frontend: add FolderTree component

frontend/src/components/FolderTree.vue

@@ -0,0 +1,61 @@
+<template>
+  <q-tree
+    :nodes="nodes"
+    node-key="path"
+    label-key="label"
+    v-model:selected="selected"
+    no-selection-unset
+  />
+</template>
+
+<script setup>
+import { computed, ref, watch } from 'vue'
+
+const props = defineProps({
+  modelValue: { type: String, default: '' },
+  items: { type: Array, default: () => [] },
+})
+
+const emit = defineEmits(['update:modelValue'])
+
+const selected = ref(props.modelValue)
+
+watch(selected, (val) => emit('update:modelValue', val))
+watch(
+  () => props.modelValue,
+  (val) => {
+    selected.value = val
+  },
+)
+
+const nodes = computed(() => buildTree(props.items))
+
+function buildTree(items) {
+  const dirs = items.filter((i) => i.type === 'tree')
+  const root = []
+  const map = new Map()
+
+  for (const { path } of dirs) {
+    const parts = path.split('/')
+    let parent = root
+    let fullPath = ''
+
+    for (const part of parts) {
+      fullPath = fullPath ? `${fullPath}/${part}` : part
+      if (!map.has(fullPath)) {
+        const node = { label: part, path: fullPath, children: [] }
+        map.set(fullPath, node)
+        parent.push(node)
+      }
+      parent = map.get(fullPath).children
+    }
+  }
+
+  // strip empty children arrays for leaf dirs
+  for (const node of map.values()) {
+    if (node.children.length === 0) delete node.children
+  }
+
+  return root
+}
+</script>