Jay Brown
78 lines
2.1 KiB
Go
78 lines
2.1 KiB
Go
package documentdownload
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import (
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"context"
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"fmt"
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"io"
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"mime"
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"path/filepath"
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"github.com/aws/aws-sdk-go-v2/service/s3"
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"github.com/google/uuid"
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)
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// DownloadResult contains the data needed to stream a document file to the client.
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type DownloadResult struct {
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Body io.ReadCloser // S3 object body - caller must close
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Filename string // Original filename (for Content-Disposition)
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ContentType string // MIME type detected from filename extension
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Size int64 // File size in bytes (for Content-Length)
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}
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// GetDownload retrieves the document file bytes from S3.
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// Returns a DownloadResult with a streaming body that the caller must close.
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func (s *Service) GetDownload(ctx context.Context, id uuid.UUID) (*DownloadResult, error) {
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// Get document metadata (filename) from DB
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doc, err := s.cfg.GetDBQueries().GetDocumentEnriched(ctx, id)
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if err != nil {
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return nil, fmt.Errorf("document not found: %w", err)
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}
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// Get S3 entry (bucket, key) from documentEntries
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entry, err := s.cfg.GetDBQueries().GetDocumentEntry(ctx, id)
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if err != nil {
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return nil, fmt.Errorf("no S3 entry for document: %w", err)
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}
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// GetObject from S3
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output, err := s.cfg.GetStoreClient().GetObject(ctx, &s3.GetObjectInput{
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Bucket: &entry.Bucket,
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Key: &entry.Key,
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})
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if err != nil {
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return nil, fmt.Errorf("failed to retrieve file from S3: %w", err)
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}
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// Detect MIME type from filename extension
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filename := ""
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if doc.Filename != nil {
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filename = *doc.Filename
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}
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contentType := detectContentType(filename)
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// Get file size
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var size int64
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if output.ContentLength != nil {
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size = *output.ContentLength
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}
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return &DownloadResult{
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Body: output.Body,
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Filename: filename,
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ContentType: contentType,
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Size: size,
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}, nil
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}
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// detectContentType determines the MIME type based on file extension.
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func detectContentType(filename string) string {
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if filename == "" {
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return "application/octet-stream"
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}
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contentType := mime.TypeByExtension(filepath.Ext(filename))
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if contentType == "" {
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return "application/octet-stream"
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}
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return contentType
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}
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