dramaling-vocab-learning/backend/DramaLing.Api/Services/AI/Generation/GenerationPipelineService.cs

using DramaLing.Api.Data;
using DramaLing.Api.Models.DTOs;
using DramaLing.Api.Services.Storage;
using DramaLing.Api.Services;
using Microsoft.EntityFrameworkCore;
using System.Diagnostics;
using System.Text.Json;

namespace DramaLing.Api.Services.AI.Generation;

public class GenerationPipelineService : IGenerationPipelineService
{
    private readonly IServiceProvider _serviceProvider;
    private readonly IGenerationStateManager _stateManager;
    private readonly IImageSaveManager _imageSaveManager;
    private readonly ILogger<GenerationPipelineService> _logger;

    public GenerationPipelineService(
        IServiceProvider serviceProvider,
        IGenerationStateManager stateManager,
        IImageSaveManager imageSaveManager,
        ILogger<GenerationPipelineService> logger)
    {
        _serviceProvider = serviceProvider ?? throw new ArgumentNullException(nameof(serviceProvider));
        _stateManager = stateManager ?? throw new ArgumentNullException(nameof(stateManager));
        _imageSaveManager = imageSaveManager ?? throw new ArgumentNullException(nameof(imageSaveManager));
        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
    }

    public async Task ExecuteGenerationPipelineAsync(Guid requestId)
    {
        var totalStopwatch = Stopwatch.StartNew();

        using var scope = _serviceProvider.CreateScope();
        var dbContext = scope.ServiceProvider.GetRequiredService<DramaLingDbContext>();
        var geminiService = scope.ServiceProvider.GetRequiredService<IGeminiService>();
        var replicateService = scope.ServiceProvider.GetRequiredService<IReplicateService>();
        var storageService = scope.ServiceProvider.GetRequiredService<IImageStorageService>();
        var imageProcessingService = scope.ServiceProvider.GetRequiredService<IImageProcessingService>();

        try
        {
            _logger.LogInformation("Starting generation pipeline for request {RequestId}", requestId);

            var request = await dbContext.ImageGenerationRequests
                .Include(r => r.Flashcard)
                .FirstOrDefaultAsync(r => r.Id == requestId);

            if (request == null)
            {
                _logger.LogError("Generation request {RequestId} not found in pipeline", requestId);
                return;
            }

            var options = JsonSerializer.Deserialize<GenerationRequest>(request.OriginalRequest);

            // 第一階段：Gemini 描述生成
            _logger.LogInformation("Starting Gemini description generation for request {RequestId}", requestId);

            await _stateManager.UpdateRequestStatusAsync(requestId, "description_generating", "processing", "pending");

            var optimizedPrompt = await geminiService.GenerateImageDescriptionAsync(
                request.Flashcard,
                options?.Options ?? new GenerationOptionsDto());

            if (string.IsNullOrWhiteSpace(optimizedPrompt))
            {
                await _stateManager.MarkRequestAsFailedAsync(requestId, "gemini", "Generated prompt is empty");
                return;
            }

            await _stateManager.UpdateGeminiResultAsync(requestId, optimizedPrompt);

            // 第二階段：Replicate 圖片生成
            _logger.LogInformation("Starting Replicate image generation for request {RequestId}", requestId);

            await _stateManager.UpdateRequestStatusAsync(requestId, "image_generating", "completed", "processing");

            var modelName = "ideogram-v2a-turbo";
            _logger.LogInformation("Using Replicate model: {ModelName}", modelName);

            var imageResult = await replicateService.GenerateImageAsync(
                optimizedPrompt,
                modelName,
                new ReplicateGenerationOptions
                {
                    Width = options?.Width ?? 512,
                    Height = options?.Height ?? 512,
                    TimeoutMinutes = 5
                });

            if (!imageResult.Success)
            {
                await _stateManager.MarkRequestAsFailedAsync(requestId, "replicate", imageResult.Error);
                return;
            }

            // 下載並儲存圖片
            var savedImage = await _imageSaveManager.SaveGeneratedImageAsync(
                dbContext, storageService, imageProcessingService, request, optimizedPrompt, imageResult);

            // 完成請求
            await _stateManager.CompleteRequestAsync(requestId, savedImage.Id, totalStopwatch.ElapsedMilliseconds);

            _logger.LogInformation("Generation pipeline completed successfully for request {RequestId} in {ElapsedMs}ms",
                requestId, totalStopwatch.ElapsedMilliseconds);
        }
        catch (Exception ex)
        {
            totalStopwatch.Stop();
            _logger.LogError(ex, "Generation pipeline failed for request {RequestId}", requestId);
            await _stateManager.MarkRequestAsFailedAsync(requestId, "system", ex.Message);
        }
    }
}