#4257 Added functionality to create previews for post links using open graph data from those links. (#4890)

2017-01-20 23:11:13 +05:30
--- a/api/post.go
+++ b/api/post.go
@@ -8,6 +8,7 @@ import (
 	"strconv"

 	l4g "github.com/alecthomas/log4go"
+	"github.com/dyatlov/go-opengraph/opengraph"
 	"github.com/gorilla/mux"
 	"github.com/mattermost/platform/app"
 	"github.com/mattermost/platform/model"
@@ -18,6 +19,8 @@ import (
 func InitPost() {
 	l4g.Debug(utils.T("api.post.init.debug"))

+	BaseRoutes.ApiRoot.Handle("/get_opengraph_metadata", ApiUserRequired(getOpenGraphMetadata)).Methods("POST")
+
 	BaseRoutes.NeedTeam.Handle("/posts/search", ApiUserRequiredActivity(searchPosts, true)).Methods("POST")
 	BaseRoutes.NeedTeam.Handle("/posts/flagged/{offset:[0-9]+}/{limit:[0-9]+}", ApiUserRequired(getFlaggedPosts)).Methods("GET")
 	BaseRoutes.NeedTeam.Handle("/posts/{post_id}", ApiUserRequired(getPostById)).Methods("GET")
@@ -649,3 +652,29 @@ func getFileInfosForPost(c *Context, w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte(model.FileInfosToJson(infos)))
 	}
 }
+
+func getOpenGraphMetadata(c *Context, w http.ResponseWriter, r *http.Request) {
+	props := model.StringInterfaceFromJson(r.Body)
+	og := opengraph.NewOpenGraph()
+
+	res, err := http.Get(props["url"].(string))
+	if err != nil {
+		writeOpenGraphToResponse(w, og)
+		return
+	}
+
+	if err := og.ProcessHTML(res.Body); err != nil {
+		writeOpenGraphToResponse(w, og)
+		return
+	}
+
+	writeOpenGraphToResponse(w, og)
+}
+
+func writeOpenGraphToResponse(w http.ResponseWriter, og *opengraph.OpenGraph) {
+	ogJson, err := og.ToJSON()
+	if err != nil {
+		w.Write([]byte(`{"url": ""}`))
+	}
+	w.Write(ogJson)
+}
--- a/api/post_test.go
+++ b/api/post_test.go
@@ -5,6 +5,7 @@ package api

 import (
 	"encoding/json"
+	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -1298,3 +1299,33 @@ func TestGetPermalinkTmp(t *testing.T) {
 		t.Fatal("should not be empty")
 	}
 }
+
+func TestGetOpenGraphMetadata(t *testing.T) {
+	th := Setup().InitBasic()
+	Client := th.BasicClient
+
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/og-data/" {
+			fmt.Fprintln(w, `
+				<html><head><meta property="og:type" content="article" />
+		  		<meta property="og:title" content="Test Title" />
+		  		<meta property="og:url" content="http://example.com/" />
+				</head><body></body></html>
+			`)
+		} else if r.URL.Path == "/no-og-data/" {
+			fmt.Fprintln(w, `<html><head></head><body></body></html>`)
+		}
+	}))
+
+	for _, data := range [](map[string]string){{"path": "/og-data/", "title": "Test Title"}, {"path": "/no-og-data/", "title": ""}} {
+		res, err := Client.DoApiPost("/get_opengraph_metadata", fmt.Sprintf("{\"url\":\"%s\"}", ts.URL+data["path"]))
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		ogData := model.StringInterfaceFromJson(res.Body)
+		if strings.Compare(ogData["title"].(string), data["title"]) != 0 {
+			t.Fatal(fmt.Sprintf("OG data title mismatch for path \"%s\". Expected title: \"%s\". Actual title: \"%s\"", data["path"], data["title"], ogData["title"]))
+		}
+	}
+}