feat(share): add Open Graph support for social media previews

- Detect social media bots (Facebook, Twitter, Discord, etc.)
- Render OG meta tags with file name, size, and owner info
- Auto-redirect to share page after preview is rendered

routers/controllers/share.go

@@ -1,11 +1,13 @@
 package controllers
 
 import (
+	"net/http"
+	"strings"
+
 	"github.com/cloudreve/Cloudreve/v4/pkg/hashid"
 	"github.com/cloudreve/Cloudreve/v4/pkg/serializer"
 	"github.com/cloudreve/Cloudreve/v4/service/share"
 	"github.com/gin-gonic/gin"
-	"net/http"
 )
 
 // CreateShare 创建分享
@@ -74,5 +76,48 @@ func DeleteShare(c *gin.Context) {
 
 func ShareRedirect(c *gin.Context) {
 	service := ParametersFromContext[*share.ShortLinkRedirectService](c, share.ShortLinkRedirectParamCtx{})
+
+	// Check if the request is from a social media bot
+	if isSocialMediaBot(c.GetHeader("User-Agent")) {
+		html, err := service.RenderOGPage(c)
+		if err == nil {
+			c.Header("Content-Type", "text/html; charset=utf-8")
+			c.String(http.StatusOK, html)
+			return
+		}
+		// Fall back to redirect on error
+	}
+
 	c.Redirect(http.StatusFound, service.RedirectTo(c))
 }
+
+// isSocialMediaBot checks if the User-Agent belongs to a social media crawler
+func isSocialMediaBot(ua string) bool {
+	bots := []string{
+		"facebookexternalhit",
+		"twitterbot",
+		"linkedinbot",
+		"whatsapp",
+		"slackbot",
+		"discordbot",
+		"telegrambot",
+		"applebot",
+		"pinterest",
+		"googlebot",
+		"bingbot",
+		"yandexbot",
+		"duckduckbot",
+		"baiduspider",
+		"sogou",
+		"exabot",
+		"facebot",
+		"ia_archiver",
+	}
+	ua = strings.ToLower(ua)
+	for _, bot := range bots {
+		if strings.Contains(ua, bot) {
+			return true
+		}
+	}
+	return false
+}

service/share/og_template.go

@@ -0,0 +1,77 @@
+package share
+
+import (
+	"bytes"
+	"fmt"
+	"html/template"
+)
+
+// ShareOGData contains data for rendering Open Graph HTML page
+type ShareOGData struct {
+	SiteName     string
+	FileName     string
+	FileSize     string
+	OwnerName    string
+	ShareURL     string
+	ThumbnailURL string
+	RedirectURL  string
+}
+
+const ogHTMLTemplate = `<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <meta property="og:title" content="{{.FileName}}">
+    <meta property="og:description" content="{{.FileSize}}{{if .OwnerName}} · {{.OwnerName}}{{end}}">
+    <meta property="og:image" content="{{.ThumbnailURL}}">
+    <meta property="og:url" content="{{.ShareURL}}">
+    <meta property="og:type" content="website">
+    <meta property="og:site_name" content="{{.SiteName}}">
+    <meta name="twitter:card" content="summary">
+    <meta name="twitter:title" content="{{.FileName}}">
+    <meta name="twitter:description" content="{{.FileSize}}{{if .OwnerName}} · {{.OwnerName}}{{end}}">
+    <meta name="twitter:image" content="{{.ThumbnailURL}}">
+    <title>{{.FileName}} - {{.SiteName}}</title>
+</head>
+<body>
+    <script>window.location.href = "{{.RedirectURL}}";</script>
+    <noscript>
+        <p><a href="{{.RedirectURL}}">{{.FileName}}</a></p>
+    </noscript>
+</body>
+</html>`
+
+var ogTemplate = template.Must(template.New("og").Parse(ogHTMLTemplate))
+
+// RenderOGHTML renders the Open Graph HTML page
+func RenderOGHTML(data *ShareOGData) (string, error) {
+	var buf bytes.Buffer
+	if err := ogTemplate.Execute(&buf, data); err != nil {
+		return "", fmt.Errorf("failed to render OG template: %w", err)
+	}
+	return buf.String(), nil
+}
+
+// FormatFileSize formats file size to human readable format
+func FormatFileSize(size int64) string {
+	const (
+		B  = 1
+		KB = 1024 * B
+		MB = 1024 * KB
+		GB = 1024 * MB
+		TB = 1024 * GB
+	)
+
+	switch {
+	case size >= TB:
+		return fmt.Sprintf("%.2f TB", float64(size)/TB)
+	case size >= GB:
+		return fmt.Sprintf("%.2f GB", float64(size)/GB)
+	case size >= MB:
+		return fmt.Sprintf("%.2f MB", float64(size)/MB)
+	case size >= KB:
+		return fmt.Sprintf("%.2f KB", float64(size)/KB)
+	default:
+		return fmt.Sprintf("%d B", size)
+	}
+}

