import type { Root as MdastRoot } from "mdast";
import type { Text } from "mdast";
import { visit, SKIP } from "unist-util-visit";
import { splitInlineShortcodes } from "@/lib/inlineShortcodes";

const QUICK_RE = /==|\[(?:kbd|color|bg)[=\]]/i;

type MdastParent = { children: Array<Record<string, unknown>>; type: string };

/** 行内短代码 → mdast 节点（mdast-util-to-hast 支持 data.hName / data.hProperties） */
function segToNodes(
  seg: Exclude<ReturnType<typeof splitInlineShortcodes>, null>[number]
): Record<string, unknown>[] {
  if (seg.type === "text") return [{ type: "text", value: seg.value }];
  if (seg.type === "mark" || seg.type === "kbd") {
    return [
      {
        type: "emphasis",
        data: { hName: seg.type },
        children: [{ type: "text", value: seg.value }],
      },
    ];
  }
  const style = [
    seg.fg ? `color:${seg.fg}` : null,
    seg.bg ? `background-color:${seg.bg}` : null,
  ]
    .filter(Boolean)
    .join(";");
  return [
    {
      type: "emphasis",
      data: { hName: "span", hProperties: { style } },
      children: [{ type: "text", value: seg.value }],
    },
  ];
}

/**
 * remark 插件：把文本节点中的 ==高亮== / [kbd] / [color] / [bg] 展开为
 * mark/kbd/span 节点。code/inlineCode 是字面节点没有子文本，天然免疫；
 * 未命中短代码的文本原样保留。
 */
export function remarkInlineShortcodes() {
  return (tree: MdastRoot) => {
    visit(tree, "text", (node: Text, index, parent) => {
      const p = parent as unknown as MdastParent | null;
      if (!p || index === undefined) return;
      const value = node.value;
      if (!QUICK_RE.test(value)) return;
      const segs = splitInlineShortcodes(value);
      if (!segs) return;
      const nodes = segs.flatMap(segToNodes);
      p.children.splice(index, 1, ...nodes);
      return [SKIP, index + nodes.length];
    });
  };
}