using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using CsvHelper;
using CsvHelper.Configuration;
using MileageTraker.Web.Models;
using MileageTraker.Web.Utility;

namespace MileageTraker.Web.DAL
{
	public class FuelmanCsvImporter
    {
		private sealed class FuelmanCsvClassMap : CsvClassMap<FuelLog>
		{
			public FuelmanCsvClassMap()
			{
				Map(m => m.Date).ConvertUsing(row =>
					{
						var date = row.GetField("CEDATE");
						var time = row.GetField<int>("CETIME");
						var dttm = string.Format(@"{0} {1:00:00}", date, time);
						return DateTime.ParseExact(dttm, @"M/d/yyyy HH:mm", CultureInfo.InvariantCulture);
					});
				Map(m => m.DriverFullName).ConvertUsing(row =>
					{
						var name = row.GetField("CEEMNAME");
						return NameNormalizer.Normalize(name);
					});

				Map(m => m.TagNumber).Name("CEVEHNO");
				Map(m => m.Odometer).Name("CEODOMETER");
				Map(m => m.CityName).ConvertUsing(row =>
					{
						var city = row.GetField("CESITCTY");
						return city.ToLower().ToTitleCase();
					});
				Map(m => m.MPG).Name("CEMPG");
				Map(m => m.GasPurchased).Name("CEQTY");
				Map(m => m.TotalPrice).Name("CECUSAMT");
			}
		}

		public static IEnumerable<FuelLog> Import(string filename)
		{
			var fileInfo = new FileInfo(filename);
			if (!fileInfo.Exists)
				throw new ImportException("Cannot find file '" + filename + "'");

			using (var tr = File.OpenText(fileInfo.FullName))
			{
 				var csv = new CsvReader(tr);
				csv.Configuration.RegisterClassMap<FuelmanCsvClassMap>();

				var fuelLogs = new List<FuelLog>();
				while (csv.Read())
				{
					try
					{
						// Skip non-FUEL entries
						if (csv.GetField<string>("CEPRDTYPE") != "FUEL")
							continue;

						fuelLogs.Add(csv.GetRecord<FuelLog>());
					}
					catch (Exception ex)
					{
						throw new ImportException("Problem with document encountered on row " + csv.Row + ". " + ex.Message);
					}
				}

				return fuelLogs;
			}
		}
    }
}