using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

public static class ListExtension
{
    /// <summary>
    /// Save the List data to CSV file
    /// </summary>
    /// <param name="list">data source</param>
    /// <param name="file">file</param>
    /// <returns>success flag</returns>
    public static string ToCsvFile<T>(this List<T> list, string file)
    {
        PropertyInfo[] props = GetPropertyInfoArray<T>();
        using (var sw = new StreamWriter(file))
        {
            StringBuilder strColumn = new StringBuilder();
            for (int i = 0; i < props.Length; i++)
            {
                strColumn.Append(props[i].Name);
                strColumn.Append(",");
            }
            strColumn.Remove(strColumn.Length - 1, 1);
            sw.WriteLine(strColumn);    //write the column name
            for (int i = 0; i < list.Count; i++)
            {
                StringBuilder strValue = new StringBuilder();
                int idx = 0;
                foreach (var prop in props)
                {
                    var val = prop.GetValue(list[i]);
                    strValue.Append(val);
                    if (idx < props.Length-1)
                        strValue.Append(",");
                    idx++;
                }
                sw.WriteLine(strValue); //write the row value
            }
        }
        FileInfo f = new FileInfo(file);
        return f.FullName;
    }


    private static PropertyInfo[] GetPropertyInfoArray<T>()
    {
        PropertyInfo[] props = null;
        Type type = typeof(T);
        object obj = Activator.CreateInstance(type);
        props = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
        return props.Where(p => p.CanRead && !p.GetMethod.IsVirtual && !p.GetMethod.IsAbstract).ToArray();
    }

}