feat: enhance audio processing with context cancellation and improved…

… error handling

- Added context cancellation support to audio file analysis, allowing for graceful shutdowns during processing.
- Implemented signal handling for user-initiated cancellations, ensuring clean exits without errors.
- Enhanced error handling in file and directory analysis, providing clearer feedback on issues encountered during processing.
- Updated the WAV and FLAC file validation logic to improve robustness and accuracy in file readiness checks.

These changes improve the user experience by allowing for more responsive and controlled audio processing, especially in long-running tasks.

cmd/file/file.go

@@ -1,8 +1,12 @@
 package file
 
 import (
+	"context"
 	"fmt"
+	"log"
 	"os"
+	"os/signal"
+	"syscall"
 
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
@@ -18,12 +22,37 @@ func Command(settings *conf.Settings) *cobra.Command {
 		Long:  `Analyze a single audio file for bird calls and songs.`,
 		Args:  cobra.ExactArgs(1), // the command expects exactly one argument
 		RunE: func(cmd *cobra.Command, args []string) error {
+			// Create a context that can be cancelled
+			ctx, cancel := context.WithCancel(context.Background())
+			defer cancel()
+
+			// Set up signal handling
+			sigChan := make(chan os.Signal, 1)
+			signal.Notify(sigChan, syscall.SIGTERM, syscall.SIGINT, syscall.SIGHUP)
+
+			// Handle shutdown in a separate goroutine
+			go func() {
+				sig := <-sigChan
+				fmt.Print("\n") // Add newline before the interrupt message
+				log.Printf("Received signal %v, initiating graceful shutdown...", sig)
+				cancel()
+			}()
+
 			// Input file path is the first argument
 			settings.Input.Path = args[0]
-			return analysis.FileAnalysis(settings)
+			err := analysis.FileAnalysis(settings, ctx)
+			if err == context.Canceled {
+				// Return nil for user-initiated cancellation
+				return nil
+			}
+			return err
 		},
 	}
 
+	// Disable printing usage on error
+	cmd.SilenceUsage = true
+	cmd.SilenceErrors = true
+
 	// Set up flags specific to the 'file' command
 	if err := setupFlags(cmd, settings); err != nil {
 		fmt.Printf("error setting up flags: %v\n", err)