webapi: Footer update time relative not absolute.

Using a relative time rather than absolute requires far less effort for
a reader to understand, e.g. compare "25 Oct 2024 11:12:49 UTC" to "3
minutes ago".

As a nice side-effect this also fixes a minor privacy issue where using
the full absolute timestamp would expose the server timezone to the
public.

internal/webapi/cache.go

@@ -1,4 +1,4 @@
-// Copyright (c) 2020-2023 The Decred developers
+// Copyright (c) 2020-2024 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -34,7 +34,7 @@ type cacheData struct {
 	// the first time.
 	Initialized bool
 
-	UpdateTime          string
+	UpdateTime          time.Time
 	PubKey              string
 	DatabaseSize        string
 	Voting              int64
@@ -118,7 +118,7 @@ func (c *cache) update() error {
 	defer c.mtx.Unlock()
 
 	c.data.Initialized = true
-	c.data.UpdateTime = dateTime(time.Now().Unix())
+	c.data.UpdateTime = time.Now()
 	c.data.DatabaseSize = humanize.Bytes(dbSize)
 	c.data.Voting = voting
 	c.data.Voted = voted

internal/webapi/formatting.go

@@ -1,3 +1,7 @@
+// Copyright (c) 2020-2024 The Decred developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
 package webapi
 
 import (
@@ -9,6 +13,7 @@ import (
 
 	"github.com/decred/dcrd/dcrutil/v4"
 	"github.com/decred/slog"
+	"github.com/dustin/go-humanize"
 )
 
 func addressURL(blockExplorerURL string) func(string) string {
@@ -29,10 +34,19 @@ func blockURL(blockExplorerURL string) func(int64) string {
 	}
 }
 
+// dateTime returns a human readable representation of the provided unix
+// timestamp. It includes the local timezone of the server so use on public
+// webpages is not recommended.
 func dateTime(t int64) string {
 	return time.Unix(t, 0).Format("2 Jan 2006 15:04:05 MST")
 }
 
+// timeAgo compares the provided unix timestamp to the current time to return a
+// string like "3 minutes ago".
+func timeAgo(t time.Time) string {
+	return humanize.Time(t)
+}
+
 func stripWss(input string) string {
 	input = strings.ReplaceAll(input, "wss://", "")
 	input = strings.ReplaceAll(input, "/ws", "")

internal/webapi/templates/footer.html

@@ -5,7 +5,7 @@
   <footer class="row m-0">
         <div class="col-md-8 col-12 d-flex justify-content-center align-items-center">
             <p class="py-4 m-0">
-              <strong>Stats&nbsp;updated:</strong>&nbsp;{{ .WebApiCache.UpdateTime }}
+              <strong>Stats&nbsp;updated:</strong>&nbsp;{{ timeAgo .WebApiCache.UpdateTime }}
               <br />
               <strong>Support:</strong>&nbsp;<a href="mailto:{{ .WebApiCfg.SupportEmail }}" rel="noopener noreferrer">{{ .WebApiCfg.SupportEmail }}</a>
               <br />

internal/webapi/webapi.go

@@ -210,6 +210,7 @@ func (w *WebAPI) router(cookieSecret []byte, dcrd rpc.DcrdConnect, wallets rpc.W
 		"addressURL":       addressURL(explorerURL),
 		"blockURL":         blockURL(explorerURL),
 		"dateTime":         dateTime,
+		"timeAgo":          timeAgo,
 		"stripWss":         stripWss,
 		"indentJSON":       indentJSON(w.log),
 		"atomsToDCR":       atomsToDCR,