feat: add screenshot OCR extraction

internal/application/capture_ocr.go

@@ -0,0 +1,57 @@
+package application
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/mmmy/snapgo/internal/infrastructure/clipboard"
+)
+
+// OCRRecognizer describes a provider capable of extracting text from a PNG
+// screenshot.
+type OCRRecognizer interface {
+	RecognizeText(ctx context.Context, pngBytes []byte) (string, error)
+}
+
+// CaptureOCRService wires screenshot bytes -> OCR provider -> clipboard. It
+// leaves progress reporting to the caller so native and web overlays can share
+// the same status HUD.
+type CaptureOCRService struct {
+	Recognizer OCRRecognizer
+	Clipboard  clipboard.Writer
+}
+
+// Recognize asks the configured OCR provider to extract text from the PNG.
+func (s *CaptureOCRService) Recognize(ctx context.Context, pngBytes []byte) (string, error) {
+	if s.Recognizer == nil {
+		return "", fmt.Errorf("ocr is not configured")
+	}
+	if len(pngBytes) == 0 {
+		return "", fmt.Errorf("empty screenshot")
+	}
+	text, err := s.Recognizer.RecognizeText(ctx, pngBytes)
+	if err != nil {
+		return "", err
+	}
+	text = strings.TrimSpace(text)
+	if text == "" {
+		return "", fmt.Errorf("ocr result is empty")
+	}
+	return text, nil
+}
+
+// CopyText writes the extracted text to the clipboard.
+func (s *CaptureOCRService) CopyText(_ context.Context, text string) error {
+	text = strings.TrimSpace(text)
+	if text == "" {
+		return fmt.Errorf("empty ocr text")
+	}
+	if s.Clipboard == nil {
+		return fmt.Errorf("clipboard is not configured")
+	}
+	if err := s.Clipboard.WriteText(text); err != nil {
+		return fmt.Errorf("clipboard write failed: %w", err)
+	}
+	return nil
+}

internal/application/capture_ocr_test.go

@@ -0,0 +1,50 @@
+package application
+
+import (
+	"context"
+	"testing"
+)
+
+type fakeOCRRecognizer struct {
+	image []byte
+	text  string
+}
+
+func (f *fakeOCRRecognizer) RecognizeText(_ context.Context, pngBytes []byte) (string, error) {
+	f.image = append([]byte(nil), pngBytes...)
+	if f.text == "" {
+		return "extracted text", nil
+	}
+	return f.text, nil
+}
+
+func TestCaptureOCRServiceRecognizesAndCopies(t *testing.T) {
+	ctx := context.Background()
+	recognizer := &fakeOCRRecognizer{}
+	clip := &fakeClipboard{}
+	svc := &CaptureOCRService{Recognizer: recognizer, Clipboard: clip}
+
+	text, err := svc.Recognize(ctx, []byte("png"))
+	if err != nil {
+		t.Fatalf("recognize: %v", err)
+	}
+	if string(recognizer.image) != "png" {
+		t.Fatalf("expected screenshot bytes forwarded, got %q", string(recognizer.image))
+	}
+	if text != "extracted text" {
+		t.Fatalf("expected extracted text, got %q", text)
+	}
+	if err := svc.CopyText(ctx, text); err != nil {
+		t.Fatalf("copy text: %v", err)
+	}
+	if clip.text != "extracted text" {
+		t.Fatalf("expected ocr text copied, got %q", clip.text)
+	}
+}
+
+func TestCaptureOCRServiceRejectsEmptyResult(t *testing.T) {
+	svc := &CaptureOCRService{Recognizer: &fakeOCRRecognizer{text: " \n "}}
+	if _, err := svc.Recognize(context.Background(), []byte("png")); err == nil {
+		t.Fatalf("expected empty OCR result to fail")
+	}
+}