fix(export): add error handling for duplicated slugs

Close #4

internal/cmd/preview.go

@@ -33,7 +33,8 @@ func preview(cmd *cobra.Command, args []string) {
 	log.Debug("Creating Preview...")
 
 	config := config.Shared()
-	index := indexer.Build(config.GetSectionMetadata(), config.GetExtractOption())
+	index, err := indexer.Build(config.GetSectionMetadata(), config.GetExtractOption())
+	utils.CheckFatalError(err, "Failed to build index")
 
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		handleRoot(
@@ -62,7 +63,7 @@ func preview(cmd *cobra.Command, args []string) {
 	}
 
 	log.Info("Server started -> http://localhost:%d", port)
-	err := http.ListenAndServe(fmt.Sprintf(":%d", port), nil)
+	err = http.ListenAndServe(fmt.Sprintf(":%d", port), nil)
 	utils.CheckFatalError(err, "Failed to listen the port")
 }
 

internal/export/export.go

@@ -25,7 +25,7 @@ type ProgressFunc func(path string)
 
 type Context interface {
 	cleanDirectory(outputPath string) error
-	buildIndex(cfg config.Config) []indexer.Section
+	buildIndex(cfg config.Config) ([]indexer.Section, error)
 	exportPhotos(sections []indexer.Section, outputPath string, cache cache.Cache, progressFunc ProgressFunc)
 	generateIndexHtml(cfg config.Config, sections []indexer.Section, path string, minimize bool)
 	processOtherFolders(folders []string, outputPath string, minimize bool, messageFunc func(src string, dst string))
@@ -59,7 +59,12 @@ func export(cfg config.Config, outputPath string, minimize bool, cache cache.Cac
 
 	spinnerMsg("Building index %s", outputPath)
 	photosDirectory := files.OutputPhotosFilePath(outputPath)
-	section := ctx.buildIndex(cfg)
+	section, err := ctx.buildIndex(cfg)
+	if err != nil {
+		ctx.cleanDirectory(outputPath)
+		utils.CheckFatalError(err, "Failed t build index.")
+	}
+
 	ctx.exportPhotos(section, photosDirectory, cache, func(path string) {
 		spinnerMsg("%s", path)
 	})
@@ -84,7 +89,7 @@ func (ctx DefaultExportContext) cleanDirectory(outputPath string) error {
 	return files.PruneDirectory(outputPath)
 }
 
-func (ctx DefaultExportContext) buildIndex(cfg config.Config) []indexer.Section {
+func (ctx DefaultExportContext) buildIndex(cfg config.Config) ([]indexer.Section, error) {
 	return indexer.Build(cfg.GetSectionMetadata(), cfg.GetExtractOption())
 }
 

internal/export/export_test.go

@@ -40,8 +40,17 @@ func (m *MockContext) cleanDirectory(outputPath string) error {
 	return m.Called(outputPath).Error(0)
 }
 
-func (m *MockContext) buildIndex(cfg config.Config) []indexer.Section {
-	return m.Called(cfg).Get(0).([]indexer.Section)
+func (m *MockContext) buildIndex(cfg config.Config) ([]indexer.Section, error) {
+	args := m.Called(cfg)
+	var sections []indexer.Section
+	var err error
+	if args.Get(0) != nil {
+		sections = args.Get(0).([]indexer.Section)
+	}
+	if args.Get(1) != nil {
+		err = args.Get(1).(error)
+	}
+	return sections, err
 }
 
 func (m *MockContext) exportPhotos(sections []indexer.Section, outputPath string, cache cache.Cache, progressFunc ProgressFunc) {
@@ -104,7 +113,7 @@ func TestExportPhotos(t *testing.T) {
 
 	mockCtx := new(MockContext)
 	mockCtx.On("cleanDirectory", mock.Anything).Return(nil)
-	mockCtx.On("buildIndex", mock.Anything).Return(sections)
+	mockCtx.On("buildIndex", mock.Anything).Return(sections, nil)
 	mockCtx.On("exportPhotos", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return()
 	mockCtx.On("generateIndexHtml", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return()
 	mockCtx.On("processOtherFolders", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return()

internal/indexer/indexer.go

@@ -1,6 +1,7 @@
 package indexer
 
 import (
+	"fmt"
 	"html/template"
 	"os"
 	"path/filepath"
@@ -28,23 +29,31 @@ type ImageSet struct {
 	OriginalSize  ImageSize
 }
 
-func Build(metadata []config.SectionMetadata, option config.ExtractOption) []Section {
+func Build(metadata []config.SectionMetadata, option config.ExtractOption) ([]Section, error) {
 	sections := []Section{}
+	slugs := map[string]bool{}
+
 	for _, val := range metadata {
+		slug := val.Slug
+		if slugs[slug] {
+			return nil, fmt.Errorf("Slug \"%s\" already exists. Slug needs to be unique.", slug)
+		}
+
+		log.Debug("Extacting section [%s][/%s] %s", val.Title, val.Slug, val.Folder)
 		s := Section{
 			Title:     val.Title,
 			Text:      val.Text,
-			Slug:      val.Slug,
+			Slug:      slug,
 			Folder:    val.Folder,
 			Ascending: val.Ascending,
 			ImageSets: buildImageSets(val.Folder, val.Ascending, option),
 		}
-		log.Debug("Extacting section [%s][/%s] %s", val.Title, val.Slug, val.Folder)
+		slugs[slug] = true
 
 		sections = append(sections, s)
 	}
 
-	return sections
+	return sections, nil
 }
 
 func buildImageSets(folder string, ascending bool, option config.ExtractOption) []ImageSet {

internal/indexer/indexer_test.go

@@ -26,7 +26,7 @@ func TestBuild(t *testing.T) {
 
 	data := []config.SectionMetadata{meta1, meta2}
 
-	sections := Build(data, defaultOption)
+	sections, _ := Build(data, defaultOption)
 	assert.Equal(t, 2, len(sections))
 	assert.Equal(t, testdata.Collection1["title"], sections[0].Title)
 
@@ -38,6 +38,19 @@ func TestBuild(t *testing.T) {
 	assert.Equal(t, testdata.Collection2FileName3, sections[1].ImageSets[0].FileName)
 }
 
+func TestBuildDuplicatedSlugs(t *testing.T) {
+	var meta1 config.SectionMetadata
+	var meta2 config.SectionMetadata
+	mapstructure.Decode(testdata.Collection1, &meta1)
+	mapstructure.Decode(testdata.Collection2, &meta2)
+	meta2.Slug = meta1.Slug
+
+	data := []config.SectionMetadata{meta1, meta2}
+
+	_, err := Build(data, defaultOption)
+	assert.NotNil(t, err)
+}
+
 func TestBuildImageSets(t *testing.T) {
 	expectedAscendingFileNames := []string{
 		testdata.Collection1FileName1,