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

namespace EnvelopeGenerator.Server.Client.Services;

/// <summary>
/// Fetches and caches the CustomImages configuration (signFLOW + company logos)
/// from GET /api/CustomImages.
///
/// Config changes rarely (deployment-time only), so results are cached in-memory
/// for the lifetime of the service (WASM app session). No TTL needed.
/// </summary>
public class CustomImagesService(IHttpClientFactory clientFactory)
{
    private static readonly JsonSerializerOptions _json = new(JsonSerializerDefaults.Web);
    private const string Endpoint = "/api/CustomImages";

    private CustomImagesDto? _cached;

    /// <summary>
    /// Returns logo configuration. Fetches once from server; all subsequent calls
    /// are served from memory with zero network overhead.
    /// Returns defaults (empty Src) on auth failure (401) — components must handle gracefully.
    /// </summary>
    public async Task<CustomImagesDto> GetAsync(CancellationToken ct = default)
    {
        if (_cached is not null)
            return _cached;

        try
        {
            var client = clientFactory.CreateClient("EnvelopeGenerator.Server");
            var response = await client.GetAsync(Endpoint, ct);

            if (!response.IsSuccessStatusCode)
            {
                // Not authenticated yet (login page) — return defaults silently.
                _cached = new CustomImagesDto();
                return _cached;
            }

            _cached = await response.Content.ReadFromJsonAsync<CustomImagesDto>(_json, ct)
                      ?? new CustomImagesDto();
            return _cached;
        }
        catch (Exception)
        {
            // Network error or server unavailable — return defaults so UI still renders.
            return new CustomImagesDto();
        }
    }

    /// <summary>Call after logout to force re-fetch on next login.</summary>
    public void Invalidate() => _cached = null;
}