#!/usr/bin/env node
import fs from "fs/promises";
import path from "path";
const ROOT = "public";
const OUT = path.join(ROOT, "index.json");
const STATIC_TOPLEVEL = new Set(["about","contact","legal"]);
const MAX_BYTES = 64 * 1024;

function dateFromName(name){
  const m=name.match(/^(\d{4}-\d{2}-\d{2})/);
  return m?new Date(m[1]).getTime():null;
}
async function readHead(abs){
  const fh=await fs.open(abs,"r");
  const buf=Buffer.alloc(MAX_BYTES);
  const {bytesRead}=await fh.read(buf,0,MAX_BYTES,0);
  await fh.close();
  return buf.slice(0,bytesRead).toString("utf8");
}
function parseTitle(raw,ext){
  if(ext===".md") return raw.match(/^\s*#\s+(.+?)\s*$/m)?.[1].trim();
  if(ext===".html") return raw.match(/<title[^>]*>([^<]+)<\/title>/i)?.[1].trim();
  return null;
}

async function walk(relBase=""){
  const abs=path.join(ROOT,relBase);
  const entries=await fs.readdir(abs,{withFileTypes:true});
  const dir={type:"dir",name:path.basename(relBase)||"",path:relBase,children:[]};
  for(const e of entries){
    if(e.name.startsWith(".")) continue;
    const rel=path.posix.join(relBase,e.name);
    const absPath=path.join(ROOT,rel);
    if(e.isDirectory()){
      const top=rel.split("/")[0];
      if(STATIC_TOPLEVEL.has(top)){continue;}
      const child=await walk(rel);
      dir.children.push(child);
      continue;
    }
    const ext=path.extname(e.name);
    if(![".md",".html"].includes(ext)) continue;
    const st=await fs.stat(absPath);
    const raw=await readHead(absPath);
    const title=parseTitle(raw,ext)||e.name;
    const date=dateFromName(e.name);
    dir.children.push({
      type:"file",
      name:e.name,
      title,
      path:rel,
      ext,
      pinned:rel.startsWith("pinned/"),
      mtime:date||st.mtimeMs
    });
  }
  return dir;
}

(async()=>{
  const tree=await walk();
  const flat=[];
  (function flatten(n){for(const c of n.children){if(c.type==="file")flat.push(c);else flatten(c);}})(tree);
  const sections=[...new Set(flat.map(f=>f.path.split("/")[0]))];
  await fs.writeFile(OUT,JSON.stringify({tree:tree.children,flat,sections},null,2));
  console.log("index.json built:",OUT);
})();