// fills <!--gallery--> in index.html from whatever is in public/
// one tile per name: shows the .webp (or the .gif if that's all there is) and links every format
// tile images get ?v=<hash> so browsers drop old copies when a file changes, links stay clean for hotlinking
import{readdirSync as rd,readFileSync as rf}from'fs'
import{createHash}from'crypto'
const hidden=['cat/tail.gif']  // same drawing as cat/wag.gif, kept so old links still work
const walk=d=>rd(d,{withFileTypes:true}).flatMap(e=>e.isDirectory()?walk(`${d}/${e.name}`):`${d}/${e.name}`)
const dims=(b,x)=>x=='gif'?[b.readUInt16LE(6),b.readUInt16LE(8)]:[b.readUIntLE(24,3)+1,b.readUIntLE(27,3)+1]
const gallery=()=>{
  const g={}
  for(const f of walk('public').filter(f=>/\.(webp|gif)$/.test(f)).sort()){
    const p=f.slice(7),x=p.split('.').pop()
    if(!hidden.includes(p))(g[p.slice(0,-x.length-1)]??={})[x]=f
  }
  return Object.entries(g).map(([id,fm])=>{
    const x=fm.webp?'webp':'gif',b=rf(fm[x]),[w,h]=dims(b,x),v=createHash('md5').update(b).digest('hex').slice(0,8)
    const links=['webp','gif'].filter(k=>fm[k]).map(k=>`<a href="/${id}.${k}">${k}</a>`).join(' ')
    return`<figure><a href="/${id}.${x}"><img src="/${id}.${x}?v=${v}" alt="${id.replace('/',' ')}" width="${w}" height="${h}" loading="lazy" decoding="async"></a><figcaption>${links}</figcaption></figure>`
  }).join('\n')
}
export default{plugins:[{name:'gallery',transformIndexHtml:h=>h.replace('<!--gallery-->',gallery())}]}