/* global jsPDF html2canvas */
/**
 * Copyright (c) 2018 Erik Koopmans
 * Released under the MIT License.
 *
 * Licensed under the MIT License.
 * http://opensource.org/licenses/mit-license
 */

/**
 * jsPDF html PlugIn
 *
 * @name html
 * @module
 */
(function (jsPDFAPI, global) {
  'use strict';

  if (typeof Promise === 'undefined') {
    // eslint-disable-next-line no-console
    console.warn('Promise not found. html-Plugin will not work');
    return;
  }
  /**
  * Determine the type of a variable/object.
  * 
  * @private
  * @ignore
  */
  var objType = function (obj) {
    var type = typeof obj;
    if (type === 'undefined') return 'undefined';
    else if (type === 'string' || obj instanceof String) return 'string';
    else if (type === 'number' || obj instanceof Number) return 'number';
    else if (type === 'function' || obj instanceof Function) return 'function';
    else if (!!obj && obj.constructor === Array) return 'array';
    else if (obj && obj.nodeType === 1) return 'element';
    else if (type === 'object') return 'object';
    else return 'unknown';
  };

  /**
  * Create an HTML element with optional className, innerHTML, and style.
  * 
  * @private
  * @ignore
  */
  var createElement = function (tagName, opt) {
    var el = document.createElement(tagName);
    if (opt.className) el.className = opt.className;
    if (opt.innerHTML) {
      el.innerHTML = opt.innerHTML;
      var scripts = el.getElementsByTagName('script');
      for (var i = scripts.length; i-- > 0;) {
        scripts[i].parentNode.removeChild(scripts[i]);
      }
    }
    for (var key in opt.style) {
      el.style[key] = opt.style[key];
    }
    return el;
  };

  /**
  * Deep-clone a node and preserve contents/properties.
  * 
  * @private
  * @ignore
  */
  var cloneNode = function (node, javascriptEnabled) {
    // Recursively clone the node.
    var clone = node.nodeType === 3 ? document.createTextNode(node.nodeValue) : node.cloneNode(false);
    for (var child = node.firstChild; child; child = child.nextSibling) {
      if (javascriptEnabled === true || child.nodeType !== 1 || child.nodeName !== 'SCRIPT') {
        clone.appendChild(cloneNode(child, javascriptEnabled));
      }
    }

    if (node.nodeType === 1) {
      // Preserve contents/properties of special nodes.
      if (node.nodeName === 'CANVAS') {
        clone.width = node.width;
        clone.height = node.height;
        clone.getContext('2d').drawImage(node, 0, 0);
      } else if (node.nodeName === 'TEXTAREA' || node.nodeName === 'SELECT') {
        clone.value = node.value;
      }

      // Preserve the node's scroll position when it loads.
      clone.addEventListener('load', function () {
        clone.scrollTop = node.scrollTop;
        clone.scrollLeft = node.scrollLeft;
      }, true);
    }

    // Return the cloned node.
    return clone;
  };

  /* ----- CONSTRUCTOR ----- */

  var Worker = function Worker(opt) {
    // Create the root parent for the proto chain, and the starting Worker.
    var root = Object.assign(Worker.convert(Promise.resolve()),
      JSON.parse(JSON.stringify(Worker.template)));
    var self = Worker.convert(Promise.resolve(), root);

    // Set progress, optional settings, and return.
    self = self.setProgress(1, Worker, 1, [Worker]);
    self = self.set(opt);
    return self;
  };

  // Boilerplate for subclassing Promise.
  Worker.prototype = Object.create(Promise.prototype);
  Worker.prototype.constructor = Worker;

  // Converts/casts promises into Workers.
  Worker.convert = function convert(promise, inherit) {
    // Uses prototypal inheritance to receive changes made to ancestors' properties.
    promise.__proto__ = inherit || Worker.prototype;
    return promise;
  };

  Worker.template = {
    prop: {
      src: null,
      container: null,
      overlay: null,
      canvas: null,
      img: null,
      pdf: null,
      pageSize: null,
      callback: function () { }
    },
    progress: {
      val: 0,
      state: null,
      n: 0,
      stack: []
    },
    opt: {
      filename: 'file.pdf',
      margin: [0, 0, 0, 0],
      enableLinks: true,
      x: 0,
      y: 0,
      html2canvas: {},
      jsPDF: {}
    }
  };

