using System;
using System.Collections.Generic;
using System.Globalization;
using System.Text.RegularExpressions;
using System.Windows.Forms;

using BizHawk.Emulation.Common;
using BizHawk.Client.Common;

using BizHawk.Emulation.Cores.Consoles.Sega.gpgx;

namespace BizHawk.Client.EmuHawk
{
	[Tool(false, null)]
	public partial class GenGameGenie : Form, IToolFormAutoConfig
	{
		#pragma warning disable 675

		/// <summary>
		/// For now this is is an unnecessary restriction to make sure it doesn't show up as available for non-genesis cores
		/// Note: this unnecessarily prevents it from being on the Genesis core, but that's okay it isn't released
		/// Eventually we want a generic game genie tool and a hack like this won't be necessary
		/// </summary>
		[RequiredService]
		private GPGX Emulator { get; set; }

		[RequiredService]
		private IMemoryDomains MemoryDomains { get; set; }

		private readonly Dictionary<char, int> _gameGenieTable = new Dictionary<char, int>
		{
			['A'] = 0,
			['B'] = 1,
			['C'] = 2,
			['D'] = 3,
			['E'] = 4,
			['F'] = 5,
			['G'] = 6,
			['H'] = 7,
			['J'] = 8,
			['K'] = 9,
			['L'] = 10,
			['M'] = 11,
			['N'] = 12,
			['P'] = 13,
			['R'] = 14,
			['S'] = 15,
			['T'] = 16,
			['V'] = 17,
			['W'] = 18,
			['X'] = 19,
			['Y'] = 20,
			['Z'] = 21,
			['0'] = 22,
			['1'] = 23,
			['2'] = 24,
			['3'] = 25,
			['4'] = 26,
			['5'] = 27,
			['6'] = 28,
			['7'] = 29,
			['8'] = 30,
			['9'] = 31
		};

		private bool _processing;

		#region Public API

		public bool AskSaveChanges() => true;

		public bool UpdateBefore => false;

		public void Restart()
		{
			if (Emulator.SystemId != "GEN")
			{
				Close();
			}
		}

		public void NewUpdate(ToolFormUpdateType type) { }

		public void UpdateValues()
		{
			if (Emulator.SystemId != "GEN")
			{
				Close();
			}
		}

		public void FastUpdate()
		{
			// Do nothing
		}

		public GenGameGenie()
		{
			InitializeComponent();
		}

		#endregion

		// code is code to be converted, val is pointer to value, add is pointer to address
		private void GenGGDecode(string code, ref int val, ref int add)
		{
			long hexCode = 0;

			// convert code to a long binary string
			foreach (var t in code)
			{
				hexCode <<= 5;
				_gameGenieTable.TryGetValue(t, out var y);
				hexCode |= y;
			}

			long decoded = (hexCode & 0xFF00000000) >> 32;
			decoded |= hexCode & 0x00FF000000;
			decoded |= (hexCode & 0x0000FF0000) << 16;
			decoded |= (hexCode & 0x00000000700) << 5;
			decoded |= (hexCode & 0x000000F800) >> 3;
			decoded |= (hexCode & 0x00000000FF) << 16;

			val = (int)(decoded & 0x000000FFFF);
			add = (int)((decoded & 0xFFFFFF0000) >> 16);
		}

		private static string GenGGEncode(int val, int add)
		{
			string code = null;

			var encoded = (long)(val & 0x00FF) << 32;
			encoded |= (val & 0xE000) >> 5;
			encoded |= (val & 0x1F00) << 3;
			encoded |= add & 0xFF0000;
			encoded |= (add & 0x00FF00) << 16;
			encoded |= add & 0x0000FF;

			char[] letters = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'V', 'W', 'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
			for (var i = 0; i < 8; i++)
			{
				var chr = (int)(encoded & 0x1F);
				code += letters[chr];
				encoded >>= 5; 
			}

			// reverse string, as its build backward
			var array = code.ToCharArray();
			Array.Reverse(array);
			return new string(array);
		}

		#region Dialog and Control Events

		private void GGCodeMaskBox_KeyPress(object sender, KeyPressEventArgs e)
		{
			// ignore I O Q U
			if ((e.KeyChar == 73) || (e.KeyChar == 79) || (e.KeyChar == 81) || (e.KeyChar == 85) ||
					(e.KeyChar == 105) || (e.KeyChar == 111) || (e.KeyChar == 113) || (e.KeyChar == 117))
			{
				e.KeyChar = '\n';
			}
		}

		private void GGCodeMaskBox_TextChanged(object sender, EventArgs e)
		{
			if (_processing == false)
			{
				_processing = true;

