using System;
using Microsoft.Xna.Framework.Graphics;

namespace FreedomFighter;

/// <summary>
/// Port of TOmegaBitmapFont: a fixed-cell bitmap font backed by an image list item,
/// with mutable color/alpha state (the credits animate Alpha on the shared font).
/// </summary>
public class BitmapFont
{
    public string Characters = "";
    public OmegaImage Image = null!;
    public int Red = 255, Green = 255, Blue = 255;
    public int Alpha = 255;

    public int CharWidth => Image.TileWidth;
    public int CharHeight => Image.TileHeight;

    public BitmapFont(OmegaImage image, string characters)
    {
        Image = image;
        Characters = characters;
    }

    public void PrintFast(SpriteBatch sb, float x, float y, char c)
    {
        int idx = Characters.IndexOf(c);
        if (idx < 0) return;
        Image.Draw(sb, x, y, 0, 0, 0, 1, 1, Red, Green, Blue, Math.Clamp(Alpha, 0, 255), idx);
    }

    public void Print(SpriteBatch sb, float x, float y, string text)
    {
        for (int i = 0; i < text.Length; i++)
            PrintFast(sb, x + i * CharWidth, y, text[i]);
    }
}

/// <summary>
/// Port of the TGameText helper (GameText.pas): typewriter printing and
/// fade in/out of text through a bitmap font's shared Alpha.
/// </summary>
public class GameText
{
    string _text;
    int _length;
    int _curChar;
    int _maxLength;
    int _timer;
    int _speed = 10;
    bool _done;
    readonly BitmapFont _font;

    public GameText(string msg, int rowLength, BitmapFont font)
    {
        _text = msg;
        _length = msg.Length;
        _maxLength = rowLength;
        _font = font;
    }

    public void SetText(string msg)
    {
        _text = msg;
        _length = msg.Length;
        _curChar = 0;
        _timer = 0;
    }

    public void SetSpeed(int speed) => _speed = speed;
    public bool IsDone => _done;
    public string GetText() => _text;
    public int GetLength() => _length * _font.CharWidth;

    // The Pascal original indexed the 1-based string with i = 0..CurChar; index 0 was a no-op.
    void PrintChars(SpriteBatch sb, float x, float y, int upTo)
    {
        for (int i = 1; i <= upTo && i <= _length; i++)
        {
            char c = _text[i - 1];
            if (i <= _maxLength)
                _font.PrintFast(sb, x + i * _font.CharWidth, y, c);
            else
            {
                int tempChar = i;
                while (tempChar > _maxLength) tempChar -= _maxLength;
                _font.PrintFast(sb, x + tempChar * 12, y + (int)Math.Ceiling(i / (double)_maxLength) * 24 - 24, c);
            }
        }
    }

    public void TypePrint(SpriteBatch sb, float x, float y)
    {
        _done = false;
        PrintChars(sb, x, y, _curChar);

        if (_curChar < _length)
        {
            _timer++;
            if (_timer > _speed)
            {
                _curChar++;
                if (_curChar <= _length && _curChar >= 1 && _text[_curChar - 1] == ' ')
                    _curChar++;
                _timer = 0;
            }
        }
        else
            _done = true;
    }

    public void FadeIn(SpriteBatch sb, float x, float y, int speed)
    {
        _done = false;
        PrintChars(sb, x, y, _length);
        _timer++;
        if (_timer > speed && _font.Alpha < 255)
            _font.Alpha++;
        else
            _done = true;   // original quirk: also "done" while the timer is still counting
    }

    public void FadeOut(SpriteBatch sb, float x, float y, int speed)
    {
        _done = false;
        PrintChars(sb, x, y, _length);
        _timer++;
        if (_timer > speed && _font.Alpha > 0)
            _font.Alpha--;
        else
            _done = true;
    }

    public void Reset()
    {
        _curChar = 0;
        _timer = 0;
        _speed = 10;
        _done = false;
    }
}