  /* ----- FROM / TO ----- */

  Worker.prototype.from = function from(src, type) {
    function getType(src) {
      switch (objType(src)) {
        case 'string': return 'string';
        case 'element': return src.nodeName.toLowerCase === 'canvas' ? 'canvas' : 'element';
        default: return 'unknown';
      }
    }

    return this.then(function from_main() {
      type = type || getType(src);
      switch (type) {
        case 'string': return this.set({ src: createElement('div', { innerHTML: src }) });
        case 'element': return this.set({ src: src });
        case 'canvas': return this.set({ canvas: src });
        case 'img': return this.set({ img: src });
        default: return this.error('Unknown source type.');
      }
    });
  };

  Worker.prototype.to = function to(target) {
    // Route the 'to' request to the appropriate method.
    switch (target) {
      case 'container':
        return this.toContainer();
      case 'canvas':
        return this.toCanvas();
      case 'img':
        return this.toImg();
      case 'pdf':
        return this.toPdf();
      default:
        return this.error('Invalid target.');
    }
  };

  Worker.prototype.toContainer = function toContainer() {
    // Set up function prerequisites.
    var prereqs = [function checkSrc() {
      return this.prop.src || this.error('Cannot duplicate - no source HTML.');
    }, function checkPageSize() {
      return this.prop.pageSize || this.setPageSize();
    }];
    return this.thenList(prereqs).then(function toContainer_main() {
      // Define the CSS styles for the container and its overlay parent.
      var overlayCSS = {
        position: 'fixed',
        overflow: 'hidden',
        zIndex: 1000,
        left: '-100000px',
        right: 0,
        bottom: 0,
        top: 0
      };
      var containerCSS = {
        position: 'relative',
        display: 'inline-block',
        width: Math.max(this.prop.src.clientWidth, this.prop.src.scrollWidth, this.prop.src.offsetWidth) + 'px',
        left: 0,
        right: 0,
        top: 0,
        margin: 'auto',
        backgroundColor: 'white'
      }; // Set the overlay to hidden (could be changed in the future to provide a print preview).

      var source = cloneNode(this.prop.src, this.opt.html2canvas.javascriptEnabled);

      if (source.tagName === 'BODY') {
        containerCSS.height = Math.max(document.body.scrollHeight, document.body.offsetHeight, document.documentElement.clientHeight, document.documentElement.scrollHeight, document.documentElement.offsetHeight) + 'px';
      }

      this.prop.overlay = createElement('div', {
        className: 'html2pdf__overlay',
        style: overlayCSS
      });
      this.prop.container = createElement('div', {
        className: 'html2pdf__container',
        style: containerCSS
      });
      this.prop.container.appendChild(source);
      this.prop.container.firstChild.appendChild(createElement('div', {
        style: {
          clear: 'both',
          border: '0 none transparent',
          margin: 0,
          padding: 0,
          height: 0
        }
      }));
      this.prop.container.style.float = 'none';
      this.prop.overlay.appendChild(this.prop.container);
      document.body.appendChild(this.prop.overlay);
      this.prop.container.firstChild.style.position = 'relative';
      this.prop.container.height = Math.max(this.prop.container.firstChild.clientHeight, this.prop.container.firstChild.scrollHeight, this.prop.container.firstChild.offsetHeight) + 'px';
    });
  };

  Worker.prototype.toCanvas = function toCanvas() {
    // Set up function prerequisites.
    var prereqs = [
      function checkContainer() {
        return document.body.contains(this.prop.container)
          || this.toContainer();
      }
    ];

    // Fulfill prereqs then create the canvas.
    return this.thenList(prereqs).then(function toCanvas_main() {
      // Handle old-fashioned 'onrendered' argument.
      var options = Object.assign({}, this.opt.html2canvas);
      delete options.onrendered;

      if (!this.isHtml2CanvasLoaded()) {
        return;
      }
      return html2canvas(this.prop.container, options);
    }).then(function toCanvas_post(canvas) {
      // Handle old-fashioned 'onrendered' argument.
      var onRendered = this.opt.html2canvas.onrendered || function () { };
      onRendered(canvas);

      this.prop.canvas = canvas;
      document.body.removeChild(this.prop.overlay);
    });
  };

  Worker.prototype.toContext2d = function toContext2d() {
    // Set up function prerequisites.
    var prereqs = [
      function checkContainer() {
        return document.body.contains(this.prop.container)
          || this.toContainer();
      }
    ];

