Add extra filter for file picker

Makes it possible to be more flexible when filtering entries to be
displayed.

Signed-off-by: Vincent Petry <vincent@nextcloud.com>
Signed-off-by: nextcloud-command <nextcloud-command@users.noreply.github.com>

core/src/OC/dialogs.js

@@ -243,6 +243,7 @@ const Dialogs = {
 	 * @param {string} [type] Type of file picker : Choose, copy, move, copy and move
 	 * @param {string} [path] path to the folder that the the file can be picket from
 	 * @param {Object} [options] additonal options that need to be set
+	 * @param {Function} [options.filter] filter function for advanced filtering
 	 */
 	filepicker: function(title, callback, multiselect, mimetypeFilter, modal, type, path, options) {
 		var self = this
@@ -296,6 +297,9 @@ const Dialogs = {
 				sizeCol: t('core', 'Size'),
 				modifiedCol: t('core', 'Modified')
 			}).data('path', path).data('multiselect', multiselect).data('mimetype', mimetypeFilter).data('allowDirectoryChooser', options.allowDirectoryChooser)
+			if (typeof(options.filter) === 'function') {
+				self.$filePicker.data('filter', options.filter)
+			}
 
 			if (modal === undefined) {
 				modal = false
@@ -1124,6 +1128,7 @@ const Dialogs = {
 		this.$filelistContainer.addClass('icon-loading')
 		this.$filePicker.data('path', dir)
 		var filter = this.$filePicker.data('mimetype')
+		var advancedFilter = this.$filePicker.data('filter')
 		if (typeof (filter) === 'string') {
 			filter = [filter]
 		}
@@ -1142,6 +1147,10 @@ const Dialogs = {
 				})
 			}
 
+			if (advancedFilter) {
+				files = files.filter(advancedFilter)
+			}
+
 			// Check if the showHidden input field exist and if it exist follow it
 			// Otherwise just show the hidden files
 			const showHiddenInput = document.getElementById('showHiddenFiles')