using System;
using System.Collections.Generic;
using System.Data;
using System.Reflection;
using Fasterflect;

namespace DataModel.Helpers
{
    /// <summary>
    /// IEnumerable extension helpers
    /// </summary>
    public static class GenericListDataReaderExtensions
    {
        /// <summary>
        /// Generates generic data reader for bulk copies from list
        /// </summary>
        /// <typeparam name="T">Element data type</typeparam>
        /// <param name="list">Source list</param>
        /// <returns>Data reader to parse list contents</returns>
        public static GenericListDataReader<T> GetDataReader<T>(this IEnumerable<T> list) where T : class
        {
            return new GenericListDataReader<T>(list);
        }
    }

    /// <summary>
    /// Data reader that parses list of generic elements
    /// </summary>
    public class GenericListDataReader : IDataReader
    {
        public int Count { get; set; }
        private readonly IEnumerator<object> list = null;
        private readonly List<PropertyInfo> properties = new List<PropertyInfo>();
        private readonly Dictionary<string, int> nameLookup = new Dictionary<string, int>();
        private readonly string[] propertyNames;

        public GenericListDataReader(IEnumerable<object> list, Type type)
        {
            this.list = list.GetEnumerator();

            properties.AddRange(type.GetProperties(BindingFlags.GetProperty | BindingFlags.Instance | BindingFlags.Public | BindingFlags.DeclaredOnly));
            propertyNames = new string[properties.Count];

            for (int i = 0; i < properties.Count; i++)
            {
                nameLookup[properties[i].Name] = i;
                propertyNames[i] = properties[i].Name;
            }
        }

        public void Close()
        {
            list.Dispose();
        }

        public int Depth => throw new NotImplementedException();

        public DataTable GetSchemaTable()
        {
            throw new NotImplementedException();
        }

        public bool IsClosed => false;

        public bool NextResult()
        {
            throw new NotImplementedException();
        }

        public bool Read()
        {
            bool readResult = list.MoveNext();

            //Update counter
            if (readResult)
            {
                Count++;
            }

            return readResult;
        }

        public int RecordsAffected => throw new NotImplementedException();

        public void Dispose()
        {
            Close();
        }

        public int FieldCount => properties.Count;

        public bool GetBoolean(int i)
        {
            return (bool)GetValue(i);
        }

        public byte GetByte(int i)
        {
            return (byte)GetValue(i);
        }

        public long GetBytes(int i, long fieldOffset, byte[] buffer, int bufferoffset, int length)
        {
            throw new NotImplementedException();
        }

        public char GetChar(int i)
        {
            return (char)GetValue(i);
        }

        public long GetChars(int i, long fieldoffset, char[] buffer, int bufferoffset, int length)
        {
            throw new NotImplementedException();
        }

        public IDataReader GetData(int i)
        {
            throw new NotImplementedException();
        }

        public string GetDataTypeName(int i)
        {
            throw new NotImplementedException();
        }

        public DateTime GetDateTime(int i)
        {
            return (DateTime)GetValue(i);
        }

        public decimal GetDecimal(int i)
        {
            return (decimal)GetValue(i);
        }

        public double GetDouble(int i)
        {
            return (double)GetValue(i);
        }

        public Type GetFieldType(int i)
        {
            return properties[i].PropertyType;
        }

        public float GetFloat(int i)
        {
            return (float)GetValue(i);
        }

        public Guid GetGuid(int i)
        {
            return (Guid)GetValue(i);
        }

        public short GetInt16(int i)
        {
            return (short)GetValue(i);
        }

        public int GetInt32(int i)
        {
            return (int)GetValue(i);
        }

        public long GetInt64(int i)
        {
            return (long)GetValue(i);
        }

        public string GetName(int i)
        {
            return properties[i].Name;
        }

        public int GetOrdinal(string name)
        {
            if (nameLookup.ContainsKey(name))
            {
                return nameLookup[name];
            }
            else
            {
                return -1;
            }
        }

        public string GetString(int i)
        {
            return (string)GetValue(i);
        }

        public object GetValue(int i)
        {
            string name = propertyNames[i];
            return list.Current.GetPropertyValue(name);
        }

        public int GetValues(object[] values)
        {
            int getValues = Math.Max(FieldCount, values.Length);

            for (int i = 0; i < getValues; i++)
            {
                values[i] = GetValue(i);
            }

            return getValues;
        }

        public bool IsDBNull(int i)
        {
            return GetValue(i) == null;
        }

        public object this[string name] => list.Current.GetPropertyValue(name);

        public object this[int i] => GetValue(i);
    }

    /// <summary>
    /// Data reader that parses list of generic elements
    /// </summary>
    /// <typeparam name="T">Element data type</typeparam>
    public class GenericListDataReader<T> : GenericListDataReader where T : class
    {
        public GenericListDataReader(IEnumerable<T> list)
            : base(list, typeof(T))
        {

        }
    }
}