    // Fulfill prereqs then create the canvas.
    return this.thenList(prereqs).then(function toContext2d_main() {
      // Handle old-fashioned 'onrendered' argument.

      var pdf = this.opt.jsPDF;
      var options = Object.assign({
        async: true,
        allowTaint: true,
        backgroundColor: '#ffffff',
        imageTimeout: 15000,
        logging: true,
        proxy: null,
        removeContainer: true,
        foreignObjectRendering: false,
        useCORS: false
      }, this.opt.html2canvas);
      delete options.onrendered;

      pdf.context2d.autoPaging = true;
      pdf.context2d.posX = this.opt.x;
      pdf.context2d.posY = this.opt.y;

      options.windowHeight = options.windowHeight || 0;
      options.windowHeight = (options.windowHeight == 0) ? Math.max(this.prop.container.clientHeight, this.prop.container.scrollHeight, this.prop.container.offsetHeight) : options.windowHeight;

      if (!this.isHtml2CanvasLoaded()) {
        return;
      }

      return html2canvas(this.prop.container, options);
    }).then(function toContext2d_post(canvas) {
      // Handle old-fashioned 'onrendered' argument.
      var onRendered = this.opt.html2canvas.onrendered || function () { };
      onRendered(canvas);

      this.prop.canvas = canvas;
      document.body.removeChild(this.prop.overlay);
    });
  };

  Worker.prototype.toImg = function toImg() {
    // Set up function prerequisites.
    var prereqs = [
      function checkCanvas() { return this.prop.canvas || this.toCanvas(); }
    ];

    // Fulfill prereqs then create the image.
    return this.thenList(prereqs).then(function toImg_main() {
      var imgData = this.prop.canvas.toDataURL('image/' + this.opt.image.type, this.opt.image.quality);
      this.prop.img = document.createElement('img');
      this.prop.img.src = imgData;
    });
  };

  Worker.prototype.toPdf = function toPdf() {
    // Set up function prerequisites.
    var prereqs = [
      function checkContext2d() { return this.toContext2d(); }
      //function checkCanvas() { return this.prop.canvas || this.toCanvas(); }
    ];

    // Fulfill prereqs then create the image.
    return this.thenList(prereqs).then(function toPdf_main() {
      // Create local copies of frequently used properties.
      this.prop.pdf = this.prop.pdf || this.opt.jsPDF;
    });
  };


  /* ----- OUTPUT / SAVE ----- */

  Worker.prototype.output = function output(type, options, src) {
    // Redirect requests to the correct function (outputPdf / outputImg).
    src = src || 'pdf';
    if (src.toLowerCase() === 'img' || src.toLowerCase() === 'image') {
      return this.outputImg(type, options);
    } else {
      return this.outputPdf(type, options);
    }
  };

  Worker.prototype.outputPdf = function outputPdf(type, options) {
    // Set up function prerequisites.
    var prereqs = [
      function checkPdf() { return this.prop.pdf || this.toPdf(); }
    ];

    // Fulfill prereqs then perform the appropriate output.
    return this.thenList(prereqs).then(function outputPdf_main() {
      /* Currently implemented output types:
       *    https://rawgit.com/MrRio/jsPDF/master/docs/jspdf.js.html#line992
       *  save(options), arraybuffer, blob, bloburi/bloburl,
       *  datauristring/dataurlstring, dataurlnewwindow, datauri/dataurl
       */
      return this.prop.pdf.output(type, options);
    });
  };

  Worker.prototype.outputImg = function outputImg(type) {
    // Set up function prerequisites.
    var prereqs = [
      function checkImg() { return this.prop.img || this.toImg(); }
    ];

    // Fulfill prereqs then perform the appropriate output.
    return this.thenList(prereqs).then(function outputImg_main() {
      switch (type) {
        case undefined:
        case 'img':
          return this.prop.img;
        case 'datauristring':
        case 'dataurlstring':
          return this.prop.img.src;
        case 'datauri':
        case 'dataurl':
          return document.location.href = this.prop.img.src;
        default:
          throw 'Image output type "' + type + '" is not supported.';
      }
    });
  };

  Worker.prototype.isHtml2CanvasLoaded = function () {
    var result = typeof global.html2canvas !== "undefined";
    if (!result) {
      throw new Error("html2canvas not loaded.");
    }
    return result;
  };

