Adding interplugin communication. (#12829)

* Adding interplugin communication.

* Naming changes and moving ResponseTransfer to own file.

* Fix.

* Tests and moving to buffering bytes.

* Switching API to passing plugin ID through path rather than a header.

* Review feedback.

app/plugin_api_test.go

@@ -26,7 +26,7 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func setupPluginApiTest(t *testing.T, pluginCode string, pluginManifest string, pluginId string, app *App) string {
+func setupMultiPluginApiTest(t *testing.T, pluginCodes []string, pluginManifests []string, pluginIds []string, app *App) string {
 	pluginDir, err := ioutil.TempDir("", "")
 	require.NoError(t, err)
 	webappPluginDir, err := ioutil.TempDir("", "")
@@ -37,20 +37,29 @@ func setupPluginApiTest(t *testing.T, pluginCode string, pluginManifest string,
 	env, err := plugin.NewEnvironment(app.NewPluginAPI, pluginDir, webappPluginDir, app.Log)
 	require.NoError(t, err)
 
-	backend := filepath.Join(pluginDir, pluginId, "backend.exe")
-	utils.CompileGo(t, pluginCode, backend)
+	require.Equal(t, len(pluginCodes), len(pluginIds))
+	require.Equal(t, len(pluginManifests), len(pluginIds))
 
-	ioutil.WriteFile(filepath.Join(pluginDir, pluginId, "plugin.json"), []byte(pluginManifest), 0600)
-	manifest, activated, reterr := env.Activate(pluginId)
-	require.Nil(t, reterr)
-	require.NotNil(t, manifest)
-	require.True(t, activated)
+	for i, pluginId := range pluginIds {
+		backend := filepath.Join(pluginDir, pluginId, "backend.exe")
+		utils.CompileGo(t, pluginCodes[i], backend)
+
+		ioutil.WriteFile(filepath.Join(pluginDir, pluginId, "plugin.json"), []byte(pluginManifests[i]), 0600)
+		manifest, activated, reterr := env.Activate(pluginId)
+		require.Nil(t, reterr)
+		require.NotNil(t, manifest)
+		require.True(t, activated)
+	}
 
 	app.SetPluginsEnvironment(env)
 
 	return pluginDir
 }
 
+func setupPluginApiTest(t *testing.T, pluginCode string, pluginManifest string, pluginId string, app *App) string {
+	return setupMultiPluginApiTest(t, []string{pluginCode}, []string{pluginManifest}, []string{pluginId}, app)
+}
+
 func TestPublicFilesPathConfiguration(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
@@ -1462,3 +1471,98 @@ func TestPluginAddUserToChannel(t *testing.T) {
 	require.Equal(t, th.BasicChannel.Id, member.ChannelId)
 	require.Equal(t, th.BasicUser.Id, member.UserId)
 }
+
+func TestInterpluginPluginHTTP(t *testing.T) {
+	th := Setup(t).InitBasic()
+	defer th.TearDown()
+
+	setupMultiPluginApiTest(t,
+		[]string{`
+		package main
+
+		import (
+			"github.com/mattermost/mattermost-server/plugin"
+			"bytes"
+			"net/http"
+		)
+
+		type MyPlugin struct {
+			plugin.MattermostPlugin
+		}
+
+		func (p *MyPlugin) ServeHTTP(c *plugin.Context, w http.ResponseWriter, r *http.Request) {
+			if r.URL.Path != "/api/v2/test" {
+				return
+			}
+			buf := bytes.Buffer{}
+			buf.ReadFrom(r.Body)
+			resp := "we got:" + buf.String()
+			w.WriteHeader(598)
+			w.Write([]byte(resp))
+		}
+
+		func main() {
+			plugin.ClientMain(&MyPlugin{})
+		}
+		`,
+			`
+		package main
+
+		import (
+			"github.com/mattermost/mattermost-server/plugin"
+			"github.com/mattermost/mattermost-server/model"
+			"bytes"
+			"net/http"
+			"io/ioutil"
+		)
+
+		type MyPlugin struct {
+			plugin.MattermostPlugin
+		}
+
+		func (p *MyPlugin) MessageWillBePosted(c *plugin.Context, post *model.Post) (*model.Post, string) {
+			buf := bytes.Buffer{}
+			buf.WriteString("This is the request")
+			req, err := http.NewRequest("GET", "/testplugininterserver/api/v2/test", &buf)
+			if err != nil {
+				return nil, err.Error()
+			}
+			req.Header.Add("Mattermost-User-Id", "userid")
+			resp := p.API.PluginHTTP(req)
+			if resp == nil {
+				return nil, "Nil resp"
+			}
+			if resp.Body == nil {
+				return nil, "Nil body"
+			}
+			respbody, err := ioutil.ReadAll(resp.Body)
+			if err != nil {
+				return nil, err.Error()
+			}
+			if resp.StatusCode != 598 {
+				return nil, "wrong status " + string(respbody)
+			}
+			return nil, string(respbody)
+		}
+
+		func main() {
+			plugin.ClientMain(&MyPlugin{})
+		}
+		`,
+		},
+		[]string{
+			`{"id": "testplugininterserver", "backend": {"executable": "backend.exe"}}`,
+			`{"id": "testplugininterclient", "backend": {"executable": "backend.exe"}}`,
+		},
+		[]string{
+			"testplugininterserver",
+			"testplugininterclient",
+		},
+		th.App,
+	)
+
+	hooks, err := th.App.GetPluginsEnvironment().HooksForPlugin("testplugininterclient")
+	require.NoError(t, err)
+	_, ret := hooks.MessageWillBePosted(nil, nil)
+	assert.Equal(t, "we got:This is the request", ret)
+}