Add synced themes, color modes and custom CSS snippets

internal/api/themes.go

@@ -0,0 +1,165 @@
+package api
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"net/http"
+	"os"
+	"regexp"
+)
+
+var themeIDPattern = regexp.MustCompile(`^[a-z0-9][a-z0-9_-]{0,63}$`)
+
+type themeManifest struct {
+	ID      string `json:"id"`
+	Name    string `json:"name"`
+	Version string `json:"version"`
+}
+
+func readThemeFile(root *os.Root, name string, limit int64) ([]byte, error) {
+	f, err := root.Open(name)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	info, err := f.Stat()
+	if err != nil {
+		return nil, err
+	}
+	if !info.Mode().IsRegular() {
+		return nil, fmt.Errorf("主题文件必须为普通文件")
+	}
+	data, err := io.ReadAll(io.LimitReader(f, limit+1))
+	if err != nil {
+		return nil, err
+	}
+	if int64(len(data)) > limit {
+		return nil, fmt.Errorf("主题文件过大")
+	}
+	return data, nil
+}
+
+func (s *Server) readTheme(id string) (themeManifest, string, error) {
+	var manifest themeManifest
+	if !themeIDPattern.MatchString(id) || id == "default" || s.ThemesDir == "" {
+		return manifest, "", fs.ErrNotExist
+	}
+	root, err := os.OpenRoot(s.ThemesDir)
+	if err != nil {
+		return manifest, "", err
+	}
+	defer root.Close()
+	dir, err := root.OpenRoot(id)
+	if err != nil {
+		return manifest, "", err
+	}
+	defer dir.Close()
+	data, err := readThemeFile(dir, "manifest.json", 16<<10)
+	if err != nil {
+		return manifest, "", err
+	}
+	if err := json.Unmarshal(data, &manifest); err != nil {
+		return manifest, "", fmt.Errorf("主题 %s 的 manifest.json 无法解析：%w", id, err)
+	}
+	if manifest.ID != id || manifest.Name == "" || manifest.Version == "" {
+		return manifest, "", fmt.Errorf("主题 %s 的 id、name 或 version 无效", id)
+	}
+	css, err := readThemeFile(dir, "theme.css", 256<<10)
+	return manifest, string(css), err
+}
+
+func (s *Server) listThemes(w http.ResponseWriter, r *http.Request) {
+	themes := []themeManifest{{ID: "default", Name: "默认", Version: "1"}}
+	if s.ThemesDir != "" {
+		entries, err := os.ReadDir(s.ThemesDir)
+		if err != nil && !errors.Is(err, fs.ErrNotExist) {
+			internalError(w, r, err)
+			return
+		}
+		for _, entry := range entries {
+			if !entry.IsDir() || !themeIDPattern.MatchString(entry.Name()) || entry.Name() == "default" {
+				continue
+			}
+			manifest, _, err := s.readTheme(entry.Name())
+			if err != nil {
+				internalError(w, r, err)
+				return
+			}
+			themes = append(themes, manifest)
+		}
+	}
+	writeJSON(w, 200, map[string]any{"themes": themes})
+}
+
+func (s *Server) getTheme(w http.ResponseWriter, r *http.Request) {
+	manifest, css, err := s.readTheme(r.PathValue("id"))
+	if errors.Is(err, fs.ErrNotExist) {
+		writeError(w, 404, "主题不存在或文件不完整")
+		return
+	}
+	if err != nil {
+		internalError(w, r, err)
+		return
+	}
+	writeJSON(w, 200, struct {
+		themeManifest
+		CSS string `json:"css"`
+	}{manifest, css})
+}
+
+// 只有有效分享的访客可读取外观；不返回账户、插件和其他应用设置。
+func (s *Server) publicAppearance(w http.ResponseWriter, r *http.Request) {
+	if _, ok := s.openShare(w, r); !ok {
+		return
+	}
+	settings, err := s.readSettings()
+	if err != nil {
+		internalError(w, r, err)
+		return
+	}
+	out := map[string]any{}
+	for _, key := range []string{"colorMode", "fontSize", "contentWidth"} {
+		if value, ok := settings[key]; ok {
+			out[key] = value
+		}
+	}
+	var snippets []struct {
+		ID      string `json:"id"`
+		Name    string `json:"name"`
+		CSS     string `json:"css"`
+		Enabled bool   `json:"enabled"`
+	}
+	if value, ok := settings["cssSnippets"]; ok {
+		if err := json.Unmarshal(value, &snippets); err != nil {
+			internalError(w, r, err)
+			return
+		}
+	}
+	active := snippets[:0]
+	for _, snippet := range snippets {
+		if snippet.Enabled {
+			active = append(active, snippet)
+		}
+	}
+	out["cssSnippets"] = active
+	var theme string
+	if value, ok := settings["theme"]; ok {
+		if err := json.Unmarshal(value, &theme); err != nil {
+			internalError(w, r, err)
+			return
+		}
+	}
+	if theme != "" && theme != "default" {
+		_, css, err := s.readTheme(theme)
+		if err != nil {
+			internalError(w, r, err)
+			return
+		}
+		out["themeCSS"] = css
+	}
+	out["theme"] = theme
+	writeJSON(w, 200, out)
+}