+ {{template "admin-header" .}}
+
+ {{if not .UpdateAvailable}}
+
WriteFreely is up to date.
+ {{else}}
+
WriteFreely {{.LatestVersion}} is available.
+
+ {{end}}
+
Last checked at: {{.LastChecked}}. Check now.
+
+{{template "footer" .}}
+
+{{template "body-end" .}}
+{{end}}
diff --git a/templates/user/include/header.tmpl b/templates/user/include/header.tmpl
index 312d0b8..48946d6 100644
--- a/templates/user/include/header.tmpl
+++ b/templates/user/include/header.tmpl
@@ -1,75 +1,76 @@
{{define "header"}}
{{.PageTitle}} {{if .Separator}}{{.Separator}}{{else}}—{{end}} {{.SiteName}}
{{if .SingleUser}}
{{else}}
{{end}}
{{end}}
{{define "admin-header"}}
{{end}}
diff --git a/updates.go b/updates.go
new file mode 100644
index 0000000..248f691
--- /dev/null
+++ b/updates.go
@@ -0,0 +1,103 @@
+/*
+ * Copyright © 2018-2019 A Bunch Tell LLC.
+ *
+ * This file is part of WriteFreely.
+ *
+ * WriteFreely is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, included
+ * in the LICENSE file in this source code package.
+ */
+
+package writefreely
+
+import (
+ "io/ioutil"
+ "net/http"
+ "strings"
+ "sync"
+ "time"
+)
+
+// updatesCacheTime is the default interval between cache updates for new
+// software versions
+const updatesCacheTime = 12 * time.Hour
+
+// updatesCache holds data about current and new releases of the writefreely
+// software
+type updatesCache struct {
+ mu sync.Mutex
+ frequency time.Duration
+ lastCheck time.Time
+ latestVersion string
+ currentVersion string
+}
+
+// CheckNow asks for the latest released version of writefreely and updates
+// the cache last checked time. If the version postdates the current 'latest'
+// the version value is replaced.
+func (uc *updatesCache) CheckNow() error {
+ uc.mu.Lock()
+ defer uc.mu.Unlock()
+ latestRemote, err := newVersionCheck(uc.currentVersion)
+ if err != nil {
+ return err
+ }
+ uc.lastCheck = time.Now()
+ if CompareSemver(latestRemote, uc.latestVersion) == 1 {
+ uc.latestVersion = latestRemote
+ }
+ return nil
+}
+
+// AreAvailable updates the cache if the frequency duration has passed
+// then returns if the latest release is newer than the current running version.
+func (uc updatesCache) AreAvailable() bool {
+ if time.Since(uc.lastCheck) > uc.frequency {
+ uc.CheckNow()
+ }
+ return CompareSemver(uc.latestVersion, uc.currentVersion) == 1
+}
+
+// LatestVersion returns the latest stored version available.
+func (uc updatesCache) LatestVersion() string {
+ return uc.latestVersion
+}
+
+// ReleaseURL returns the full URL to the blog.writefreely.org release notes
+// for the latest version as stored in the cache.
+func (uc updatesCache) ReleaseURL() string {
+ ver := strings.TrimPrefix(uc.latestVersion, "v")
+ ver = strings.TrimSuffix(ver, ".0")
+ return "https://blog.writefreely.org/version-" + strings.ReplaceAll(ver, ".", "-")
+}
+
+// newUpdatesCache returns an initialized updates cache
+func newUpdatesCache() *updatesCache {
+ cache := updatesCache{
+ frequency: updatesCacheTime,
+ currentVersion: "v" + softwareVer,
+ }
+ cache.CheckNow()
+ return &cache
+}
+
+// InitUpdates initializes the updates cache, if the config value is set
+func (app *App) InitUpdates() {
+ if app.cfg.App.UpdateChecks {
+ app.updates = newUpdatesCache()
+ }
+}
+
+func newVersionCheck(serverVersion string) (string, error) {
+ res, err := http.Get("https://version.writefreely.org")
+ if err == nil && res.StatusCode == http.StatusOK {
+ defer res.Body.Close()
+
+ body, err := ioutil.ReadAll(res.Body)
+ if err != nil {
+ return "", err
+ }
+ return string(body), nil
+ }
+ return "", err
+}