import {awaitWithAbort} from './abortable.js';
import { readPdfPages } from './pdfDocumentReader.js';

async function openPdf(file,signal) {
  signal?.throwIfAborted();
  const pdfjs = await import('pdfjs-dist');
  pdfjs.GlobalWorkerOptions.workerSrc = (await import('pdfjs-dist/build/pdf.worker.min.mjs?url')).default;
  let task,destruction;
  const destroy=()=>destruction ||= task?.destroy();
  try {
    const data=await awaitWithAbort(file.arrayBuffer(),signal);
    signal?.throwIfAborted();
    task = pdfjs.getDocument({data});
    return {doc:await awaitWithAbort(task.promise,signal,destroy),task:{destroy}};
  }
  catch(error) {
    await destroy();
    signal?.throwIfAborted();
    if(error.name === 'InvalidPDFException') throw new Error('PDF dosyası bozuk veya geçerli PDF biçiminde değil.');
    if(error.name === 'PasswordException') throw new Error('PDF parola korumalı; okunabilir bir kopyasını yükleyin.');
    throw new Error('PDF okunamadı. Dosyayı kontrol edip yeniden deneyin.');
  }
}

async function readPdf(file,{ocr=false,forceOcr=false,maxPages=Infinity,onProgress,signal}={}) {
  const {doc,task}=await openPdf(file,signal);
  let worker,termination,render;
  const stopWorker=()=>termination ||= worker?.terminate();
  const cancel=()=>{render?.cancel();void Promise.resolve(stopWorker()).catch(()=>{});void Promise.resolve(task.destroy()).catch(()=>{});};
  signal?.addEventListener('abort',cancel,{once:true});
  try {
    signal?.throwIfAborted();
    const result=await readPdfPages(doc,{maxPages,forceOcr,onProgress,signal,ocrPage:ocr ? async(page)=>{
      if(!worker) {
        const {createWorker}=await import('tesseract.js');
        signal?.throwIfAborted();
        worker=await awaitWithAbort(createWorker('tur').then(created=>{
          if(signal?.aborted){void created.terminate().catch(()=>{});signal.throwIfAborted();}
          return created;
        }),signal);
      }
      const viewport=page.getViewport({scale:2});
      const canvas=document.createElement('canvas');
      canvas.width=viewport.width;canvas.height=viewport.height;
      try {
        signal?.throwIfAborted();
        render=page.render({canvasContext:canvas.getContext('2d'),viewport});
        await awaitWithAbort(render.promise,signal,()=>render.cancel());
        signal?.throwIfAborted();
        return (await awaitWithAbort(worker.recognize(canvas),signal,stopWorker)).data.text;
      } finally { render=null;canvas.width=0;canvas.height=0; }
    } : undefined});
    return result;
  } finally {
    signal?.removeEventListener('abort',cancel);
    try { await stopWorker(); }
    finally { await task.destroy(); }
  }
}

export const extractPdfText=(file,options={})=>readPdf(file,{...options,ocr:false});
export const ocrPdfText=(file,options={})=>readPdf(file,{...options,ocr:true,forceOcr:true});
export async function extractPlainText(file,{signal}={}) {
  signal?.throwIfAborted();
  return {text:(await awaitWithAbort(file.text(),signal)).trim(),pageCount:1,usedPages:1,complete:true};
}
export async function extractText(file,{ocr=true,onProgress,signal}={}) {
  if((file.name || '').toLowerCase().endsWith('.pdf') || file.type==='application/pdf')
    return readPdf(file,{ocr,onProgress,signal});
  return extractPlainText(file,{signal});
}