refactor: simplify LinkShareViewHolder.setSubline()

app/src/main/java/com/owncloud/android/ui/adapter/LinkShareViewHolder.kt

@@ -98,26 +98,33 @@ internal class LinkShareViewHolder(itemView: View) : RecyclerView.ViewHolder(ite
         }
     }
 
-    private fun setSubline(binding: FileDetailsShareLinkShareItemBinding?, context: Context?, publicShare: OCShare) {
+    /**
+     * Displays download limit information when available, hides subline otherwise.
+     * Clears text on hide to prevent RecyclerView item reuse issues.
+     */
+    private fun setSubline(
+        binding: FileDetailsShareLinkShareItemBinding?,
+        context: Context?,
+        publicShare: OCShare
+    ) {
         if (binding == null || context == null) {
             return
         }
 
-        val downloadLimit = publicShare.fileDownloadLimit
-        if (downloadLimit != null) {
-            val remaining = publicShare.remainingDownloadLimit() ?: return
-            val text = context.resources.getQuantityString(
+        val remaining = publicShare.remainingDownloadLimit()?.coerceAtLeast(0)
+
+        if (remaining == null) {
+            // No download limit set at all
+            binding.subline.text = ""
+            binding.subline.visibility = View.GONE
+        } else {
+            val binding.subline.text = context.resources.getQuantityString(
                 R.plurals.share_download_limit_description,
                 remaining,
                 remaining
             )
-
-            binding.subline.text = text
             binding.subline.visibility = View.VISIBLE
-            return
         }
-
-        binding.subline.visibility = View.GONE
     }
 
     private fun setPermissionName(

app/src/main/java/com/owncloud/android/ui/fragment/FileDetailsSharingProcessFragment.kt

@@ -42,6 +42,8 @@ import com.owncloud.android.utils.ClipboardUtil
 import com.owncloud.android.utils.DisplayUtils
 import com.owncloud.android.utils.theme.CapabilityUtils
 import com.owncloud.android.utils.theme.ViewThemeUtils
+import java.text.NumberFormat
+import java.text.ParseException
 import java.text.SimpleDateFormat
 import java.util.Date
 import java.util.Locale
@@ -491,22 +493,24 @@ class FileDetailsSharingProcessFragment :
         }
     }
 
+    /**
+     * Pre-fills download limit controls with current remaining count for existing share.
+     * Clamps negative values to 0. Returns early if no limit is set.
+     */
     private fun updateFileDownloadLimitView() {
         if (!canSetDownloadLimit()) {
             return
         }
 
-        // user can set download limit thus no need to rely on current limit to show download limit
-        showFileDownloadLimitInput(true)
+        showFileDownloadLimitInput(true) // only other option
         binding.shareProcessSetDownloadLimitSwitch.visibility = View.VISIBLE
         binding.shareProcessSetDownloadLimitInput.visibility = View.VISIBLE
 
-        val currentLimit = share?.remainingDownloadLimit() ?: return
-        if (currentLimit > 0) {
-            binding.shareProcessSetDownloadLimitSwitch.isChecked = true
-            binding.shareProcessSetDownloadLimitInput.setText(
-                "%d".format(Locale.getDefault(), currentLimit)
-            )
+        val currentLimit = share?.remainingDownloadLimit()?.coerceAtLeast(0) ?: return
+
+        binding.shareProcessSetDownloadLimitSwitch.isChecked = true
+        binding.shareProcessSetDownloadLimitInput.setText(
+            NumberFormat.getInstance(Locale.getDefault()).format(currentLimit)
         }
     }
 
@@ -844,16 +848,50 @@ class FileDetailsSharingProcessFragment :
         }
     }
 
+    /**
+     * Validates and applies the download limit from the input field.
+     *
+     * Parses the user's input using locale-aware number formatting to handle
+     * grouping separators (e.g., "1,000" in US or "1.000" in Germany).
+     * Shows inline error messages for invalid input.
+     *
+     * @see [updateFileDownloadLimitView] for how the field is populated
+     */
     private fun setDownloadLimit() {
+        if (!binding.shareProcessSetDownloadLimitSwitch.isChecked) {
+            // User wants to remove the download limit
+            fileOperationsHelper?.updateFilesDownloadLimit(share, 0)
+            return
+        }
+
         val downloadLimitInput = binding.shareProcessSetDownloadLimitInput.text.toString().trim()
-        val downloadLimit =
-            if (binding.shareProcessSetDownloadLimitSwitch.isChecked && downloadLimitInput.isNotEmpty()) {
-                downloadLimitInput.toInt()
-            } else {
-                0
-            }
 
-        fileOperationsHelper?.updateFilesDownloadLimit(share, downloadLimit)
+        if (downloadLimitInput.isEmpty()) {
+            binding.shareProcessSetDownloadLimitInput.error = getString(R.string.share_download_limit_required)
+            return
+        }
+
+        // Parse with locale awareness to match formatting in updateFileDownloadLimitView
+        val downloadLimit = try {
+            NumberFormat.getInstance(Locale.getDefault())
+                .parse(downloadLimitInput)?.toInt()
+        } catch (e: ParseException) {
+            null
+        }
+
+        when {
+            downloadLimit == null -> {
+                binding.shareProcessSetDownloadLimitInput.error = getString(R.string.share_download_limit_invalid)
+                return
+            }
+            downloadLimit <= 0 -> {
+                binding.shareProcessSetDownloadLimitInput.error = getString(R.string.share_download_limit_must_be_positive)
+                return
+            }
+            else -> {
+                fileOperationsHelper?.updateFilesDownloadLimit(share, downloadLimit)
+            }
+        }
     }
 
     private fun createShare(noteText: String) {

app/src/main/res/values/strings.xml

@@ -1452,9 +1452,13 @@
     <string name="set_download_limit_failed">Unable to set download limit. Please check capabilities.</string>
     <string name="download_limit">Download limit</string>
     <plurals name="share_download_limit_description">
+        <item quantity="zero">No downloads remaining</item>
         <item quantity="one">%1$d download remaining</item>
         <item quantity="other">%1$d downloads remaining</item>
     </plurals>
+    <string name="share_download_limit_required">Download limit is required</string>
+    <string name="share_download_limit_invalid">Please enter a valid number</string>
+    <string name="share_download_limit_must_be_positive">Download limit must be greater than 0</string>
     <string name="sign_tos_failed">Please manually check terms of service!</string>
     <string name="terms_of_service_title">Terms of service</string>
     <string name="terms_of_services_agree">I agree to the above ToS</string>