Download logic

internal/api/handlers.download.go

@@ -0,0 +1,73 @@
+package api
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+)
+
+// handleGetDropMetadata returns info about the file (name, size, salt)
+// The CLI needs this *before* it starts downloading to set up decryption.
+func (s *Server) handleGetDropMetadata() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		dropID := chi.URLParam(r, "id")
+
+		var resp GetDropMetadataResponse
+		var expiresAt time.Time
+
+		// 1. Fetch metadata from Postgres
+		query := `
+			SELECT file_name, file_size, encryption_salt, expires_at 
+			FROM drops WHERE id = $1`
+
+		err := s.DB.QueryRow(query, dropID).Scan(
+			&resp.FileName, &resp.FileSize, &resp.EncryptionSalt, &expiresAt,
+		)
+
+		if err != nil {
+			http.Error(w, "Drop not found", http.StatusNotFound)
+			return
+		}
+
+		// 2. Check Expiry
+		if time.Now().After(expiresAt) {
+			http.Error(w, "Drop has expired", http.StatusGone)
+			return
+		}
+
+		// 3. Get chunk count (to know how many pieces to expect)
+		err = s.DB.QueryRow("SELECT COUNT(*) FROM chunks WHERE drop_id = $1", dropID).Scan(&resp.ChunkCount)
+		if err != nil {
+			http.Error(w, "Database error", http.StatusInternalServerError)
+			return
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(resp)
+	}
+}
+
+// handleDownloadChunk retrieves a specific piece of binary data
+func (s *Server) handleDownloadChunk() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		dropID := chi.URLParam(r, "id")
+		chunkIndex := chi.URLParam(r, "chunkIndex") // We'll add this param to router
+
+		// 1. Construct S3 Key
+		key := fmt.Sprintf("drops/%s/%s", dropID, chunkIndex)
+
+		// 2. Fetch from S3
+		data, err := s.Store.DownloadChunk(key)
+		if err != nil {
+			http.Error(w, "Chunk not found or storage error", http.StatusNotFound)
+			return
+		}
+
+		// 3. Stream binary back
+		w.Header().Set("Content-Type", "application/octet-stream")
+		w.Write(data)
+	}
+}

internal/api/models.go

@@ -28,3 +28,11 @@ type ChunkUploadResponse struct {
 // 2. Server responds with CreateDropResponse (drop ID and expiration time)
 // 3. CLI uploads file chunks to /api/v1/drops/{drop_id}/chunks (POST) with ChunkUploadResponse confirming each chunk
 
+// GetDropMetadataResponse is what the server sends back when the CLI requests metadata about a drop
+type GetDropMetadataResponse struct {
+	FileName       string `json:"file_name"`
+	FileSize       int64  `json:"file_size"`
+	EncryptionSalt string `json:"encryption_salt"`
+	ChunkCount     int    `json:"chunk_count"`
+}
+

internal/api/router.go

@@ -52,5 +52,9 @@ func (s *Server) routes() {
 		// Upload Endpoints
 		r.Post("/drop", s.handleCreateDrop())
 		r.Post("/drop/{id}/chunk", s.handleUploadChunk())
+
+		// Download Endpoints
+		r.Get("/drop/{id}", s.handleGetDropMetadata())
+		r.Get("/drop/{id}/chunk/{chunkIndex}", s.handleDownloadChunk())
 	})
 }