feat(web): enhance KYC upload with validation, previews, test ids

- Add file type (JPG/PNG/WEBP/PDF) and 5MB size validation
- Show image previews with cleanup of object URLs
- Add data-testid attributes on inputs, buttons, previews, alerts for E2E
- Improve error messaging for expired/failed presigned uploads (403 vs other)
- Guard step 2->3 advance when front image missing

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/web/app/[locale]/(dashboard)/dashboard/kyc/page.tsx

@@ -1,6 +1,6 @@
 'use client';
 
-import { useState, useCallback } from 'react';
+import { useState, useCallback, useEffect } from 'react';
 import { Badge } from '@/components/ui/badge';
 import { Button } from '@/components/ui/button';
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
@@ -32,6 +32,20 @@ const KYC_STEPS = [
 const API_BASE_URL =
   process.env['NEXT_PUBLIC_API_URL'] || 'http://localhost:3001/api/v1';
 
+const MAX_FILE_SIZE_BYTES = 5 * 1024 * 1024; // 5MB
+const ACCEPTED_MIME_TYPES = ['image/jpeg', 'image/jpg', 'image/png', 'image/webp', 'application/pdf'];
+const ACCEPTED_ACCEPT_ATTR = 'image/jpeg,image/png,image/webp,application/pdf';
+
+function validateFile(file: File): string | null {
+  if (!ACCEPTED_MIME_TYPES.includes(file.type)) {
+    return 'Định dạng không hợp lệ. Vui lòng chọn JPG, PNG, WEBP hoặc PDF.';
+  }
+  if (file.size > MAX_FILE_SIZE_BYTES) {
+    return 'Kích thước tệp vượt quá 5MB. Vui lòng chọn tệp nhỏ hơn.';
+  }
+  return null;
+}
+
 function getCsrfToken(): string | undefined {
   const csrfMatch = document.cookie.match(/(?:^|;\s*)XSRF-TOKEN=([^;]*)/);
   return csrfMatch?.[1] ? decodeURIComponent(csrfMatch[1]) : undefined;
@@ -71,8 +85,10 @@ function uploadFileWithProgress(
       if (xhr.status >= 200 && xhr.status < 300) {
         onProgress(100);
         resolve();
+      } else if (xhr.status === 403) {
+        reject(new Error('Liên kết tải lên đã hết hạn. Vui lòng thử lại.'));
       } else {
-        reject(new Error(`Upload thất bại (${xhr.status})`));
+        reject(new Error(`Tải ảnh thất bại (${xhr.status}). Vui lòng thử lại.`));
       }
     });
 
@@ -96,6 +112,48 @@ export default function KycPage() {
   const [frontImage, setFrontImage] = useState<File | null>(null);
   const [backImage, setBackImage] = useState<File | null>(null);
   const [selfieImage, setSelfieImage] = useState<File | null>(null);
+  const [frontPreview, setFrontPreview] = useState<string | null>(null);
+  const [backPreview, setBackPreview] = useState<string | null>(null);
+  const [selfiePreview, setSelfiePreview] = useState<string | null>(null);
+
+  // Revoke object URLs on cleanup to avoid memory leaks
+  useEffect(() => {
+    return () => {
+      if (frontPreview) URL.revokeObjectURL(frontPreview);
+      if (backPreview) URL.revokeObjectURL(backPreview);
+      if (selfiePreview) URL.revokeObjectURL(selfiePreview);
+    };
+  }, [frontPreview, backPreview, selfiePreview]);
+
+  const handleFileSelect = useCallback(
+    (
+      field: 'front' | 'back' | 'selfie',
+      file: File | null,
+    ) => {
+      if (!file) return;
+      const validationError = validateFile(file);
+      if (validationError) {
+        setError(validationError);
+        return;
+      }
+      setError(null);
+      const previewUrl = file.type.startsWith('image/') ? URL.createObjectURL(file) : null;
+      if (field === 'front') {
+        if (frontPreview) URL.revokeObjectURL(frontPreview);
+        setFrontImage(file);
+        setFrontPreview(previewUrl);
+      } else if (field === 'back') {
+        if (backPreview) URL.revokeObjectURL(backPreview);
+        setBackImage(file);
+        setBackPreview(previewUrl);
+      } else {
+        if (selfiePreview) URL.revokeObjectURL(selfiePreview);
+        setSelfieImage(file);
+        setSelfiePreview(previewUrl);
+      }
+    },
+    [frontPreview, backPreview, selfiePreview],
+  );
 
   const kycStatus = user?.kycStatus ?? 'NONE';
   const kycInfo = KYC_STATUS_MAP[kycStatus] ?? { label: 'Chưa xác minh', variant: 'outline' as const, description: 'Bạn chưa gửi hồ sơ xác minh danh tính.' };
@@ -197,7 +255,7 @@ export default function KycPage() {
   };
 
   return (
-    <div className="space-y-6">
+    <div className="space-y-6" data-testid="kyc-page">
       <div>
         <h1 className="text-2xl font-bold sm:text-3xl">Xác minh danh tính (KYC)</h1>
         <p className="mt-2 text-muted-foreground">
@@ -219,7 +277,11 @@ export default function KycPage() {
       </Card>
 
