package application

import (
	"context"
	"fmt"
	"time"

	"github.com/mmmy/snapgo/internal/domain"
	"github.com/mmmy/snapgo/internal/infrastructure/clipboard"
)

// VisionSummarizer describes a multimodal model capable of reading a public
// image URL and returning a textual summary.
type VisionSummarizer interface {
	SummarizeImage(ctx context.Context, prompt string, imageURL string) (string, error)
}

// CaptureSummaryService wires screenshot bytes -> S3 public URL -> LLM
// summary -> clipboard. It intentionally does not notify UI state itself:
// the caller emits fine-grained "uploading / recognizing / done" progress.
type CaptureSummaryService struct {
	Provider   domain.OSSProvider
	Summarizer VisionSummarizer
	Clipboard  clipboard.Writer
	Prompt     string
	PathPrefix string
}

// UploadImage uploads the screenshot and returns the public URL visible to
// the multimodal provider.
func (s *CaptureSummaryService) UploadImage(ctx context.Context, pngBytes []byte) (*domain.UploadResult, error) {
	if s.Provider == nil {
		return nil, fmt.Errorf("s3 is not configured")
	}
	if len(pngBytes) == 0 {
		return nil, fmt.Errorf("empty screenshot")
	}
	key := buildObjectKey(s.PathPrefix)
	start := time.Now()
	url, err := s.Provider.Upload(ctx, key, pngBytes, "image/png")
	if err != nil {
		return nil, fmt.Errorf("s3 put object: %w", err)
	}
	return &domain.UploadResult{
		URL:      url,
		Key:      key,
		Provider: s.Provider.Name(),
		Elapsed:  time.Since(start),
	}, nil
}

// Summarize asks the configured model to summarize the uploaded image URL.
func (s *CaptureSummaryService) Summarize(ctx context.Context, imageURL string) (string, error) {
	if s.Summarizer == nil {
		return "", fmt.Errorf("llm is not configured")
	}
	return s.Summarizer.SummarizeImage(ctx, s.Prompt, imageURL)
}

// CopySummary writes the final summary text to the clipboard.
func (s *CaptureSummaryService) CopySummary(_ context.Context, summary string) error {
	if summary == "" {
		return fmt.Errorf("empty summary")
	}
	if s.Clipboard == nil {
		return fmt.Errorf("clipboard is not configured")
	}
	if err := s.Clipboard.WriteText(summary); err != nil {
		return fmt.Errorf("clipboard write failed: %w", err)
	}
	return nil
}