using System.Net.Http.Json;
using System.Text.Json;
using EnvelopeGenerator.ReceiverUI.Models;
using EnvelopeGenerator.ReceiverUI.Options;
using Microsoft.Extensions.Options;

namespace EnvelopeGenerator.ReceiverUI.Services;

/// <summary>
/// Retrieves annotation positions from the API.
/// The URL is composed as <c>{BaseUrl}/api/Annotation/{envelopeKey}</c>.
/// During development, <c>BaseUrl</c> is empty so the request resolves to the
/// YARP-proxied route on the same origin, which currently serves
/// <c>fake-data/annotations.json</c>. To switch to real data, update the
/// YARP route in <c>yarp.json</c> — no code change required.
/// </summary>
public class AnnotationService(HttpClient http, IOptions<ApiOptions> apiOptions)
{
    private static readonly JsonSerializerOptions _jsonOptions = new(JsonSerializerDefaults.Web);

    public async Task<IReadOnlyList<AnnotationDto>> GetAnnotationsAsync(string envelopeKey, CancellationToken cancel = default)
    {
        var url = $"{apiOptions.Value.BaseUrl}/api/Annotation/{Uri.EscapeDataString(envelopeKey)}";
        var response = await http.GetAsync(url, cancel);

        if (!response.IsSuccessStatusCode)
            return [];

        var result = await response.Content.ReadFromJsonAsync<List<AnnotationDto>>(_jsonOptions, cancel);
        return result ?? [];
    }
}