  Worker.prototype.save = function save(filename) {
    // Set up function prerequisites.
    var prereqs = [
      function checkPdf() { return this.prop.pdf || this.toPdf(); }
    ];

    if (!this.isHtml2CanvasLoaded()) {
      return;
    }

    // Fulfill prereqs, update the filename (if provided), and save the PDF.
    return this.thenList(prereqs).set(
      filename ? { filename: filename } : null
    ).then(function save_main() {
      this.prop.pdf.save(this.opt.filename);
    });
  };

  Worker.prototype.doCallback = function doCallback() {
    // Set up function prerequisites.
    var prereqs = [
      function checkPdf() { return this.prop.pdf || this.toPdf(); }
    ];

    if (!this.isHtml2CanvasLoaded()) {
      return;
    }
    // Fulfill prereqs, update the filename (if provided), and save the PDF.
    return this.thenList(prereqs)
      .then(function doCallback_main() {
        this.prop.callback(this.prop.pdf);
      });
  };

  /* ----- SET / GET ----- */

  Worker.prototype.set = function set(opt) {
    // TODO: Implement ordered pairs?

    // Silently ignore invalid or empty input.
    if (objType(opt) !== 'object') {
      return this;
    }

    // Build an array of setter functions to queue.
    var fns = Object.keys(opt || {}).map(function (key) {
      if (key in Worker.template.prop) {
        // Set pre-defined properties.
        return function set_prop() { this.prop[key] = opt[key]; }
      } else {
        switch (key) {
          case 'margin':
            return this.setMargin.bind(this, opt.margin);
          case 'jsPDF':
            return function set_jsPDF() { this.opt.jsPDF = opt.jsPDF; return this.setPageSize(); }
          case 'pageSize':
            return this.setPageSize.bind(this, opt.pageSize);
          default:
            // Set any other properties in opt.
            return function set_opt() { this.opt[key] = opt[key] };
        }
      }
    }, this);

    // Set properties within the promise chain.
    return this.then(function set_main() {
      return this.thenList(fns);
    });
  };

  Worker.prototype.get = function get(key, cbk) {
    return this.then(function get_main() {
      // Fetch the requested property, either as a predefined prop or in opt.
      var val = (key in Worker.template.prop) ? this.prop[key] : this.opt[key];
      return cbk ? cbk(val) : val;
    });
  };

  Worker.prototype.setMargin = function setMargin(margin) {
    return this.then(function setMargin_main() {
      // Parse the margin property.
      switch (objType(margin)) {
        case 'number':
          margin = [margin, margin, margin, margin];
        // eslint-disable-next-line no-fallthrough
        case 'array':
          if (margin.length === 2) {
            margin = [margin[0], margin[1], margin[0], margin[1]];
          }
          if (margin.length === 4) {
            break;
          }
        // eslint-disable-next-line no-fallthrough
        default:
          return this.error('Invalid margin array.');
      }

      // Set the margin property, then update pageSize.
      this.opt.margin = margin;
    }).then(this.setPageSize);
  };

  Worker.prototype.setPageSize = function setPageSize(pageSize) {
    function toPx(val, k) {
      return Math.floor(val * k / 72 * 96);
    }

    return this.then(function setPageSize_main() {
      // Retrieve page-size based on jsPDF settings, if not explicitly provided.
      pageSize = pageSize || jsPDF.getPageSize(this.opt.jsPDF);

      // Add 'inner' field if not present.
      if (!pageSize.hasOwnProperty('inner')) {
        pageSize.inner = {
          width: pageSize.width - this.opt.margin[1] - this.opt.margin[3],
          height: pageSize.height - this.opt.margin[0] - this.opt.margin[2]
        };
        pageSize.inner.px = {
          width: toPx(pageSize.inner.width, pageSize.k),
          height: toPx(pageSize.inner.height, pageSize.k)
        };
        pageSize.inner.ratio = pageSize.inner.height / pageSize.inner.width;
      }

      // Attach pageSize to this.
      this.prop.pageSize = pageSize;
    });
  };

  Worker.prototype.setProgress = function setProgress(val, state, n, stack) {
    // Immediately update all progress values.
    if (val != null) this.progress.val = val;
    if (state != null) this.progress.state = state;
    if (n != null) this.progress.n = n;
    if (stack != null) this.progress.stack = stack;
    this.progress.ratio = this.progress.val / this.progress.state;

