/**
 * Copyright (c) Microsoft Corporation. All rights reserved.
 * Licensed under the MIT License.
 */

/**
 * Helper class containing string utility methods.
 */
export class StringUtils {
  /**
     * Truncate string with ...
     *
     * @param text Text.
     * @param length Length to truncate text.
     * @returns Original string modified.
     */
  static ellipsis (text: string, length: number): string {
    text = text || ''
    if (text.length <= length) {
      return text
    }

    return `${text.substr(0, length)}...`
  }

  /**
     * UniqueHash - create a unique hash from a string.
     *
     * @param text Text to hash.
     * @returns A string which is an unique hash.
     *
     * @remarks
     * The source for this function was derived from the following article:
     * https://werxltd.com/wp/2010/05/13/javascript-implementation-of-javas-string-hashcode-method/
     *
     */
  static hash (text: string): string {
    const length = text.length
    let hash = 0
    for (let i = 0; i < length; i++) {
      const chr = text.charCodeAt(i)
      hash = (hash << 5) - hash + chr
      hash |= 0 // Convert to 32 bit integer
    }
    return hash.toString()
  }

  /**
     * EllipsisHash - create truncated string with unique hash for the truncated part.
     *
     * @param text Text to truncate.
     * @param length Length to truncate at.
     * @returns The truncated string with unique hash for the truncated part.
     */
  static ellipsisHash (text: string, length: number): string {
    text = text || ''
    if (text.length <= length) {
      return text
    }

    return `${this.ellipsis(text, length)}${this.hash(text)}`
  }
}