deepdrft/DeepDrftPublic.Client/Clients/TrackMediaClient.cs

using System.Net;
using System.Net.Http.Json;
using DeepDrftModels.DTOs;
using Microsoft.Extensions.DependencyInjection;
using NetBlocks.Models;

namespace DeepDrftPublic.Client.Clients;

public class TrackMediaResponse : IDisposable
{
    public Stream Stream { get; }
    public long ContentLength { get; }

    public TrackMediaResponse(Stream stream, long contentLength)
    {
        Stream = stream;
        ContentLength = contentLength;
    }

    public void Dispose()
    {
        Stream?.Dispose();
    }
}

public class TrackMediaClient
{
    private readonly HttpClient _http;

    public TrackMediaClient(IHttpClientFactory httpClientFactory)
    {
        _http = httpClientFactory.CreateClient("DeepDrft.Content");
    }

    /// <summary>
    /// Fetches the WAV stream for a track, optionally starting from a byte offset.
    /// The cancellation token is forwarded to <see cref="HttpClient.GetAsync"/> so a
    /// navigation or seek-replacement aborts the in-flight server connection rather
    /// than leaving the server draining bytes into a dead socket.
    /// </summary>
    public async Task<ApiResult<TrackMediaResponse>> GetTrackMedia(
        string trackId,
        long byteOffset = 0,
        CancellationToken cancellationToken = default)
    {
        try
        {
            // Build URL with optional offset parameter
            var url = byteOffset > 0
                ? $"api/track/{trackId}?offset={byteOffset}"
                : $"api/track/{trackId}";

            // Use HttpCompletionOption.ResponseHeadersRead to get stream immediately
            var response = await _http.GetAsync(url, HttpCompletionOption.ResponseHeadersRead, cancellationToken);
            response.EnsureSuccessStatusCode();

            var contentLength = response.Content.Headers.ContentLength ?? 0;
            var stream = await response.Content.ReadAsStreamAsync(cancellationToken);

            return ApiResult<TrackMediaResponse>.CreatePassResult(new TrackMediaResponse(stream, contentLength));
        }
        catch (Exception e)
        {
            return ApiResult<TrackMediaResponse>.CreateFailResult(e.Message);
        }
    }

    /// <summary>
    /// Fetches a track's stored waveform loudness profile. A 404 means no profile is stored
    /// (existing tracks predate profiling, or computation failed at upload); callers treat that
    /// as "render a flat seekbar" rather than an error, so it surfaces as a fail result with a
    /// stable message rather than throwing.
    /// </summary>
    public async Task<ApiResult<WaveformProfileDto>> GetWaveformProfileAsync(string trackId, CancellationToken cancellationToken = default)
    {
        try
        {
            var response = await _http.GetAsync($"api/track/{trackId}/waveform", cancellationToken);
            if (response.StatusCode == HttpStatusCode.NotFound)
            {
                return ApiResult<WaveformProfileDto>.CreateFailResult("No waveform profile available");
            }

            response.EnsureSuccessStatusCode();

            var profile = await response.Content.ReadFromJsonAsync<WaveformProfileDto>();
            if (profile is null)
            {
                return ApiResult<WaveformProfileDto>.CreateFailResult("Waveform profile response was empty");
            }

            return ApiResult<WaveformProfileDto>.CreatePassResult(profile);
        }
        catch (Exception e)
        {
            return ApiResult<WaveformProfileDto>.CreateFailResult(e.Message);
        }
    }
}