[PLT-959] Browser Compatibility (#6945)

* Error page implimentation

* Update Browser Compatibility check to check Chrome, FF, IE, Edge, and Safai

* Update strings with proper edge version

* undo uneeded changes and move to go template.

* more unneeded additions

* eliminate js and add local triangle

* fix typo

* Correct debug logging of browser version

* Modify Browser Check to pass user_agent object only and write test.

* Fix chrome version typo and correct testing change that broke chrome UA chack

* simplity browser version detection by using maps instead of string splitting

2 files changed, 53 insertions, 12 deletions

diff --git a/web/web.go b/web/web.go
index e70129221..221e1dc1c 100644
--- a/web/web.go
+++ b/web/web.go
@@ -5,6 +5,7 @@ package web
 
 import (
 	"net/http"
+	"strconv"
 	"strings"
 
 	"github.com/NYTimes/gziphandler"
@@ -46,19 +47,28 @@ func staticHandler(handler http.Handler) http.Handler {
 	})
 }
 
-var browsersNotSupported string = "MSIE/8;MSIE/9;MSIE/10;Internet Explorer/8;Internet Explorer/9;Internet Explorer/10;Safari/7;Safari/8"
+//map should be of minimum required browser version.
+//var browsersNotSupported string = "MSIE/11;Internet Explorer/11;Safari/9;Chrome/43;Edge/15;Firefox/52"
+//var browserMinimumSupported = [6]string{"MSIE/11", "Internet Explorer/11", "Safari/9", "Chrome/43", "Edge/15", "Firefox/52"}
+var browserMinimumSupported = map[string]int{
+	"MSIE":              11,
+	"Internet Explorer": 11,
+	"Safari":            9,
+	"Chrome":            43,
+	"Edge":              15,
+	"Firefox":           52,
+}
 
-func CheckBrowserCompatability(c *api.Context, r *http.Request) bool {
-	ua := user_agent.New(r.UserAgent())
+func CheckBrowserCompatability(ua *user_agent.UserAgent) bool {
 	bname, bversion := ua.Browser()
 
-	browsers := strings.Split(browsersNotSupported, ";")
-	for _, browser := range browsers {
-		version := strings.Split(browser, "/")
+	l4g.Debug("Detected Browser: %v %v", bname, bversion)
 
-		if strings.HasPrefix(bname, version[0]) && strings.HasPrefix(bversion, version[1]) {
-			return false
-		}
+	curVersion := strings.Split(bversion, ".")
+	intCurVersion, _ := strconv.Atoi(curVersion[0])
+
+	if version, exist := browserMinimumSupported[bname]; exist && intCurVersion < version {
+		return false
 	}
 
 	return true
@@ -66,10 +76,12 @@ func CheckBrowserCompatability(c *api.Context, r *http.Request) bool {
 }
 
 func root(c *api.Context, w http.ResponseWriter, r *http.Request) {
-	if !CheckBrowserCompatability(c, r) {
+	if !CheckBrowserCompatability(user_agent.New(r.UserAgent())) {
 		w.Header().Set("Cache-Control", "no-store")
-		w.WriteHeader(http.StatusBadRequest)
-		w.Write([]byte(c.T("web.check_browser_compatibility.app_error")))
+		page := utils.NewHTMLTemplate("unsupported_browser", c.Locale)
+		page.Props["Title"] = c.T("web.error.unsupported_browser.title")
+		page.Props["Message"] = c.T("web.error.unsupported_browser.message")
+		page.RenderToWriter(w)
 		return
 	}
 
diff --git a/web/web_test.go b/web/web_test.go
index e1cdb0714..4ea7cd8ee 100644
--- a/web/web_test.go
+++ b/web/web_test.go
@@ -13,6 +13,7 @@ import (
 	"github.com/mattermost/platform/model"
 	"github.com/mattermost/platform/store"
 	"github.com/mattermost/platform/utils"
+	"github.com/mssola/user_agent"
 )
 
 var ApiClient *model.Client
@@ -120,3 +121,31 @@ func TestZZWebTearDown(t *testing.T) {
 	time.Sleep(2 * time.Second)
 	TearDown()
 }
+
+func TestCheckBrowserCompatability(t *testing.T) {
+
+	//test should fail browser compatibility check with Mozilla FF 40.1
+	ua := "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:40.0) Gecko/20100101 Firefox/40.1"
+	t.Logf("Checking Mozzila 40.1 with U.A. String: \n%v", ua)
+	if result := CheckBrowserCompatability(user_agent.New(ua)); result == true {
+		t.Error("Fail: should have failed browser compatibility")
+	} else {
+		t.Log("Pass: User Agent correctly failed!")
+	}
+
+	ua = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.90 Safari/537.36"
+	t.Logf("Checking Chrome 60 with U.A. String: \n%v", ua)
+	if result := CheckBrowserCompatability(user_agent.New(ua)); result == false {
+		t.Error("Fail: should have passed browser compatibility")
+	} else {
+		t.Log("Pass: User Agent correctly passed!")
+	}
+
+	ua = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.79 Safari/537.36 Edge/14.14393"
+	t.Logf("Checking Edge 14.14393 with U.A. String: \n%v", ua)
+	if result := CheckBrowserCompatability(user_agent.New(ua)); result == true {
+		t.Log("Warning: Edge should have failed browser compatibility. It is probably still detecting as Chrome.")
+	} else {
+		t.Log("Pass: User Agent correctly failed!")
+	}
+}