ContentGen_BE/media-worker/Services/SunoMusicService.cs

using System.Text;
using System.Text.Json;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using SaasMediaWorker.Configuration;
using SaasMediaWorker.Models;

namespace SaasMediaWorker.Services;

/// <summary>
/// Suno AI API Client — Background müzik üretimi.
/// Projenin musicPrompt'unu kullanarak AI müzik üretir.
/// </summary>
public class SunoMusicService
{
    private readonly HttpClient _httpClient;
    private readonly ILogger<SunoMusicService> _logger;
    private readonly ApiSettings _settings;

    public SunoMusicService(
        HttpClient httpClient,
        ILogger<SunoMusicService> logger,
        IOptions<ApiSettings> settings)
    {
        _httpClient = httpClient;
        _logger = logger;
        _settings = settings.Value;

        _httpClient.BaseAddress = new Uri(_settings.SunoBaseUrl);
        _httpClient.DefaultRequestHeaders.Add("Authorization", $"Bearer {_settings.SunoApiKey}");
        _httpClient.Timeout = TimeSpan.FromMinutes(5);
    }

    /// <summary>
    /// Proje için background müzik üretir ve dosyaya kaydeder.
    /// </summary>
    public async Task<GeneratedMediaFile> GenerateMusicAsync(
        string musicPrompt,
        int targetDurationSeconds,
        string outputDirectory,
        CancellationToken ct)
    {
        _logger.LogInformation(
            "🎵 Müzik üretimi — Prompt: \"{Prompt}\", Süre: {Duration}s",
            musicPrompt[..Math.Min(80, musicPrompt.Length)],
            targetDurationSeconds);

        var requestBody = new
        {
            prompt = musicPrompt,
            duration = Math.Min(120, targetDurationSeconds + 5), // Biraz fazla üret (fade-out için)
            make_instrumental = true, // Vokal olmadan
            model = "chirp-v3"
        };

        var content = new StringContent(
            JsonSerializer.Serialize(requestBody),
            Encoding.UTF8,
            "application/json");

        var response = await _httpClient.PostAsync("/generations", content, ct);
        response.EnsureSuccessStatusCode();

        var responseJson = await response.Content.ReadAsStringAsync(ct);
        var result = JsonSerializer.Deserialize<JsonElement>(responseJson);

        // Generation ID al
        var generationId = result.GetProperty("id").GetString()
            ?? throw new InvalidOperationException("Suno generation ID alınamadı");

        _logger.LogInformation("Suno generation başlatıldı: {Id}", generationId);

        // Polling — müzik hazır olana kadar bekle
        var musicUrl = await PollForCompletionAsync(generationId, ct);

        // Müzik dosyasını indir
        var outputPath = Path.Combine(outputDirectory, "background_music.mp3");
        await DownloadFileAsync(musicUrl, outputPath, ct);

        var fileInfo = new FileInfo(outputPath);

        _logger.LogInformation("Müzik indirildi: {Path} ({Size} bytes)", outputPath, fileInfo.Length);

        return new GeneratedMediaFile
        {
            SceneId = string.Empty, // Proje seviyesi — sahneye bağlı değil
            SceneOrder = 0,
            Type = MediaFileType.AudioMusic,
            LocalPath = outputPath,
            FileSizeBytes = fileInfo.Length,
            DurationSeconds = targetDurationSeconds,
            MimeType = "audio/mpeg",
            AiProvider = "suno"
        };
    }

    private async Task<string> PollForCompletionAsync(string generationId, CancellationToken ct)
    {
        var maxAttempts = 60; // 5 dakika (5s × 60)
        for (var i = 0; i < maxAttempts; i++)
        {
            ct.ThrowIfCancellationRequested();
            await Task.Delay(5000, ct);

            var response = await _httpClient.GetAsync($"/generations/{generationId}", ct);
            response.EnsureSuccessStatusCode();

            var json = await response.Content.ReadAsStringAsync(ct);
            var result = JsonSerializer.Deserialize<JsonElement>(json);
            var status = result.GetProperty("status").GetString();

            if (status == "completed" || status == "complete")
            {
                return result.GetProperty("audio_url").GetString()
                    ?? throw new InvalidOperationException("Müzik URL bulunamadı");
            }

            if (status == "failed" || status == "error")
            {
                var errorMsg = result.TryGetProperty("error", out var err)
                    ? err.GetString() : "Bilinmeyen hata";
                throw new InvalidOperationException($"Suno müzik üretimi başarısız: {errorMsg}");
            }
        }

        throw new TimeoutException($"Suno müzik üretimi zaman aşımına uğradı: {generationId}");
    }

    private async Task DownloadFileAsync(string url, string outputPath, CancellationToken ct)
    {
        using var response = await _httpClient.GetAsync(url, HttpCompletionOption.ResponseHeadersRead, ct);
        response.EnsureSuccessStatusCode();

        await using var fileStream = File.Create(outputPath);
        await response.Content.CopyToAsync(fileStream, ct);
    }
}