import { h } from '@ui-arch/frame';
import { diffLines } from './diffKit.js';
import type { DiffViewProps } from './types.js';

/*** 文本差异对比：行级对齐 + 增删着色 + 双行号列，超限时退化为整段替换（只影响精度不影响语义） ***/
export function diffView(props: DiffViewProps): HTMLElement {
  const ignore = props.ignoreWhitespace === true; // 只在显式开启时归一行内空白
  const ops = diffLines(props.before, props.after, ignore); // 纯逻辑在 diffKit：这里只负责把它画出来
  const added = ops.filter((o) => o.type === 'add').length; // 新增行数：统计条与读屏共用
  const removed = ops.filter((o) => o.type === 'del').length; // 删除行数
  let oldNo = 0;
  let newNo = 0;
  const rows = ops.map((op) => {
    if (op.type !== 'add') oldNo += 1; // same 与 del 占旧行号
    if (op.type !== 'del') newNo += 1; // same 与 add 占新行号
    const sign = op.type === 'add' ? '+' : op.type === 'del' ? '−' : ' ';
    return h(
      'div',
      { class: `ua-diff-row is-${op.type}` },
      h('span', { class: 'ua-diff-no' }, op.type === 'add' ? '' : String(oldNo)),
      h('span', { class: 'ua-diff-no' }, op.type === 'del' ? '' : String(newNo)),
      h('span', { class: 'ua-diff-sign', 'aria-hidden': 'true' }, sign),
      h('span', { class: 'ua-diff-text' }, op.text || ' '),
    );
  });
  const stats = props.showStats === false
    ? null
    : h(
      'div',
      { class: 'ua-diff-stats' },
      h('span', { class: 'ua-diff-add' }, `+${added}`),
      h('span', { class: 'ua-diff-del' }, `−${removed}`),
      ignore ? h('span', { class: 'ua-diff-note' }, '已忽略行内空白差异') : null, // 归一口径必须写在脸上，否则「为什么不报这几行」说不清
    );
  return h(
    'div',
    { class: 'ua-diff', role: 'group', 'aria-label': props.ariaLabel ?? `文本差异：新增 ${added} 行，删除 ${removed} 行` },
    stats,
    h('div', { class: 'ua-diff-body' }, ...rows),
  );
}