				// remove Invalid I O Q P if pasted
				GGCodeMaskBox.Text = GGCodeMaskBox.Text.Replace("I", "");
				GGCodeMaskBox.Text = GGCodeMaskBox.Text.Replace("O", "");
				GGCodeMaskBox.Text = GGCodeMaskBox.Text.Replace("Q", "");
				GGCodeMaskBox.Text = GGCodeMaskBox.Text.Replace("U", "");

				if (GGCodeMaskBox.Text.Length > 0)
				{
					int val = 0;
					int add = 0;
					GenGGDecode(GGCodeMaskBox.Text, ref val, ref add);
					AddressBox.Text = $"{add:X6}";
					ValueBox.Text = $"{val:X4}";
					AddCheatButton.Enabled = true;
				}
				else
				{
					AddressBox.Text = "";
					ValueBox.Text = "";
					AddCheatButton.Enabled = false;
				}

				_processing = false;
			}
		}

		private void AddressBox_TextChanged(object sender, EventArgs e)
		{
			// remove invalid character when pasted
			if (_processing == false)
			{
				_processing = true;
				if (Regex.IsMatch(AddressBox.Text, @"[^a-fA-F0-9]"))
				{
					AddressBox.Text = Regex.Replace(AddressBox.Text, @"[^a-fA-F0-9]", "");
				}

				if ((AddressBox.Text.Length > 0) || (ValueBox.Text.Length > 0))
				{
					int val = 0;
					int add = 0;
					if (ValueBox.Text.Length > 0)
					{
						val = int.Parse(ValueBox.Text, NumberStyles.HexNumber);
					}

					if (AddressBox.Text.Length > 0)
					{
						add = int.Parse(AddressBox.Text, NumberStyles.HexNumber);
					}

					GGCodeMaskBox.Text = GenGGEncode(val, add);
					AddCheatButton.Enabled = true;
				}
				else
				{
					GGCodeMaskBox.Text = "";
					AddCheatButton.Enabled = false;
				}

				_processing = false;
			}
		}

		private void ValueBox_TextChanged(object sender, EventArgs e)
		{
			if (_processing == false)
			{
				_processing = true;

				// remove invalid character when pasted
				if (Regex.IsMatch(ValueBox.Text, @"[^a-fA-F0-9]"))
				{
					ValueBox.Text = Regex.Replace(ValueBox.Text, @"[^a-fA-F0-9]", "");
				}

				if ((AddressBox.Text.Length > 0) || (ValueBox.Text.Length > 0))
				{
					int val = 0;
					int add = 0;
					if (ValueBox.Text.Length > 0)
					{
						val = int.Parse(ValueBox.Text, NumberStyles.HexNumber);
					}

					if (AddressBox.Text.Length > 0)
					{
						add = int.Parse(AddressBox.Text, NumberStyles.HexNumber);
					}

					GGCodeMaskBox.Text = GenGGEncode(val, add);
					AddCheatButton.Enabled = true;
				}
				else
				{
					GGCodeMaskBox.Text = "";
					AddCheatButton.Enabled = false;
				}

				_processing = false;
			}
		}

		private void ClearButton_Click(object sender, EventArgs e)
		{
			AddressBox.Text = "";
			ValueBox.Text = "";
			GGCodeMaskBox.Text = "";
			AddCheatButton.Enabled = false;
		}

		private void AddCheatButton_Click(object sender, EventArgs e)
		{
			string name;
			var address = 0;
			var value = 0;

			if (!string.IsNullOrWhiteSpace(cheatname.Text))
			{
				name = cheatname.Text;
			}
			else
			{
				_processing = true;
				GGCodeMaskBox.TextMaskFormat = MaskFormat.IncludeLiterals;
				name = GGCodeMaskBox.Text;
				GGCodeMaskBox.TextMaskFormat = MaskFormat.ExcludePromptAndLiterals;
				_processing = false;
			}

			if (!string.IsNullOrWhiteSpace(AddressBox.Text))
			{
				address = int.Parse(AddressBox.Text, NumberStyles.HexNumber);
			}

			if (!string.IsNullOrWhiteSpace(ValueBox.Text))
			{
				value = ValueBox.ToRawInt() ?? 0;
			}

			var watch = Watch.GenerateWatch(
				MemoryDomains["M68K BUS"],
				address,
				WatchSize.Word,
				Common.DisplayType.Hex,
				true,
				name
			);

			Global.CheatList.Add(new Cheat(
				watch,
				value
			));
		}

		#endregion
	}
}