package recognition

import (
	"context"
	"log/slog"
	"sync"

	"github.com/food-ai/backend/internal/adapters/ai"
	"github.com/food-ai/backend/internal/adapters/kafka"
)

// ProductWorkerPool processes product/receipt recognition jobs from a single Kafka topic.
type ProductWorkerPool struct {
	productJobRepo ProductJobRepository
	enricher       *itemEnricher
	recognizer     Recognizer
	consumer       *kafka.Consumer
	workerCount    int
	jobs           chan string
}

// NewProductWorkerPool creates a ProductWorkerPool with five workers consuming from a single consumer.
func NewProductWorkerPool(
	productJobRepo ProductJobRepository,
	recognizer Recognizer,
	productRepo ProductRepository,
	consumer *kafka.Consumer,
) *ProductWorkerPool {
	return &ProductWorkerPool{
		productJobRepo: productJobRepo,
		enricher:       newItemEnricher(recognizer, productRepo),
		recognizer:     recognizer,
		consumer:       consumer,
		workerCount:    defaultWorkerCount,
		jobs:           make(chan string, 100),
	}
}

// Start launches the Kafka feeder goroutine and all worker goroutines.
func (pool *ProductWorkerPool) Start(workerContext context.Context) {
	go pool.consumer.Run(workerContext, pool.jobs)
	for i := 0; i < pool.workerCount; i++ {
		go pool.runWorker(workerContext)
	}
}

func (pool *ProductWorkerPool) runWorker(workerContext context.Context) {
	for {
		select {
		case jobID := <-pool.jobs:
			pool.processJob(workerContext, jobID)
		case <-workerContext.Done():
			return
		}
	}
}

func (pool *ProductWorkerPool) processJob(workerContext context.Context, jobID string) {
	job, fetchError := pool.productJobRepo.GetProductJobByID(workerContext, jobID)
	if fetchError != nil {
		slog.Error("product worker: fetch job", "job_id", jobID, "err", fetchError)
		return
	}

	if updateError := pool.productJobRepo.UpdateProductJobStatus(workerContext, jobID, JobStatusProcessing, nil, nil); updateError != nil {
		slog.Error("product worker: set processing status", "job_id", jobID, "err", updateError)
	}
	if notifyError := pool.productJobRepo.NotifyProductJobUpdate(workerContext, jobID); notifyError != nil {
		slog.Warn("product worker: notify processing", "job_id", jobID, "err", notifyError)
	}

	var recognizedItems []ai.RecognizedItem
	var unrecognized []ai.UnrecognizedItem
	var recognizeError error

	switch job.JobType {
	case "receipt":
		if len(job.Images) == 0 {
			errMsg := "no images in job"
			_ = pool.productJobRepo.UpdateProductJobStatus(workerContext, jobID, JobStatusFailed, nil, &errMsg)
			_ = pool.productJobRepo.NotifyProductJobUpdate(workerContext, jobID)
			return
		}
		imagePayload := job.Images[0]
		var receiptResult *ai.ReceiptResult
		receiptResult, recognizeError = pool.recognizer.RecognizeReceipt(workerContext, imagePayload.ImageBase64, imagePayload.MimeType, job.Lang)
		if recognizeError == nil && receiptResult != nil {
			recognizedItems = receiptResult.Items
			unrecognized = receiptResult.Unrecognized
		}

	case "products":
		allItems := make([][]ai.RecognizedItem, len(job.Images))
		var wg sync.WaitGroup
		for index, imagePayload := range job.Images {
			wg.Add(1)
			go func(workerIndex int, payload ProductImagePayload) {
				defer wg.Done()
				items, itemsError := pool.recognizer.RecognizeProducts(workerContext, payload.ImageBase64, payload.MimeType, job.Lang)
				if itemsError != nil {
					slog.WarnContext(workerContext, "product worker: recognize products from image", "index", workerIndex, "err", itemsError)
					return
				}
				allItems[workerIndex] = items
			}(index, imagePayload)
		}
		wg.Wait()
		recognizedItems = MergeAndDeduplicate(allItems)

	default:
		errMsg := "unknown job type: " + job.JobType
		slog.Error("product worker: unknown job type", "job_id", jobID, "job_type", job.JobType)
		_ = pool.productJobRepo.UpdateProductJobStatus(workerContext, jobID, JobStatusFailed, nil, &errMsg)
		_ = pool.productJobRepo.NotifyProductJobUpdate(workerContext, jobID)
		return
	}

	if recognizeError != nil {
		slog.Error("product worker: recognize", "job_id", jobID, "err", recognizeError)
		errMsg := "recognition failed, please try again"
		_ = pool.productJobRepo.UpdateProductJobStatus(workerContext, jobID, JobStatusFailed, nil, &errMsg)
		_ = pool.productJobRepo.NotifyProductJobUpdate(workerContext, jobID)
		return
	}

	enriched := pool.enricher.enrich(workerContext, recognizedItems)
	resultItems := make([]ProductJobResultItem, len(enriched))
	for index, item := range enriched {
		resultItems[index] = ProductJobResultItem{
			Name:               item.Name,
			Quantity:           item.Quantity,
			Unit:               item.Unit,
			Category:           item.Category,
			Confidence:         item.Confidence,
			QuantityConfidence: item.QuantityConfidence,
			MappingID:          item.MappingID,
			StorageDays:        item.StorageDays,
		}
	}

	jobResult := &ProductJobResult{
		JobType:      job.JobType,
		Items:        resultItems,
		Unrecognized: unrecognized,
	}

	if updateError := pool.productJobRepo.UpdateProductJobStatus(workerContext, jobID, JobStatusDone, jobResult, nil); updateError != nil {
		slog.Error("product worker: set done status", "job_id", jobID, "err", updateError)
	}
	if notifyError := pool.productJobRepo.NotifyProductJobUpdate(workerContext, jobID); notifyError != nil {
		slog.Warn("product worker: notify done", "job_id", jobID, "err", notifyError)
	}
}