using Microsoft.Extensions.Caching.Memory;
using CodePlay.Core.Interfaces;
using CodePlay.Core.Models;
using CodePlay.Core.Common;
using System.Security.Cryptography;
using System.Text;

namespace CodePlay.Core.Services;

public class CachedConversionService
{
    private readonly IConverter _innerConverter;
    private readonly IMemoryCache _cache;
    private readonly CacheOptions _cacheOptions;
    
    public CachedConversionService(IConverter innerConverter, IMemoryCache cache)
    {
        _innerConverter = innerConverter;
        _cache = cache;
        _cacheOptions = new CacheOptions { ExpirationMinutes = 60, UseCache = true };
    }
    
    public async Task<ConversionResult> ConvertAsync(SyntaxTree syntaxTree, LanguageType targetLanguage, ConversionOptions? options = null, CancellationToken cancellationToken = default)
    {
        if (!_cacheOptions.UseCache)
            return await _innerConverter.ConvertAsync(syntaxTree, targetLanguage, options, cancellationToken);
        
        var cacheKey = GenerateCacheKey(syntaxTree.SourceCode ?? "", syntaxTree.Language.ToString(), targetLanguage.ToString(), options);
        
        if (_cache.TryGetValue<ConversionResult>(cacheKey, out var cachedResult) && cachedResult != null)
            return cachedResult;
        
        var result = await _innerConverter.ConvertAsync(syntaxTree, targetLanguage, options, cancellationToken);
        _cache.Set(cacheKey, result, TimeSpan.FromMinutes(_cacheOptions.ExpirationMinutes));
        
        return result;
    }
    
    private string GenerateCacheKey(string sourceCode, string sourceLanguage, string targetLanguage, ConversionOptions? options)
    {
        var keySource = $"{sourceCode}|{sourceLanguage}|{targetLanguage}|{options?.KeepComments}|{options?.KeepDocStrings}";
        using var sha256 = SHA256.Create();
        return Convert.ToHexString(sha256.ComputeHash(Encoding.UTF8.GetBytes(keySource)));
    }
    
    public void InvalidateCache() { }
}

public class CacheOptions { public bool UseCache { get; set; } = true; public int ExpirationMinutes { get; set; } = 60; }