using System;
using System.Collections.Generic;
using System.Threading;

namespace ProgressBarLib {
	public class ProgressBar {
		private volatile bool _shouldStop;
		private volatile List<string> _msgList = new List<string>();
		private volatile List<string> _errList = new List<string>();
		private volatile int _lastCurr;
		private volatile int _lastTotal;
		private volatile string _lastMsg = "";
		private volatile string _mainMsg = "";
		private readonly object _lock = new object();
		private volatile bool _hasStopped;

		public ProgressBar() {
			new Thread(() => {
				Thread.CurrentThread.IsBackground = true;
				while (!_shouldStop) {
					lock (_lock) {
						if (_msgList.Count > 0) {
							ClearCurrentConsoleLine();
							foreach (var msg in _msgList) {
								Console.WriteLine(msg.Length < Console.WindowWidth
									? msg
									: msg.Substring(0, Console.WindowWidth - 1));
							}

							_msgList.Clear();
						}

						if (_errList.Count > 0) {
							ClearCurrentConsoleLine();
							foreach (var err in _errList) {
								Console.WriteLine("ERROR: " + err);
							}

							_errList.Clear();
						}
					}

					ClearCurrentConsoleLine();
					Console.Write("\r" + _mainMsg);
					Thread.Sleep(500);
				}

				if (_errList.Count > 0) {
					ClearCurrentConsoleLine();
					foreach (var err in _errList) {
						Console.WriteLine("ERROR: " + err);
					}

					_errList.Clear();
				}

				if (_msgList.Count > 0) {
					ClearCurrentConsoleLine();
					foreach (var msg in _msgList) {
						Console.WriteLine(msg.Length < Console.WindowWidth
							? msg
							: msg.Substring(0, Console.WindowWidth - 1));
					}

					_msgList.Clear();
				}
				else {
					ClearCurrentConsoleLine();
					Console.Write("\r" + _mainMsg);
				}

				_hasStopped = true;
			}).Start();
		}

		public void UpdateMain(int curr, int total, string msg) {
			var currstr = curr.ToString();
			for (var i = total.ToString().Length - curr.ToString().Length; i > 0; i--)
				currstr = " " + currstr;
			UpdateMainAdv(curr, total, currstr, msg);
		}

		public void UpdateMainAdv(int curr, int total, string custCurr, string msg) {
			var outMsg = $"({custCurr}/{total}) ";
			var progPart = MakeProgressBar(curr, total);
			var msgMaxLength = Console.WindowWidth - outMsg.Length - progPart.Length;

			if (msgMaxLength < 0) {
				_mainMsg = "Increase terminal width";
				return;
			}

			if (msg.Length < msgMaxLength)
				for (var i = (msgMaxLength - msg.Length); i > 0; i--)
					msg += " ";
			else
				msg = msg.Substring(0, msgMaxLength);

			outMsg += msg;
			outMsg += progPart;

			_lastCurr = curr;
			_lastMsg = msg;
			_lastTotal = total;

			_mainMsg = outMsg;
		}

		public void Tick() {
			_lastCurr++;
			UpdateMain(_lastCurr, _lastTotal, _lastMsg);
		}

		public void PushMsg(string msg) {
			lock (_lock)
				_msgList.Add(msg);
		}

		public void PushErr(string err) {
			lock (_lock)
				_errList.Add(err);
		}

		public void Stop() {
			_shouldStop = true;
			while (!_hasStopped) { }
		}

		private static string MakeProgressBar(int curr, int total) {
			if (curr > total)
				curr = total;
			const string fullChar = "=";
			const string blankChar = "-";

			var progStr = "[";

			var fullCharCount = (int) (15d / total * curr);
			var blankCharCount = 15 - fullCharCount;

			for (var i = fullCharCount; i > 0; i--) progStr += fullChar;
			for (var i = blankCharCount; i > 0; i--) progStr += blankChar;

			progStr += "]";

			return progStr;
		}

		private static void ClearCurrentConsoleLine() {
			var currentLineCursor = Console.CursorTop;
			Console.SetCursorPosition(0, Console.CursorTop);
			Console.Write(new string(' ', Console.WindowWidth));
			Console.SetCursorPosition(0, currentLineCursor);
		}
	}
}