using System;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics.CodeAnalysis;

namespace Kit.Helpers.SqlHelperAbstract
{
    public interface IDataRecordSpecified
    {
        IDataReader Src { get; }
        Npgsql.INpgsqlNameTranslator NameTranslator { get; }
        TValue Convert<TValue>(object value);
    }

    internal class DataRecordSpecified : IDataRecordSpecified
    {
        public IDataReader Src { get; }
        public Npgsql.INpgsqlNameTranslator NameTranslator { get; }
        public virtual TValue Convert<TValue>(object value)
        {
            return (TValue)value;
        }

        public DataRecordSpecified(IDataReader dataReader, Npgsql.INpgsqlNameTranslator nameTranslator)
        {
            Src = dataReader;
            NameTranslator = nameTranslator;
        }
    }

    public static class DataRecordSpecifiedExtensions
    {
        /// <summary>
        /// Проверка на наличие столбца в запросе
        /// </summary>
        /// <param name="reader"></param>
        /// <param name="name"></param>
        /// <returns></returns>
        public static bool HasColumn(this IDataRecordSpecified reader, string name)
        {
            string nameTranslated = reader.NameTranslator.TranslateMemberName(name).ToLower();
            for (int n = 0; n < reader.Src.FieldCount; n++)
            {
                string fieldNameTranslated = reader.NameTranslator.TranslateMemberName(reader.Src.GetName(n)).ToLower();
                if (fieldNameTranslated == nameTranslated) return true;
            }
            return false;
        }

        private static string GetTranslatedName(this IDataRecordSpecified record, string fieldName) => record.NameTranslator.TranslateMemberName(fieldName);
#if NETFRAMEWORK
        private static TValue TryGet<TValue>(this IDataRecordSpecified record, string fieldName, bool isStrict)
#elif NETCOREAPP
        private static TValue? TryGet<TValue>(this IDataRecordSpecified record, string fieldName, bool isStrict)
#endif
        {
            fieldName = GetTranslatedName(record, fieldName);
            object value = record.Src[fieldName];

            if (value == DBNull.Value)
            {
                if (isStrict)
                    throw new InvalidCastException(string.Format("{0} {1} нельзя привести к {2}", fieldName, typeof(DBNull).FullName, typeof(TValue).FullName));

                return default;
            }

            try
            {
                return record.Convert<TValue>(value);
            }
            catch (InvalidCastException ex)
            {
                throw new InvalidCastException(string.Format("{0} {1} нельзя привести к {2}", fieldName, value.GetType().FullName, typeof(TValue).FullName), ex);
            }
        }

        public static bool IsDbNull(this IDataRecordSpecified record, string fieldName) => record.Src[fieldName] == DBNull.Value;
        public static bool IsNotDbNull(this IDataRecordSpecified record, string fieldName) => !record.IsDbNull(fieldName);

        public static TValue Get<TValue>(this IDataRecordSpecified record, string fieldName) => record.TryGet<TValue>(fieldName, isStrict: true);
#if NETFRAMEWORK
        public static TValue GetN<TValue>(this IDataRecordSpecified record, string fieldName)
#elif NETCOREAPP
        public static TValue? GetN<TValue>(this IDataRecordSpecified record, string fieldName)
#endif
            => record.TryGet<TValue>(fieldName, isStrict: false);

        internal static void ProcessExtraSelect<TEntity>(this IDataRecordSpecified readerSpecified, IList<TEntity> selectResult, SelectType extraSelectType = SelectType.Default)
        {
            switch (extraSelectType)
            {
                case SelectType.Page:
                    {
                        var result = (IEnumerableWithPage<TEntity>)selectResult;
                        // считывание данных постраничного вывода
                        while (readerSpecified.Src.Read())
                        {
                            if (readerSpecified.HasColumn("FilteredRows")) result.FilterRow = readerSpecified.Get<int>("filteredRows");
                            if (readerSpecified.HasColumn("TotalRows")) result.TotalRows = readerSpecified.Get<int>("totalRows");
                            if (readerSpecified.HasColumn("PageNo")) result.PageNo = readerSpecified.Get<int>("pageNo");
                            if (readerSpecified.HasColumn("PageSize")) result.PageSize = readerSpecified.Get<int>("pageSize");
                            if (readerSpecified.HasColumn("Sort")) result.Sort = readerSpecified.Get<string>("sort");
                            //if (readerSpecified.HasColumn("Dir")) result.Dir = readerSpecified.Get<string>("dir");
                        }
                    }
                    break;
                case SelectType.Offer:
                    {
                        var result = (IEnumerableWithOffer<TEntity>)selectResult;
                        // считывание данных постраничного вывода
                        while (readerSpecified.Src.Read())
                        {
                            if (readerSpecified.HasColumn("FilteredRows")) result.FilterRow = readerSpecified.Get<int>("FilteredRows");
                            if (readerSpecified.HasColumn("TotalRows")) result.TotalRows = readerSpecified.Get<int>("TotalRows");
                            if (readerSpecified.HasColumn("Start")) result.Start = readerSpecified.Get<int>("Start");
                            if (readerSpecified.HasColumn("Length")) result.Lenght = readerSpecified.Get<int>("Length");
                            if (readerSpecified.HasColumn("Sort")) result.Sort = readerSpecified.Get<string>("Sort");
                            //if (readerSpecified.HasColumn("Dir")) result.Dir = readerSpecified.Get<string>("Dir");
                        }
                    }
                    break;
                case SelectType.Default:
                default:
                    break;
            }
        }
    }
}