feat(cmd): integrate structured logging throughout application

- add `--log` flag to specify custom log file path
- initialize logger at application startup with error handling
- add comprehensive logging to presentation loading and parsing
- add logging to file watcher and live reload functionality
- add error logging for config loading and TUI failures
- log application lifecycle events (start, end, reload)

Author: tharropoulos

cmd/root.go

@@ -12,18 +12,21 @@ import (
 	"github.com/spf13/cobra"
 
 	"github.com/museslabs/kyma/internal/config"
+	"github.com/museslabs/kyma/internal/logger"
 	"github.com/museslabs/kyma/internal/tui"
 	"github.com/museslabs/kyma/internal/tui/transitions"
 )
 
 var (
 	static     bool
 	configPath string
+	logPath    string
 )
 
 func init() {
 	rootCmd.Flags().BoolVarP(&static, "static", "s", false, "Disable live reload (watch mode is enabled by default)")
 	rootCmd.Flags().StringVarP(&configPath, "config", "c", "", "Path to config file")
+	rootCmd.Flags().StringVarP(&logPath, "log", "l", "", "Path to log file (default: ~/.config/kyma/logs/<timestamp>.kyma.log)")
 	rootCmd.AddCommand(versionCmd)
 }
 
@@ -43,27 +46,41 @@ var rootCmd = &cobra.Command{
 		DisableDefaultCmd: true,
 	},
 	RunE: func(cmd *cobra.Command, args []string) error {
+		if err := logger.Load(logPath); err != nil {
+			return fmt.Errorf("failed to initialize logger: %w", err)
+		}
+
+		logger.Info("Starting Kyma")
+
 		if err := config.Load(configPath); err != nil {
+			logger.Error("Failed to load config", "error", err, "config_path", configPath)
 			return err
 		}
 
 		filename := args[0]
+		logger.Info("Loading presentation", "filename", filename)
 
 		data, err := os.ReadFile(filename)
 		if err != nil {
+			logger.Error("Failed to read presentation file", "error", err, "filename", filename)
 			return err
 		}
 
 		root, err := parseSlides(string(data))
 		if err != nil {
+			logger.Error("Failed to parse slides", "error", err, "filename", filename)
 			return err
 		}
 
+		logger.Info("Successfully parsed presentation")
+
 		p := tea.NewProgram(tui.New(root), tea.WithAltScreen(), tea.WithMouseAllMotion())
 
 		if !static {
+			logger.Info("Starting file watcher for live reload")
 			watcher, err := fsnotify.NewWatcher()
 			if err != nil {
+				logger.Error("Failed to create file watcher", "error", err)
 				p.Send(tui.UpdateSlidesMsg{NewRoot: createErrorSlide(err, "none")})
 				return nil
 			}
@@ -97,10 +114,13 @@ var rootCmd = &cobra.Command{
 			go watchFileChanges(watcher, p, filename, absPath, configPath)
 		}
 
+		logger.Info("Starting TUI program")
 		if _, err := p.Run(); err != nil {
+			logger.Error("TUI program failed", "error", err)
 			return err
 		}
 
+		logger.Info("Kyma session ended")
 		return nil
 	},
 }
@@ -130,23 +150,29 @@ func watchFileChanges(
 						debounceTimer.Stop()
 					}
 					debounceTimer = time.AfterFunc(100*time.Millisecond, func() {
+						logger.Info("File changed, reloading presentation", "file", event.Name)
+
 						data, err := os.ReadFile(filename)
 						if err != nil {
+							logger.Error("Failed to read file during reload", "error", err, "filename", filename)
 							p.Send(tui.UpdateSlidesMsg{NewRoot: createErrorSlide(err, "none")})
 							return
 						}
 
 						if err := config.Load(configPath); err != nil {
+							logger.Error("Failed to reload config", "error", err, "config_path", configPath)
 							p.Send(tui.UpdateSlidesMsg{NewRoot: createErrorSlide(err, "none")})
 							return
 						}
 
 						newRoot, err := parseSlides(string(data))
 						if err != nil {
+							logger.Error("Failed to parse slides during reload", "error", err, "filename", filename)
 							p.Send(tui.UpdateSlidesMsg{NewRoot: createErrorSlide(err, "none")})
 							return
 						}
 
+						logger.Info("Successfully reloaded presentation")
 						p.Send(tui.UpdateSlidesMsg{NewRoot: newRoot})
 					})
 				}
@@ -162,6 +188,7 @@ func watchFileChanges(
 
 func Execute() {
 	if err := rootCmd.Execute(); err != nil {
+		logger.Error("Application failed", "error", err)
 		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
 	}