using System;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;
using Microsoft.Extensions.Caching.Memory;

namespace JobTrackerApi.Services
{
    public interface ISummarizerService
    {
        Task<string?> SummarizeAsync(string text, int maxLength = 150, int minLength = 30);
    }

    public class SummarizerService : ISummarizerService
    {
        private readonly IHttpClientFactory _httpFactory;
        private readonly IMemoryCache _cache;

        public SummarizerService(IHttpClientFactory httpFactory, IMemoryCache cache)
        {
            _httpFactory = httpFactory;
            _cache = cache;
        }

        public async Task<string?> SummarizeAsync(string text, int maxLength = 150, int minLength = 30)
        {
            if (string.IsNullOrWhiteSpace(text)) return null;

            var key = $"summ:{text.GetHashCode()}:{maxLength}:{minLength}";
            if (_cache.TryGetValue<string>(key, out var cached)) return cached;

            var client = _httpFactory.CreateClient("summarizer");
            var payload = JsonSerializer.Serialize(new { text, max_length = maxLength, min_length = minLength });
            using var content = new StringContent(payload, Encoding.UTF8, "application/json");

            try
            {
                var res = await client.PostAsync("/summarize", content);
                if (!res.IsSuccessStatusCode) return null;

                using var stream = await res.Content.ReadAsStreamAsync();
                using var doc = await JsonDocument.ParseAsync(stream);
                if (doc.RootElement.TryGetProperty("summary", out var el))
                {
                    var s = el.GetString();
                    if (!string.IsNullOrWhiteSpace(s)) _cache.Set(key, s, TimeSpan.FromHours(6));
                    return s;
                }

                return null;
            }
            catch
            {
                return null;
            }
        }
    }
}