modweb/utils/joinedfs.go

package utils

import (
	"fmt"
	"net/http"
	"os"
	"strings"
)

type JoinedFilesystem struct {
	DefaultSystem http.FileSystem
	Systems       map[string]http.FileSystem
}

func Stat(fs http.FileSystem, filename string) (os.FileInfo, error) {
	file, err := fs.Open(filename)
	if err != nil {
		return nil, err
	}
	return file.Stat()
}

func Readdir(fs http.FileSystem, filename string) ([]os.FileInfo, error) {
	file, err := fs.Open(filename)
	if err != nil {
		return nil, err
	}
	return file.Readdir(-1)
}

func (s *JoinedFilesystem) GetRoot() (http.File, error) {
	root, err := s.DefaultSystem.Open("/")
	if err != nil {
		return nil, err
	}

	rootStat, err := root.Stat()
	if err != nil {
		return nil, err
	}

	rootContent, err := root.Readdir(-1)
	if err != nil {
		return nil, err
	}

	for prefix, fs := range s.Systems {
		fsRoot, err := fs.Open("/")
		if err != nil {
			fmt.Println(err)
			continue
		}

		fsRootStat, err := fsRoot.Stat()
		if err != nil {
			fmt.Println(err)
			continue
		}

		rootContent = append(rootContent, ChangeFileInfoName(fsRootStat, prefix))
	}

	return FakeDir{Self: rootStat, Content: rootContent}, nil
}

func (s *JoinedFilesystem) Open(filename string) (http.File, error) {
	if filename == "/" {
		return s.GetRoot()
	}

	parts := strings.Split(filename, "/")
	var newFilename string
	if len(parts) == 2 {
		newFilename = "/"
	} else {
		newFilename = strings.Join(parts[2:], "/")
	}

	for prefix, fs := range s.Systems {
		if parts[1] == prefix {
			file, err := fs.Open(newFilename)
			if err == nil {
				return file, nil
			}
		}
	}

	return s.DefaultSystem.Open(filename)
}

func (s *JoinedFilesystem) Register(prefix string, system http.FileSystem) {
	s.Systems[prefix] = system
}

func JoinedFS(def http.FileSystem) *JoinedFilesystem {
	return &JoinedFilesystem{DefaultSystem: def, Systems: map[string]http.FileSystem{}}
}