feat: add toc to readme

app/components/ReadmeTocDropdown.vue

@@ -0,0 +1,246 @@
+<script setup lang="ts">
+import type { TocItem } from '#shared/types/readme'
+import { onClickOutside, useEventListener } from '@vueuse/core'
+import { scrollToAnchor } from '~/utils/scrollToAnchor'
+
+const props = defineProps<{
+  toc: TocItem[]
+  activeId?: string | null
+  scrollToHeading?: (id: string) => void
+}>()
+
+interface TocNode extends TocItem {
+  children: TocNode[]
+}
+
+function buildTocTree(items: TocItem[]): TocNode[] {
+  const result: TocNode[] = []
+  const stack: TocNode[] = []
+
+  for (const item of items) {
+    const node: TocNode = { ...item, children: [] }
+
+    // Find parent: look for the last item with smaller depth
+    while (stack.length > 0 && stack[stack.length - 1]!.depth >= item.depth) {
+      stack.pop()
+    }
+
+    if (stack.length === 0) {
+      result.push(node)
+    } else {
+      stack[stack.length - 1]!.children.push(node)
+    }
+
+    stack.push(node)
+  }
+
+  return result
+}
+
+const tocTree = computed(() => buildTocTree(props.toc))
+
+// Create a map from id to index for efficient lookup
+const idToIndex = computed(() => {
+  const map = new Map<string, number>()
+  props.toc.forEach((item, index) => map.set(item.id, index))
+  return map
+})
+
+const listRef = useTemplateRef('listRef')
+const triggerRef = useTemplateRef('triggerRef')
+const isOpen = shallowRef(false)
+const highlightedIndex = shallowRef(-1)
+
+const dropdownPosition = shallowRef<{ top: number; right: number } | null>(null)
+
+function getDropdownStyle(): Record<string, string> {
+  if (!dropdownPosition.value) return {}
+  return {
+    top: `${dropdownPosition.value.top}px`,
+    right: `${document.documentElement.clientWidth - dropdownPosition.value.right}px`,
+  }
+}
+
+// Close on scroll (but not when scrolling inside the dropdown)
+function handleScroll(event: Event) {
+  if (!isOpen.value) return
+  if (listRef.value && event.target instanceof Node && listRef.value.contains(event.target)) {
+    return
+  }
+  close()
+}
+useEventListener('scroll', handleScroll, true)
+
+// Generate unique ID for accessibility
+const inputId = useId()
+const listboxId = `${inputId}-toc-listbox`
+
+function toggle() {
+  if (isOpen.value) {
+    close()
+  } else {
+    if (triggerRef.value) {
+      const rect = triggerRef.value.getBoundingClientRect()
+      dropdownPosition.value = {
+        top: rect.bottom + 4,
+        right: rect.right,
+      }
+    }
+    isOpen.value = true
+    // Highlight active item if any
+    const activeIndex = idToIndex.value.get(props.activeId ?? '')
+    highlightedIndex.value = activeIndex ?? 0
+  }
+}
+
+function close() {
+  isOpen.value = false
+  highlightedIndex.value = -1
+}
+
+function select(id: string) {
+  scrollToAnchor(id, props.scrollToHeading)
+  close()
+  triggerRef.value?.focus()
+}
+
+function getIndex(id: string): number {
+  return idToIndex.value.get(id) ?? -1
+}
+
+// Check for reduced motion preference
+const prefersReducedMotion = useMediaQuery('(prefers-reduced-motion: reduce)')
+
+onClickOutside(listRef, close, { ignore: [triggerRef] })
+
+function handleKeydown(event: KeyboardEvent) {
+  if (!isOpen.value) return
+
+  const itemCount = props.toc.length
+
+  switch (event.key) {
+    case 'ArrowDown':
+      event.preventDefault()
+      highlightedIndex.value = (highlightedIndex.value + 1) % itemCount
+      break
+    case 'ArrowUp':
+      event.preventDefault()
+      highlightedIndex.value =
+        highlightedIndex.value <= 0 ? itemCount - 1 : highlightedIndex.value - 1
+      break
+    case 'Enter': {
+      event.preventDefault()
+      const item = props.toc[highlightedIndex.value]
+      if (item) {
+        select(item.id)
+      }
+      break
+    }
+    case 'Escape':
+      close()
+      triggerRef.value?.focus()
+      break
+  }
+}
+</script>
+
+<template>
+  <button
+    ref="triggerRef"
+    type="button"
