1 files changed, 162 insertions, 0 deletions
diff --git a/hugolib/paths/themes.go b/hugolib/paths/themes.go
new file mode 100644
index 000000000..abe6121ae
--- /dev/null
+++ b/hugolib/paths/themes.go
@@ -0,0 +1,162 @@
+// Copyright 2018 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package paths
+
+import (
+	"path/filepath"
+	"strings"
+
+	"github.com/gohugoio/hugo/config"
+	"github.com/spf13/afero"
+	"github.com/spf13/cast"
+	"github.com/spf13/viper"
+)
+
+type ThemeConfig struct {
+	// The theme name as provided by the folder name below /themes.
+	Name string
+
+	// Optional configuration filename (e.g. "/themes/mytheme/config.json").
+	ConfigFilename string
+
+	// Optional config read from the ConfigFile above.
+	Cfg config.Provider
+}
+
+// Create file system, an ordered theme list from left to right, no duplicates.
+type themesCollector struct {
+	themesDir string
+	fs        afero.Fs
+	seen      map[string]bool
+	themes    []ThemeConfig
+}
+
+func (c *themesCollector) isSeen(theme string) bool {
+	loki := strings.ToLower(theme)
+	if c.seen[loki] {
+		return true
+	}
+	c.seen[loki] = true
+	return false
+}
+
+func (c *themesCollector) addAndRecurse(themes ...string) error {
+	for i := 0; i < len(themes); i++ {
+		theme := themes[i]
+		configFilename := c.getConfigFileIfProvided(theme)
+		if !c.isSeen(theme) {
+			tc, err := c.add(theme, configFilename)
+			if err != nil {
+				return err
+			}
+			if err := c.addTemeNamesFromTheme(tc); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func (c *themesCollector) add(name, configFilename string) (ThemeConfig, error) {
+	var cfg config.Provider
+	var tc ThemeConfig
+
+	if configFilename != "" {
+		v := viper.New()
+		v.SetFs(c.fs)
+		v.AutomaticEnv()
+		v.SetEnvPrefix("hugo")
+		v.SetConfigFile(configFilename)
+
+		err := v.ReadInConfig()
+		if err != nil {
+			return tc, err
+		}
+		cfg = v
+
+	}
+
+	tc = ThemeConfig{Name: name, ConfigFilename: configFilename, Cfg: cfg}
+	c.themes = append(c.themes, tc)
+	return tc, nil
+
+}
+
+func collectThemeNames(p *Paths) ([]ThemeConfig, error) {
+	return CollectThemes(p.Fs.Source, p.AbsPathify(p.ThemesDir), p.Themes())
+
+}
+
+func CollectThemes(fs afero.Fs, themesDir string, themes []string) ([]ThemeConfig, error) {
+	if len(themes) == 0 {
+		return nil, nil
+	}
+
+	c := &themesCollector{
+		fs:        fs,
+		themesDir: themesDir,
+		seen:      make(map[string]bool)}
+
+	for i := 0; i < len(themes); i++ {
+		theme := themes[i]
+		if err := c.addAndRecurse(theme); err != nil {
+			return nil, err
+		}
+	}
+
+	return c.themes, nil
+
+}
+
+func (c *themesCollector) getConfigFileIfProvided(theme string) string {
+	configDir := filepath.Join(c.themesDir, theme)
+
+	var (
+		configFilename string
+		exists         bool
+	)
+
+	// Viper supports more, but this is the sub-set supported by Hugo.
+	for _, configFormats := range []string{"toml", "yaml", "yml", "json"} {
+		configFilename = filepath.Join(configDir, "config."+configFormats)
+		exists, _ = afero.Exists(c.fs, configFilename)
+		if exists {
+			break
+		}
+	}
+
+	if !exists {
+		// No theme config set.
+		return ""
+	}
+
+	return configFilename
+
+}
+
+func (c *themesCollector) addTemeNamesFromTheme(theme ThemeConfig) error {
+	if theme.Cfg != nil && theme.Cfg.IsSet("theme") {
+		v := theme.Cfg.Get("theme")
+		switch vv := v.(type) {
+		case []string:
+			return c.addAndRecurse(vv...)
+		case []interface{}:
+			return c.addAndRecurse(cast.ToStringSlice(vv)...)
+		default:
+			return c.addAndRecurse(cast.ToString(vv))
+		}
+	}
+
+	return nil
+}