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

namespace FlowScope.Save
{
    public sealed class PlayerPrefsSaveStorage : ISaveStorage
    {
        private const string Prefix = "FlowScope.Save.";

        public Task WriteAsync(string key, byte[] data, CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();
            if (data == null)
            {
                throw new ArgumentNullException(nameof(data));
            }

            PlayerPrefs.SetString(ToPrefsKey(key), Convert.ToBase64String(data));
            PlayerPrefs.Save();
            return Task.CompletedTask;
        }

        public Task<byte[]> ReadAsync(string key, CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();
            var prefsKey = ToPrefsKey(key);
            return Task.FromResult(PlayerPrefs.HasKey(prefsKey)
                ? Convert.FromBase64String(PlayerPrefs.GetString(prefsKey))
                : null);
        }

        public void Delete(string key)
        {
            PlayerPrefs.DeleteKey(ToPrefsKey(key));
            PlayerPrefs.Save();
        }

        public bool Exists(string key)
        {
            return PlayerPrefs.HasKey(ToPrefsKey(key));
        }

        private static string ToPrefsKey(string key)
        {
            if (string.IsNullOrWhiteSpace(key))
            {
                throw new ArgumentException("Save key is required.", nameof(key));
            }

            return Prefix + key;
        }
    }
}