+    class="flex items-center gap-1.5 px-2 py-2 font-mono text-xs text-fg-muted bg-bg-subtle border border-border-subtle border-solid rounded-md transition-colors duration-150 hover:(text-fg border-border-hover) active:scale-95 focus:border-border-hover focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-fg/50 hover:text-fg"
+    :aria-expanded="isOpen"
+    aria-haspopup="listbox"
+    :aria-label="$t('package.readme.toc_title')"
+    :aria-controls="listboxId"
+    @click="toggle"
+    @keydown="handleKeydown"
+  >
+    <span class="i-carbon:list w-3.5 h-3.5" aria-hidden="true" />
+    <span
+      class="i-carbon:chevron-down w-3 h-3"
+      :class="[
+        { 'rotate-180': isOpen },
+        prefersReducedMotion ? '' : 'transition-transform duration-200',
+      ]"
+      aria-hidden="true"
+    />
+  </button>
+
+  <Teleport to="body">
+    <Transition
+      :enter-active-class="prefersReducedMotion ? '' : 'transition-opacity duration-150'"
+      :enter-from-class="prefersReducedMotion ? '' : 'opacity-0'"
+      enter-to-class="opacity-100"
+      :leave-active-class="prefersReducedMotion ? '' : 'transition-opacity duration-100'"
+      leave-from-class="opacity-100"
+      :leave-to-class="prefersReducedMotion ? '' : 'opacity-0'"
+    >
+      <div
+        v-if="isOpen"
+        :id="listboxId"
+        ref="listRef"
+        role="listbox"
+        :aria-activedescendant="
+          highlightedIndex >= 0 ? `${listboxId}-${toc[highlightedIndex]?.id}` : undefined
+        "
+        :aria-label="$t('package.readme.toc_title')"
+        :style="getDropdownStyle()"
+        class="fixed bg-bg-subtle border border-border rounded-md shadow-lg z-50 max-h-80 overflow-y-auto w-56 overscroll-contain"
+      >
+        <template v-for="node in tocTree" :key="node.id">
+          <div
+            :id="`${listboxId}-${node.id}`"
+            role="option"
+            :aria-selected="activeId === node.id"
+            class="flex items-center gap-2 px-3 py-1.5 text-sm cursor-pointer transition-colors duration-150"
+            :class="[
+              activeId === node.id ? 'text-fg font-medium' : 'text-fg-muted',
+              highlightedIndex === getIndex(node.id) ? 'bg-bg-elevated' : 'hover:bg-bg-elevated',
+            ]"
+            @click="select(node.id)"
+            @mouseenter="highlightedIndex = getIndex(node.id)"
+          >
+            <span class="truncate">{{ node.text }}</span>
+          </div>
+
+          <template v-for="child in node.children" :key="child.id">
+            <div
+              :id="`${listboxId}-${child.id}`"
+              role="option"
+              :aria-selected="activeId === child.id"
+              class="flex items-center gap-2 px-3 py-1.5 ps-6 text-sm cursor-pointer transition-colors duration-150"
+              :class="[
+                activeId === child.id ? 'text-fg font-medium' : 'text-fg-subtle',
+                highlightedIndex === getIndex(child.id) ? 'bg-bg-elevated' : 'hover:bg-bg-elevated',
+              ]"
+              @click="select(child.id)"
+              @mouseenter="highlightedIndex = getIndex(child.id)"
+            >
+              <span class="truncate">{{ child.text }}</span>
+            </div>
+
+            <div
+              v-for="grandchild in child.children"
+              :id="`${listboxId}-${grandchild.id}`"
+              :key="grandchild.id"
+              role="option"
+              :aria-selected="activeId === grandchild.id"
+              class="flex items-center gap-2 px-3 py-1.5 ps-9 text-sm cursor-pointer transition-colors duration-150"
+              :class="[
+                activeId === grandchild.id ? 'text-fg font-medium' : 'text-fg-subtle',
+                highlightedIndex === getIndex(grandchild.id)
+                  ? 'bg-bg-elevated'
+                  : 'hover:bg-bg-elevated',
+              ]"
+              @click="select(grandchild.id)"
+              @mouseenter="highlightedIndex = getIndex(grandchild.id)"
+            >
+              <span class="truncate">{{ grandchild.text }}</span>
+            </div>
+          </template>
+        </template>
+      </div>
+    </Transition>
+  </Teleport>
+</template>