feat: same-time checkbox for multi-day class groups

- "Одинаковое время" checkbox (default on) syncs time across all days
- Uncheck to set per-day times (e.g., Mon 12:00, Fri 18:00)
- Checkbox only appears when 2+ days selected
- Single day: just shows one time field, no checkbox
- Unified day selector for both new and edit modes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app/admin/schedule/page.tsx

@@ -254,6 +254,13 @@ function ClassModal({
 
   const [dayTimes, setDayTimes] = useState<Record<string, string>>(initialDayTimes);
 
+  // "Same time for all days" — default true if all existing times match
+  const allTimesMatch = useMemo(() => {
+    const vals = Object.values(initialDayTimes);
+    return vals.length <= 1 || vals.every((t) => t === vals[0]);
+  }, [initialDayTimes]);
+  const [sameTime, setSameTime] = useState(allTimesMatch);
+
   const selectedDays = new Set(Object.keys(dayTimes));
 
   function toggleDay(day: string) {
@@ -265,13 +272,34 @@ function ClassModal({
         delete next[day];
         return next;
       }
-      // New day gets time from current day
+      // New day gets time from current day or first existing
-      return { ...prev, [day]: prev[currentDay] || cls.time };
+      const refTime = sameTime
+        ? (Object.values(prev)[0] || cls.time)
+        : (prev[currentDay] || cls.time);
+      return { ...prev, [day]: refTime };
     });
   }
 
   function updateDayTime(day: string, time: string) {
-    setDayTimes((prev) => ({ ...prev, [day]: time }));
+    if (sameTime) {
+      // Update all days at once
+      setDayTimes((prev) => {
+        const next: Record<string, string> = {};
+        for (const d of Object.keys(prev)) next[d] = time;
+        return next;
+      });
+    } else {
+      setDayTimes((prev) => ({ ...prev, [day]: time }));
+    }
+  }
+
+  function updateSharedTime(time: string) {
+    setDraft({ ...draft, time });
+    setDayTimes((prev) => {
+      const next: Record<string, string> = {};
+      for (const d of Object.keys(prev)) next[d] = time;
+      return next;
+    });
   }
 
   // Compute what changed for the hint (edit mode only)
@@ -300,61 +328,25 @@ function ClassModal({
             <div>
               <label className="block text-sm text-neutral-400 mb-2">Дни</label>
 
-              {/* Selected days with per-day time (edit mode) or simple buttons (new mode) */}
+              {/* Day toggle buttons */}
-              {!isNew && selectedDays.size > 0 && (
-                <div className="space-y-1.5 mb-2">
-                  {allDays.filter((d) => selectedDays.has(d.day)).map((d) => (
-                    <div key={d.day} className="flex items-center gap-2">
-                      <button
-                        type="button"
-                        onClick={() => toggleDay(d.day)}
-                        className="shrink-0 rounded-lg px-2.5 py-1 text-xs font-medium bg-gold/20 text-gold border border-gold/40 min-w-[36px]"
-                      >
-                        {d.dayShort}
-                      </button>
-                      <div className="flex-1">
-                        <TimeRangeField
-                          label=""
-                          value={dayTimes[d.day] || ""}
-                          onChange={(v) => updateDayTime(d.day, v)}
-                        />
-                      </div>
-                    </div>
-                  ))}
-                </div>
-              )}
-
-              {/* Unselected days — toggle buttons */}
               <div className="flex flex-wrap gap-1.5">
-                {isNew
+                {allDays.map((d) => {
-                  ? allDays.map((d) => {
+                  const active = selectedDays.has(d.day);
-                      const active = selectedDays.has(d.day);
+                  return (
-                      return (
+                    <button
-                        <button
+                      key={d.day}
-                          key={d.day}
+                      type="button"
-                          type="button"
+                      onClick={() => toggleDay(d.day)}
-                          onClick={() => toggleDay(d.day)}
+                      className={`rounded-lg px-3 py-1.5 text-xs font-medium transition-all ${
-                          className={`rounded-lg px-3 py-1.5 text-xs font-medium transition-all ${
+                        active
-                            active
+                          ? "bg-gold/20 text-gold border border-gold/40"
-                              ? "bg-gold/20 text-gold border border-gold/40"
+                          : "border border-white/10 text-neutral-500 hover:text-white hover:border-white/20"
-                              : "border border-white/10 text-neutral-500 hover:text-white hover:border-white/20"
+                      }`}
-                          }`}
+                    >
-                        >
+                      {d.dayShort}
-                          {d.dayShort}
+                    </button>
-                        </button>
+                  );
-                      );
+                })}
-                    })
-                  : allDays.filter((d) => !selectedDays.has(d.day)).map((d) => (
-                      <button
-                        key={d.day}
-                        type="button"
-                        onClick={() => toggleDay(d.day)}
-                        className="rounded-lg px-3 py-1.5 text-xs font-medium border border-white/10 text-neutral-500 hover:text-white hover:border-white/20 transition-all"
-                      >
-                        + {d.dayShort}
-                      </button>
-                    ))
-                }
               </div>
 
               {!isNew && (addedDays.length > 0 || removedDays.length > 0) && (
@@ -374,21 +366,55 @@ function ClassModal({
             </div>
           )}
 
-          {/* Time — only for new class (edit mode has per-day times above) */}
+          {/* Same time checkbox + time fields */}
-          {isNew && (
+          {selectedDays.size > 1 && (
+            <label className="flex items-center gap-2 text-sm text-neutral-300 cursor-pointer select-none">
+              <input
+                type="checkbox"
+                checked={sameTime}
+                onChange={(e) => {
+                  const checked = e.target.checked;
+                  setSameTime(checked);
+                  if (checked) {
+                    // Sync all days to current day's time
+                    const refTime = dayTimes[currentDay] || Object.values(dayTimes)[0] || cls.time;
+                    setDayTimes((prev) => {
+                      const next: Record<string, string> = {};
+                      for (const d of Object.keys(prev)) next[d] = refTime;
+                      return next;
+                    });
+                  }
+                }}
+                className="rounded border-white/20 bg-neutral-800 text-gold focus:ring-gold/50"
+              />
+              Одинаковое время
+            </label>
+          )}
+
+          {sameTime || selectedDays.size <= 1 ? (
             <TimeRangeField
               label="Время"
-              value={draft.time}
+              value={Object.values(dayTimes)[0] || draft.time}
-              onChange={(v) => {
+              onChange={updateSharedTime}
-                setDraft({ ...draft, time: v });
-                // Update all selected day times
-                setDayTimes((prev) => {
-                  const next: Record<string, string> = {};
-                  for (const day of Object.keys(prev)) next[day] = v;
-                  return next;
-                });
-              }}
             />
+          ) : (
+            <div className="space-y-1.5">
+              <label className="block text-sm text-neutral-400">Время по дням</label>
+              {allDays.filter((d) => selectedDays.has(d.day)).map((d) => (
+                <div key={d.day} className="flex items-center gap-2">
+                  <span className="shrink-0 text-xs font-medium text-neutral-400 min-w-[28px]">
+                    {d.dayShort}
+                  </span>
+                  <div className="flex-1">
+                    <TimeRangeField
+                      label=""
+                      value={dayTimes[d.day] || ""}
+                      onChange={(v) => updateDayTime(d.day, v)}
+                    />
+                  </div>
+                </div>
+              ))}
+            </div>
           )}
 
           <SelectField