refactor(tpl): adjust theme interface

- hide template and assets data from external package
- rename `Theme` to `MemTheme`
- `Theme` is now an interface
- extract default theme

Author: marjune163

src/app/main.go

@@ -52,14 +52,20 @@ func NewApp(params []*param.Param) *App {
 		errHandler := serverErrHandler.NewErrHandler(logger)
 
 		// theme
-		var err error
-		themeKey, err := filepath.Abs(p.Theme)
-		serverErrHandler.CheckFatal(err)
-		theme, themeExists := themes[themeKey]
-		if !themeExists {
-			theme, err = tpl.LoadTheme(p.Theme)
+		var theme tpl.Theme
+		if len(p.Theme) == 0 {
+			theme = tpl.DefaultTheme
+		} else {
+			themeKey, err := filepath.Abs(p.Theme)
 			serverErrHandler.CheckFatal(err)
-			themes[themeKey] = theme
+
+			var themeExists bool
+			theme, themeExists = themes[themeKey]
+			if !themeExists {
+				theme, err = tpl.LoadMemTheme(p.Theme)
+				serverErrHandler.CheckFatal(err)
+				themes[themeKey] = theme
+			}
 		}
 
 		// vHostMux

src/serverHandler/asset.go

@@ -8,16 +8,10 @@ import (
 var initTime = time.Now()
 
 func (h *handler) asset(w http.ResponseWriter, r *http.Request, assetPath string) {
-	content, ok := h.theme.Assets.Get(assetPath)
-	if !ok {
-		return
-	}
-
 	header := w.Header()
-	header.Set("X-Content-Type-Options","nosniff")
-	header.Set("Content-Type", content.ContentType)
+	header.Set("X-Content-Type-Options", "nosniff")
 	header.Set("Cache-Control", "public, max-age=3600")
 	if needResponseBody(r.Method) {
-		http.ServeContent(w, r, assetPath, initTime, content.ReadSeeker)
+		h.theme.RenderAsset(w, r, assetPath)
 	}
 }

src/serverHandler/page.go

@@ -89,7 +89,7 @@ func (h *handler) page(w http.ResponseWriter, r *http.Request, data *responseDat
 	w.WriteHeader(data.Status)
 
 	updateSubItemsHtml(data)
-	err := h.theme.Template.Execute(bodyW, data)
+	err := h.theme.RenderPage(bodyW, data)
 	if err != nil {
 		go h.errHandler.LogError(err)
 	}

src/tpl/asset.go

@@ -3,44 +3,27 @@ package tpl
 import (
 	"../util"
 	"bytes"
-	_ "embed"
 	"io"
 )
 
 type asset struct {
-	ContentType string
-	ReadSeeker  io.ReadSeeker
+	contentType string
+	readSeeker  io.ReadSeeker
 }
 
 type assets map[string]asset
 
-func (assets assets) Set(path string, content []byte) error {
+func (assets assets) set(path string, content []byte) error {
 	rd := bytes.NewReader(content)
 	ctype, err := util.GetContentType(path, rd)
 	if err != nil {
 		return err
 	}
 
 	asset := asset{
-		ContentType: ctype,
-		ReadSeeker:  rd,
+		contentType: ctype,
+		readSeeker:  rd,
 	}
 	assets[path] = asset
 	return nil
 }
-
-func (assets assets) Get(path string) (asset, bool) {
-	c, ok := assets[path]
-	return c, ok
-}
-
-//go:embed frontend/index.css
-var css []byte
-
-//go:embed frontend/index.js
-var js []byte
-
-var defaultAssets = map[string]asset{
-	"index.css": {"text/css", bytes.NewReader(css)},
-	"index.js":  {"application/javascript", bytes.NewReader(js)},
-}

src/tpl/defaultTheme.go

@@ -0,0 +1,31 @@
+package tpl
+
+import (
+	"bytes"
+	_ "embed"
+)
+
+//go:embed frontend/index.html
+var defaultTplStr string
+
+//go:embed frontend/index.css
+var defaultCss []byte
+
+//go:embed frontend/index.js
+var defaultJs []byte
+
+var DefaultTheme MemTheme
+
+func init() {
+	defaultTpl, err := ParsePageTpl(defaultTplStr)
+	if err != nil {
+		defaultTpl, _ = ParsePageTpl("Builtin Template Error")
+	}
+	DefaultTheme.template = defaultTpl
+
+	defaultAssets := map[string]asset{
+		"index.css": {"text/css", bytes.NewReader(defaultCss)},
+		"index.js":  {"application/javascript", bytes.NewReader(defaultJs)},
+	}
+	DefaultTheme.assets = defaultAssets
+}

