at-container-registry/themes/seamark/embed.go

// Package seamark provides the Seamark visual theme for the ATCR AppView.
// Import with a blank identifier to register: _ "atcr.io/themes/seamark"
// Enable with ATCR_UI_THEME=seamark.
package seamark

import (
	"embed"
	"io/fs"

	"atcr.io/pkg/appview"
)

//go:embed public
var publicFS embed.FS

//go:embed theme.css
var themeCSS string

func init() {
	appview.RegisterTheme("seamark", branding)
}

func branding() *appview.BrandingOverrides {
	// Strip the leading "public" directory so the overlay FS matches the
	// structure expected by resolvePublicFS (which looks under "public/").
	pubSub, err := fs.Sub(publicFS, "public")
	if err != nil {
		panic("seamark: bad embed layout: " + err.Error())
	}

	return &appview.BrandingOverrides{
		PublicFS: prefixFS{sub: pubSub},
		ExtraCSS: themeCSS,
	}
}

// prefixFS re-adds the "public/" prefix so the overlay FS works with
// atcr.io's resolvePublicFS which opens paths like "public/favicon.svg".
type prefixFS struct{ sub fs.FS }

func (p prefixFS) Open(name string) (fs.File, error) {
	const prefix = "public/"
	if len(name) > len(prefix) && name[:len(prefix)] == prefix {
		return p.sub.Open(name[len(prefix):])
	}
	// Non-public paths: return not-found so the overlay falls through.
	return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrNotExist}
}

func (p prefixFS) ReadDir(name string) ([]fs.DirEntry, error) {
	const prefix = "public/"
	if name == "public" {
		return fs.ReadDir(p.sub, ".")
	}
	if len(name) > len(prefix) && name[:len(prefix)] == prefix {
		return fs.ReadDir(p.sub, name[len(prefix):])
	}
	return nil, &fs.PathError{Op: "readdir", Path: name, Err: fs.ErrNotExist}
}

func (p prefixFS) ReadFile(name string) ([]byte, error) {
	const prefix = "public/"
	if len(name) > len(prefix) && name[:len(prefix)] == prefix {
		return fs.ReadFile(p.sub, name[len(prefix):])
	}
	return nil, &fs.PathError{Op: "readfile", Path: name, Err: fs.ErrNotExist}
}