using System;
using System.Collections.Generic;
using System.Text;

namespace Sarand.Net.Standard.Base.Data
{
	//=======================================================================
	/// <summary>
	/// Very basic CSV data handling.
	/// <para>For more advanced CSV features, see SaCsvHelper in SacsWinOffice.</para>
	/// </summary>
	public static class SacsCsvHandler
	{
		//-------------------------------------------------------------------
		// Properties.

		//-------------------------------------------------------------------
		public static String ToCsv (this IEnumerable<String> values, char fieldDelimiter = ',', char textDelimiter = '"')
		{
			String data = "";
			int valueCount = 0;
			foreach (String rawValue in values)
			{
				valueCount++;
				String value = rawValue;
				if (value.Contains(fieldDelimiter.ToString()) || value.Contains(textDelimiter.ToString()))
					value = textDelimiter + value.Replace(textDelimiter.ToString(), textDelimiter.ToString() + textDelimiter.ToString()) + textDelimiter;
				data += (valueCount > 1 ? fieldDelimiter.ToString() : "") + value;
			}
			return data;
		}

		//-------------------------------------------------------------------
		/// <summary>
		/// Extract comma delimited fields from data record.
		/// <para>Fields starting with double quotes are terminated with the next single double quotes character.</para>
		/// <para>Embedded double quotes pairs are treated as a single double quotes character.</para>
		/// </summary>
		/// <param name="data"></param>
		/// <returns></returns>
		public static List<String> ParseCsvRecord (String data, char fieldDelimiter = ',', char textDelimiter = '"')
		{
			List<String> fields = new List<string>();
			if (data == null) return fields;

			// Parse control properties.
			String currentField = "";
			bool inTextField = false;
			bool previousCharTextDelim = false;

			// Parse the data.
			foreach (char c in data)
			{
				if (inTextField)
				{
					if (c == textDelimiter)
					{
						// Text delimiter found.
						if (!previousCharTextDelim)
						{
							// Make a note that a text delimiter has been found.
							previousCharTextDelim = true;
							continue;
						}
						else
						{
							// 2nd text delimiter found - add single text delimiter to field.
							currentField += c;
							previousCharTextDelim = false;
							continue;
						}
					}
					if (previousCharTextDelim)
					{
						// Non-text delimiter foudn after text delimiter - End of text field.
						inTextField = false;
						previousCharTextDelim = false;
						if (c == fieldDelimiter)
						{
							// End of field.
							fields.Add(currentField);
							currentField = "";
							continue;
						}
						continue;
					}
					currentField += c;
				}
				else
				{
					// Non-text field.
					if (c == fieldDelimiter)
					{
						// End of field.
						fields.Add(currentField);
						currentField = "";
						continue;
					}
					if (currentField.Length == 0 && c == textDelimiter)
					{
						// First character of field is text delimiter.
						inTextField = true;
						continue;
					}
					// Append character to field.
					currentField += c;
				}
			}
			fields.Add(currentField);

			return fields;
		}

		//-------------------------------------------------------------------
	}
	//=======================================================================
}