namespace HrynCo.Common.Caching;

using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Caching.Memory;

public sealed class InMemorySessionPromptStore : ISessionPromptStore
{
    private readonly IMemoryCache _cache;

    public InMemorySessionPromptStore(IMemoryCache cache)
    {
        _cache = cache;
    }

    public Task<string?> GetAsync(Guid userId, string provider, CancellationToken cancellationToken = default)
    {
        _ = cancellationToken;
        _cache.TryGetValue(BuildKey(userId, provider), out string? prompt);
        return Task.FromResult(prompt);
    }

    public Task RemoveAsync(Guid userId, string provider, CancellationToken cancellationToken = default)
    {
        _ = cancellationToken;
        _cache.Remove(BuildKey(userId, provider));
        return Task.CompletedTask;
    }

    public Task SaveAsync(
        Guid userId,
        string provider,
        string prompt,
        TimeSpan ttl,
        CancellationToken cancellationToken = default)
    {
        _ = cancellationToken;
        _cache.Set(
            BuildKey(userId, provider),
            prompt,
            new MemoryCacheEntryOptions
            {
                AbsoluteExpirationRelativeToNow = ttl,
                SlidingExpiration = TimeSpan.FromMinutes(30)
            });

        return Task.CompletedTask;
    }

    private static string BuildKey(Guid userId, string provider)
    {
        return $"ai-session-prompt:{provider}:{userId:N}";
    }
}