using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.IO;

namespace SRP.Processor
{
    public class TradeProcessor
    {
        private static float LotSize = 100000f;

        private List<TradeRecord> ValidateTrades(List<string> lines)
        {
            var trades = new List<TradeRecord>();

            var lineCount = 1;
            foreach (var line in lines)
            {
                var fields = line.Split(new char[] { ';' });

                if (fields.Length != 3)
                {
                    Console.WriteLine($"WARN: Line {lineCount} malformed. Only {fields.Length} field(s) found.");
                    continue;
                }

                if (fields[0].Length != 6)
                {
                    Console.WriteLine($"WARN: Trade currencies on line {lineCount} malformed: '{fields[0]}'");
                    continue;
                }

                int tradeAmount;
                if (!int.TryParse(fields[1], out tradeAmount))
                {
                    Console.WriteLine($"WARN: Trade amount on line {lineCount} not a valid integer: '{fields[1]}'");
                }

                decimal tradePrice;
                if (!decimal.TryParse(fields[2], out tradePrice))
                {
                    Console.WriteLine($"WARN: Trade price on line {lineCount} not a valid decimal: '{fields[2]}'");
                }

                trades.Add(CreateTrade(fields[0], tradeAmount, tradePrice));

                lineCount++;
            }

            return trades;
        }

        private TradeRecord CreateTrade(string name, int tradeAmount, decimal tradePrice)
        {
            var sourceCurrencyCode = name.Substring(0, 3);
            var destinationCurrencyCode = name.Substring(3, 3);

            // calculate values
            var trade = new TradeRecord
            {
                SourceCurrency = sourceCurrencyCode,
                DestinationCurrency = destinationCurrencyCode,
                Lots = tradeAmount / LotSize,
                Price = tradePrice
            };

            return trade;
        }

        private List<string> ReadTrades(Stream stream)
        {
            // read rows
            var lines = new List<string>();
            using (var reader = new StreamReader(stream))
            {
                string line;
                while ((line = reader.ReadLine()) != null)
                {
                    lines.Add(line);
                }
            }

            return lines;
        }

        private void WriteTradesToDatabase(List<TradeRecord> trades)
        {
            using (var connection = new SqlConnection(@"Data Source=.\sqlexpress;Initial Catalog=TradeProcessor;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False"))
            {
                connection.Open();
                using (var transaction = connection.BeginTransaction())
                {
                    foreach (var trade in trades)
                    {
                        var command = connection.CreateCommand();
                        command.Transaction = transaction;
                        command.CommandType = System.Data.CommandType.StoredProcedure;
                        command.CommandText = "dbo.insert_trade";
                        command.Parameters.AddWithValue("@sourceCurrency", trade.SourceCurrency);
                        command.Parameters.AddWithValue("@destinationCurrency", trade.DestinationCurrency);
                        command.Parameters.AddWithValue("@lots", trade.Lots);
                        command.Parameters.AddWithValue("@price", trade.Price);

                        command.ExecuteNonQuery();
                    }

                    transaction.Commit();
                }
                connection.Close();
            }
        }

        public void ProcessTrades(Stream stream)
        {
            var lines = ReadTrades(stream);

            var trades = ValidateTrades(lines);

            WriteTradesToDatabase(trades);

            Console.WriteLine($"INFO: {trades.Count} trades processed");
        }
    }
}