// This file is part of Capy64 - https://github.com/Ale32bit/Capy64
// Copyright 2023 Alessandro "AlexDevs" Proto
//
// Licensed under the Apache License, Version 2.0 (the "License").
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using Capy64.API;
using Capy64.Eventing.Events;
using KeraLua;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using System;
using static Capy64.Utils;

namespace Capy64.Runtime.Libraries;

internal class Term : IComponent
{
    private struct Char
    {
        public char Character;
        public Color Foreground;
        public Color Background;
        public bool Underline;
    }

    public const int CharWidth = 6;
    public const int CharHeight = 12;

    public const int CursorDelay = 30;

    public static int Width { get; private set; } = 57;
    public static int Height { get; private set; } = 23;
    public static int RealWidth => CharWidth * Width;
    public static int RealHeight => CharHeight * Height;
    public static Vector2 CharOffset => new(0, -1);
    public static Vector2 CursorPosition => _cursorPosition + Vector2.One;
    private static Vector2 _cursorPosition { get; set; }
    public static Color ForegroundColor { get; set; }
    public static Color BackgroundColor { get; set; }
    private static Char?[] CharGrid;

    private static IGame _game;
    private static bool cursorState = false;
    private static bool enableCursor = true;
    private static Texture2D cursorTexture;
    public Term(IGame game)
    {
        _game = game;

        _cursorPosition = Vector2.Zero;
        ForegroundColor = Color.White;
        BackgroundColor = Color.Black;

        cursorTexture = new(_game.Game.GraphicsDevice, 1, CharHeight - 3);
        var textureData = new Color[CharHeight - 3];
        Array.Fill(textureData, Color.White);
        cursorTexture.SetData(textureData);

        UpdateSize();

        _game.EventEmitter.OnOverlay += OnOverlay;
        _game.EventEmitter.OnScreenSizeChange += OnScreenSizeChange;
    }

    private LuaRegister[] TermLib = new LuaRegister[]
    {
        new()
        {
            name = "write",
            function = L_Write,
        },
        new()
        {
            name = "getPos",
            function = L_GetPos,
        },
        new()
        {
            name = "setPos",
            function = L_SetPos,
        },
        new()
        {
            name = "getSize",
            function = L_GetSize,
        },
        new()
        {
            name = "setSize",
            function = L_SetSize,
        },
        new()
        {
            name = "getForeground",
            function = L_GetForegroundColor,
        },
        new()
        {
            name = "setForeground",
            function = L_SetForegroundColor,
        },
        new()
        {
            name = "getBackground",
            function = L_GetBackgroundColor,
        },
        new()
        {
            name = "setBackground",
            function = L_SetBackgroundColor,
        },
        new()
        {
            name = "toRealPos",
            function = L_ToReal,
        },
        new()
        {
            name = "fromRealPos",
            function = L_FromReal,
        },
        new()
        {
            name = "clear",
            function = L_Clear,
        },
        new()
        {
            name = "clearLine",
            function = L_ClearLine,
        },
        new()
        {
            name = "scroll",
            function = L_Scroll,
        },
        new()
        {
            name = "getBlink",
            function = L_GetBlink,
        },
        new()
        {
            name = "setBlink",
            function = L_SetBlink,
        },
        new()
        {
            name = "blit",
            function = L_Blit,
        },
        new(),
    };

    public void LuaInit(Lua state)
    {
        state.RequireF("term", Open, false);
    }

    public int Open(IntPtr state)
    {
        var l = Lua.FromIntPtr(state);
        l.NewLib(TermLib);
        return 1;
    }

    public static void UpdateSize(bool resize = true)
    {
        Array.Resize(ref CharGrid, Width * Height);

        if (resize)
        {
            _game.Width = RealWidth;
            _game.Height = RealHeight;
            _game.UpdateSize();
        }
    }

    public static Vector2 ToRealPos(Vector2 termPos)
    {
        return new(termPos.X * CharWidth, termPos.Y * CharHeight);
    }

    public static void PlotChar(Vector2 pos, char ch, Color? fgc = null, Color? bgc = null, bool underline = false, bool save = true)
    {
        if (pos.X < 0 || pos.Y < 0 || pos.X >= Width || pos.Y >= Height)
            return;

        var fg = fgc ?? ForegroundColor;
        var bg = bgc ?? BackgroundColor;

        var realpos = ToRealPos(pos);
        var charpos = realpos + CharOffset;
        _game.Drawing.DrawRectangle(realpos, new(CharWidth, CharHeight), bg, Math.Min(CharWidth, CharHeight));
        //_game.Drawing.DrawRectangle(realpos, new(CharWidth, CharHeight), Color.Red, 1);

        try
        {
            _game.Drawing.DrawString(charpos, ch.ToString(), fg);

