using System.Net.Http;
using System.Text;
using System.Text.Json;

namespace JobTrackerApi.Services;

public sealed record CvBlockClassificationResult(
    string? Section,
    double? Confidence,
    string? Reason,
    string? Title,
    string? Company,
    string? Location,
    string? Start,
    string? End,
    List<string>? Bullets,
    List<string>? Summary,
    List<string>? Skills);

public interface ICvAiClassifier
{
    Task<CvBlockClassificationResult?> ClassifyBlockAsync(string block, CancellationToken cancellationToken = default);
}

public sealed class CvAiClassifier : ICvAiClassifier
{
    private readonly IHttpClientFactory _httpClientFactory;

    public CvAiClassifier(IHttpClientFactory httpClientFactory)
    {
        _httpClientFactory = httpClientFactory;
    }

    public async Task<CvBlockClassificationResult?> ClassifyBlockAsync(string block, CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrWhiteSpace(block)) return null;

        try
        {
            var client = _httpClientFactory.CreateClient("ai-service");
            var payload = JsonSerializer.Serialize(new { block });
            using var content = new StringContent(payload, Encoding.UTF8, "application/json");
            using var response = await client.PostAsync("/cv/classify-block", content, cancellationToken);
            if (!response.IsSuccessStatusCode) return null;

            await using var stream = await response.Content.ReadAsStreamAsync(cancellationToken);
            var parsed = await JsonSerializer.DeserializeAsync<CvBlockClassificationResult>(stream, new JsonSerializerOptions(JsonSerializerDefaults.Web)
            {
                PropertyNameCaseInsensitive = true
            }, cancellationToken);

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

public sealed class NoOpCvAiClassifier : ICvAiClassifier
{
    public static NoOpCvAiClassifier Instance { get; } = new();
    private NoOpCvAiClassifier() { }
    public Task<CvBlockClassificationResult?> ClassifyBlockAsync(string block, CancellationToken cancellationToken = default)
        => Task.FromResult<CvBlockClassificationResult?>(null);
}