const mm2pt=mm=>mm*72/25.4;
const sizes={A4:[595.28,841.89],Letter:[612,792],Legal:[612,1008],A3:[841.89,1190.55]};
const state={items:[]};
const file=document.getElementById("file");
const drop=document.getElementById("drop");
const thumbs=document.getElementById("thumbs");
const clearBtn=document.getElementById("clearBtn");
const reverseBtn=document.getElementById("reverseBtn");
const build=document.getElementById("build");
const buildSplit=document.getElementById("buildSplit");
const download=document.getElementById("download");
const out=document.getElementById("out");
const statusEl=document.getElementById("status");
const rangeEl=document.getElementById("range");
const subsetEl=document.getElementById("subset");
const outfileEl=document.getElementById("outfile");

drop.onclick=()=>file.click();
drop.ondragover=e=>{e.preventDefault();drop.style.borderColor="var(--brand)";};
drop.ondragleave=()=>{drop.style.borderColor="var(--line)";};
drop.ondrop=e=>{e.preventDefault();drop.style.borderColor="var(--line)";addFiles(e.dataTransfer.files)};
file.onchange=e=>addFiles(e.target.files);
clearBtn.onclick=()=>{state.items.forEach(it=>URL.revokeObjectURL(it.url));state.items=[];renderThumbs();resetPreview();};
reverseBtn.onclick=()=>{state.items.reverse();renderThumbs()};

function resetPreview(){out.innerHTML='<span class="small" id="t-preview">'+(i18n[document.documentElement.lang]||i18n.en).preview+'</span>';download.classList.add("hidden");statusEl.textContent=""}

function addFiles(list){
  const arr=[...list].filter(f=>/^image\//.test(f.type));
  arr.forEach(async f=>{
    const url=URL.createObjectURL(f);
    const img=new Image();img.loading="eager";
    img.onload=()=>{state.items.push({file:f,url,w:img.naturalWidth,h:img.naturalHeight});renderThumbs()};
    img.src=url;
  });
}

function renderThumbs(){
  thumbs.innerHTML=state.items.map((it,i)=>`
    <div class="thumb" data-i="${i}">
      <img src="${it.url}" alt="Page ${i+1}">
      <div class="row">
        <button class="icon-btn" data-act="up" data-i="${i}">↑</button>
        <button class="icon-btn" data-act="down" data-i="${i}">↓</button>
        <button class="icon-btn" data-act="del" data-i="${i}">✕</button>
      </div>
    </div>`).join("");
  thumbs.querySelectorAll(".icon-btn").forEach(b=>b.onclick=thumbAction);
}

function thumbAction(e){
  const i=+e.currentTarget.dataset.i;
  const a=e.currentTarget.dataset.act;
  if(a==="up"&&i>0){[state.items[i-1],state.items[i]]=[state.items[i],state.items[i-1]]}
  else if(a==="down"&&i<state.items.length-1){[state.items[i+1],state.items[i]]=[state.items[i],state.items[i+1]]}
  else if(a==="del"){URL.revokeObjectURL(state.items[i].url);state.items.splice(i,1)}
  renderThumbs();
}

function pageBox(){
  const size=document.getElementById("size").value;
  const ori=document.getElementById("orientation").value;
  let [w,h]=sizes[size];
  if(ori==="landscape"){[w,h]=[h,w]}
  return [w,h];
}

function placeRect(imgW,imgH,w,h,margin,mode){
  const boxW=w-2*margin,boxH=h-2*margin;const rImg=imgW/imgH;const rBox=boxW/boxH;
  let dW,dH;if(mode==="cover"){if(rImg>rBox){dH=boxH;dW=dH*rImg}else{dW=boxW;dH=dW/rImg}}
  else{if(rImg>rBox){dW=boxW;dH=dW/rImg}else{dH=boxH;dW=dH*rImg}}
  const tx=margin+(boxW-dW)/2;const ty=margin+(boxH-dH)/2;return [dW,dH,tx,ty]
}

function toU8(s){return new TextEncoder().encode(s)}
function pad10(n){n=("0000000000"+n).slice(-10);return n}
function hexToRgb01(hex){let c=hex.replace("#","");if(c.length===3){c=c[0]+c[0]+c[1]+c[1]+c[2]+c[2]}const r=parseInt(c.slice(0,2),16)/255,g=parseInt(c.slice(2,4),16)/255,b=parseInt(c.slice(4,6),16)/255;return [r,g,b]}

