using System.Data;
using System.Threading.Tasks;

namespace brecal.model
{
    public abstract class DbEntity
    {
        /// <summary>
        /// DB primary key
        /// </summary>
        public uint Id { get; set; }

        /// <summary>
        /// Creation timestamp, if null record is unsaved
        /// </summary>
        public DateTime? Created { get; set; }

        /// <summary>
        /// Modified timestamp, if null record was never modified
        /// </summary>
        public DateTime? Modified { get; set; }

        /// <summary>
        /// Set query and cmd parameters for an update query
        /// </summary>
        /// <param name="cmd">CMD created by DB manager</param>
        public abstract void SetUpdate(IDbCommand cmd);

        /// <summary>
        /// set query and cmd parameters for a create query
        /// </summary>
        /// <param name="cmd">CMD created by DB manager</param>
        public abstract void SetCreate(IDbCommand cmd);

        /// <summary>
        /// set query and cmd parameters for a delete query
        /// </summary>
        /// <param name="cmd">CMD created by DB manager</param>
        public abstract void SetDelete(IDbCommand cmd);

        public virtual void SetNonQuery(IDbCommand cmd)
        {
            // default: do nothing
        }

        /// <summary>
        /// Each database entity must be able to save itself to the database
        /// </summary>
        public async Task Save(IDBManager manager)
        {
            if (this.Created.HasValue)
            {
                await manager.ExecuteNonQuery(this.SetUpdate);
            }
            else
            {
                this.Id = (uint)await manager.ExecuteNonQuery(this.SetCreate);
            }
        }

        /// <summary>
        /// Each entity must be able to delete itself
        /// </summary>
        public async Task Delete(IDBManager manager)
        {            
            await manager.ExecuteNonQuery(this.SetDelete);
        }

        public async Task ExecuteNonQuery(IDBManager manager)
        {
            await manager.ExecuteNonQuery(this.SetNonQuery);
        }

    }
}