quran-meta/src/getPageMeta.ts

Library with meta data and functionality related to Holy Quran

import { findSurahAyahByAyahId } from "./findSurahAyahByAyahId"
import type { RiwayaData } from "./lists/types"
import type { AyahId, Page, PageMeta } from "./types"
import { checkValidPage } from "./validation"

/**
 * Retrieves metadata for a specific page of the Quran.
 *
 * @param pageNum - The page number to retrieve metadata for (1-604)
 * @param data - The Lists object for the riwaya.
 * @returns {@link PageMeta} An object containing the page number, first ayah, and last ayah on the page
 * @throws {@link RangeError} If the page number is not between 1 and 604
 */
export function getPageMeta(
  pageNum: Page,
  data: RiwayaData
): PageMeta {
  checkValidPage(pageNum, data.meta)
  const PageList = data.PageList
  const [firstAyahId, nextPage]: [AyahId, AyahId] = [
    PageList[pageNum],
    PageList[pageNum + 1]
  ]
  const lastAyahId = nextPage - 1

  return {
    pageNum,
    firstAyahId,
    lastAyahId,
    first: findSurahAyahByAyahId(firstAyahId, data),
    last: findSurahAyahByAyahId(lastAyahId, data)
  }
}