using System.Diagnostics.CodeAnalysis;
using System.Linq;

using DaggerFramework.Utils;

namespace DaggerFramework.Resources
{
    public class ResourceManager
    {
        public string ResourceRoot { get; set; } = "Resources/";

        public bool TryLoad<T>(string resourceId, string path) where T : Resource
        {
            T? resource = null;

            var fullPath = Path.Combine(ResourceRoot, path);

            // TODO: don't check if file doesn't exist in the file system, make it more generic but for now it's fine
            if (!File.Exists(fullPath))
            {
                _logger.Error($"File at \"{path}\" doesn't exist!");
                return false;
            }

            _logger.Info($"Loading {path} as {typeof(T)} with id \"{resourceId}\"...");

            if (!TryGetLoader(out IResourceLoader<T>? loader))
            {
                return false;
            }

            var extension = Path.GetExtension(fullPath);
            var hasExtension = loader.SupportedExtensions.Any(ext => extension[1..] == ext);

            if (!hasExtension)
            {
                _logger.Error($"Extension {extension} is not supported!");
            }

            if (loader.Load(fullPath) is not T loadedResource)
            {
                return false;
            }

            resource = loadedResource;
            _loadedResources.Add(resourceId, resource);

            _logger.Info($"\"{resourceId}\" was loaded successfully.");

            return true;
        }

        public bool TrySave<T>(string path, in T resource) where T : Resource
        {
            if (!TryGetSaver(out IResourceSaver<T>? saver))
            {
                return false;
            }

            if (!saver.TrySave(path, in resource))
            {
                return false;
            }

            return true;
        }

        public bool TryGetResource<T>(string resourceId, [NotNullWhen(true)] out T? resource) where T : Resource
        {
            resource = null;

            if (!IsResourceLoaded(resourceId))
            {
                _logger.Error($"Resource \"{resourceId}\" has not yet been loaded!");
                return false;
            }

            var expectedResource = _loadedResources[resourceId];

            if (expectedResource is not T loadedResource)
            {
                _logger.Error($"Given resource is of wrong type: provided {typeof(T)}, expected {expectedResource.GetType()}!");
                return false;
            }

            resource = loadedResource;

            return true;
        }

        public bool IsResourceLoaded(string resourceId) => _loadedResources.ContainsKey(resourceId);

        public void AddResourceLoaderAssociation<T>(IResourceLoader<T> loader) where T : Resource
        {
            _logger.Info($"Added resource loader association for {typeof(T)}.");
            _resourceLoaderAssociations.Add(typeof(T), loader);
        }

        public void AddResourceSaverAssociation<T>(IResourceSaver<T> saver) where T : Resource
        {
            _logger.Info($"Added resource saver association for {typeof(T)}.");
            _resourceSaverAssociations.Add(typeof(T), saver);
        }

        private bool TryGetLoader<T>([NotNullWhen(true)] out IResourceLoader<T>? loader) where T : Resource
        {
            loader = null;

            if (!_resourceLoaderAssociations.ContainsKey(typeof(T)))
            {
                _logger.Error($"No loader association found for {typeof(T)}.");
                return false;
            }

            loader = _resourceLoaderAssociations[typeof(T)] as IResourceLoader<T>;

            if (loader is not null)
            {
                _logger.Info($"Using {loader.GetType()} for loading...");
            }
            else
            {
                _logger.Error($"No loader association found for {typeof(T)}.");
                return false;
            }

            return true;
        }

        private bool TryGetSaver<T>([NotNullWhen(true)] out IResourceSaver<T>? saver) where T : Resource
        {
            saver = null;

            if (!_resourceSaverAssociations.ContainsKey(typeof(T)))
            {
                _logger.Error($"No saver association found for {typeof(T)}.");
                return false;
            }

            saver = _resourceSaverAssociations[typeof(T)] as IResourceSaver<T>;

            if (saver is not null)
            {
                _logger.Info($"Using {saver.GetType()} for saving...");
            }
            else
            {
                _logger.Error($"No saver association found for {typeof(T)}.");
                return false;
            }

            return true;
        }

        private Logger _logger = new(nameof(ResourceManager));

        private readonly Dictionary<Type, object> _resourceLoaderAssociations = new()
        {
            {typeof(Sound), new SoundLoader()},
            {typeof(Texture2d), new Texture2dLoader()},
            {typeof(Font), new FontLoader()}
        };

        private readonly Dictionary<Type, object> _resourceSaverAssociations = new()
        {

        };

        private Dictionary<string, Resource> _loadedResources = new();
    }
}