getWisdomByDomain(domain) {
    try { return stmts.getWisdomByDomain.all('%' + domain + '%'); } catch { return []; }
  },

  hitungWisdom() {
    try { return stmts.getWisdomCount.get().count; } catch { return 0; }
  },

  getDomainStats() {
    try { return stmts.getDomainStats.all(); } catch { return []; }
  },

  // Inject ke system prompt — prioritas wisdom dengan confidence tinggi
  // dan yang relevan dengan domain (deteksi dari kata kunci)
  injectMemory(contextHint = '') {
    try {
      let rows;

      // Jika ada hint domain, inject yang relevan + general
      if (contextHint) {
        const domain = contextHint.toLowerCase().replace(/[^a-z0-9_/]/g, '_').substring(0, 30);
        const domainRows  = stmts.getWisdomByDomain.all('%' + domain + '%');
        const generalRows = stmts.getWisdom.all();

        // Gabung, deduplicate by rule text, ambil 50 teratas
        const seen = new Set();
        rows = [...domainRows, ...generalRows].filter(r => {
          if (seen.has(r.rule)) return false;
          seen.add(r.rule);
          return true;
        }).slice(0, 50);
      } else {
        rows = stmts.getWisdom.all();
      }

      if (rows.length === 0) return '';

      let ctx = '\n\n[INGATAN TEKNIS — RULES YANG SUDAH TERBUKTI]:\n';
      ctx += '(Gunakan jika relevan. Jangan disebut jika tidak relevan.)\n';
      rows.forEach((row, i) => {
        const conf = row.confidence >= 90 ? '★' : row.confidence >= 80 ? '◆' : '·';
        ctx += `${i + 1}. ${conf} [${row.domain}] ${row.rule}\n`;
      });
      return ctx;
    } catch { return ''; }
  },

  // ── TOPICS ───────────────────────────────────────────────────

  createTopic(title) {
    const id = crypto.randomBytes(8).toString('hex');
    try {
      stmts.createTopic.run(id, (title || 'Sesi').substring(0, 120));
    } catch (e) {
      console.error('[DB] createTopic error:', e.message);
    }
    return id;
  },

  topicExists(id) {
    try {
      const row = stmts.topicExists.get(id);
      return !!row;
    } catch { return false; }
  },

  updateTopicTitle(id, title) {
    try {
      stmts.updateTitle.run((title || 'Sesi').substring(0, 120), id);
    } catch { /* tidak fatal */ }
  },

  getTopics() {
    try { return stmts.getTopics.all(); } catch { return []; }
  },

  // ── MESSAGES ─────────────────────────────────────────────────

  saveMessage(topicId, role, content) {
    try {
      stmts.insertMessage.run(topicId, role, (content || '').substring(0, 32000));
    } catch (e) {
      console.error('[DB] saveMessage error:', e.message);
    }
  },

  getChatHistory(topicId) {
    try { return stmts.getMessages.all(topicId); } catch { return []; }
  },

  countMessages(topicId) {
    try { return stmts.countMessages.get(topicId).count; } catch { return 0; }
  }
};