async function rasterizeWithWM(srcUrl,opts){
  const img=new Image();img.src=srcUrl;await img.decode();
  const maxW=parseInt(document.getElementById("maxW").value,10)||0;
  const scale=(maxW>0 && img.naturalWidth>maxW)?maxW/img.naturalWidth:1;
  const w=Math.max(1,Math.round(img.naturalWidth*scale));
  const h=Math.max(1,Math.round(img.naturalHeight*scale));
  const can=document.createElement("canvas");can.width=w;can.height=h;
  const ctx=can.getContext("2d");
  ctx.fillStyle=opts.bg;ctx.fillRect(0,0,w,h); /* keep for PNG transparency */
  ctx.drawImage(img,0,0,w,h);
  if(opts.wm){
    const sample=ctx.getImageData((w/2)|0,(h/2)|0,1,1).data;
    const luma=0.2126*sample[0]+0.7152*sample[1]+0.0722*sample[2];
    const dark=luma<128;
    const fill=dark?"#ffffff":"#000000";
    const stroke=dark?"#000000":"#ffffff";
    ctx.save();ctx.textAlign="center";ctx.textBaseline="middle";ctx.translate(w/2,h/2);ctx.rotate(-Math.PI/6);
    ctx.font=opts.wmSize+"px system-ui, Arial, sans-serif";
    ctx.lineWidth=3;ctx.strokeStyle=stroke;ctx.fillStyle=fill;
    if(opts.wmTile==="grid"){
      ctx.globalAlpha=0.18;
      const step=opts.wmSize*6;
      for(let y=-h;y<=h;y+=step){
        for(let x=-w;x<=w;x+=step){
          ctx.save();ctx.translate(x,y);ctx.strokeText(opts.wm,0,0);ctx.fillText(opts.wm,0,0);ctx.restore();
        }
      }
    }else{
      ctx.globalAlpha=0.22;ctx.strokeText(opts.wm,0,0);ctx.fillText(opts.wm,0,0);
    }
    ctx.restore();
  }
  const blob=await new Promise(r=>can.toBlob(r,"image/jpeg",opts.quality));
  const arr=new Uint8Array(await blob.arrayBuffer());
  return {data:arr,w,h}
}

function buildPDFBytes(pages,pw,ph,margin,fit,bgRgb){
  const chunks=[];let offset=0;const offsets=[null];let obj=0;
  function push(buf){chunks.push(buf);offset+=buf.length}
  function wobj(str){obj++;offsets[obj]=offset;push(toU8(obj+" 0 obj\n"+str+"\nendobj\n"))}
  push(toU8("%PDF-1.4\n"));
  const pageIds=[];
  const xobjs=[];
  const drawBg = !(Math.abs(bgRgb[0]-1)<1e-6 && Math.abs(bgRgb[1]-1)<1e-6 && Math.abs(bgRgb[2]-1)<1e-6);
  const bgCmd = drawBg ? (`q ${bgRgb[0].toFixed(4)} ${bgRgb[1].toFixed(4)} ${bgRgb[2].toFixed(4)} rg 0 0 ${pw.toFixed(2)} ${ph.toFixed(2)} re f Q\n`) : "";
  for(let i=0;i<pages.length;i++){
    const im=pages[i];
    obj++;offsets[obj]=offset;
    push(toU8(obj+" 0 obj\n<< /Type /XObject /Subtype /Image /Width "+im.w+" /Height "+im.h+" /ColorSpace /DeviceRGB /BitsPerComponent 8 /Filter /DCTDecode /Length "+im.data.length+" >>\nstream\n"));
    push(im.data);
    push(toU8("\nendstream\nendobj\n"));
    xobjs.push(obj);
    const [dw,dh,tx,ty]=placeRect(im.w,im.h,pw,ph,margin,fit);
    const content = bgCmd + "q "+dw.toFixed(2)+" 0 0 "+dh.toFixed(2)+" "+tx.toFixed(2)+" "+ty.toFixed(2)+" cm /Im"+obj+" Do Q";
    obj++;offsets[obj]=offset;
    const cbuf=toU8(content);
    push(toU8(obj+" 0 obj\n<< /Length "+cbuf.length+" >>\nstream\n"));push(cbuf);push(toU8("\nendstream\nendobj\n"));
    const contentsId=obj;
    obj++;offsets[obj]=offset;
    push(toU8(obj+" 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 "+pw.toFixed(2)+" "+ph.toFixed(2)+"] /Resources << /XObject << /Im"+xobjs[i]+" "+xobjs[i]+" 0 R >> /ProcSet [/PDF /ImageC] >> /Contents "+contentsId+" 0 R >>\nendobj\n"));
    pageIds.push(obj);
  }
  wobj("<< /Type /Pages /Kids [ "+pageIds.map(id=>id+" 0 R").join(" ")+" ] /Count "+pageIds.length+" >>");const pagesId=obj;
  wobj("<< /Type /Catalog /Pages "+pagesId+" 0 R >>");const rootId=obj;
  wobj("<< /Producer (Sys-Metrics PDF Toolkit) /Creator (Sys-Metrics) /Title (PDF Toolkit) >>");const infoId=obj;
  const xrefStart=offset;
  let xref="xref\n0 "+(obj+1)+"\n0000000000 65535 f \n";
  for(let i=1;i<=obj;i++){xref+=pad10(offsets[i]||0)+" 00000 n \n"}
  const trailer="trailer\n<< /Size "+(obj+1)+" /Root "+rootId+" 0 R /Info "+infoId+" 0 R >>\nstartxref\n"+xrefStart+"\n%%EOF";
  push(toU8(xref+trailer));
  const total=chunks.reduce((a,b)=>a+b.length,0);
  const out=new Uint8Array(total);let p=0;for(const c of chunks){out.set(c,p);p+=c.length}
  return out
}

