[APIv4] add getChannelMembersTimezone (#9286)

* add getChannelMembersTimezone

* update per feedback review

* add delimeter to error

3 files changed, 35 insertions, 5 deletions

diff --git a/model/client4.go b/model/client4.go
index 903687ece..6a613b6b3 100644
--- a/model/client4.go
+++ b/model/client4.go
@@ -1746,6 +1746,17 @@ func (c *Client4) GetChannelStats(channelId string, etag string) (*ChannelStats,
 	}
 }
 
+// GetChannelMembersTimezones gets a list of timezones for a channel.
+func (c *Client4) GetChannelMembersTimezones(channelId string) ([]string, *Response) {
+	r, err := c.DoApiGet(c.GetChannelRoute(channelId)+"/timezones", "")
+	if err != nil {
+		return nil, BuildErrorResponse(r, err)
+	}
+
+	defer closeBody(r)
+	return ArrayFromJson(r.Body), BuildResponse(r)
+}
+
 // GetPinnedPosts gets a list of pinned posts.
 func (c *Client4) GetPinnedPosts(channelId string, etag string) (*PostList, *Response) {
 	if r, err := c.DoApiGet(c.GetChannelRoute(channelId)+"/pinned", etag); err != nil {
diff --git a/model/user.go b/model/user.go
index 781bcae66..06ad9294f 100644
--- a/model/user.go
+++ b/model/user.go
@@ -499,11 +499,7 @@ func (u *User) IsSAMLUser() bool {
 }
 
 func (u *User) GetPreferredTimezone() string {
-	if u.Timezone["useAutomaticTimezone"] == "true" {
-		return u.Timezone["automaticTimezone"]
-	}
-
-	return u.Timezone["manualTimezone"]
+	return GetPreferredTimezone(u.Timezone)
 }
 
 // UserFromJson will decode the input and return a User
diff --git a/model/utils.go b/model/utils.go
index 172b78242..849e529c1 100644
--- a/model/utils.go
+++ b/model/utils.go
@@ -564,3 +564,26 @@ func IsDomainName(s string) bool {
 
 	return ok
 }
+
+func RemoveDuplicateStrings(in []string) []string {
+	out := []string{}
+	seen := make(map[string]bool, len(in))
+
+	for _, item := range in {
+		if !seen[item] {
+			out = append(out, item)
+
+			seen[item] = true
+		}
+	}
+
+	return out
+}
+
+func GetPreferredTimezone(timezone StringMap) string {
+	if timezone["useAutomaticTimezone"] == "true" {
+		return timezone["automaticTimezone"]
+	}
+
+	return timezone["manualTimezone"]
+}