@applicaster/zapp-react-native-utils/appUtils/accessibilityManager/utils.ts

Applicaster Zapp React Native utilities package

import { createLogger } from "../../logger";

const { log_error } = createLogger({
  category: "AccessibilityManager",
  subsystem: "AppUtils",
});

/**
 * Calculates the reading time for a given text based on word count
 * @param text - The text to calculate the reading time for (string or number)
 * @param wordsPerMinute - Words per minute reading speed (default: 140)
 * @param minimumPause - Minimum pause time in milliseconds (default: 500)
 * @param announcementDelay - Additional delay for announcement in milliseconds (default: 700)
 * @returns The reading time in milliseconds
 */
export function calculateReadingTime(
  text: string | number,
  wordsPerMinute: number = 140,
  minimumPause: number = 500,
  announcementDelay: number = 700
): number {
  if (typeof text !== "string" && typeof text !== "number") {
    log_error(
      `Invalid text input for reading time calculation got: ${
        typeof text === "symbol" ? String(text) : text
      }`
    );

    return 0;
  }

  const trimmed = typeof text === "number" ? String(text) : text.trim();

  if (!trimmed) {
    return 0;
  }

  // Count words (split on whitespace and punctuation, keep alnum boundaries)
  const words = trimmed
    .split(/(?<=\d)(?=[a-zA-Z])|(?<=[a-zA-Z])(?=\d)|[^\w\s]+|\s+/)
    .filter(Boolean).length;

  // Count spaces - multiple consecutive spaces add extra pause time
  const spaceMatches: string[] = trimmed.match(/\s+/g) || [];

  const totalSpaces = spaceMatches.reduce(
    (sum: number, match: string) => sum + match.length,
    0
  );

  const extraSpaces = Math.max(0, totalSpaces - (words - 1)); // words-1 is normal spacing

  // Heuristic: punctuation increases TTS duration beyond word-based WPM.
  // Commas typically introduce short pauses, sentence terminators longer ones.
  const commaCount = (trimmed.match(/,/g) || []).length;
  const semicolonCount = (trimmed.match(/;/g) || []).length;
  const colonCount = (trimmed.match(/:/g) || []).length;
  const dashCount = (trimmed.match(/\u2013|\u2014|-/g) || []).length; // – — -
  const sentenceEndCount = (trimmed.match(/[.!?](?!\d)/g) || []).length;

  const commaPauseMs = 220; // short prosody pause for ","
  const midPauseMs = 260; // for ";", ":", dashes
  const sentenceEndPauseMs = 420; // for ".", "!", "?"
  const extraSpacePauseMs = 50; // per extra space beyond normal spacing

  const punctuationPause =
    commaCount * commaPauseMs +
    (semicolonCount + colonCount + dashCount) * midPauseMs +
    sentenceEndCount * sentenceEndPauseMs +
    extraSpaces * extraSpacePauseMs;

  const baseByWordsMs = (words / wordsPerMinute) * 60 * 1000;
  const estimatedMs = Math.max(minimumPause, baseByWordsMs + punctuationPause);

  return estimatedMs + announcementDelay;
}