/**
 * components/kf-empty.js —— <kf-empty> 空态 / 错误态 / 加载骨架。
 * 空态 = 图标 + 一句主文案（≤15 字）+ 一个按钮；不放复合解释。
 *
 * 属性：title / hint / action-label（有值时渲染按钮，点击派发 empty-action）
 *       kind: empty | error | loading
 */
import { LitElement, html, css } from 'lit';
import { useTokens, define } from './base.js';
import { icon } from './icons.js';

export class KfEmpty extends LitElement {
  static properties = {
    title: { type: String },
    hint: { type: String },
    actionLabel: { type: String, attribute: 'action-label' },
    kind: { type: String, reflect: true },
  };

  constructor() {
    super();
    this.title = '这里将来会出现内容';
    this.hint = '';
    this.actionLabel = '';
    this.kind = 'empty';
  }

  connectedCallback() {
    super.connectedCallback();
    useTokens(this);
  }

  static styles = css`
    :host { display: block; min-width: 0; }
    /* 空态（v10 任务书 2.9）：图标 24px opacity .6 + 一句 13px 说明 + 次级按钮；
       最小高度 = 正常内容高度（168px），切换筛选时页面不跳。 */
    .e { min-height: 168px; box-sizing: border-box; display: grid; justify-items: center; align-content: center; justify-content: center;
      gap: 8px; padding: 32px 16px; text-align: center; }
    .ico { display: grid; place-items: center; width: 24px; height: 24px; opacity: 0.6; }
    .ico svg { width: 24px; height: 24px; stroke: var(--kf-ink-3); }
    :host([kind="error"]) .ico svg { stroke: var(--kf-danger); }
    .t { color: var(--kf-ink); font-weight: 500; font-size: 14px; line-height: 1.4; letter-spacing: 0; overflow-wrap: anywhere; }
    .h { color: var(--kf-ink-3); font-size: 14px; max-width: 46ch; min-width: 0; line-height: 1.6; overflow-wrap: anywhere; }
    .e .kf-btn { margin-top: 8px; height: 28px; font-size: 14px; }
    /* 加载骨架：与空态同高，数据回来不跳 */
    .e.load { justify-items: stretch; justify-content: stretch; gap: 12px; padding: 24px; }
    .bar { width: 100%; height: 12px; }
  `;

  render() {
    if (this.kind === 'loading') {
      return html`<div class="e load" aria-busy="true" aria-live="polite" aria-label=${this.title || '加载中'}>
        <div class="kf-skel" style="height:20px;width:40%"></div>
        <div class="kf-skel bar"></div><div class="kf-skel bar"></div><div class="kf-skel bar" style="width:64%"></div>
      </div>`;
    }
    const ico = this.kind === 'error' ? icon('alert', 24) : icon('inbox', 24);
    return html`
      <div class="e" role=${this.kind === 'error' ? 'alert' : 'status'}>
        <div class="ico" aria-hidden="true">${ico}</div>
        <div class="t">${this.title}</div>
        ${this.hint ? html`<div class="h">${this.hint}</div>` : ''}
        ${this.actionLabel ? html`<button class="kf-btn" @click=${() => this.dispatchEvent(new CustomEvent('empty-action', { bubbles: true, composed: true }))}>${this.actionLabel}</button>` : ''}
      </div>
    `;
  }
}

define('kf-empty', KfEmpty);