feat(utils): add utility functions for reading time, date formatting, pluralization, and KMP search

src/shared/utils.ts

@@ -0,0 +1,172 @@
+/**
+ * @name calculateReadingTime
+ * @description Calculates the reading time for a given content based on an average reading speed of 200 words per minute.
+ *
+ * @param {string} content - The content for which to calculate the reading time.
+ * @returns {number} The estimated reading time in minutes, rounded up to the nearest whole number.
+ *
+ * @example
+ * const time = calculateReadingTime("This is a sample content to test the reading time calculation.");
+ * console.log(time); // Outputs: 1
+ */
+export function calculateReadingTime(content: string) {
+  const wordsPerMinute = 200;
+  const words = content.split(/\s+/).length;
+
+  return Math.ceil(words / wordsPerMinute);
+}
+
+/**
+ * @name formatDate
+ * @description Formats a date string into a more readable format.
+ *
+ * @param {string} dateString - The date string to format.
+ * @returns {string} The formatted date string in the format "dd MMMM".
+ *
+ * @example
+ * const formattedDate = formatDate("2023-10-01T12:00:00Z");
+ * console.log(formattedDate); // Outputs: "9 Apr"
+ */
+export function formatDate(dateString: string) {
+  const date = new Date(dateString);
+
+  const month = date.toLocaleDateString('ru-RU', {
+    month: 'short',
+  });
+
+  return `${date.getDate()} ${month.charAt(0).toUpperCase() + month.slice(1, -1)}`;
+}
+
+/**
+ * @name formatDateTime
+ * @description Formats a date string into a more readable format with time.
+ *
+ * @param {string} dateString - The date string to format.
+ * @returns {string} The formatted date string in the format "dd.MMMM.yyyy в HH:mm".
+ *
+ * @example
+ * const formattedDateTime = formatDateTime("2023-10-01T12:00:00Z");
+ * console.log(formattedDateTime); // Outputs: "1.04.2025 в 12:00"
+ */
+export function formatDateTime(dateString: string) {
+  const date = new Date(dateString);
+
+  const onlyDate = date.toLocaleDateString('ru-RU', {
+    year: 'numeric',
+    month: 'numeric',
+    day: 'numeric',
+  });
+
+  const time = date.toLocaleTimeString('ru-RU', {
+    hour: '2-digit',
+    minute: '2-digit',
+  });
+
+  return `${onlyDate} в ${time}`;
+}
+
+/**
+ * @name pluralize
+ * @description Returns a pluralized form of a word based on the count.
+ *
+ * @param {number} count - The count to determine the pluralization.
+ * @param {string[]} forms - An array containing the singular, plural, and genitive forms of the word.
+ * @returns {string} The appropriate form of the word based on the count.
+ *
+ * @example
+ * const word = pluralize(1, ['яблоко', 'яблока', 'яблок']);
+ * console.log(word); // Outputs: "яблоко"
+ */
+export function pluralize(count: number, forms: string[]) {
+  const [singular, plural, genitive] = forms;
+
+  if (count === 1)
+    return singular;
+  if (count > 1 && count < 5)
+    return plural;
+
+  return genitive;
+}
+
+/**
+ * @name computeLPS
+ * @description Computes the Longest Prefix Suffix (LPS) array for the KMP algorithm.
+ *
+ * @param {string} pattern - The pattern for which to compute the LPS array.
+ * @returns {number[]} The LPS array where lps[i] is the length of the longest proper prefix which is also a suffix for the substring pattern[0..i].
+ *
+ * @example
+ * const lps = computeLPS("ABABAC");
+ * console.log(lps); // Outputs: [0, 0, 1, 2, 0, 1]
+ */
+function computeLPS(pattern: string) {
+  const lps = Array.from<number>({ length: pattern.length }).fill(0);
+  let len = 0;
+  let i = 1;
+
+  while (i < pattern.length) {
+    if (pattern[i] === pattern[len]) {
+      len++;
+      lps[i] = len;
+      i++;
+    }
+    else {
+      if (len !== 0) {
+        len = lps[len - 1]!;
+      }
+      else {
+        lps[i] = 0;
+        i++;
+      }
+    }
+  }
+
+  return lps;
+}
+
+/**
+ * @name kmpSearch
+ * @description Implements the Knuth-Morris-Pratt (KMP) algorithm for substring search.
+ *
+ * @param {string} text - The text in which to search for the pattern.
+ * @param {string} pattern - The pattern to search for in the text.
+ * @returns {boolean} Returns true if the pattern is found in the text, otherwise false.
+ *
+ * @example
+ * const found = kmpSearch("hello world", "world");
+ * console.log(found); // Outputs: true
+ */
+export function kmpSearch(text: string, pattern: string) {
+  if (pattern.length === 0)
+    return true;
+  if (text.length === 0)
+    return false;
+
+  const textLower = text.toLowerCase();
+  const patternLower = pattern.toLowerCase();
+  const lps = computeLPS(patternLower);
+
+  let i = 0; // index for text
+  let j = 0; // index for pattern
+
+  while (i < textLower.length) {
+    if (patternLower[j] === textLower[i]) {
+      i++;
+      j++;
+    }
+
+    if (j === patternLower.length) {
+      return true; // Found match
+    }
+    else if (i < textLower.length && patternLower[j] !== textLower[i]) {
+      if (j !== 0) {
+        j = lps[j - 1]!;
+      }
+      else {
+        i++;
+      }
+    }
+  }
+
+  return false;
+}