Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/channels/api4/openGraph.go

@@ -0,0 +1,41 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package api4
+
+import (
+	"net/http"
+
+	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/server/platform/shared/mlog"
+)
+
+func (api *API) InitOpenGraph() {
+	api.BaseRoutes.OpenGraph.Handle("", api.APISessionRequired(getOpenGraphMetadata)).Methods("POST")
+}
+
+func getOpenGraphMetadata(c *Context, w http.ResponseWriter, r *http.Request) {
+	if !*c.App.Config().ServiceSettings.EnableLinkPreviews {
+		c.Err = model.NewAppError("getOpenGraphMetadata", "api.post.link_preview_disabled.app_error", nil, "", http.StatusNotImplemented)
+		return
+	}
+
+	props := model.StringInterfaceFromJSON(r.Body)
+
+	url := ""
+	ok := false
+	if url, ok = props["url"].(string); url == "" || !ok {
+		c.SetInvalidParam("url")
+		return
+	}
+
+	buf, err := c.App.GetOpenGraphMetadata(url)
+	if err != nil {
+		mlog.Warn("GetOpenGraphMetadata request failed",
+			mlog.String("requestURL", url),
+			mlog.Err(err))
+		w.Write([]byte(`{"url": ""}`))
+		return
+	}
+	w.Write(buf)
+}