Add dump feature, enhance code quality (#1)

cmd/store.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"errors"
 	"fmt"
+	"log"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -21,20 +22,28 @@ func StoreProgress(conf *Config, progress int) error {
 	cfgpath := conf.GetConfigDir()
 
 	if err := Mkdir(cfgpath); err != nil {
-		return err
+		return fmt.Errorf("failed to mkdir config path %s: %w", cfgpath, err)
 	}
 
 	filename := filepath.Join(cfgpath, Slug(conf.Document))
 
 	fd, err := os.OpenFile(filename, os.O_CREATE|os.O_WRONLY, 0644)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to open state file %s: %w", filename, err)
 	}
-	defer fd.Close()
+	defer func() {
+		if err := fd.Close(); err != nil {
+			log.Fatal(err)
+		}
+	}()
 
-	_, err = fd.WriteString(fmt.Sprintf("%d\n", progress))
+	if err := fd.Truncate(0); err != nil {
+		return fmt.Errorf("failed to truncate state file %s: %w", filename, err)
+	}
+
+	_, err = fmt.Fprintf(fd, "%d\n", progress)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to write to state file %s: %w", filename, err)
 	}
 
 	return nil
@@ -49,7 +58,11 @@ func GetProgress(conf *Config) (int64, error) {
 	if err != nil {
 		return 0, nil // ignore errors and return no progress
 	}
-	defer fd.Close()
+	defer func() {
+		if err := fd.Close(); err != nil {
+			log.Fatal(err)
+		}
+	}()
 
 	scanner := bufio.NewScanner(fd)
 	var line string