blob: b888445cc73f9351857af7488c1ca1cb1ff8f43f [file] [log] [blame]
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package middleware
import (
"bytes"
"context"
"net/http"
"regexp"
"strings"
"golang.org/x/pkgsite/internal/log"
)
const (
latestClassPlaceholder = "$$GODISCOVERY_LATESTCLASS$$"
LatestVersionPlaceholder = "$$GODISCOVERY_LATESTVERSION$$"
)
// latestInfoRegexp extracts values needed to determine the latest-version badge from a page's HTML.
var latestInfoRegexp = regexp.MustCompile(`data-version="([^"]*)" data-mpath="([^"]*)" data-ppath="([^"]*)" data-pagetype="([^"]*)"`)
type latestFunc func(ctx context.Context, packagePath, modulePath, pageType string) string
// LatestVersion supports the badge that displays whether the version of the
// package or module being served is the latest one.
func LatestVersion(latest latestFunc) Middleware {
return func(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// TODO(b/144509703): avoid copying if possible
crw := &capturingResponseWriter{ResponseWriter: w}
h.ServeHTTP(crw, r)
body := crw.bytes()
matches := latestInfoRegexp.FindSubmatch(body)
if matches != nil {
version := string(matches[1])
// The html/template package converts '+' to its HTML entity.
// Wrapping the value in the special types template.HTML and
// template.HTMLAttxsr did not help.
version = strings.Replace(version, "+", "+", -1)
modulePath := string(matches[2])
packagePath := string(matches[3])
pageType := string(matches[4])
latestVersion := latest(r.Context(), packagePath, modulePath, pageType)
latestClass := "DetailsHeader-badge"
switch {
case latestVersion == "":
latestClass += "--unknown"
case latestVersion == version:
latestClass += "--latest"
default:
latestClass += "--goToLatest"
}
// TODO(b/144509703): make only a single copy here, if this is slow
body = bytes.ReplaceAll(body, []byte(latestClassPlaceholder), []byte(latestClass))
body = bytes.ReplaceAll(body, []byte(LatestVersionPlaceholder), []byte(latestVersion))
}
if _, err := w.Write(body); err != nil {
log.Errorf(r.Context(), "LatestVersion, writing: %v", err)
}
})
}
}