using SDL2;

namespace KumiScript.Renderer
{
    public class ManagedFont : IDisposable
    {
        SDLFont _font;
        int _cachesize;
        SDL.SDL_Color _color;
        SDLRenderer _renderer;
        Dictionary<char, Glyph> _glyphs;
        LinkedList<char> _incidence;

        public ManagedFont(string path, int points, SDL.SDL_Color color, SDLRenderer renderer, int num_cache)
        {
            _font = new SDLFont(path, points);
            _renderer = renderer;
            _color = color;
            _glyphs = new Dictionary<char, Glyph>();
            _incidence = new LinkedList<char>();
            _cachesize = num_cache;
        }

        public Glyph GetGlyph(char c)
        {
            UpdateFreq(c);
            Glyph? g;
            if (!_glyphs.TryGetValue(c, out g))
                return CacheGlyph(c);
            
            return g;
        }

        private Glyph CacheGlyph(char c)
        {
            if (_glyphs.Count >= _cachesize)
                PurgeCache();

            Glyph g = new Glyph(c, _font, _color, _renderer);
            _glyphs.Add(c, g);
            return g;
        }

        private void UpdateFreq(char c)
        {
            _incidence.Remove(c);
            _incidence.AddFirst(c);
            return;
        }

        private void PurgeCache()
        {
            for (int i = _cachesize - 1; i > _cachesize * .75; i--)
            {
                char c = _incidence.Last();
                Glyph g = _glyphs[c];
                _glyphs.Remove(c);
                g.Dispose();
                _incidence.RemoveLast();
            }
            return;
        }

        public void Dispose()
        {
            List<Glyph> glyphs = _glyphs.Values.ToList();
            foreach (Glyph g in glyphs)
                g.Dispose();
            
            _font.Dispose();
        }
    }
}