refactor: Simplify transfer.sh file interaction

internal/transfer/file.go

@@ -1,12 +1,26 @@
 package transfer
 
+import (
+	"net/http"
+	"net/url"
+
+	"fmt"
+)
+
 // TransferShFile is information pertaining to a file uploaded to transfer.sh,
 // including the download URL and the deletion token.
 type TransferShFile struct {
 	downloadURL string
 	deleteToken string
 }
 
+func NewFile(downloadURL, deleteToken string) *TransferShFile {
+	return &TransferShFile{
+		downloadURL: downloadURL,
+		deleteToken: deleteToken,
+	}
+}
+
 // DownloadURL is the full URL that can be used to download the contents of a
 // file uploaded to the https://transfer.sh file store.
 func (tshFile TransferShFile) DownloadURL() string {
@@ -18,3 +32,27 @@ func (tshFile TransferShFile) DownloadURL() string {
 func (tshFile TransferShFile) DeleteToken() string {
 	return tshFile.deleteToken
 }
+
+// Delete attempts to delete the file from transfer.sh using the file's download
+// link and delete token. If an error is returned this may indicate that the
+// file has already been deleted or that the request to delete was simply not
+// successful.
+func (tshFile TransferShFile) Delete() error {
+	deleteURL, err := url.JoinPath(tshFile.downloadURL, tshFile.deleteToken)
+	if err != nil {
+		return fmt.Errorf("failed to generate valid url for transfer.sh file delete")
+	}
+	req, err := http.NewRequest(http.MethodDelete, deleteURL, nil)
+	if err != nil {
+		return fmt.Errorf("failed to generate file delete request: %w", err)
+	}
+	resp, err := (&http.Client{}).Do(req)
+	if err != nil {
+		return fmt.Errorf("failed to perform the delete request: %w", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		return fmt.Errorf("failed to delete file from transfer.sh: %w", err)
+	}
+	return nil
+}

internal/transfer/upload.go

@@ -86,8 +86,5 @@ func (tsh TransferSh) Upload(data string) (*TransferShFile, error) {
 	if deleteURL == "" || downloadURL == "" {
 		return nil, fmt.Errorf("failed to obtain all urls for the transfer.sh upload")
 	}
-	return &TransferShFile{
-		downloadURL: downloadURL,
-		deleteToken: path.Base(deleteURL),
-	}, nil
+    return NewFile(downloadURL, path.Base(deleteURL)), nil
 }