/*
  KeePass Password Safe - The Open-Source Password Manager
  Copyright (C) 2003-2021 Dominik Reichl <dominik.reichl@t-online.de>

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

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

using KeePassLib.Utility;

namespace KeePass.DataExchange
{
	public sealed class CsvOptions
	{
		private char m_chFieldSep = ',';
		public char FieldSeparator
		{
			get { return m_chFieldSep; }
			set { m_chFieldSep = value; }
		}

		private char m_chRecSep = '\n';
		public char RecordSeparator
		{
			get { return m_chRecSep; }
			set { m_chRecSep = value; }
		}

		private char m_chTextQual = '\"';
		public char TextQualifier
		{
			get { return m_chTextQual; }
			set { m_chTextQual = value; }
		}

		private bool m_bBackEscape = true;
		public bool BackslashIsEscape
		{
			get { return m_bBackEscape; }
			set { m_bBackEscape = value; }
		}

		private bool m_bTrimFields = true;
		public bool TrimFields
		{
			get { return m_bTrimFields; }
			set { m_bTrimFields = value; }
		}

		private string m_strNewLineSeq = "\r\n";
		public string NewLineSequence
		{
			get { return m_strNewLineSeq; }
			set
			{
				if(value == null) throw new ArgumentNullException("value");
				m_strNewLineSeq = value;
			}
		}
	}

	public sealed class CsvStreamReaderEx
	{
		private CharStream m_sChars;
		private CsvOptions m_opt;

		public CsvStreamReaderEx(string strData)
		{
			Init(strData, null);
		}

		public CsvStreamReaderEx(string strData, CsvOptions opt)
		{
			Init(strData, opt);
		}

		private void Init(string strData, CsvOptions opt)
		{
			if(strData == null) throw new ArgumentNullException("strData");

			m_opt = (opt ?? new CsvOptions());

			string strInput = strData;

			// Normalize to Unix "\n" right now; the new lines are
			// converted back in the <c>AddField</c> method
			strInput = StrUtil.NormalizeNewLines(strInput, false);

			strInput = strInput.Trim(new char[] { (char)0 });

			m_sChars = new CharStream(strInput);
		}

		public string[] ReadLine()
		{
			char chFirst = m_sChars.PeekChar();
			if(chFirst == char.MinValue) return null;

			List<string> v = new List<string>();
			StringBuilder sb = new StringBuilder();
			bool bInText = false;

			char chFS = m_opt.FieldSeparator, chRS = m_opt.RecordSeparator;
			char chTQ = m_opt.TextQualifier;

			while(true)
			{
				char ch = m_sChars.ReadChar();
				if(ch == char.MinValue) break;

				Debug.Assert(ch != '\r'); // Was normalized to Unix "\n"

				if((ch == '\\') && m_opt.BackslashIsEscape)
				{
					char chEsc = m_sChars.ReadChar();
					if(chEsc == char.MinValue) break;

					if(chEsc == 'n') sb.Append('\n');
					else if(chEsc == 'r') sb.Append('\r');
					else if(chEsc == 't') sb.Append('\t');
					else if(chEsc == 'u')
					{
						char chNum1 = m_sChars.ReadChar();
						char chNum2 = m_sChars.ReadChar();
						char chNum3 = m_sChars.ReadChar();
						char chNum4 = m_sChars.ReadChar();
						if(chNum4 != char.MinValue) // Implies the others
						{
							StringBuilder sbNum = new StringBuilder();
							sbNum.Append(chNum3); // Little-endian
							sbNum.Append(chNum4);
							sbNum.Append(chNum1);
							sbNum.Append(chNum2);

							byte[] pbNum = MemUtil.HexStringToByteArray(sbNum.ToString());
							ushort usNum = MemUtil.BytesToUInt16(pbNum);

							sb.Append((char)usNum);
						}
					}
					else sb.Append(chEsc);
				}
				else if(ch == chTQ)
				{
					if(!bInText) bInText = true;
					else // bInText
					{
						char chNext = m_sChars.PeekChar();
						if(chNext == chTQ)
						{
							m_sChars.ReadChar();
							sb.Append(chTQ);
						}
						else bInText = false;
					}
				}
				else if((ch == chRS) && !bInText) break;
				else if(bInText) sb.Append(ch);
				else if(ch == chFS)
				{
					AddField(v, sb.ToString());
					if(sb.Length > 0) sb.Remove(0, sb.Length);
				}
				else sb.Append(ch);
			}
			// Debug.Assert(!bInText);
			AddField(v, sb.ToString());

			return v.ToArray();
		}

		private void AddField(List<string> v, string strField)
		{
			// Escape characters might have been used to insert
			// new lines that might not conform to Unix "\n"
			strField = StrUtil.NormalizeNewLines(strField, false);

			// Transform to final form of new lines
			strField = strField.Replace("\n", m_opt.NewLineSequence);

			if(m_opt.TrimFields) strField = strField.Trim();

			v.Add(strField);
		}
	}
}