service/share/visit.go

@@ -2,6 +2,7 @@ package share
 
 import (
 	"context"
+	"net/url"
 	"strings"
 
 	"github.com/cloudreve/Cloudreve/v4/application/dependency"
@@ -48,6 +49,68 @@ func (s *ShortLinkRedirectService) RedirectTo(c *gin.Context) string {
 	return shareLongUrl.String()
 }
 
+// RenderOGPage renders an Open Graph HTML page for social media previews
+func (s *ShortLinkRedirectService) RenderOGPage(c *gin.Context) (string, error) {
+	dep := dependency.FromContext(c)
+	shareClient := dep.ShareClient()
+	settings := dep.SettingProvider()
+
+	// Load share with user and file info
+	ctx := context.WithValue(c, inventory.LoadShareUser{}, true)
+	ctx = context.WithValue(ctx, inventory.LoadShareFile{}, true)
+	share, err := shareClient.GetByHashID(ctx, s.ID)
+	if err != nil {
+		return "", err
+	}
+
+	// Check if share is valid
+	if err := inventory.IsValidShare(share); err != nil {
+		return "", err
+	}
+
+	// Get site settings
+	siteBasic := settings.SiteBasic(c)
+	pwa := settings.PWA(c)
+	base := settings.SiteURL(c)
+
+	// Build share URL
+	shareURL := routes.MasterShareUrl(base, s.ID, "")
+
+	// Build thumbnail URL - use PWA large icon (PNG), fallback to medium icon
+	thumbnailURL := pwa.LargeIcon
+	if thumbnailURL == "" {
+		thumbnailURL = pwa.MediumIcon
+	}
+	if thumbnailURL != "" && !isAbsoluteURL(thumbnailURL) {
+		thumbnailURL = base.ResolveReference(&url.URL{Path: thumbnailURL}).String()
+	}
+
+	// Get file info
+	fileName := share.Edges.File.Name
+	fileSize := FormatFileSize(share.Edges.File.Size)
+
+	// Get owner name (don't expose email for privacy)
+	ownerName := share.Edges.User.Nick
+
+	// Prepare OG data
+	ogData := &ShareOGData{
+		SiteName:     siteBasic.Name,
+		FileName:     fileName,
+		FileSize:     fileSize,
+		OwnerName:    ownerName,
+		ShareURL:     shareURL.String(),
+		ThumbnailURL: thumbnailURL,
+		RedirectURL:  s.RedirectTo(c),
+	}
+
+	return RenderOGHTML(ogData)
+}
+
+// isAbsoluteURL checks if the URL is absolute (starts with http:// or https://)
+func isAbsoluteURL(u string) bool {
+	return strings.HasPrefix(u, "http://") || strings.HasPrefix(u, "https://")
+}
+
 type (
 	ShareInfoService struct {
 		Password      string `form:"password"`