caleb531 / workday-time-calculator / 6983834262

import Emitter from 'tiny-emitter';

import AutocompletionWorker from '../autocompletion-worker.js?worker';

import appStorage from './app-storage.js';

class EditorAutocompleter extends Emitter {

  constructor({ autocompleteMode } = {}) {

    super();

    this.mode = autocompleteMode;

    this.cancel();

    // Use a web worker to perform the computationally-heavy work of processing

    // terms, which may involve processing thousands of words within the user's

    // log entries

    this.setMode(autocompleteMode);

  }

  setMode(newMode) {

    this.mode = newMode;

    if (

      appStorage.usingIDB() &&

      newMode !== 'off' &&

      typeof Worker !== 'undefined'

    ) {

      this.worker = new AutocompletionWorker();

      this.worker.onmessage = (event) => {

        this.receiveCompletions(event);

      };

    } else {

      if (this.worker) {

        this.worker.terminate();

        delete this.worker;

      }

    }

  }

  get isEnabled() {

    return this.mode !== 'off';

  }

  // Dismiss the current completion suggestion

  cancel() {

    this.isReady = false;

    this.matchingCompletion = '';

    this.completionPlaceholder = '';

  }

  // Since the Quill editor is loaded asynchronously apart from this

  // autocomplete engine, we have a dedicated function to set the editor as

  // soon as it is ready

  setEditor(editor) {

    this.editor = editor;

  }

  // Compute the currently-typed term (can be more than one word) for which to

  // show suggestions of what the user may be typing

  getCompletionQuery() {

    const editorSelection = this.editor.getSelection();

    // Do not autocomplete anything if multiple characters of text are actually

    // selected

    const editorText = this.editor.getText();

    // Do not attempt to autocomplete when text cursor is between letters

    const characters = [];

    for (let i = editorSelection.index - 1; i >= 0; i -= 1) {

      const character = editorText[i];

      // Only search back to the beginning of the line (and let the worker

      // decide which terms on that line are relevant for the autocompletion)

      if (character === '\n') {

        break;

      }

      characters.unshift(character);

    }

    return characters.join('');

  }

  // Receive the top suggestion of the autocompletion that best matches what

  // the user is currently typing, and any other data that may be relevant for

  // that purpose

  receiveCompletions(event) {

    this.matchingCompletion = event.data.matchingCompletion;

    this.completionPlaceholder = event.data.completionPlaceholder;

    this.emit('receive-completions', this.getCompletionPlaceholder());

  }

  // Fetch autocompletion matches for the currently-typed line of text (the

  // query)

  fetchCompletions() {

    const completionQuery = this.getCompletionQuery();

    if (!completionQuery) {

      // Reset the current completion placeholder if we are at the start of the

      // line, or if a space precedes the text cursor

      this.cancel();

      return;

    }

    if (this.worker && this.isEnabled) {

      this.isReady = true;

      this.worker.postMessage({

        completionQuery,

        autocompleteMode: this.mode

      });

    }

  }

  // If the user can currently autocomplete something, return the last-fetched

  // placeholder text to indicate that the current text can be autocompleted

  getCompletionPlaceholder() {

    return this.completionPlaceholder;

  }

}

export default EditorAutocompleter;