using System.Collections.Generic;
using System.IO;
using System.Text;
using CsvHelper;
using NUnit.Framework;
using PriorBankParser.Dtos;
using static PriorBankParser.Constants.SectionNames;
using static PriorBankParser.Constants.SourceConfig;

namespace PriorBankParser
{
    public class Parser
    {
        [Test]
        public void Run()
        {
            const string sourceDirectoryPath = @"D:\Cloud-storage\Dropbox\Home\Finance\Raw Source\";
            const string resultFileName = @"ConvertedResult.csv";
            var result = ParseFilesInDirectory(sourceDirectoryPath);
            var resultFilePath = Path.Combine(sourceDirectoryPath, resultFileName);
            WriteResult(resultFilePath, result);
        }

        private ICollection<TransactionDto> ParseFilesInDirectory(string directoryPath)
        {
            var files = Directory.GetFiles(directoryPath, "*.csv");
            var result = new List<TransactionDto>();

            foreach (var file in files)
            {
                result.AddRange(ParseFile(file));
            }

            return result;
        }

        private ICollection<TransactionDto> ParseFile(string filePath)
        {
            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);

            var result = new List<TransactionDto>();
            using var reader = new StreamReader(filePath, Encoding.GetEncoding(CodePage));

            var contractName = SeekToTheTransactions(reader);

            if (string.IsNullOrEmpty(contractName))
            {
                return result;
            }

            using var csvReader = new CsvReader(reader, SrcCsvConfiguration);

            var isHeader = true;
            var ignore = false;

            while (csvReader.Read())
            {
                var field = csvReader.GetField(0);

                if (field.Equals(StatementTotalSectionPrefix))
                {
                    break;
                }

                if (field.Equals(CardTotalSectionPrefix))
                {
                    ignore = true;
                }

                if (field.StartsWith(OperationSectionPrefix))
                {
                    contractName = GetCardName(field);
                    isHeader = true;
                    continue;
                }

                if (isHeader)
                {
                    csvReader.ReadHeader();
                    isHeader = false;
                    ignore = false;
                    continue;
                }

                if (ignore)
                {
                    continue;
                }

                var record = csvReader.GetRecord<TransactionDto>();
                record.Contract = contractName;
                result.Add(record);
            }

            return result;
        }

        private void WriteResult(string resultFilePath, IEnumerable<TransactionDto> records)
        {
            using var writer = new StreamWriter(resultFilePath, false, Encoding.UTF8);
            using var csv = new CsvWriter(writer, Constants.GetWriteConfig());
            csv.WriteRecords(records);
        }

        private string SeekToTheTransactions(StreamReader reader)
        {
            while (!reader.EndOfStream)
            {
                var line = reader.ReadLine();
                if (line != null && line.StartsWith(OperationSectionPrefix))
                {
                    return GetCardName(line);
                }
            }

            return null;
        }

        private string GetCardName(string sectionName)
        {
            return sectionName.Replace(OperationSectionPrefix, string.Empty);
        }
    }
}