using System;

using System.Text.RegularExpressions;



using NOS.Registration.EntryPositioning;



namespace NOS.Registration

{

	internal class PageFormatter : IPageFormatter

	{

		readonly ILogger _logger;

		readonly IOpinionEvaluator _opinionEvaluator;



		public PageFormatter(ILogger logger, IOpinionEvaluator opinionEvaluator)

		{

			_logger = logger;

			_opinionEvaluator = opinionEvaluator;

		}



		#region IPageFormatter Members

		public string AddEntry(string content, string entry, User user, IPluginConfiguration configuration)

		{

			var entryMatcher = NewRegex(configuration.EntryPattern);

			var listStartMatcher = NewRegex(configuration.ListStartPattern);

			var listEndMatcher = NewRegex(configuration.ListEndPattern);

			var waitingListEndMatcher = NewRegex(configuration.WaitingListEndPattern);



			int listStart = AssertMatchesOnce(content, listStartMatcher, "list start");

			int listEnd = AssertMatchesOnce(content, listEndMatcher, "list end");

			int waitingListEnd = AssertMatchesOnce(content, waitingListEndMatcher, "waiting list end");

			if (listEnd == -1 || listEnd == -1 || waitingListEnd == -1)

			{

				throw new InvalidOperationException(

					"The list and/or waiting list regular expressions did not match once. See previous errors.");

			}



			if (listEnd < listStart)

			{

				_logger.Error(String.Format("The list end position ({0}) is before the list start position ({1})",

				                            listEnd,

				                            listStart),

				              "SYSTEM");

				throw new InvalidOperationException("The list start and end positions are not sanitized. See previous error.");

			}



			int numberOfAttendees = CountNumberOfEntries(content.Substring(listStart, listEnd - listStart), entryMatcher);



			int addAtIndex = _opinionEvaluator.Evaluate(new EvaluationContext

				                           {

				                           	NumberOfAttendees = numberOfAttendees,

				                           	ListEnd = listEnd,

				                           	WaitingListEnd = waitingListEnd,

				                           	Configuration = configuration,

				                           	User = user,

				                           	Logger = _logger

				                           });



			return content.Insert(addAtIndex, entry);

		}

		#endregion



		int AssertMatchesOnce(string content, Regex matcher, string matchType)

		{

			MatchCollection matches = matcher.Matches(content);

			if (matches.Count == 0)

			{

				_logger.Error(String.Format("The {0} cannot be found: {1}", matchType, matcher), "SYSTEM");

				return -1;

			}



			if (matches.Count > 1)

			{

				_logger.Error(String.Format("The {0} was found {1} times: {2}", matchType, matches.Count, matcher),

				              "SYSTEM");

				return -1;

			}



			return matches[0].Captures[0].Index;

		}



		static Regex NewRegex(string value)

		{

			return new Regex(value, RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.Multiline);

		}



		static int CountNumberOfEntries(string content, Regex matcher)

		{

			return matcher.Matches(content).Count;

		}

	}

}