feat: schedule modal validation + time range guard

- Validate trainer, type, and time before saving
- Show overlap warnings for conflicting classes
- Reset end time when start time exceeds it
- Block setting end time earlier than start
- Remove day change hints from modal

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

src/app/admin/_components/FormField.tsx

@@ -140,6 +140,21 @@ export function TimeRangeField({ label, value, onChange, onBlur }: TimeRangeFiel
     }
   }
 
+  function handleStartChange(newStart: string) {
+    // Reset end if start >= end
+    if (newStart && end && newStart >= end) {
+      update(newStart, "");
+    } else {
+      update(newStart, end);
+    }
+  }
+
+  function handleEndChange(newEnd: string) {
+    // Ignore if end <= start
+    if (start && newEnd && newEnd <= start) return;
+    update(start, newEnd);
+  }
+
   return (
     <div>
       <label className="block text-sm text-neutral-400 mb-1.5">{label}</label>
@@ -147,7 +162,7 @@ export function TimeRangeField({ label, value, onChange, onBlur }: TimeRangeFiel
         <input
           type="time"
           value={start}
-          onChange={(e) => update(e.target.value, end)}
+          onChange={(e) => handleStartChange(e.target.value)}
           onBlur={onBlur}
           className="flex-1 rounded-lg border border-white/10 bg-neutral-800 px-3 py-2.5 text-white outline-none focus:border-gold transition-colors"
         />
@@ -155,7 +170,7 @@ export function TimeRangeField({ label, value, onChange, onBlur }: TimeRangeFiel
         <input
           type="time"
           value={end}
-          onChange={(e) => update(start, e.target.value)}
+          onChange={(e) => handleEndChange(e.target.value)}
           onBlur={onBlur}
           className="flex-1 rounded-lg border border-white/10 bg-neutral-800 px-3 py-2.5 text-white outline-none focus:border-gold transition-colors"
         />

src/app/admin/schedule/page.tsx

@@ -302,10 +302,57 @@ function ClassModal({
     });
   }
 
-  // Compute what changed for the hint (edit mode only)
-  const originalDays = new Set(Object.keys(initialDayTimes));
-  const addedDays = [...selectedDays].filter((d) => !originalDays.has(d));
-  const removedDays = [...originalDays].filter((d) => !selectedDays.has(d));
+  const [touched, setTouched] = useState(false);
+
+  // Validation
+  const errors = useMemo(() => {
+    const errs: string[] = [];
+    if (!draft.trainer) errs.push("Выберите тренера");
+    if (!draft.type) errs.push("Выберите тип занятия");
+    const times = Object.values(dayTimes);
+    for (const t of times) {
+      if (!t || !t.includes("–")) {
+        errs.push("Укажите время");
+        break;
+      }
+      const [s, e] = t.split("–").map((p) => timeToMinutes(p.trim()));
+      if (!s || !e) {
+        errs.push("Неверный формат времени");
+        break;
+      }
+      if (e <= s) {
+        errs.push("Время окончания должно быть позже начала");
+        break;
+      }
+    }
+    return errs;
+  }, [draft.trainer, draft.type, dayTimes]);
+
+  const isValid = errors.length === 0;
+
+  // Check for time overlaps on each selected day
+  const overlaps = useMemo(() => {
+    const result: { day: string; dayShort: string; conflicting: string[] }[] = [];
+    for (const [dayName, time] of Object.entries(dayTimes)) {
+      const dayData = allDays.find((d) => d.day === dayName);
+      if (!dayData || !time) continue;
+      const dayShort = DAYS.find((d) => d.day === dayName)?.dayShort || dayName;
+      // Build a temporary class to check overlap
+      const tempCls: ScheduleClass = { ...draft, time };
+      const conflicts: string[] = [];
+      for (const existing of dayData.classes) {
+        // Skip the class being edited (same group)
+        if (!isNew && isSameGroup(existing, cls)) continue;
+        if (hasOverlap(tempCls, existing)) {
+          conflicts.push(`${existing.time} ${existing.type} (${existing.trainer})`);
+        }
+      }
+      if (conflicts.length > 0) {
+        result.push({ day: dayName, dayShort, conflicting: conflicts });
+      }
+    }
+    return result;
+  }, [dayTimes, allDays, draft, cls, isNew]);
 
   return (
     <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/60" onClick={onClose}>
@@ -349,20 +396,6 @@ function ClassModal({
                 })}
               </div>
 
-              {!isNew && (addedDays.length > 0 || removedDays.length > 0) && (
-                <div className="mt-1.5 flex flex-wrap gap-x-3 text-[11px]">
-                  {addedDays.length > 0 && (
-                    <span className="text-emerald-400">
-                      + {addedDays.map((d) => allDays.find((ad) => ad.day === d)?.dayShort).join(", ")}
-                    </span>
-                  )}
-                  {removedDays.length > 0 && (
-                    <span className="text-red-400">
-                      − {removedDays.map((d) => allDays.find((ad) => ad.day === d)?.dayShort).join(", ")}
-                    </span>
-                  )}
-                </div>
-              )}
             </div>
           )}
 
@@ -451,14 +484,40 @@ function ClassModal({
           </div>
         </div>
 
+        {/* Overlap warning */}
+        {overlaps.length > 0 && (
+          <div className="mt-4 rounded-lg border border-amber-500/30 bg-amber-500/10 px-3 py-2.5 text-sm">
+            <div className="font-medium text-amber-400 mb-1">⚠ Пересечение времени</div>
+            {overlaps.map((o) => (
+              <div key={o.day} className="text-amber-300/80 text-xs">
+                <span className="font-medium">{o.dayShort}:</span>{" "}
+                {o.conflicting.join(", ")}
+              </div>
+            ))}
+          </div>
+        )}
+
+        {/* Validation errors */}
+        {touched && !isValid && (
+          <div className="mt-4 rounded-lg border border-red-500/30 bg-red-500/10 px-3 py-2 text-xs text-red-400">
+            {errors.map((e, i) => <div key={i}>{e}</div>)}
+          </div>
+        )}
+
         <div className="mt-6 flex items-center gap-3">
           <button
             type="button"
             onClick={() => {
+              setTouched(true);
+              if (!isValid) return;
               onSave(draft, dayTimes);
               onClose();
             }}
-            className="flex-1 rounded-lg bg-gold px-4 py-2.5 text-sm font-medium text-black hover:opacity-90 transition-opacity"
+            className={`flex-1 rounded-lg px-4 py-2.5 text-sm font-medium transition-opacity ${
+              touched && !isValid
+                ? "bg-neutral-700 text-neutral-400 cursor-not-allowed"
+                : "bg-gold text-black hover:opacity-90"
+            }`}
           >
             Сохранить
           </button>