    // Return this for command chaining.
    return this;
  };

  Worker.prototype.updateProgress = function updateProgress(val, state, n, stack) {
    // Immediately update all progress values, using setProgress.
    return this.setProgress(
      val ? this.progress.val + val : null,
      state ? state : null,
      n ? this.progress.n + n : null,
      stack ? this.progress.stack.concat(stack) : null
    );
  };

  /* ----- PROMISE MAPPING ----- */

  Worker.prototype.then = function then(onFulfilled, onRejected) {
    // Wrap `this` for encapsulation.
    var self = this;

    return this.thenCore(onFulfilled, onRejected, function then_main(onFulfilled, onRejected) {
      // Update progress while queuing, calling, and resolving `then`.
      self.updateProgress(null, null, 1, [onFulfilled]);
      return Promise.prototype.then.call(this, function then_pre(val) {
        self.updateProgress(null, onFulfilled);
        return val;
      }).then(onFulfilled, onRejected).then(function then_post(val) {
        self.updateProgress(1);
        return val;
      });
    });
  };

  Worker.prototype.thenCore = function thenCore(onFulfilled, onRejected, thenBase) {
    // Handle optional thenBase parameter.
    thenBase = thenBase || Promise.prototype.then;

    // Wrap `this` for encapsulation and bind it to the promise handlers.
    var self = this;
    if (onFulfilled) { onFulfilled = onFulfilled.bind(self); }
    if (onRejected) { onRejected = onRejected.bind(self); }

    // Cast self into a Promise to avoid polyfills recursively defining `then`.
    var isNative = Promise.toString().indexOf('[native code]') !== -1 && Promise.name === 'Promise';
    var selfPromise = isNative ? self : Worker.convert(Object.assign({}, self), Promise.prototype);

    // Return the promise, after casting it into a Worker and preserving props.
    var returnVal = thenBase.call(selfPromise, onFulfilled, onRejected);
    return Worker.convert(returnVal, self.__proto__);
  };

  Worker.prototype.thenExternal = function thenExternal(onFulfilled, onRejected) {
    // Call `then` and return a standard promise (exits the Worker chain).
    return Promise.prototype.then.call(this, onFulfilled, onRejected);
  };

  Worker.prototype.thenList = function thenList(fns) {
    // Queue a series of promise 'factories' into the promise chain.
    var self = this;
    fns.forEach(function thenList_forEach(fn) {
      self = self.thenCore(fn);
    });
    return self;
  };

  Worker.prototype['catch'] = function (onRejected) {
    // Bind `this` to the promise handler, call `catch`, and return a Worker.
    if (onRejected) { onRejected = onRejected.bind(this); }
    var returnVal = Promise.prototype['catch'].call(this, onRejected);
    return Worker.convert(returnVal, this);
  };

  Worker.prototype.catchExternal = function catchExternal(onRejected) {
    // Call `catch` and return a standard promise (exits the Worker chain).
    return Promise.prototype['catch'].call(this, onRejected);
  };

  Worker.prototype.error = function error(msg) {
    // Throw the error in the Promise chain.
    return this.then(function error_main() {
      throw new Error(msg);
    });
  };


  /* ----- ALIASES ----- */

  Worker.prototype.using = Worker.prototype.set;
  Worker.prototype.saveAs = Worker.prototype.save;
  Worker.prototype.export = Worker.prototype.output;
  Worker.prototype.run = Worker.prototype.then;

  // Get dimensions of a PDF page, as determined by jsPDF.
  jsPDF.getPageSize = function (orientation, unit, format) {
    // Decode options object
    if (typeof orientation === 'object') {
      var options = orientation;
      orientation = options.orientation;
      unit = options.unit || unit;
      format = options.format || format;
    }

    // Default options
    unit = unit || 'mm';
    format = format || 'a4';
    orientation = ('' + (orientation || 'P')).toLowerCase();
    var format_as_string = ('' + format).toLowerCase();

