using Microsoft.Data.Sqlite;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace trakker.Data
{
    public class DataAccess(string connectionString)
    {
        private readonly string _connectionString = connectionString ?? throw new ArgumentNullException(nameof(connectionString));

        /// <summary>
        /// Creates a new, unopened SqliteConnection.
        /// </summary>
        protected SqliteConnection CreateConnection() => new(_connectionString);

        /// <summary>
        /// Opens and returns a SqliteConnection (synchronous).
        /// </summary>
        protected SqliteConnection OpenConnection()
        {
            var conn = CreateConnection();
            conn.Open();
            return conn;
        }

        /// <summary>
        /// Executes arbitrary, ad-hoc SQL against the database inside a transaction.
        /// </summary>
        /// <param name="sql">A SQL statement to execute. The caller is responsible for
        /// ensuring the SQL is safe and properly parameterized to avoid SQL injection.</param>
        /// <remarks>
        /// This method is intended for one-off maintenance or administrative commands.
        /// It does not return any result; if a scalar value is produced by the SQL,
        /// the current implementation captures it but does not expose it to the caller.
        /// </remarks>
        public void Adhoc(string sql) 
        { 
            using var conn = OpenConnection();
            using var tx = conn.BeginTransaction();

            int? result = 0;
            try
            {
                using (var cmd = conn.CreateCommand())
                {
                    cmd.Transaction = tx;
                    cmd.CommandText = sql;
                    cmd.ExecuteNonQuery();
                }

                using var idCmd = conn.CreateCommand();
                idCmd.Transaction = tx;
                result = (int?)idCmd.ExecuteScalar() ;

                tx.Commit();
            }
            catch
            {
                tx.Rollback();
                throw;
            }

        }
    }
}