        }
        catch (ArgumentException ex) // UTF-16 fuckery
        {
            _game.Drawing.DrawString(charpos, "\xFFFD", fg);
        }

        if(underline)
        {
            _game.Drawing.DrawLine(charpos + new Vector2(0, CharHeight), charpos + new Vector2(CharWidth, CharHeight), fg);
        }

        if (!save)
            return;

        CharGrid[(int)pos.X + ((int)pos.Y * Width)] = new Char
        {
            Character = ch,
            Foreground = ForegroundColor,
            Background = BackgroundColor,
            Underline = underline,
        };
    }

    public static void RedrawPos(Vector2 pos)
    {
        if (pos.X < 0 || pos.Y < 0 || pos.X >= Width || pos.Y >= Height)
            return;

        var ch = CharGrid[(int)pos.X + ((int)pos.Y * Width)] ??
            new Char
            {
                Character = ' ',
                Foreground = ForegroundColor,
                Background = BackgroundColor,
            };

        PlotChar(pos, ch.Character, ch.Foreground, ch.Background, ch.Underline, false);
    }

    public static void RedrawAll()
    {
        for (int y = 0; y < Height; y++)
        {
            for (int x = 0; x < Width; x++)
            {
                RedrawPos(new(x, y));
            }
        }
    }

    public static void DumpScreen(bool clear = false)
    {
        if (clear)
            Console.Clear();
        Console.WriteLine("\n   /{0}", new string('-', Width));
        for (int i = 0; i < CharGrid.Length; i++)
        {
            if (i % Width == 0)
            {
                if (i > 0)
                    Console.Write("|\n");
                Console.Write("{0,3}:", i / Width);
            }
            Console.Write(CharGrid[i]?.Character ?? ' ');

        }
        Console.WriteLine("|\n   \\{0}", new string('-', Width));
    }

    private void OnOverlay(object sender, OverlayEvent e)
    {
        if (((int)e.TotalTicks % CursorDelay) == 0)
        {
            cursorState = !cursorState;
        }
        UpdateCursor();
    }

    private void OnScreenSizeChange(object sender, EventArgs e)
    {
        Width = _game.Width / CharWidth;
        Height = _game.Height / CharHeight;

        UpdateSize(false);
    }

    private static void UpdateCursor()
    {
        if (!enableCursor)
            return;

        if (_cursorPosition.X < 0 || _cursorPosition.Y < 0 || _cursorPosition.X >= Width || _cursorPosition.Y >= Height)
            return;

        if (cursorState)
        {
            var realpos = ToRealPos(CursorPosition - Vector2.One);
            var charpos = (realpos * _game.Scale) + (CharOffset + new Vector2(0, 2)) * _game.Scale;
            _game.Game.SpriteBatch.Draw(cursorTexture, charpos, null, ForegroundColor, 0f, Vector2.Zero, _game.Scale, SpriteEffects.None, 0);
        }
    }

    private static void ClearGrid()
    {
        CharGrid = new Char?[CharGrid.Length];
        _game.Drawing.Clear(BackgroundColor);
    }

    public static void Write(string text)
    {
        foreach (var ch in text)
        {
            PlotChar(_cursorPosition, ch);
            _cursorPosition = new(_cursorPosition.X + 1, _cursorPosition.Y);
        }
    }

    private static int L_Write(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);
        string str = "";
        if (!L.IsNone(1))
            str = L.ToString(1);

        Write(str);

        return 0;
    }

    public static void SetCursorPosition(int x, int y)
    {
        cursorState = true;
        _cursorPosition = new(x - 1, y - 1);
    }

    private static int L_GetPos(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        L.PushInteger((int)_cursorPosition.X + 1);
        L.PushInteger((int)_cursorPosition.Y + 1);

        return 2;
    }

    private static int L_SetPos(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        var x = L.CheckNumber(1);
        var y = L.CheckNumber(2);

        SetCursorPosition((int)x, (int)y);

        return 0;
    }

    public static void SetSize(int width, int height)
    {
        Width = width;
        Height = height;

        UpdateSize();
    }

    private static int L_GetSize(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        L.PushInteger(Width);
        L.PushInteger(Height);

        return 2;
    }

    private static int L_SetSize(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        var w = (int)L.CheckNumber(1);
        var h = (int)L.CheckNumber(2);

        if (w <= 0)
        {
            L.ArgumentError(1, "number must be greater than 0");
        }
        if (h <= 0)
        {
            L.ArgumentError(2, "number must be greater than 0");
        }

        SetSize(w - 1, h);

        return 0;
    }

    private static int L_GetForegroundColor(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        L.PushInteger(PackRGB(ForegroundColor));

        return 1;
    }

    private static int L_SetForegroundColor(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        var argsn = L.GetTop();

        byte r, g, b;
        // R, G, and B values
        if (argsn == 3)
        {
            r = (byte)L.CheckNumber(1);
            g = (byte)L.CheckNumber(2);
            b = (byte)L.CheckNumber(3);
        }
        // packed RGB value
        else if (argsn == 1)
        {
            var c = (uint)L.CheckInteger(1);
            UnpackRGB(c, out r, out g, out b);
        }
        else
        {
            L.ArgumentError(argsn, "expected 1 or 3 number values");
            return 0;
        }

