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

using UnityEngine;

namespace AllocsFixes.NetConnections.Servers.Web
{
	public class LogBuffer {
		private const int MAX_ENTRIES = 50000;
		private static LogBuffer instance;

		public static LogBuffer Instance {
			get {
				if (instance == null) {
					instance = new LogBuffer ();
				}
				return instance;
			}
		}

		private static Regex logMessageMatcher = new Regex (@"^([0-9]{4}-[0-9]{2}-[0-9]{2})T([0-9]{2}:[0-9]{2}:[0-9]{2}) ([0-9]+[,.][0-9]+) [A-Z]+ (.*)$");
		private List<LogEntry> logEntries = new List<LogEntry> ();
		private int listOffset = 0;

		public int OldestLine {
			get {
				lock (logEntries) {
					return listOffset;
				}
			}
		}

		public int LatestLine {
			get {
				lock (logEntries) {
					return listOffset + logEntries.Count - 1;
				}
			}
		}

		public int StoredLines {
			get {
				lock (logEntries) {
					return logEntries.Count;
				}
			}
		}

		public LogEntry this [int index] {
			get {
				lock (logEntries) {
					if (index >= listOffset && index < listOffset + logEntries.Count) {
						return logEntries [index];
					}
				}
				return null;
			}
		}

		private LogBuffer () {
			Logger.Main.LogCallbacks += LogCallback;
		}

		private void LogCallback (string _msg, string _trace, LogType _type) {
			LogEntry le = new LogEntry ();

			Match match = logMessageMatcher.Match (_msg);
			if (match.Success) {
				le.date = match.Groups [1].Value;
				le.time = match.Groups [2].Value;
				le.uptime = match.Groups [3].Value;
				le.message = match.Groups [4].Value;
			} else {
				DateTime dt = DateTime.Now;
				le.date = string.Format ("{0:0000}-{1:00}-{2:00}", dt.Year, dt.Month, dt.Day);
				le.time = string.Format ("{0:00}:{1:00}:{2:00}", dt.Hour, dt.Minute, dt.Second);
				le.uptime = "";
				le.message = _msg;
			}

			le.trace = _trace;
			le.type = _type;

			lock (logEntries) {
				logEntries.Add (le);
				if (logEntries.Count > MAX_ENTRIES) {
					listOffset += logEntries.Count - MAX_ENTRIES;
					logEntries.RemoveRange (0, logEntries.Count - MAX_ENTRIES);
				}
			}
		}

		public List<LogEntry> GetRange (ref int _start, ref int _end) {
			lock (logEntries) {
				if (_end < 0) {
					_end = listOffset + logEntries.Count;
				}

				if (_start < listOffset) {
					_start = listOffset;
				}

				if (_start >= listOffset + logEntries.Count) {
					_end = _start;
					return new List<LogEntry> ();
				}

				if (_end < _start) {
					Log.Error ("GetRange: invalid end {0} (listOffset: {1}, count: {2})", _end, listOffset, logEntries.Count);
					return null;
				}

				if (_end >= listOffset + logEntries.Count) {
					_end = listOffset + logEntries.Count - 1;
				}

				return logEntries.GetRange (_start - listOffset, _end - _start + 1);
			}
		}


		public class LogEntry {
			public string date;
			public string time;
			public string uptime;
			public string message;
			public string trace;
			public LogType type;
		}
	}
}