function parseRangeInput(count,txt){
  if(!txt.trim())return [];
  const parts=txt.split(",");const set=new Set();
  for(const part of parts){
    const s=part.trim();
    if(!s)continue;
    if(s.includes("-")){
      const [a,b]=s.split("-").map(x=>parseInt(x.trim(),10));
      if(isFinite(a)&&isFinite(b)){
        const lo=Math.max(1,Math.min(a,b)),hi=Math.min(count,Math.max(a,b));
        for(let i=lo;i<=hi;i++)set.add(i-1);
      }
    }else{
      const n=parseInt(s,10);if(isFinite(n)&&n>=1&&n<=count)set.add(n-1);
    }
  }
  return Array.from(set).sort((a,b)=>a-b)
}

async function makePDF(selectedIdx=null){
  if(!state.items.length){statusEl.textContent=(i18n[document.documentElement.lang]||i18n.en).add;return null}
  statusEl.textContent="…";download.classList.add("hidden");out.innerHTML="";
  const margin=mm2pt(parseFloat(document.getElementById("margin").value||"15"));
  const [pw,ph]=pageBox();
  const fit=document.getElementById("fit").value;
  const quality=parseFloat(document.getElementById("quality").value||"0.85");
  const bgHex=document.getElementById("bg").value;
  const bgRgb=hexToRgb01(bgHex);
  const wm=document.getElementById("wm").value.trim();
  const wmSize=parseInt(document.getElementById("wmSize").value,10);
  const wmTile=document.getElementById("wmTile").value;
  const indices=selectedIdx??state.items.map((_,i)=>i);
  const pages=[];
  for(const i of indices){
    const it=state.items[i];
    const page=await rasterizeWithWM(it.url,{bg:bgHex,wm,wmSize,wmTile,quality});
    pages.push(page);
  }
  const bytes=buildPDFBytes(pages,pw,ph,margin,fit,bgRgb);
  return new Blob([bytes],{type:"application/pdf"})
}

function previewAndLink(blob,name){
  const url=URL.createObjectURL(blob);
  const iframe=document.createElement("iframe");
  iframe.title="PDF preview";iframe.style.width="100%";iframe.style.height="480px";iframe.style.border="0";iframe.src=url;
  out.innerHTML="";out.appendChild(iframe);
  download.href=url;download.download=name;download.classList.remove("hidden");
  statusEl.textContent="OK";
}

build.onclick=async()=>{try{
  let name=(outfileEl.value||"pdf-toolkit.pdf").replace(/\s+/g,"-");
  if(!/\.pdf$/i.test(name))name+=".pdf";
  const subset=subsetEl.value==="range"?parseRangeInput(state.items.length,rangeEl.value):null;
  const blob=await makePDF(subset);
  if(blob)previewAndLink(blob,name);
}catch(e){console.error(e);statusEl.textContent="Error"}};

buildSplit.onclick=async()=>{try{
  if(!rangeEl.value.trim()){statusEl.textContent="Enter a range";return}
  const idx=parseRangeInput(state.items.length,rangeEl.value);
  if(!idx.length){statusEl.textContent="Nothing to export";return}
  const base=(outfileEl.value||"pdf-toolkit.pdf").replace(/\.pdf$/i,"");
  const blob=await makePDF(idx);
  if(blob)previewAndLink(blob,base+"-range.pdf");
}catch(e){console.error(e);statusEl.textContent="Error"}};