import { createServer } from 'node:http';
import { readFile } from 'node:fs/promises';
import { fileURLToPath } from 'node:url';
import { randomUUID } from 'node:crypto';
import { runTriage } from './workflow.mjs';
import { applyDecisions,digest } from './core.mjs';
const root=fileURLToPath(new URL('../',import.meta.url));
const port=Number(process.env.PORT??4317);
const allowedHosts=new Set([`127.0.0.1:${port}`,`localhost:${port}`]);
const staticFiles=new Map([['/',['index.html','text/html']],['/app.js',['app.js','text/javascript']],['/style.css',['style.css','text/css']]]);
let currentRun=null,currentIssues=null,busy=false;
const revisions=new Map();
function json(response,status,data){response.writeHead(status,{'Content-Type':'application/json; charset=utf-8','Cache-Control':'no-store'});response.end(JSON.stringify(data));}
async function body(request){
  if(!request.headers['content-type']?.startsWith('application/json'))throw new Error('Use application/json.');
  let bytes=0,chunks=[];
  for await(const chunk of request){bytes+=chunk.length;if(bytes>512000)throw new Error('Request body too large.');chunks.push(chunk);}
  try{return JSON.parse(Buffer.concat(chunks).toString('utf8'));}catch{throw new Error('Invalid JSON.');}
}
const server=createServer(async(request,response)=>{
  response.setHeader('X-Content-Type-Options','nosniff');
  response.setHeader('Content-Security-Policy',"default-src 'self'; script-src 'self'; style-src 'self'; img-src 'self' data:; connect-src 'self'; frame-ancestors 'none'; base-uri 'none'; form-action 'self'");
  response.setHeader('Referrer-Policy','no-referrer');
  if(!allowedHosts.has(request.headers.host)){json(response,403,{error:'Unsupported host.'});return;}
  const origin=request.headers.origin;
  if(origin&&origin!==`http://${request.headers.host}`){json(response,403,{error:'Cross-origin requests are disabled.'});return;}
  try{
    const pathname=new URL(request.url,`http://${request.headers.host}`).pathname;
    if(request.method==='GET'&&staticFiles.has(pathname)){
      const [name,type]=staticFiles.get(pathname);response.writeHead(200,{'Content-Type':type+'; charset=utf-8'});response.end(await readFile(root+'public/'+name));return;
    }
    if(request.method==='GET'&&pathname==='/api/sample'){json(response,200,JSON.parse(await readFile(root+'data/sample.json','utf8')));return;}
    if(request.method==='GET'&&pathname==='/api/evaluation'){
      let result;try{result=JSON.parse(await readFile(root+'evidence/evaluation.json','utf8'));}catch{result={available:false};}json(response,200,result);return;
    }
    if(request.method==='POST'&&pathname==='/api/triage'){
      if(busy){json(response,409,{error:'A local inference run is already in progress.'});return;}
      busy=true;
      try{const input=await body(request);const result=await runTriage(input);currentRun=result;currentIssues=result.items.map(({id,title,body,labels})=>({id,title,body,labels}));revisions.clear();json(response,200,result);}finally{busy=false;}return;
    }
    if(request.method==='POST'&&pathname==='/api/apply'){
      if(busy)throw new Error('Wait for the current triage run.');
      const input=await body(request);
      if(!currentRun||currentRun.runId!==input.runId)throw new Error('This preview is stale. Run triage again.');
      const before=structuredClone(currentIssues),after=applyDecisions(currentIssues,input.decisions),revisionId=randomUUID();
      revisions.set(revisionId,{before,afterHash:digest(after),count:input.decisions.length});currentIssues=after;
      json(response,200,{revisionId,issues:after,appliedCount:input.decisions.length});return;
    }
    if(request.method==='POST'&&pathname==='/api/undo'){
      if(busy)throw new Error('Wait for the current triage run.');
      const input=await body(request),revision=revisions.get(input.revisionId);
      if(!revision||digest(currentIssues)!==revision.afterHash)throw new Error('Undo conflicts with newer changes or the revision is no longer available.');
      currentIssues=structuredClone(revision.before);revisions.delete(input.revisionId);json(response,200,{issues:currentIssues,restoredCount:revision.count});return;
    }
    json(response,404,{error:'Not found.'});
  }catch(error){json(response,400,{error:error.message});}
});
server.listen(port,'127.0.0.1',()=>console.log(`Slow Triage is local at http://127.0.0.1:${port}. No external API calls.`));