Refactor Clock: generalize multi timezones and single timezone cases

After this refactoring:
1. Timezones parses only once on start and the we refer to saved values. All time_zone.isString() checks gone to the constructor.
2. Single timezone case handling as case of multi timezoned logic.
3. Scroll event seems more clear now.
4. Tooltip template parses on start to check if there calendar placeholder or not. To do not calculate calendar_text() if not necessary.

include/modules/clock.hpp

@@ -17,6 +17,8 @@ struct waybar_time {
   date::zoned_seconds ztime;
 };
 
+const std::string kCalendarPlaceholder = "calendar";
+
 class Clock : public ALabel {
  public:
   Clock(const std::string&, const Json::Value&);
@@ -26,18 +28,19 @@ class Clock : public ALabel {
  private:
   util::SleeperThread thread_;
   std::locale locale_;
-  const date::time_zone* time_zone_;
+  std::vector<const date::time_zone*> time_zones_;
-  bool fixed_time_zone_;
+  int current_time_zone_idx_;
-  int time_zone_idx_;
   date::year_month_day cached_calendar_ymd_ = date::January/1/0;
   std::string cached_calendar_text_;
+  bool is_calendar_in_tooltip_;
 
   bool handleScroll(GdkEventScroll* e);
 
   auto calendar_text(const waybar_time& wtime) -> std::string;
   auto weekdays_header(const date::weekday& first_dow, std::ostream& os) -> void;
   auto first_day_of_week() -> date::weekday;
-  bool setTimeZone(Json::Value zone_name);
+  const date::time_zone* current_timezone();
+  bool is_timezone_fixed();
 };
 
 }  // namespace waybar::modules

src/modules/clock.cpp

@@ -14,17 +14,51 @@
 using waybar::modules::waybar_time;
 
 waybar::modules::Clock::Clock(const std::string& id, const Json::Value& config)
-    : ALabel(config, "clock", id, "{:%H:%M}", 60, false, false, true), fixed_time_zone_(false) {
+    : ALabel(config, "clock", id, "{:%H:%M}", 60, false, false, true),
+      current_time_zone_idx_(0),
+      is_calendar_in_tooltip_(false)
+{
   if (config_["timezones"].isArray() && !config_["timezones"].empty()) {
-    time_zone_idx_ = 0;
+    for (const auto& zone_name: config_["timezones"]) {
-    setTimeZone(config_["timezones"][time_zone_idx_]);
+      if (!zone_name.isString() || zone_name.asString().empty()) {
-  } else {
+        time_zones_.push_back(nullptr);
-    setTimeZone(config_["timezone"]);
+        continue;
       }
-  if (fixed_time_zone_) {
+      time_zones_.push_back(
+        date::locate_zone(
+          zone_name.asString()
+        )
+      );
+
+    }
+    // If we parse all timezones and no one is good, add nullptr to the tmezones vector, to mark that we need to show localtime
+    if (!time_zones_.size()) {
+      time_zones_.push_back(nullptr);
+    }
+  } else {
+    time_zones_.push_back(
+        date::locate_zone(
+          config_["timezone"].asString()
+        )
+      );
+  }
+
+  if (!is_timezone_fixed()) {
     spdlog::warn("As using a timezone, some format args may be missing as the date library haven't got a release since 2018.");
   }
 
+  // Check if we have to particular placeholder in tooltip format, to know what to calculate on update
+  if (config_["tooltip-format"].isString()) {
+    std::string trimmedFormat = config_["tooltip-format"].asString();
+    trimmedFormat.erase(std::remove_if(trimmedFormat.begin(),
+                              trimmedFormat.end(),
+                              [](unsigned char x){return std::isspace(x);}),
+               trimmedFormat.end());
+    if (trimmedFormat.find("{" + kCalendarPlaceholder + "}") != std::string::npos) {
+      is_calendar_in_tooltip_ = true;
+    }
+  }
+
   if (config_["locale"].isString()) {
     locale_ = std::locale(config_["locale"].asString());
   } else {
@@ -40,53 +74,46 @@ waybar::modules::Clock::Clock(const std::string& id, const Json::Value& config)
   };
 }
 
