// Copyright (C) 2003-2026, Foxit Software Inc..
// All Rights Reserved.
//
// http://www.foxitsoftware.com
//
// The following code is copyrighted and contains proprietary information and trade secrets of Foxit Software Inc..
// You cannot distribute any part of Foxit PDF SDK to any third party or general public,
// unless there is a separate license agreement with Foxit Software Inc. which explicitly grants you such rights.
//
// This file contains an example to demonstrate how to use Foxit PDF SDK to loading PDF document asynchronously.

const FSDK = require("@foxitsoftware/foxit-pdf-sdk-node");
const fs = require('fs');
const os = require('os');
const path = require('path');

var sn = "bPxThFlBAYifO3yiW0C51bKbjPap1zHaf5aG5sX378TjFvB7Q0802A==";
var key = "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";

const input_path = "../input_files/";
const output_path = "../output_files/";

class DownloadHintDataInfo {
  constructor(offset, size, is_downloaded) {
    this.offset = offset || 0;
    this.size = size || 0;
    this.is_downloaded = is_downloaded || false;
  }
}

class AsyncFileRead {
  constructor() {
    this.file_ = null;
    this.file_path_ = "";
    this.hint_data_record_ = [];
  }

  LoadFile(file_path) {
    try {
      this.file_path_ = file_path;
      this.file_ = fs.openSync(file_path, 'r');
      return true;
    } catch (err) {
      console.error(err);
      return false;
    }
  }

  CloseFile() {
    fs.closeSync(this.file_);
  }

  GetSize() {
    try {
      let stats = fs.statSync(this.file_path_);
      return stats.size;
    } catch (err) {
      console.error(err);
      return 0;
    }
  }

  ReadBlock(offset, size_t) {
    try {
      let buffer = Buffer.alloc(size_t);
      fs.readSync(this.file_, buffer, 0, size_t, offset);
      return [true, buffer]
    } catch (err) {
      return [false, null];
    }
  }

  Release() {  }

  IsDataAvail(offset, size) {
    return this.CheckRecordDownloaded(offset, size, false);
  }

  AddDownloadHint(offset, size) {
    return this.CheckRecordDownloaded(offset, size, true);
  }

  CheckRecordDownloaded(offset, size, to_download) {
    let record_count = this.hint_data_record_.length;    
    for (let i = 0; i < record_count; i++) {
      let data_info = this.hint_data_record_[i];

      // If (offset+size) is out of current data_info, just continue to check other record in hint_data_record_.
      if (offset > data_info.offset + data_info.size) continue;
      if (offset + size < data_info.offset) continue;

      // If data defined by <offset, size> has been in/within current data info, just download the data.
      if (offset >= data_info.offset && offset + size <= data_info.offset + data_info.size) {
        if (to_download) data_info.is_downloaded = true;
        return data_info.is_downloaded;
      }

      // If only part of data defined by <offset, size> is in current data_info, download current data_info and
      // also check and download rest data.
      if (
        offset >= data_info.offset &&
        offset < data_info.offset + data_info.size &&
        offset + size > data_info.offset + data_info.size
      ) {
        if (to_download) data_info.is_downloaded = true;
        if (!data_info.is_downloaded) return data_info.is_downloaded;

        let new_offset = data_info.offset + data_info.size + 1;
        let next_size = size - 1 - (data_info.offset + data_info.size - offset);
        return this.CheckRecordDownloaded(new_offset, next_size, to_download);
      }

      if (
        offset < data_info.offset &&
        offset + size >= data_info.offset &&
        offset + size <= data_info.offset + data_info.size
      ) {
        if (to_download) data_info.is_downloaded = true;
        if (!data_info.is_downloaded) return data_info.is_downloaded;

        let new_offset = offset;
        let next_size = data_info.offset - 1 - offset;
        return this.CheckRecordDownloaded(new_offset, next_size, to_download);
      }

      if (offset < data_info.offset && offset + size > data_info.offset + data_info.size) {
        if (to_download) data_info.is_downloaded = true;
        if (!data_info.is_downloaded) return data_info.is_downloaded;

        let new_offset = offset;
        let next_size = data_info.offset - 1 - offset;
        if (this.CheckRecordDownloaded(new_offset, next_size, to_download)) {
          let new_offset = data_info.offset + data_info.size + 1;
          let next_size = size - 1 - (data_info.offset - offset + data_info.size);
          return this.CheckRecordDownloaded(new_offset, next_size, to_download);
        } else {
          return false;
        }
      }
    }
    if (to_download) {
      return this.DownloadData(offset, size);
    }
    return false;
  }
    
  DownloadData(offset, size) {    
    let new_info = new DownloadHintDataInfo(offset, size, true);
    this.hint_data_record_.push(new_info);
    return true;
  }
}


let error_code = FSDK.Library.Initialize(sn, key);
if (FSDK.e_ErrSuccess != error_code) {
  if (FSDK.e_ErrInvalidLicense == error_code)
    console.log("[Failed] Current used Foxit PDF SDK key information is invalid.");
  else
    console.log("Library Initialize Error: %d", FSDK.e_ErrSuccess);
  return;
}

let input_file = input_path + "AboutFoxit.pdf";
let output_directory = output_path + "async_load/";
let output_file = output_directory + "page0.bmp";

if (!fs.existsSync(output_directory)) {
  fs.mkdirSync(output_directory);
}

try {

  var async_read = new AsyncFileRead();
  async_read.LoadFile(input_file);
  let file_read_callback = new FSDK.AsyncReaderCallback(async_read);
  let doc = new FSDK.PDFDoc(file_read_callback, true);

  //let doc = new FSDK.PDFDoc(input_file);

  // Actually, here, application should download needed data which specified by AsyncFileRead::AddDownloadHint().
  // But here, for simple example, we just "download" these data inside AsyncFileRead::AddDownloadHint().
  // So, just continue to check the ready state here, which will trigger AsyncFileRead::AddDownloadHint() to
  // "download" data.
  let code = FSDK.e_ErrDataNotReady;
  while (code == FSDK.e_ErrDataNotReady)
    code = doc.Load("");
  if (code != FSDK.e_ErrSuccess) {
    console.log("The Doc [%s] Error: %d\n", input_file, error_code);
    return 1;
  }

  // Actually, here, application should download needed data which specified by AsyncFileRead::AddDownloadHint().
  // But here, for simple example, we just "download" these data inside AsyncFileRead::AddDownloadHint().
  // So, just continue to check the ready state here, which will trigger AsyncFileRead::AddDownloadHint() to
  // "download" data.
  let page;
  code = FSDK.e_ErrDataNotReady;
  while (code == FSDK.e_ErrDataNotReady) {
    try {
      page = doc.GetPage(0);
      break;
    } catch (e) {
      let err = e;
    }
  }

  // Parse page.
  page.StartParse(FSDK.PDFPage.e_ParsePageNormal, null, false);

  let width = page.GetWidth();
  let height = page.GetHeight();  
  let matrix = page.GetDisplayMatrix(0, 0, width, height, page.GetRotation());

  // Prepare a bitmap for rendering.
  let bitmap = new FSDK.Bitmap(width, height, FSDK.Bitmap.e_DIBArgb, null, 0);

  bitmap.FillRect(0xfffffff, null);
  // Render page
  let render = new FSDK.Renderer(bitmap, false);
  render.StartRender(page, matrix, null);

  let image = new FSDK.Image();
  image.AddFrame(bitmap);
  image.SaveAs(output_file);
  console.log("async-load demo finished.");
} catch (e) {
  console.log(e);
}

FSDK.Library.Release();