        ForegroundColor = new(r, g, b);

        return 0;
    }

    private static int L_GetBackgroundColor(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        L.PushInteger(PackRGB(BackgroundColor));

        return 1;
    }

    private static int L_SetBackgroundColor(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        var argsn = L.GetTop();

        byte r, g, b;
        // R, G, and B values
        if (argsn == 3)
        {
            r = (byte)L.CheckNumber(1);
            g = (byte)L.CheckNumber(2);
            b = (byte)L.CheckNumber(3);
        }
        // packed RGB value
        else if (argsn == 1)
        {
            var c = (uint)L.CheckInteger(1);
            UnpackRGB(c, out r, out g, out b);
        }
        else
        {
            L.ArgumentError(argsn, "expected 1 or 3 number values");
            return 0;
        }

        BackgroundColor = new(r, g, b);

        return 0;
    }

    private static int L_ToReal(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        var x = (int)L.CheckNumber(1);
        var y = (int)L.CheckNumber(2);

        L.PushInteger((x * CharWidth) - CharWidth + 1);
        L.PushInteger((y * CharHeight) - CharHeight + 1);

        return 2;
    }

    private static int L_FromReal(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        var x = (int)L.CheckNumber(1) - 1;
        var y = (int)L.CheckNumber(2) - 1;

        L.PushInteger((x / CharWidth) + 1);
        L.PushInteger((y / CharHeight) + 1);

        return 2;
    }

    public static void Clear()
    {
        ClearGrid();

        RedrawAll();
    }

    private static int L_Clear(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        Clear();

        return 0;
    }

    public static void ClearLine()
    {
        for (int x = 0; x < Width; x++)
            PlotChar(new(x, _cursorPosition.Y), ' ');
    }

    private static int L_ClearLine(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        ClearLine();

        return 0;
    }

    public static void Scroll(int lines)
    {
        if (lines == 0)
            return;

        if (lines <= -Height || lines >= Height)
        {
            ClearGrid();
            return;
        }

        var lineLength = Math.Abs(lines) * Width;
        var newGrid = new Char?[CharGrid.Length];
        if (lines < 0)
        {
            Array.Copy(CharGrid, lineLength, newGrid, 0, CharGrid.Length - lineLength);
        }
        else
        {
            Array.Copy(CharGrid, 0, newGrid, lineLength, CharGrid.Length - lineLength);
        }

        CharGrid = newGrid;

        RedrawAll();
    }

    private static int L_Scroll(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        var lines = L.CheckInteger(1) * -1;

        Scroll((int)lines);

        return 0;
    }

    public static void SetCursorBlink(bool enable)
    {
        enableCursor = enable;

        if (!enableCursor)
        {
            RedrawPos(_cursorPosition);
        }
    }

    private static int L_GetBlink(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        L.PushBoolean(enableCursor);

        return 1;
    }

    private static int L_SetBlink(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        L.CheckType(1, LuaType.Boolean);
        var enableCursor = L.ToBoolean(1);

        SetCursorBlink(enableCursor);

        return 0;
    }

    private static int L_Blit(IntPtr state)
    {
        var L = Lua.FromIntPtr(state);

        var text = L.CheckString(1);
        L.CheckType(2, LuaType.Table);
        L.CheckType(3, LuaType.Table);

        // use .Length instead of Lua's Len
        // for UTF-8 support
        var len = text.Length;
        L.ArgumentCheck(L.Length(2) == len, 2, "length does not match");
        L.ArgumentCheck(L.Length(3) == len, 3, "length does not match");

        for (int i = 1; i <= len; i++)
        {
            L.GetInteger(2, i);
            var fgv = (uint)L.CheckInteger(-1);
            L.Pop(1);

            L.GetInteger(3, i);
            var bgv = (uint)L.CheckInteger(-1);
            L.Pop(1);

            // RGB to ABGR
            fgv =
                ((fgv & 0x00_FF_00_00U) >> 16) | // move R
                (fgv & 0x00_00_FF_00U) |       // move G
                ((fgv & 0x00_00_00_FFU) << 16) | // move B
                0xFF_00_00_00U;

            bgv =
                ((bgv & 0x00_FF_00_00U) >> 16) | // move R
                (bgv & 0x00_00_FF_00U) |       // move G
                ((bgv & 0x00_00_00_FFU) << 16) | // move B
                0xFF_00_00_00U;


            ForegroundColor = new(fgv);
            BackgroundColor = new(bgv);
            Write(text[i - 1].ToString());
        }

        return 0;
    }
}