<template>
  <nav class="kole-anchor" :class="{ fixed }">
    <template v-for="(it, i) in items" :key="it.key">
      <button class="kole-anchor-item" :class="{ 'is-active': active === it.key }" @click="go(it.key)">{{ it.label }}</button>
      <div v-if="it.children" class="kole-anchor-sub">
        <button
          v-for="c in it.children" :key="c.key"
          class="kole-anchor-item" :class="{ 'is-active': active === c.key }"
          @click="go(c.key)"
        >{{ c.label }}</button>
      </div>
    </template>
  </nav>
</template>

<script>
export default {
  name: 'KoleAnchorNav',
  props: {
    items: { type: Array, required: true },   // [{ key, label, children? }]
    fixed: { type: Boolean, default: false },
    offset: { type: Number, default: 24 }
  },
  data() { return { active: this.items[0] ? this.items[0].key : '' }; },
  computed: {
    allKeys() {
      const out = [];
      (function collect(list) { list.forEach(i => { out.push(i.key); if (i.children) collect(i.children); }); })(this.items);
      return out;
    }
  },
  methods: {
    go(key) {
      const el = document.getElementById(key);
      if (el) window.scrollTo({ top: el.getBoundingClientRect().top + window.scrollY - this.offset, behavior: 'smooth' });
    },
    onScroll() {
      const pos = window.scrollY + 80;
      let cur = this.allKeys[0];
      for (const k of this.allKeys) {
        const el = document.getElementById(k);
        if (el && el.offsetTop <= pos) cur = k;
      }
      this.active = cur;
    }
  },
  mounted() { window.addEventListener('scroll', this.onScroll); },
  beforeDestroy() { window.removeEventListener('scroll', this.onScroll); }
};
</script>

<!-- 样式对齐 组件7.txt AnchorNav 规范 -->
<style>
.kole-anchor { font-family: var(--font-family, -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif); width: 160px; }
.kole-anchor.fixed { position: fixed; right: 24px; top: 80px; }
.kole-anchor-item { display: block; padding: 6px 12px; font-size: 13px; color: #6E6E6E; cursor: pointer; border-left: 2px solid #E8ECF1; line-height: 1.4; transition: color .15s, border-color .15s; background: none; border-top: none; border-right: none; border-bottom: none; text-align: left; width: 100%; }
.kole-anchor-item:hover { color: #2F54EB; }
.kole-anchor-item.is-active { color: #2F54EB; border-left-color: #2F54EB; font-weight: 500; }
.kole-anchor-sub { padding-left: 8px; }
.kole-anchor-sub .kole-anchor-item { border-left: none; padding-left: 20px; }
.kole-anchor-sub .kole-anchor-item.is-active { border-left: 2px solid #2F54EB; }
</style>
