fix(fs): get file by ext sorted by mod time

pkg/gotenberg/fs.go

@@ -4,7 +4,9 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"sort"
 	"strings"
+	"time"
 
 	"github.com/google/uuid"
 )
@@ -86,10 +88,15 @@ func (fs *FileSystem) MkdirAll() (string, error) {
 	return path, nil
 }
 
+type fileWithModTime struct {
+	path    string
+	modTime time.Time
+}
+
 // WalkDir walks through the root level of a directory and returns a list of
 // files paths that match the specified file extension.
 func WalkDir(dir, ext string) ([]string, error) {
-	var files []string
+	var files []fileWithModTime
 	err := filepath.Walk(dir, func(path string, info os.FileInfo, pathErr error) error {
 		if pathErr != nil {
 			return pathErr
@@ -98,11 +105,27 @@ func WalkDir(dir, ext string) ([]string, error) {
 			return nil
 		}
 		if strings.EqualFold(filepath.Ext(info.Name()), ext) {
-			files = append(files, path)
+			files = append(files, fileWithModTime{
+				path:    path,
+				modTime: info.ModTime(),
+			})
 		}
 		return nil
 	})
-	return files, err
+	if err != nil {
+		return nil, err
+	}
+
+	sort.Slice(files, func(i, j int) bool {
+		return files[i].modTime.Before(files[j].modTime)
+	})
+
+	sortedPaths := make([]string, len(files))
+	for i, f := range files {
+		sortedPaths[i] = f.path
+	}
+
+	return sortedPaths, nil
 }
 
 // Interface guards.

pkg/gotenberg/fs_test.go

@@ -161,7 +161,7 @@ func TestWalkDir(t *testing.T) {
 			expectError: true,
 		},
 		{
-			scenario: "find PDF files",
+			scenario: "find PDF files, sorted by mod time",
 			dir: func() string {
 				path := fmt.Sprintf("%s/a_directory", os.TempDir())
 
@@ -170,17 +170,27 @@ func TestWalkDir(t *testing.T) {
 					t.Fatalf(fmt.Sprintf("expected no error but got: %v", err))
 				}
 
-				err = os.WriteFile(fmt.Sprintf("%s/a_foo_file.pdf", path), []byte{1}, 0o755)
+				err = os.WriteFile(fmt.Sprintf("%s/2.pdf", path), []byte{1}, 0o755)
 				if err != nil {
 					t.Fatalf("expected no error but got: %v", err)
 				}
 
-				err = os.WriteFile(fmt.Sprintf("%s/a_bar_file.PDF", path), []byte{1}, 0o755)
+				err = os.WriteFile(fmt.Sprintf("%s/1.PDF", path), []byte{1}, 0o755)
 				if err != nil {
 					t.Fatalf("expected no error but got: %v", err)
 				}
 
-				err = os.WriteFile(fmt.Sprintf("%s/a_baz_file.txt", path), []byte{1}, 0o755)
+				err = os.WriteFile(fmt.Sprintf("%s/3.txt", path), []byte{1}, 0o755)
+				if err != nil {
+					t.Fatalf("expected no error but got: %v", err)
+				}
+
+				err = os.WriteFile(fmt.Sprintf("%s/10.pdf", path), []byte{1}, 0o755)
+				if err != nil {
+					t.Fatalf("expected no error but got: %v", err)
+				}
+
+				err = os.WriteFile(fmt.Sprintf("%s/11.pdf", path), []byte{1}, 0o755)
 				if err != nil {
 					t.Fatalf("expected no error but got: %v", err)
 				}
@@ -189,7 +199,7 @@ func TestWalkDir(t *testing.T) {
 			}(),
 			ext:         ".pdf",
 			expectError: false,
-			expectFiles: []string{"/tmp/a_directory/a_bar_file.PDF", "/tmp/a_directory/a_foo_file.pdf"},
+			expectFiles: []string{"/tmp/a_directory/2.pdf", "/tmp/a_directory/1.PDF", "/tmp/a_directory/10.pdf", "/tmp/a_directory/11.pdf"},
 		},
 	} {
 		t.Run(tc.scenario, func(t *testing.T) {