-auto waybar::modules::Clock::update() -> void {
+const date::time_zone* waybar::modules::Clock::current_timezone() {
-  if (!fixed_time_zone_) {
+  return time_zones_[current_time_zone_idx_] ? time_zones_[current_time_zone_idx_] : date::current_zone();
-    // Time zone can change. Be sure to pick that.
-    time_zone_ = date::current_zone();
 }
 
+bool waybar::modules::Clock::is_timezone_fixed() {
+  return time_zones_[current_time_zone_idx_] != nullptr;
+}
+
+auto waybar::modules::Clock::update() -> void {
+  auto time_zone = current_timezone();
   auto now = std::chrono::system_clock::now();
   waybar_time wtime = {locale_,
-                       date::make_zoned(time_zone_, date::floor<std::chrono::seconds>(now))};
+                       date::make_zoned(time_zone, date::floor<std::chrono::seconds>(now))};
-
+  std::string text = "";
-  std::string text;
+  if (!is_timezone_fixed()) {
-  if (!fixed_time_zone_) {
     // As date dep is not fully compatible, prefer fmt
     tzset();
     auto localtime = fmt::localtime(std::chrono::system_clock::to_time_t(now));
     text = fmt::format(format_, localtime);
-    label_.set_markup(text);
   } else {
     text = fmt::format(format_, wtime);
-    label_.set_markup(text);
   }
+  label_.set_markup(text);
 
   if (tooltipEnabled()) {
     if (config_["tooltip-format"].isString()) {
-      const auto calendar = calendar_text(wtime);
+      std::string calendarText = "";
+      if (is_calendar_in_tooltip_) {
+        calendarText = calendar_text(wtime);
+      }
       auto tooltip_format = config_["tooltip-format"].asString();
-      auto       tooltip_text = fmt::format(tooltip_format, wtime, fmt::arg("calendar", calendar));
+      text = fmt::format(tooltip_format, wtime, fmt::arg("calendar", calendarText));
-      label_.set_tooltip_markup(tooltip_text);
+    }
-    } else {
+  }
+
   label_.set_tooltip_markup(text);
-    }
-  }
   // Call parent update
   ALabel::update();
 }
 
-bool waybar::modules::Clock::setTimeZone(Json::Value zone_name) {
-  if (!zone_name.isString() || zone_name.asString().empty()) {
-      fixed_time_zone_ = false;
-      return false;
-  }
-
-  time_zone_ = date::locate_zone(zone_name.asString());
-  fixed_time_zone_ = true;
-  return true;
-}
-
 bool waybar::modules::Clock::handleScroll(GdkEventScroll *e) {
   // defer to user commands if set
   if (config_["on-scroll-up"].isString() || config_["on-scroll-down"].isString()) {
@@ -97,17 +124,18 @@ bool waybar::modules::Clock::handleScroll(GdkEventScroll *e) {
   if (dir != SCROLL_DIR::UP && dir != SCROLL_DIR::DOWN) {
     return true;
   }
-  if (!config_["timezones"].isArray() || config_["timezones"].empty()) {
+  if (time_zones_.size() == 1) {
     return true;
   }
-  auto nr_zones = config_["timezones"].size();
+
+  auto nr_zones = time_zones_.size();
   if (dir == SCROLL_DIR::UP) {
-    size_t new_idx = time_zone_idx_ + 1;
+    size_t new_idx = current_time_zone_idx_ + 1;
-    time_zone_idx_ = new_idx == nr_zones ? 0 : new_idx;
+    current_time_zone_idx_ = new_idx == nr_zones ? 0 : new_idx;
   } else {
-    time_zone_idx_ = time_zone_idx_ == 0 ? nr_zones - 1 : time_zone_idx_ - 1;
+    current_time_zone_idx_ = current_time_zone_idx_ == 0 ? nr_zones - 1 : current_time_zone_idx_ - 1;
   }
-  setTimeZone(config_["timezones"][time_zone_idx_]);
+
   update();
   return true;
 }