       {error && (
-        <div className="rounded-lg border border-red-200 bg-red-50 p-4 text-sm text-red-700">
+        <div
+          role="alert"
+          data-testid="kyc-error"
+          className="rounded-lg border border-red-200 bg-red-50 p-4 text-sm text-red-700"
+        >
           {error}
           <button onClick={() => setError(null)} className="ml-2 font-medium underline">
             Đóng
@@ -228,7 +290,11 @@ export default function KycPage() {
       )}
 
       {success && (
-        <div className="rounded-lg border border-green-200 bg-green-50 p-4 text-sm text-green-700">
+        <div
+          role="status"
+          data-testid="kyc-success"
+          className="rounded-lg border border-green-200 bg-green-50 p-4 text-sm text-green-700"
+        >
           Hồ sơ KYC đã được gửi thành công. Vui lòng chờ 1-3 ngày làm việc để được xem xét.
         </div>
       )}
@@ -299,41 +365,71 @@ export default function KycPage() {
               {/* Step 2: Upload images */}
               {currentStep === 2 && (
                 <>
+                  <p className="text-xs text-muted-foreground">
+                    Định dạng hỗ trợ: JPG, PNG, WEBP, PDF. Kích thước tối đa: 5MB.
+                  </p>
                   <div className="space-y-2">
                     <Label htmlFor="frontImg">Ảnh mặt trước *</Label>
                     <Input
                       id="frontImg"
+                      data-testid="kyc-front-input"
                       type="file"
-                      accept="image/*"
+                      accept={ACCEPTED_ACCEPT_ATTR}
-                      onChange={(e) => setFrontImage(e.target.files?.[0] ?? null)}
+                      onChange={(e) => handleFileSelect('front', e.target.files?.[0] ?? null)}
                     />
                     {frontImage && (
                       <p className="text-xs text-muted-foreground">{frontImage.name}</p>
                     )}
+                    {frontPreview && (
+                      <img
+                        src={frontPreview}
+                        alt="Xem trước mặt trước"
+                        data-testid="kyc-front-preview"
+                        className="mt-2 max-h-48 rounded-md border object-contain"
+                      />
+                    )}
                   </div>
                   <div className="space-y-2">
                     <Label htmlFor="backImg">Ảnh mặt sau</Label>
                     <Input
                       id="backImg"
+                      data-testid="kyc-back-input"
                       type="file"
-                      accept="image/*"
+                      accept={ACCEPTED_ACCEPT_ATTR}
-                      onChange={(e) => setBackImage(e.target.files?.[0] ?? null)}
+                      onChange={(e) => handleFileSelect('back', e.target.files?.[0] ?? null)}
                     />
                     {backImage && (
                       <p className="text-xs text-muted-foreground">{backImage.name}</p>
                     )}
+                    {backPreview && (
+                      <img
+                        src={backPreview}
+                        alt="Xem trước mặt sau"
+                        data-testid="kyc-back-preview"
+                        className="mt-2 max-h-48 rounded-md border object-contain"
+                      />
+                    )}
                   </div>
                   <div className="space-y-2">
                     <Label htmlFor="selfieImg">Ảnh selfie cầm giấy tờ</Label>
                     <Input
                       id="selfieImg"
+                      data-testid="kyc-selfie-input"
                       type="file"
-                      accept="image/*"
+                      accept={ACCEPTED_ACCEPT_ATTR}
-                      onChange={(e) => setSelfieImage(e.target.files?.[0] ?? null)}
+                      onChange={(e) => handleFileSelect('selfie', e.target.files?.[0] ?? null)}
                     />
                     {selfieImage && (
                       <p className="text-xs text-muted-foreground">{selfieImage.name}</p>
                     )}
+                    {selfiePreview && (
+                      <img
+                        src={selfiePreview}
+                        alt="Xem trước selfie"
+                        data-testid="kyc-selfie-preview"
+                        className="mt-2 max-h-48 rounded-md border object-contain"
+                      />
+                    )}
                   </div>
                 </>
               )}
@@ -386,7 +482,12 @@ export default function KycPage() {
               {/* Navigation buttons */}
               <div className="flex justify-between pt-2">
                 {currentStep > 1 ? (
-                  <Button variant="outline" onClick={() => setCurrentStep((s) => s - 1)} disabled={submitting}>
+                  <Button
+                    variant="outline"
+                    data-testid="kyc-back-button"
+                    onClick={() => setCurrentStep((s) => s - 1)}
+                    disabled={submitting}
+                  >
                     Quay lại
                   </Button>
                 ) : (
@@ -394,11 +495,16 @@ export default function KycPage() {
                 )}
                 {currentStep < 3 ? (
                   <Button
+                    data-testid="kyc-next-button"
                     onClick={() => {
                       if (currentStep === 1 && !documentNumber.trim()) {
                         setError('Vui lòng nhập số giấy tờ');
                         return;
                       }
+                      if (currentStep === 2 && !frontImage) {
+                        setError('Vui lòng tải ảnh mặt trước');
+                        return;
+                      }
                       setError(null);
                       setCurrentStep((s) => s + 1);
                     }}
@@ -406,7 +512,11 @@ export default function KycPage() {
                     Tiếp tục
                   </Button>
                 ) : (
-                  <Button onClick={handleSubmit} disabled={submitting}>
+                  <Button
+                    data-testid="kyc-submit-button"
+                    onClick={handleSubmit}
+                    disabled={submitting}
+                  >
                     {submitting ? 'Đang gửi...' : 'Gửi hồ sơ xác minh'}
                   </Button>
                 )}