//	Spludlow Software
//	Copyright © Samuel P. Ludlow 2020 All Rights Reserved
//	Distributed under the terms of the GNU General Public License version 3
//	Distributed WITHOUT ANY WARRANTY; without implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE
//	https://www.spludlow.co.uk/LICENCE.TXT
//	The Spludlow logo is a registered trademark of Samuel P. Ludlow and may not be used without permission
//	v1.14

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

using System.IO;
using System.Data;

namespace Spludlow.Data
{
	public class CSV
	{
		public static DataTable Read(string filename)
		{
			return Read(filename, Encoding.Default, '"');
		}
		public static DataTable Read(string filename, Encoding encoding)
		{
			return Read(filename, encoding, '"');
		}

		public static DataTable Read(string filename, Encoding encoding, char quote)
		{
			using (FileStream fileStream = new FileStream(filename, FileMode.Open))
			{
				string tableName = Spludlow.Io.Paths.LegalFileName(Path.GetFileNameWithoutExtension(filename));

				return Read(fileStream, tableName, encoding, quote);
			}
		}

		public static DataTable Read(Stream stream)
		{
			return Read(stream, null, Encoding.Default, '"');
		}
		public static DataTable Read(Stream stream, string tableName, Encoding encoding, char quote)
		{
			DataTable table = null;

			using (StreamReader reader = new StreamReader(stream, encoding))
			{
				string line;

				while ((line = reader.ReadLine()) != null)
				{
					if (table == null)
					{
						table = new DataTable();
						if (tableName != null)
							table.TableName = tableName;

						string[] columnNames = line.Split(new char[] { ',' });
						foreach (string columnName in columnNames)
							table.Columns.Add(columnName.Trim(), typeof(string));

						continue;
					}

					DataRow row = table.NewRow();

					StringBuilder word = new StringBuilder();

					int index = 0;
					bool inQuote = false;


					foreach (char ch in line)
					{
						if (ch == quote)
						{
							inQuote = !inQuote;
							continue;
						}

						if (inQuote == false && ch == ',')
						{
							row[index] = word.ToString();
							++index;
							word.Length = 0;
							continue;
						}

						word.Append(ch);
					}

					row[index] = word.ToString();

					table.Rows.Add(row);

				}
			}

			return table;
		}

		public static void Write(string filename, DataTable table)
		{
			using (FileStream fileStream = new FileStream(filename, FileMode.Create))
				Write(fileStream, table, Encoding.UTF8, '"');
		}
		public static void Write(string filename, DataTable table, Encoding encoding)
		{
			using (FileStream fileStream = new FileStream(filename, FileMode.Create))
				Write(fileStream, table, encoding, '"');
		}
		public static void Write(Stream stream, DataTable table, Encoding encoding, char quote)
		{
			using (StreamWriter writer = new StreamWriter(stream, encoding))
			{
				for (int colIndex = 0; colIndex < table.Columns.Count; ++colIndex)
				{
					if (colIndex > 0)
						writer.Write(",");

					writer.Write(table.Columns[colIndex].ColumnName);
				}
				writer.WriteLine();

				foreach (DataRow row in table.Rows)
				{
					for (int colIndex = 0; colIndex < table.Columns.Count; ++colIndex)
					{
						if (colIndex > 0)
							writer.Write(",");

						if (row.IsNull(colIndex) == false)
						{
							if (table.Columns[colIndex].DataType == typeof(string))
							{
								string value = (string)row[colIndex];
								bool needQuotes = true; // value.Contains(quote);
								if (needQuotes == true)
									writer.Write(quote);
								writer.Write(value);
								if (needQuotes == true)
									writer.Write(quote);
							}
							else
							{
								writer.Write(Convert.ToString(row[colIndex]));
							}
						}
					}
					writer.WriteLine();
				}
			}
		}
	}
}