using System;
using System.Threading;
using System.Threading.Tasks;
using UnityEngine;

namespace FlowScope.Save
{
    public sealed class SaveService : ISaveService
    {
        private readonly ISaveStorage _storage;
        private readonly ISaveSerializer _serializer;

        public SaveService(ISaveStorage storage, ISaveSerializer serializer)
        {
            _storage = storage ?? throw new ArgumentNullException(nameof(storage));
            _serializer = serializer ?? throw new ArgumentNullException(nameof(serializer));
        }

        public async Task SaveAsync<T>(string key, T data, CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();
            try
            {
                var bytes = _serializer.Serialize(data);
                await _storage.WriteAsync(key, bytes, cancellationToken);
            }
            catch (OperationCanceledException)
            {
                throw;
            }
            catch (Exception exception)
            {
                throw new InvalidOperationException($"Failed to write save key '{key}'.", exception);
            }
        }

        public async Task<T> LoadAsync<T>(string key, T defaultValue, CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();
            byte[] bytes;
            try
            {
                bytes = await _storage.ReadAsync(key, cancellationToken);
            }
            catch (OperationCanceledException)
            {
                throw;
            }
            catch (Exception exception)
            {
                Debug.LogWarning($"Failed to read save key '{key}': {exception.Message}");
                return defaultValue;
            }

            if (bytes == null)
            {
                return defaultValue;
            }

            try
            {
                return _serializer.Deserialize<T>(bytes);
            }
            catch (Exception exception)
            {
                Debug.LogWarning($"Failed to deserialize save key '{key}': {exception.Message}");
                return defaultValue;
            }
        }

        public void Delete(string key)
        {
            _storage.Delete(key);
        }

        public bool Exists(string key)
        {
            return _storage.Exists(key);
        }
    }
}