using System.IO;
using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;

namespace GifResizer.Models;

public class Gif : IDisposable
{

    private readonly string _path;
    private Image? _image;
    
    public Gif(string path)
    {
        ArgumentNullException.ThrowIfNull(path);
        if (path.Length == 0 || path.IsWhiteSpace() || !File.Exists(path)) 
            throw new ArgumentException($"File '{path}' does not exist");
        _path = path;
    }

    public void Load()
    {
        _image = Image.Load(_path);
    }
    
    public void Resize(int width, int height)
    {
        if(_image == null) throw new InvalidOperationException("Image hasn't been loaded yet");
        if(width <= 0 || height <= 0) throw new InvalidOperationException("Please specify a valid width or height.");
        if(width == _image.Width && height == _image.Height) return;
        _image.Mutate(x => x.Resize(width, height));
    }

    public void Save(string outputPath)
    {
        if(_image == null) throw new InvalidOperationException("Image hasn't been loaded yet");
        var directory = Path.GetDirectoryName(outputPath);
        if (!string.IsNullOrEmpty(directory))
        {
            Directory.CreateDirectory(directory);
        }
        _image.Save(Path.Combine(outputPath));
    }

    public void Dispose()
    {
        _image?.Dispose();
    }
}