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package frontend
import (
"crypto/sha256"
"encoding/base64"
"encoding/hex"
"hash/fnv"
"io"
"io/fs"
"path/filepath"
"strings"
"github.com/pkg/errors"
)
var Assets = &AssetCollection{
Scripts: make(map[string]*Asset),
Stylesheets: make(map[string]*Asset),
ByImmutablePath: make(map[string]*Asset),
}
type Asset struct {
URL string
Filename string
Base64SHA256 string
}
type AssetCollection struct {
Scripts map[string]*Asset
Stylesheets map[string]*Asset
ByImmutablePath map[string]*Asset
}
func newAsset(filename string) (*Asset, error) {
file, err := Files.Open(filename)
if err != nil {
return nil, errors.WithMessagef(err, "could not open file %s", filename)
}
defer file.Close()
shasum := sha256.New()
hash := fnv.New64a()
if _, err := io.Copy(io.MultiWriter(shasum, hash), file); err != nil {
return nil, errors.WithMessagef(err, "could not hash file %s", filename)
}
return &Asset{
URL: makeImmutablePath(filename, hex.EncodeToString(hash.Sum(nil))),
Filename: filename,
Base64SHA256: base64.StdEncoding.EncodeToString(shasum.Sum(nil)),
}, nil
}
func makeImmutablePath(filename string, hash string) string {
ext := filepath.Ext(filename)
return "/" + strings.Replace(filename, ext, "."+hash+ext, 1)
}
func hashScripts() error {
scripts, err := fs.Glob(Files, "static/**.js")
if err != nil {
return errors.WithMessage(err, "could not glob files")
}
for _, filename := range scripts {
asset, err := newAsset(filename)
if err != nil {
return err
}
Assets.Scripts[filename] = asset
Assets.ByImmutablePath[asset.URL] = asset
}
return nil
}
func hashStyles() error {
styles, err := fs.Glob(Files, "static/**.css")
if err != nil {
return errors.WithMessage(err, "could not glob files")
}
for _, filename := range styles {
asset, err := newAsset(filename)
if err != nil {
return err
}
Assets.Stylesheets[filename] = asset
Assets.ByImmutablePath[asset.URL] = asset
}
return nil
}
func Rehash() (err error) {
err = hashScripts()
if err != nil {
return err
}
err = hashStyles()
if err != nil {
return err
}
return nil
}
func init() {
err := Rehash()
if err != nil {
panic(err)
}
}
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