ui/project_form: Improve file handling in UI

- Enhance file input handling in the UI to avoid losing selected files when adding new inputs.
- Introduce a `selectedFiles` array to store and manage selected files.
- Display selected files in the UI with additional features, including a delete button.
- Update the `removeFile` function to correctly remove files from both the UI and the `selectedFiles` array.

Fixes: nexB#991
Signed-off-by: Jayanth Kumar <jknani111@gmail.com>

scancodeio/static/add-inputs.js

@@ -21,15 +21,33 @@
 // Visit https://github.com/nexB/scancode.io for support and download.
 
 const fileInput = document.querySelector('#id_input_files');
+let selectedFiles = []; // Store selected files
+
 fileInput.onchange = updateFiles;
 
 // Update the list of files to be uploaded in the UI
 function updateFiles() {
   if (fileInput.files.length > 0) {
     const fileName = document.querySelector('#inputs_file_name');
     fileName.innerHTML = "";
-    for (let file of fileInput.files) {
-      fileName.innerHTML += `<span class="is-block">${file.name}</span>`;
+
+    // Update the selectedFiles array
+    selectedFiles = selectedFiles.concat(Array.from(fileInput.files));
+
+    for (let file of selectedFiles) {
+      const fileNameWithoutSpaces = file.name.replace(/\s/g, '');
+      fileName.innerHTML += `
+      <span class="is-flex is-justify-content-space-between is-block" id="file-name-${fileNameWithoutSpaces}">
+        <span class="is-block">${file.name}</span>
+        <a href="#" onclick="removeFile('${fileNameWithoutSpaces}')" class="model-button" id="file-delete-btn-${fileNameWithoutSpaces}">
+          <i class="fa-solid fa-trash-can mr-2"></i>
+        </a>
+      </span>
+      `;
+      document.getElementById("file-delete-btn-"+ fileNameWithoutSpaces).addEventListener("click", function(event){
+        disableEvent(event);
+        removeFile(fileNameWithoutSpaces);
+      });
     }
   }
 }
@@ -40,6 +58,25 @@ function disableEvent(event) {
   event.preventDefault();
 }
 
+function removeFile(fileName) {
+  selectedFiles = selectedFiles.filter(file => {
+    const fileNameWithoutSpaces = file.name.replace(/\s/g, '');
+    return fileNameWithoutSpaces !== fileName;
+  });
+
+  const fileNameElement = document.getElementById(`file-name-${fileName}`);
+  if (fileNameElement) {
+    fileNameElement.remove();
+  }
+
+  const dataTransfer = new DataTransfer();
+  for (let file of selectedFiles) {
+    dataTransfer.items.add(file);
+  }
+
+  fileInput.files = dataTransfer.files;
+}
+
 function dropHandler(event) {
   disableEvent(event);
   const droppedFiles = event.dataTransfer.files;