Implement date uniqueness validation in DataManager and update MedTrackerApp for duplicate checks

src/main.py

@@ -119,9 +119,11 @@ class MedTrackerApp:
 
     def _create_edit_window(self, item_id: str, values: tuple[str, ...]) -> None:
         """Create a new Toplevel window for editing an entry."""
+        original_date = values[0]  # Store the original date
+
         # Define callbacks for edit window buttons
         callbacks: dict[str, Callable] = {
-            "save": self._save_edit,
+            "save": lambda win, *args: self._save_edit(win, original_date, *args),
             "delete": lambda win: self._delete_entry(win, item_id),
         }
 
@@ -131,6 +133,7 @@ class MedTrackerApp:
     def _save_edit(
         self,
         edit_win: tk.Toplevel,
+        original_date: str,
         date: str,
         dep: int,
         anx: int,
@@ -156,7 +159,7 @@ class MedTrackerApp:
             note,
         ]
 
-        if self.data_manager.update_entry(date, values):
+        if self.data_manager.update_entry(original_date, values):
             edit_win.destroy()
             messagebox.showinfo(
                 "Success", "Entry updated successfully!", parent=self.root
@@ -164,7 +167,17 @@ class MedTrackerApp:
             self._clear_entries()
             self.load_data()
         else:
-            messagebox.showerror("Error", "Failed to save changes", parent=edit_win)
+            # Check if it's a duplicate date issue
+            df = self.data_manager.load_data()
+            if original_date != date and not df.empty and date in df["date"].values:
+                messagebox.showerror(
+                    "Error",
+                    f"An entry for date '{date}' already exists. "
+                    "Please use a different date.",
+                    parent=edit_win,
+                )
+            else:
+                messagebox.showerror("Error", "Failed to save changes", parent=edit_win)
 
     def on_closing(self) -> None:
         if messagebox.askokcancel(
@@ -189,6 +202,11 @@ class MedTrackerApp:
         ]
         logger.debug(f"Adding entry: {entry}")
 
+        # Check if date is empty
+        if not self.date_var.get().strip():
+            messagebox.showerror("Error", "Please enter a date.", parent=self.root)
+            return
+
         if self.data_manager.add_entry(entry):
             messagebox.showinfo(
                 "Success", "Entry added successfully!", parent=self.root
@@ -196,7 +214,17 @@ class MedTrackerApp:
             self._clear_entries()
             self.load_data()
         else:
-            messagebox.showerror("Error", "Failed to add entry", parent=self.root)
+            # Check if it's a duplicate date by trying to load existing data
+            df = self.data_manager.load_data()
+            if not df.empty and self.date_var.get() in df["date"].values:
+                messagebox.showerror(
+                    "Error",
+                    f"An entry for date '{self.date_var.get()}' already exists. "
+                    "Please use a different date or edit the existing entry.",
+                    parent=self.root,
+                )
+            else:
+                messagebox.showerror("Error", "Failed to add entry", parent=self.root)
 
     def _delete_entry(self, edit_win: tk.Toplevel, item_id: str) -> None:
         """Delete the selected entry from the CSV file."""