    // Size in pt of various paper formats
    var pageFormats = {
      'a0': [2383.94, 3370.39], 'a1': [1683.78, 2383.94],
      'a2': [1190.55, 1683.78], 'a3': [841.89, 1190.55],
      'a4': [595.28, 841.89], 'a5': [419.53, 595.28],
      'a6': [297.64, 419.53], 'a7': [209.76, 297.64],
      'a8': [147.40, 209.76], 'a9': [104.88, 147.40],
      'a10': [73.70, 104.88], 'b0': [2834.65, 4008.19],
      'b1': [2004.09, 2834.65], 'b2': [1417.32, 2004.09],
      'b3': [1000.63, 1417.32], 'b4': [708.66, 1000.63],
      'b5': [498.90, 708.66], 'b6': [354.33, 498.90],
      'b7': [249.45, 354.33], 'b8': [175.75, 249.45],
      'b9': [124.72, 175.75], 'b10': [87.87, 124.72],
      'c0': [2599.37, 3676.54], 'c1': [1836.85, 2599.37],
      'c2': [1298.27, 1836.85], 'c3': [918.43, 1298.27],
      'c4': [649.13, 918.43], 'c5': [459.21, 649.13],
      'c6': [323.15, 459.21], 'c7': [229.61, 323.15],
      'c8': [161.57, 229.61], 'c9': [113.39, 161.57],
      'c10': [79.37, 113.39], 'dl': [311.81, 623.62],
      'letter': [612, 792],
      'government-letter': [576, 756],
      'legal': [612, 1008],
      'junior-legal': [576, 360],
      'ledger': [1224, 792],
      'tabloid': [792, 1224],
      'credit-card': [153, 243]
    };

    var k;
    // Unit conversion
    switch (unit) {
      case 'pt': k = 1; break;
      case 'mm': k = 72 / 25.4; break;
      case 'cm': k = 72 / 2.54; break;
      case 'in': k = 72; break;
      case 'px': k = 72 / 96; break;
      case 'pc': k = 12; break;
      case 'em': k = 12; break;
      case 'ex': k = 6; break;
      default:
        throw ('Invalid unit: ' + unit);
    }
    var pageHeight = 0;
    var pageWidth = 0;

    // Dimensions are stored as user units and converted to points on output
    if (pageFormats.hasOwnProperty(format_as_string)) {
      pageHeight = pageFormats[format_as_string][1] / k;
      pageWidth = pageFormats[format_as_string][0] / k;
    } else {
      try {
        pageHeight = format[1];
        pageWidth = format[0];
      } catch (err) {
        throw new Error('Invalid format: ' + format);
      }
    }

    var tmp;
    // Handle page orientation
    if (orientation === 'p' || orientation === 'portrait') {
      orientation = 'p';
      if (pageWidth > pageHeight) {
        tmp = pageWidth;
        pageWidth = pageHeight;
        pageHeight = tmp;
      }
    } else if (orientation === 'l' || orientation === 'landscape') {
      orientation = 'l';
      if (pageHeight > pageWidth) {
        tmp = pageWidth;
        pageWidth = pageHeight;
        pageHeight = tmp;
      }
    } else {
      throw ('Invalid orientation: ' + orientation);
    }

    // Return information (k is the unit conversion ratio from pts)
    var info = { 'width': pageWidth, 'height': pageHeight, 'unit': unit, 'k': k, 'orientation': orientation};
    return info;
  };

  /**
   * Generate a PDF from an HTML element or string using.
   *
   * @name html
   * @function
   * @param {HTMLElement|string} source The source HTMLElement or a string containing HTML.
   * @param {Object} [options] Collection of settings
   * @param {string} [options.callback] The mandatory callback-function gets as first parameter the current jsPDF instance
   * 
   * @example
   * var doc = new jsPDF();   
   * 
   * doc.html(document.body, {
   *    callback: function (doc) {
   *      doc.save();
   *    }
   * });
   */
  jsPDFAPI.html = function (src, options) {
    'use strict';

    options = options || {};
    options.callback = options.callback || function () { };
    options.html2canvas = options.html2canvas || {};
    options.html2canvas.canvas = options.html2canvas.canvas || this.canvas;
    options.jsPDF = options.jsPDF || this;
    // Create a new worker with the given options.
    var worker = new Worker(options);

    if (!options.worker) {
      // If worker is not set to true, perform the traditional 'simple' operation.
      return worker.from(src).doCallback();
    } else {
      // Otherwise, return the worker for new Promise-based operation.
      return worker;
    }
  };
})(jsPDF.API, (typeof window !== "undefined" && window || typeof global !== "undefined" && global));
