fs_embed.go

package noodle

import (
	"archive/zip"
	"bytes"
	"net/http"
	"os"

	"github.com/dyweb/gommon/errors"
)

var (
	_ http.FileSystem = (*EmbedBowel)(nil)
	_ Bowel           = (*EmbedBowel)(nil)
)

type EmbedBowel struct {
	Dirs  map[string]EmbedDir
	Data  []byte
	files map[string]EmbedFile
}

type EmbedFile struct {
	FileInfo
	Data   []byte
	reader *bytes.Reader
}

var _ http.File = (*EmbedDir)(nil)

type EmbedDir struct {
	FileInfo
	Entries []FileInfo
}

func (d *EmbedDir) Read(p []byte) (int, error) {
	return 0, os.ErrNotExist
}

func (d *EmbedDir) Seek(offset int64, whence int) (int64, error) {
	return 0, os.ErrNotExist
}

func (d *EmbedDir) Stat() (os.FileInfo, error) {
	return &d.FileInfo, nil
}

func (d *EmbedDir) Close() error {
	return nil
}

func (d *EmbedDir) Readdir(count int) ([]os.FileInfo, error) {
	log.Debugf("readdir %d", count)
	files := make([]os.FileInfo, 0, len(d.Entries))
	// FIXED: learn this the hard way .. https://github.com/dyweb/gommon/issues/50
	// the element is range syntax is created when loop start and it is reused between iterations, thus same pointer
	// https://tam7t.com/golang-range-and-pointers/
	//for _, f := range d.Entries {
	//	log.Infof("file %s", f.Name())
	//	files = append(files, &f)
	//}
	for i := range d.Entries {
		files = append(files, &d.Entries[i])
	}
	return files, nil
}

func (b *EmbedBowel) Open(name string) (http.File, error) {
	// check dir first
	log.Debugf("open %s", name)
	// trim /
	name = name[1:]
	if d, exists := b.Dirs[name]; exists {
		// TODO: allow disable list dir here
		log.Debugf("%s entries %d", name, len(d.Entries))
		return &d, nil
	}
	// check file
	if f, exists := b.files[name]; exists {
		return &f, nil
	}
	return nil, os.ErrNotExist
}

func (b *EmbedBowel) ExtractFiles() error {
	r, err := zip.NewReader(bytes.NewReader(b.Data), int64(len(b.Data)))
	if err != nil {
		errors.Wrap(err, "can't read zipped data")
	}
	b.files = make(map[string]EmbedFile)
	for _, f := range r.File {
		if bs, err := unzip(f); err != nil {
			return err
		} else {
			b.files[f.Name] = EmbedFile{
				FileInfo: *NewFileInfo(f.FileInfo()),
				Data:     bs,
			}
		}
	}
	return nil
}

func (f *EmbedFile) Read(p []byte) (int, error) {
	if f.reader == nil {
		f.reader = bytes.NewReader(f.Data)
	}
	return f.reader.Read(p)
}

func (f *EmbedFile) Seek(offset int64, whence int) (int64, error) {
	if f.reader == nil {
		f.reader = bytes.NewReader(f.Data)
	}
	return f.reader.Seek(offset, whence)
}

func (f *EmbedFile) Stat() (os.FileInfo, error) {
	return &f.FileInfo, nil
}

func (f *EmbedFile) Readdir(count int) ([]os.FileInfo, error) {
	// TODO: what's the correct error when Readdir is called on File
	return nil, os.ErrInvalid
}

func (f *EmbedFile) Close() error {
	// TODO: I think we can do nothing?
	//if f.reader != nil {
	//	f.reader = nil
	//}
	return nil
}