fix file submissions

services/frontend/src/pages/CompetitionSession/modules/TaskSolution/components/FileSolution/index.tsx

@@ -7,17 +7,23 @@ interface FileSolutionProps {
   setSelectedFile: (file: File | null) => void;
   fileInputRef: React.RefObject<HTMLInputElement>;
   existingFileUrl?: string | null; 
+  onClearExistingFile?: () => void; // New prop to clear existing file URL
 }
 
 const FileSolution: React.FC<FileSolutionProps> = ({ 
   selectedFile, 
   setSelectedFile, 
   fileInputRef,
-  existingFileUrl = null
+  existingFileUrl = null,
+  onClearExistingFile
 }) => {
   const handleFileChange = (event: React.ChangeEvent<HTMLInputElement>) => {
     if (event.target.files && event.target.files[0]) {
       setSelectedFile(event.target.files[0]);
+      // Clear existing file URL when a new file is selected
+      if (existingFileUrl && onClearExistingFile) {
+        onClearExistingFile();
+      }
     }
   };
 
@@ -41,9 +47,28 @@ const FileSolution: React.FC<FileSolutionProps> = ({
     
     if (e.dataTransfer.files && e.dataTransfer.files[0]) {
       setSelectedFile(e.dataTransfer.files[0]);
+      // Clear existing file URL when a new file is dropped
+      if (existingFileUrl && onClearExistingFile) {
+        onClearExistingFile();
+      }
     }
   };
 
+  // Handle clearing the file
+  const handleClearFile = () => {
+    setSelectedFile(null);
+    // Also clear the existing file URL if it exists
+    if (existingFileUrl && onClearExistingFile) {
+      onClearExistingFile();
+    }
+  };
+
+  // Handle selecting a new file when an existing file is shown
+  const handleSelectNewFile = () => {
+    // Just trigger the file input click - the actual clearing will happen in handleFileChange
+    fileInputRef.current?.click();
+  };
+
   const fileName = selectedFile 
     ? selectedFile.name 
     : existingFileUrl 
@@ -79,13 +104,33 @@ const FileSolution: React.FC<FileSolutionProps> = ({
                   Скачать
                 </a>
               )}
-              <Button 
-                variant="ghost" 
-                className="text-blue-500 text-sm p-0 h-auto hover:bg-transparent hover:text-blue-600 font-hse-sans"
-                onClick={() => setSelectedFile(null)}
-              >
-                {!selectedFile && existingFileUrl ? "Выбрать другой файл" : "Очистить"}
-              </Button>
+              
+              {selectedFile ? (
+                <Button 
+                  variant="ghost" 
+                  className="text-blue-500 text-sm p-0 h-auto hover:bg-transparent hover:text-blue-600 font-hse-sans"
+                  onClick={handleClearFile}
+                >
+                  Очистить
+                </Button>
+              ) : existingFileUrl ? (
+                <div className="flex gap-3">
+                  <Button 
+                    variant="ghost" 
+                    className="text-blue-500 text-sm p-0 h-auto hover:bg-transparent hover:text-blue-600 font-hse-sans"
+                    onClick={handleSelectNewFile}
+                  >
+                    Выбрать другой файл
+                  </Button>
+                  <Button 
+                    variant="ghost" 
+                    className="text-red-500 text-sm p-0 h-auto hover:bg-transparent hover:text-red-600 font-hse-sans"
+                    onClick={handleClearFile}
+                  >
+                    Очистить
+                  </Button>
+                </div>
+              ) : null}
             </div>
           </div>
         </div>

services/frontend/src/pages/CompetitionSession/modules/TaskSolution/index.tsx

@@ -44,15 +44,18 @@ const TaskSolution: React.FC<TaskSolutionProps> = ({
     setIsHistoryOpen(true);
   };
 
-  const latestSolution = solutionHistory && solutionHistory.length > 0 ? solutionHistory[solutionHistory.length - 1] : null;
+  const latestSolution = solutionHistory && solutionHistory.length > 0 ? solutionHistory[0] : null;
 
   const handleSolutionSelect = async (solution: Solution) => {
     if (!solution.content) return;
     
-    setSelectedSolutionUrl(solution.content);
-    
     try {
-      if (task.type !== TaskType.FILE) {
+      if (task.type === TaskType.FILE) {
+        // For file tasks, just store the URL
+        setSelectedFile(null); // Clear any selected file first
+        setSelectedSolutionUrl(solution.content);
+      } else {
+        // For INPUT and CODE tasks, fetch the content and set as answer
         const response = await fetch(solution.content);
         if (!response.ok) {
           throw new Error(`Failed to fetch solution content: ${response.status}`);
@@ -65,6 +68,11 @@ const TaskSolution: React.FC<TaskSolutionProps> = ({
     } 
   };
 
+  // Function to clear the existing file URL
+  const handleClearExistingFile = () => {
+    setSelectedSolutionUrl(null);
+  };
+
   return (
     <div className="md:w-[500px] flex flex-col gap-4">
       {latestSolution ? (
@@ -85,6 +93,7 @@ const TaskSolution: React.FC<TaskSolutionProps> = ({
           setSelectedFile={setSelectedFile} 
           fileInputRef={fileInputRef}
           existingFileUrl={selectedSolutionUrl}
+          onClearExistingFile={handleClearExistingFile}
         />
       )}