'use strict';
const {createHash}=require('node:crypto');
const {detectType}=require('./file-transfer.cjs');
// Typed binary carriers supplement text normalization. No whole decoded file
// may be released on the strength of an allow verdict for its outer JSON text.
function extractEncodedDocuments(bytes,{maxDecodedBytes=16777216,maxParts=16,maxNodes=20000,maxDepth=32,jsonRequired=false}={}){
 if(!Buffer.isBuffer(bytes)||bytes.length>16777216||![maxDecodedBytes,maxParts,maxNodes,maxDepth].every(Number.isSafeInteger)||maxDecodedBytes<1||maxDecodedBytes>16777216||maxParts<1||maxParts>64||maxNodes<1||maxNodes>20000||maxDepth<1||maxDepth>32)throw Error('encoded-document-configuration-invalid');
 if(typeof jsonRequired!=='boolean')throw Error('encoded-document-configuration-invalid');
 const parts=[],seen=new Set(),encodings=new Set();let total=0,nodes=0,complete=true;
 const result=()=>Object.freeze({parts:Object.freeze(parts),complete,decodedBytes:total,visitedNodes:nodes,dispose});
 const dispose=()=>{for(const part of parts)part.bytes.fill(0);};
 function candidate(value){
  if(!complete||typeof value!=='string')return;
  let encoded=value.trim(),explicit=false,mime;
  if(/^data:/i.test(encoded)){
   const match=/^data:([a-z0-9.+/-]+)?(?:;[a-z0-9-]+=[a-z0-9._-]+)*;base64,([\s\S]*)$/i.exec(encoded);
   if(!match){complete=false;return;}mime=(match[1]||'application/octet-stream').toLowerCase();encoded=match[2];explicit=true;
   if(encoded.includes('%')){try{encoded=decodeURIComponent(encoded);}catch{complete=false;return;}}
  }
  if(!explicit&&encoded.length<16)return;
  if(!/^[A-Za-z0-9+/_-]*={0,2}$/.test(encoded)||encoded.length%4===1){if(explicit)complete=false;return;}
  const normalized=encoded.replace(/-/g,'+').replace(/_/g,'/').replace(/=+$/,'');
  const encodingKey=createHash('sha256').update(normalized).update('\0'+(mime||'')).digest('hex');
  if(encodings.has(encodingKey))return;
  const projected=Math.floor(normalized.length*3/4);
  if(total+projected>maxDecodedBytes){complete=false;return;}
  const decoded=Buffer.from(normalized,'base64');
  total+=decoded.length;encodings.add(encodingKey);
  const type=detectType(decoded);
  if(decoded.toString('base64').replace(/=+$/,'')!==normalized){decoded.fill(0);if(explicit||type!=='unknown')complete=false;return;}
  if(!explicit&&type==='unknown'){decoded.fill(0);return;}
  const digest=createHash('sha256').update(decoded).digest('hex');
  const identity=digest+'\0'+(mime||'');
  if(seen.has(identity)){decoded.fill(0);return;}
  if(parts.length>=maxParts){decoded.fill(0);complete=false;return;}
  seen.add(identity);parts.push(Object.freeze({bytes:decoded,...(mime?{mime}:{})}));
 }
 function scanText(value,percentDepth=0){
  candidate(value);
  const carriers=[];
  for(const match of value.matchAll(/data:[^\s,"'<>]+,[A-Za-z0-9+/_=%-]+/gi)){if(++nodes>maxNodes){complete=false;break;}carriers.push([match.index,match.index+match[0].length]);candidate(match[0]);}
  let carrier=0;
  for(const match of value.matchAll(/[A-Za-z0-9+/_-]{16,}={0,2}/g)){
   while(carrier<carriers.length&&carriers[carrier][1]<=match.index)carrier++;
   if(carrier<carriers.length&&match.index>=carriers[carrier][0]&&match.index<carriers[carrier][1])continue;
   if(++nodes>maxNodes){complete=false;break;}candidate(match[0]);
  }
  if(complete&&value.includes('%')){
   if(percentDepth>=4){complete=false;return;}
   try{const decoded=decodeURIComponent(value);if(decoded!==value)scanText(decoded,percentDepth+1);}catch{if(/data%3a/i.test(value))complete=false;}
  }
 }
 try{
  const text=new TextDecoder('utf-8',{fatal:true}).decode(bytes),trimmed=text.trim();
  if(jsonRequired||trimmed.startsWith('{')||trimmed.startsWith('[')){
   let root;try{root=JSON.parse(trimmed);}catch{if(jsonRequired)complete=false;else scanText(trimmed);return result();}
   const stack=[{value:root,depth:0}];
   while(stack.length&&complete){const {value,depth}=stack.pop();if(++nodes>maxNodes||depth>maxDepth){complete=false;break;}
    if(typeof value==='string')scanText(value);
    else if(Array.isArray(value)){
     if(value.length>maxNodes-nodes||stack.length+value.length>maxNodes){complete=false;break;}
     for(const child of value)stack.push({value:child,depth:depth+1});
    }else if(value&&typeof value==='object'){
     // Avoid Object.entries allocating an unbounded array of key/value pairs
     // before the traversal budget is checked on a hostile JSON collection.
     for(const key in value){if(!Object.hasOwn(value,key))continue;scanText(key);stack.push({value:value[key],depth:depth+1});if(stack.length>maxNodes||!complete){complete=false;break;}}
    }
   }
  }else{
   scanText(trimmed);
  }
 }catch{complete=false;}
 return result();
}
module.exports={extractEncodedDocuments};