Implement file upload validation (types and size limit)

src/app/components/main-chat/chat-msg-box/chat-msg-box.component.html

@@ -25,8 +25,9 @@
       name="file"
       autocomplete="off"
       style="display: none"
-      (change)="onFileChange($event)"
+      (change)="handleFileSelection($event)"
       multiple
+      accept=".png,.gif,.jpg,.jpeg,.pdf,.doc,.docx,.mp3,.wav,.mp4,.wmv,.avi"
     />
   </div>
   <textarea

src/app/components/main-chat/chat-msg-box/chat-msg-box.component.ts

@@ -169,10 +169,28 @@ export class ChatMsgBoxComponent {
       'video/x-ms-wmv': 4,
       'video/avi': 4,
     };
-
     return this.getFileIcons[fileTypeMap[fileInfo.type] ?? 5];
   }
 
+  /**
+   * Processes the file selection and checks whether file types and file sizes meet the requirements.
+   * @param {Event} event - The file input change event that contains the uploaded files.
+   */
+  handleFileSelection(event: any) {
+    const files = event.target.files;
+    const maxSize = 1 * 1024 * 1024; // 3 MB in Bytes
+
+    for (let i = 0; i < files.length; i++) {
+      const file = files[i];
+
+      // Prüfen der Dateigröße
+      if (file.size > maxSize) {
+        this.fileSizeError = false;
+      }
+      this.fileSizeError = true;
+    }
+  }
+
   /**
    * Deletes the selected file.
    * @param file The file to be deleted.