using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Text;

using System.Web;

namespace BFF.ExportData

{

    public class ExportFile

    {

        #region Export

        public static MemoryStream StreamToCSV<T>(IEnumerable<T> dataSource, string fileName)

            where T : class

        {

            var result = string.Empty;

            //Header

            StringBuilder headerRow = new StringBuilder();

            var properties = typeof(T).GetProperties().Select(p => new

            {

                PropertyInfo = p,

                HeaderAttr = p.GetFirstCustomAttribute<ExportHeaderAttribute>() as ExportHeaderAttribute

            })

                                                            .Where(p => p.HeaderAttr != null)

                                                            .OrderBy(p => p.HeaderAttr.Order)

                                                            .ThenBy(p => p.PropertyInfo.Name)

                                                            .ToList();

            var propertiesCount = properties.Count();

            for (int i = ; i < propertiesCount; i++)

            {

                if (i < propertiesCount - )

                    headerRow.Append(properties[i].HeaderAttr.DisplayName).Append(",");

                else

                    headerRow.Append(properties[i].HeaderAttr.DisplayName).Append(Environment.NewLine);

            }

            //Data

            StringBuilder fields = new StringBuilder();

            foreach (var item in dataSource)

            {

                if (item == null)

                    continue;

                for (int i = ; i < propertiesCount; i++)

                {

                    var propertyValue = properties[i].PropertyInfo.GetValue(item, null);

                    var displayPropertyValue = propertyValue == null ? string.Empty : propertyValue.ToString();

                    if (i < propertiesCount - )

                        formatStringToCSVForm(fields, displayPropertyValue, false);

                    else

                        formatStringToCSVForm(fields, displayPropertyValue, true);

                }

                fields.Append(Environment.NewLine);

            }

            //build

            result = headerRow.ToString() + fields.ToString();

            //return result;

            byte[] bytetxt = Encoding.UTF8.GetBytes(result);

            MemoryStream memstream = new MemoryStream();

            memstream.Write(bytetxt, , bytetxt.Length);

            memstream.Seek(, SeekOrigin.Begin);

            return memstream;

        }

        public static void ExportToCSV<T>(IEnumerable<T> dataSource, string fileName)

            where T : class

        {

            var result = string.Empty;

            //Header

            StringBuilder headerRow = new StringBuilder();

            var properties = typeof(T).GetProperties().Select(p => new

            {

                PropertyInfo = p,

                HeaderAttr = p.GetFirstCustomAttribute<ExportHeaderAttribute>() as ExportHeaderAttribute

            })

                                                            .Where(p => p.HeaderAttr != null)

                                                            .OrderBy(p => p.HeaderAttr.Order)

                                                            .ThenBy(p => p.PropertyInfo.Name)

                                                            .ToList();

            var propertiesCount = properties.Count();

            for (int i = ; i < propertiesCount; i++)

            {

                if (i < propertiesCount - )

                    headerRow.Append(properties[i].HeaderAttr.DisplayName).Append(",");

                else

                    headerRow.Append(properties[i].HeaderAttr.DisplayName).Append(Environment.NewLine);

            }

            //Data

            StringBuilder fields = new StringBuilder();

            foreach (var item in dataSource)

            {

                if (item == null)

                    continue;

                for (int i = ; i < propertiesCount; i++)

                {

                    var propertyValue = properties[i].PropertyInfo.GetValue(item, null);

                    var displayPropertyValue = propertyValue == null ? string.Empty : propertyValue.ToString();

                    if (i < propertiesCount - )

                        formatStringToCSVForm(fields, displayPropertyValue, false);

                    else

                        formatStringToCSVForm(fields, displayPropertyValue, true);

                }

                fields.Append(Environment.NewLine);

            }

            //build

            result = headerRow.ToString() + fields.ToString();

            //return result;

            byte[] bytetxt = Encoding.UTF8.GetBytes(result);

            FileStream f = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);

            f.Write(bytetxt,,bytetxt.Length);

            f.Close();

        }

        private static void formatStringToCSVForm(StringBuilder sb, string field, bool isLast)

        {

            if (string.IsNullOrEmpty(field))

                sb.Append(",");

            else

            {

                sb.AppendFormat("\"{0}\"", field.Replace("\"", "\"\""));

                if (!isLast)

                    sb.Append(",");

            }

        }

        #endregion

    }

}