feat: implement basic filepicker on viewer

packages/form-js-viewer/assets/form-js-base.css

@@ -456,6 +456,7 @@
 .fjs-container .fjs-input[type='tel'],
 .fjs-container .fjs-input[type='number'],
 .fjs-container .fjs-button[type='submit'],
+.fjs-container .fjs-button[type='button'],
 .fjs-container .fjs-button[type='reset'],
 .fjs-container .fjs-textarea,
 .fjs-container .fjs-select {
@@ -631,7 +632,8 @@
   margin: 6px 10px 6px 4px;
 }
 
-.fjs-container .fjs-button[type='submit'] {
+.fjs-container .fjs-button[type='submit'],
+.fjs-container .fjs-button[type='button'] {
   color: var(--cds-text-inverse, var(--color-white));
   background-color: var(--color-accent);
   border-color: var(--color-accent);
@@ -644,12 +646,14 @@
 }
 
 .fjs-container .fjs-button[type='submit'],
+.fjs-container .fjs-button[type='button'],
 .fjs-container .fjs-button[type='reset'] {
   min-width: 100px;
   width: auto;
 }
 
-.fjs-container .fjs-button[type='submit'] {
+.fjs-container .fjs-button[type='submit'],
+.fjs-container .fjs-button[type='button'] {
   font-weight: 600;
 }
 
@@ -660,6 +664,7 @@
 .fjs-container .fjs-input[type='tel']:focus,
 .fjs-container .fjs-input[type='number']:focus,
 .fjs-container .fjs-button[type='submit']:focus,
+.fjs-container .fjs-button[type='button']:focus,
 .fjs-container .fjs-button[type='reset']:focus,
 .fjs-container .fjs-textarea:focus,
 .fjs-container .fjs-select:focus {
@@ -676,7 +681,8 @@
   outline: none;
 }
 
-.fjs-container .fjs-button[type='submit']:focus {
+.fjs-container .fjs-button[type='submit']:focus,
+.fjs-container .fjs-button[type='button']:focus {
   border-color: var(--color-accent);
 }
 
@@ -719,13 +725,15 @@
 }
 
 .fjs-container .fjs-button[type='submit']:disabled,
+.fjs-container .fjs-button[type='button']:disabled,
 .fjs-container .fjs-button[type='reset']:disabled {
   color: var(--cds-text-on-color-disabled, var(--color-text-light));
   background-color: var(--color-background-disabled);
   border-color: var(--color-borders-disabled);
 }
 
 .fjs-container .fjs-button[type='submit']:read-only,
+.fjs-container .fjs-button[type='button']:read-only,
 .fjs-container .fjs-button[type='reset']:read-only {
   color: var(--text-light);
   background-color: var(--color-background-readonly);
@@ -1269,3 +1277,14 @@
 .fjs-container .flatpickr-calendar {
   width: 326px;
 }
+
+.fjs-hidden {
+  display: none;
+}
+
+.fjs-container .fjs-filepicker-container {
+  display: flex;
+  flex-direction: row;
+  align-items: center;
+  gap: 8px;
+}

packages/form-js-viewer/src/render/components/form-fields/FilePicker.js

@@ -1,8 +1,86 @@
+import { formFieldClasses } from '../Util';
+import { Label } from '../Label';
+import { Errors } from '../Errors';
+import { useRef, useState } from 'preact/hooks';
+import { useSingleLineTemplateEvaluation } from '../../hooks';
+
+const type = 'filepicker';
+
 /**
+ * @typedef Props
+ * @property {(props: { value: string }) => void} onChange
+ * @property {string} domId
+ * @property {string[]} errors
+ * @property {boolean} disabled
+ * @property {boolean} readonly
+ * @property {boolean} required
+ * @property {Object} field
+ * @property {string} field.id
+ * @property {string} [field.label]
+ * @property {string} [field.accept]
+ * @property {boolean} [field.multiple]
+ *
+ * @param {Props} props
  * @returns {import("preact").JSX.Element}
  */
-export function FilePicker() {
-  return null;
+export function FilePicker(props) {
+  /** @type {import("preact/hooks").Ref<HTMLInputElement>} */
+  const fileInputRef = useRef(null);
+  /** @type {[File[],import("preact/hooks").StateUpdater<File[]>]} */
+  const [selectedFiles, setSelectedFiles] = useState([]);
+  const { field, onChange, domId, errors = [], disabled, readonly, required } = props;
+  const { label, multiple = '', accept = '', id } = field;
+  const evaluatedAccept = useSingleLineTemplateEvaluation(accept);
+  const evaluatedMultiple =
+    useSingleLineTemplateEvaluation(typeof multiple === 'string' ? multiple : multiple.toString()) === 'true';
+  const errorMessageId = `${domId}-error-message`;
+
+  return (
+    <div class={formFieldClasses(type, { errors, disabled, readonly })}>
+      <Label htmlFor={domId} label={label} required={required} />
+      <input
+        type="file"
+        className="fjs-hidden"
+        ref={fileInputRef}
+        id={domId}
+        name={domId}
+        multiple={evaluatedMultiple === false ? undefined : evaluatedMultiple}
+        accept={evaluatedAccept === '' ? undefined : evaluatedAccept}
+        onChange={(event) => {
+          const input = /** @type {HTMLInputElement} */ (event.target);
+
+          if (input.files === null || input.files.length === 0) {
+            onChange({
+              value: null,
+            });
+            return;
+          }
+
+          const files = Array.from(input.files);
+
+          onChange({
+            value: `${id}_value_key`,
+          });
+
+          setSelectedFiles(files);
+        }}
+      />
+      <div className="fjs-filepicker-container">
+        <button
+          type="button"
+          disabled={disabled}
+          readonly={readonly}
+          class="fjs-button"
+          onClick={() => {
+            fileInputRef.current.click();
+          }}>
+          Browse
+        </button>
+        <span className="fjs-form-field-label">{getSelectedFilesLabel(selectedFiles)}</span>
+      </div>
+      <Errors id={errorMessageId} errors={errors} />
+    </div>
+  );
 }
 
 FilePicker.config = {
@@ -16,3 +94,21 @@ FilePicker.config = {
   },
   create: (options = {}) => ({ ...options }),
 };
+
+// helper //////////
+
+/**
+ * @param {File[]} files
+ * @returns {string}
+ */
+function getSelectedFilesLabel(files) {
+  if (files.length === 0) {
+    return 'No files selected';
+  }
+
+  if (files.length === 1) {
+    return files[0].name;
+  }
+
+  return `${files.length} files selected`;
+}