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

namespace Tango.CSV
{
    public class DynamicCsvFile : IDisposable
    {
        private bool _isDisposed;
        private Stream _stream;
        private StreamWriter _writer;
        private bool _disposeStream;
        private bool _columnsWritten;

        public List<DynamicCsvFileColumn> Columns { get; set; }

        public DynamicCsvFile()
        {
            Columns = new List<DynamicCsvFileColumn>();
        }

        public DynamicCsvFile(Stream stream) : this()
        {
            _stream = stream;
            _writer = new StreamWriter(_stream);
        }

        public DynamicCsvFile(String file) : this(new FileStream(file, FileMode.Create))
        {
            _disposeStream = true;
        }

        private void WriteColumns()
        {
            if (!_columnsWritten)
            {
                _columnsWritten = true;
                _writer.WriteLine(String.Join(",", Columns.Select(x => x.Name)));
            }
        }

        public void Append(params Object[] values)
        {
            Append((IEnumerable)values);
        }

        public void Append<T>(IEnumerable<T> values, Func<T, Object> modifier = null)
        {
            if (modifier != null)
            {
                Append((IEnumerable)values, (x) => { return modifier((T)x); });
            }
            else
            {
                Append((IEnumerable)values, null);
            }
        }

        public void Append(IEnumerable values, Func<Object, Object> modifier = null)
        {
            if (!_columnsWritten)
            {
                WriteColumns();
            }

            List<String> valuesStr = new List<string>();

            foreach (var value in values)
            {
                Object finalValue = value;

                if (modifier != null)
                {
                    finalValue = modifier(finalValue);
                }

                valuesStr.Add(finalValue != null ? finalValue.ToString() : String.Empty);
            }

            _writer.WriteLine(String.Join(",", valuesStr));
            _writer.Flush();
        }

        public void Dispose()
        {
            if (!_isDisposed)
            {
                _isDisposed = true;

                if (_disposeStream)
                {
                    _writer?.Dispose();
                    _stream?.Dispose();
                }
            }
        }
    }
}