/**
 * SQLITE.INFO - operational info: path, version, counts by type, WAL.
 */

import type { CommandReply, Engine } from '../types.ts';

/** SQLite info as ordered [name, value] pairs, shared with INFO. */
export function readSqliteInfo(engine: Engine): [string, string][] {
  const db = engine._db;
  const keys = engine._keys;
  const path = db.name || '';
  const versionRow = db.prepare('SELECT sqlite_version() AS v').get();
  const version = versionRow ? versionRow.v : '';
  const total = keys.count();
  const byType: { type: number; n: number }[] = db.prepare('SELECT type, COUNT(*) AS n FROM redis_keys GROUP BY type').all();
  const stringCount = byType.find((r) => r.type === 1)?.n ?? 0;
  const hashCount = byType.find((r) => r.type === 2)?.n ?? 0;
  const setCount = byType.find((r) => r.type === 3)?.n ?? 0;
  const listCount = byType.find((r) => r.type === 4)?.n ?? 0;
  let journalMode = 'unknown';
  try {
    const walRow = db.prepare('PRAGMA journal_mode').get();
    journalMode = (walRow && (walRow.journal_mode || Object.values(walRow)[0])) || 'unknown';
  } catch (_) {}
  return [
    ['path', path],
    ['version', version],
    ['total_keys', String(total)],
    ['string_keys', String(stringCount)],
    ['hash_keys', String(hashCount)],
    ['set_keys', String(setCount)],
    ['list_keys', String(listCount)],
    ['journal_mode', journalMode],
  ];
}

export function handleSqliteInfo(engine: Engine, args: Buffer[]): CommandReply {
  if (!engine._db) return { error: 'ERR SQLite not available' };
  return readSqliteInfo(engine).flat();
}