using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;
using static System.Text.Json.JsonSerializer;

namespace AnotherReplayReader
{
    internal sealed class Cache
    {
        public static string CacheDirectory => Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "RA3Bar.Lanyi.AnotherReplayReader");
        public static string CacheFilePath => Path.Combine(CacheDirectory, "AnotherReplayReader.cache");

        private readonly ConcurrentDictionary<string, string> _storage = new();
        
        public Task Initialization { get; }

        public Cache()
        {
            Initialization = Task.Run(async () =>
            {
                try
                {
                    if (!Directory.Exists(CacheDirectory))
                    {
                        Directory.CreateDirectory(CacheDirectory);
                    }

                    using var cacheStream = File.OpenRead(CacheFilePath);
                    var futureCache = DeserializeAsync<Dictionary<string, string>>(cacheStream).ConfigureAwait(false);
                    if (await futureCache is not { } cached)
                    {
                        return;
                    }
                    foreach (var kv in cached)
                    {
                        _storage.TryAdd(kv.Key, kv.Value);
                    }
                }
                catch { }
            });
        }

        public T GetOrDefault<T>(string key, in T defaultValue)
        {
            try
            {
                if (_storage.TryGetValue(key, out var valueString))
                {
                    return Deserialize<T>(valueString) ?? defaultValue;
                }
            }
            catch { }
            return defaultValue;
        }

        public void Set<T>(string key, in T value)
        {
            try
            {
                _storage[key] = Serialize(value);
                Save();
            }
            catch { }
        }

        public void SetValues(params (string Key, object Value)[] values)
        {
            try
            {
                foreach (var (key, value) in values)
                {
                    _storage[key] = Serialize(value);
                }
                Save();
            }
            catch { }
        }

        public void Remove(string key)
        {
            _storage.TryRemove(key, out _);
            Save();
        }

        public async void Save()
        {
            try
            {
                using var cacheStream = File.Open(CacheFilePath, FileMode.Create, FileAccess.Write);
                await SerializeAsync(cacheStream, _storage).ConfigureAwait(false);
            }
            catch { }
        }
    }
}