src/tpl/memTheme.go

@@ -0,0 +1,77 @@
+package tpl
+
+import (
+	"archive/zip"
+	"errors"
+	"html/template"
+	"io"
+	"net/http"
+	"time"
+)
+
+type MemTheme struct {
+	template *template.Template
+	assets   assets
+}
+
+var initTime = time.Now()
+
+func LoadMemTheme(themePath string) (theme MemTheme, err error) {
+	var currentTheme = MemTheme{
+		template: nil,
+		assets:   make(assets, 2),
+	}
+
+	// assume to be a zip file
+	var zipRd *zip.ReadCloser
+	zipRd, err = zip.OpenReader(themePath)
+	if err != nil {
+		return
+	}
+	defer zipRd.Close()
+
+	for _, f := range zipRd.File {
+		var rd io.ReadCloser
+		rd, err = f.Open()
+		if err != nil {
+			continue
+		}
+		var raw []byte
+		raw, err = io.ReadAll(rd)
+		rd.Close()
+		if err != nil {
+			return
+		}
+		if f.Name == "index.html" {
+			currentTheme.template, err = ParsePageTpl(string(raw))
+			if err != nil {
+				return
+			}
+		} else {
+			currentTheme.assets.set(f.Name, raw)
+		}
+	}
+
+	if currentTheme.template != nil {
+		theme = currentTheme
+		return
+	}
+
+	err = errors.New("lacks of page template 'index.html' in theme")
+	return
+}
+
+func (theme MemTheme) RenderPage(w io.Writer, data interface{}) error {
+	return theme.template.Execute(w, data)
+}
+
+func (theme MemTheme) RenderAsset(w http.ResponseWriter, r *http.Request, assetPath string) {
+	asset, ok := theme.assets[assetPath]
+	if !ok {
+		w.WriteHeader(http.StatusNotFound)
+		return
+	}
+
+	w.Header().Set("Content-Type", asset.contentType)
+	http.ServeContent(w, r, assetPath, initTime, asset.readSeeker)
+}

src/tpl/template.go

@@ -1,28 +1,10 @@
 package tpl
 
 import (
-	"../serverErrHandler"
 	"./util"
-	_ "embed"
 	"html/template"
 )
 
-//go:embed frontend/index.html
-var defaultTplStr string
-
-var defaultTpl *template.Template
-
-func init() {
-	tpl := template.New("page")
-	tpl = addFuncMap(tpl)
-
-	var err error
-	defaultTpl, err = tpl.Parse(defaultTplStr)
-	if serverErrHandler.CheckError(err) {
-		defaultTpl = template.Must(tpl.Parse("Builtin Template Error"))
-	}
-}
-
 func ParsePageTpl(tplText string) (tpl *template.Template, err error) {
 	tpl = template.New("page")
 	tpl = addFuncMap(tpl)

src/tpl/theme.go

@@ -1,67 +1,11 @@
 package tpl
 
 import (
-	"archive/zip"
-	"html/template"
 	"io"
+	"net/http"
 )
 
-type Theme struct {
-	Template *template.Template
-	Assets   assets
-}
-
-var DefaultTheme Theme
-
-// wait for `defaultTpl` initialized
-func init() {
-	DefaultTheme = Theme{defaultTpl, defaultAssets}
-}
-
-func LoadTheme(themePath string) (theme Theme, err error) {
-	theme = DefaultTheme
-
-	if len(themePath) == 0 {
-		return
-	}
-
-	var currentTheme = Theme{
-		Template: nil,
-		Assets:   make(assets, 2),
-	}
-	// assume to be a zip file
-	var zipRd *zip.ReadCloser
-	zipRd, err = zip.OpenReader(themePath)
-	if err != nil {
-		return
-	}
-	defer zipRd.Close()
-
-	for _, f := range zipRd.File {
-		var rd io.ReadCloser
-		rd, err = f.Open()
-		if err != nil {
-			continue
-		}
-		var raw []byte
-		raw, err = io.ReadAll(rd)
-		rd.Close()
-		if err != nil {
-			return
-		}
-		if f.Name == "index.html" {
-			currentTheme.Template, err = ParsePageTpl(string(raw))
-			if err != nil {
-				return
-			}
-		} else {
-			currentTheme.Assets.Set(f.Name, raw)
-		}
-	}
-
-	if currentTheme.Template != nil {
-		theme = currentTheme
-	}
-
-	return
+type Theme interface {
+	RenderPage(w io.Writer, data interface{}) error
+	RenderAsset(w http.ResponseWriter, r *http.Request, assetPath string)
 }