tender single document download

internal/tender/service.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"mime"
 	"path"
 	"path/filepath"
 	"strings"
@@ -53,6 +54,7 @@ type Service interface {
 	GetDocumentSummaries(ctx context.Context, id string) ([]DocumentSummary, error)
 	GetDocuments(ctx context.Context, id string) (*TenderDocumentsResponse, error)
 	DownloadDocuments(ctx context.Context, id string) (*TenderDocumentDownload, error)
+	DownloadDocument(ctx context.Context, id, filename string) (*TenderDocumentDownload, error)
 
 	// AI summarization operations
 	GetAISummary(ctx context.Context, id string) (*AISummaryResponse, error)
@@ -624,6 +626,96 @@ func (s *tenderService) DownloadDocuments(ctx context.Context, id string) (*Tend
 	}, nil
 }
 
+// DownloadDocument streams a single scraped document for a tender.
+func (s *tenderService) DownloadDocument(ctx context.Context, id, filename string) (*TenderDocumentDownload, error) {
+	if id == "" {
+		return nil, fmt.Errorf("tender ID cannot be empty")
+	}
+	if strings.TrimSpace(filename) == "" {
+		return nil, fmt.Errorf("document filename cannot be empty")
+	}
+	if s.aiSummarizerStorage == nil {
+		return nil, ErrTenderDocumentStorageUnavailable
+	}
+
+	tender, err := s.repository.GetByID(ctx, id)
+	if err != nil {
+		s.logger.Error("Failed to get tender for document download", map[string]interface{}{
+			"tender_id": id,
+			"filename":  filename,
+			"error":     err.Error(),
+		})
+		return nil, fmt.Errorf("failed to get tender: %w", err)
+	}
+	if tender == nil {
+		return nil, fmt.Errorf("tender not found")
+	}
+	if strings.TrimSpace(tender.ContractFolderID) == "" {
+		return nil, ErrTenderDocumentNotFound
+	}
+
+	documents, err := s.listDocumentsForTender(ctx, tender)
+	if err != nil {
+		s.logger.Error("Failed to list tender documents for download", map[string]interface{}{
+			"tender_id":          id,
+			"filename":           filename,
+			"contract_folder_id": tender.ContractFolderID,
+			"error":              err.Error(),
+		})
+		return nil, fmt.Errorf("failed to list tender documents: %w", err)
+	}
+
+	doc, ok := findStoredDocumentByFilename(documents, filename)
+	if !ok {
+		return nil, ErrTenderDocumentNotFound
+	}
+
+	reader, err := s.aiSummarizerStorage.DownloadDocument(ctx, doc.ObjectName)
+	if err != nil {
+		s.logger.Error("Failed to open tender document from storage", map[string]interface{}{
+			"tender_id":   id,
+			"filename":    filename,
+			"object_name": doc.ObjectName,
+			"error":       err.Error(),
+		})
+		return nil, fmt.Errorf("failed to download document: %w", err)
+	}
+
+	downloadName := path.Base(doc.DocumentName)
+	contentType := mime.TypeByExtension(filepath.Ext(downloadName))
+	if contentType == "" {
+		contentType = "application/octet-stream"
+	}
+
+	s.logger.Info("Tender document download prepared", map[string]interface{}{
+		"tender_id": id,
+		"filename":  downloadName,
+		"size":      doc.Size,
+	})
+
+	return &TenderDocumentDownload{
+		Reader:      reader,
+		Filename:    downloadName,
+		ContentType: contentType,
+		Size:        doc.Size,
+	}, nil
+}
+
+func findStoredDocumentByFilename(documents []ai_summarizer.StoredDocument, filename string) (ai_summarizer.StoredDocument, bool) {
+	filename = strings.TrimSpace(filename)
+	if filename == "" {
+		return ai_summarizer.StoredDocument{}, false
+	}
+
+	wantBase := path.Base(filename)
+	for _, doc := range documents {
+		if doc.DocumentName == filename || path.Base(doc.DocumentName) == wantBase {
+			return doc, true
+		}
+	}
+	return ai_summarizer.StoredDocument{}, false
+}
+
 func (s *tenderService) writeDocumentsArchive(ctx context.Context, writer *io.PipeWriter, documents []ai_summarizer.StoredDocument) {
 	zipWriter := zip.NewWriter(writer)
 	usedNames := make(map[string]int, len(documents))