/**
 * Data access layer for Śrī Īśopaniṣad (ISO).
 *
 * Delegates to the generic book data layer (BFF API) for prose intro segments,
 * and to lib/api.ts for verse (mantra) lookups.
 */

import {
  getBookMeta,
  getIntroSegments,
  getIntroSegment,
  getContent,
  getSidebarItems,
  type BookMeta,
  type IntroSegment,
  type Chapter,
  type SidebarItem,
} from "@/lib/books";
import { getSingleVerse, type VerseRecord } from "@/lib/api";

const CODE = "iso";

export type IsoMeta = BookMeta;
export type IsoIntroSegment = IntroSegment;
export type IsoChapter = Chapter;
export type IsoSidebarItem = SidebarItem;
export type IsoVerse = VerseRecord;

export async function getIsoMeta() {
  return getBookMeta(CODE);
}
export async function getIsoIntroSegments() {
  return getIntroSegments(CODE);
}
export async function getIsoIntroSegment(slug: string) {
  return getIntroSegment(CODE, slug);
}

/**
 * A single verse/mantra by slug.
 *
 * ISO verses are stored with: book "iso", no division,
 * chapter = mantra number (0 for invocation), verse = 1.
 */
export async function getIsoVerse(slug: string): Promise<IsoVerse | null> {
  let mantraNum: number;

  if (slug === "invocation") {
    mantraNum = 0;
  } else {
    const num = parseInt(slug, 10);
    if (isNaN(num) || num < 1 || num > 18) return null;
    mantraNum = num;
  }

  return getSingleVerse(CODE, null, mantraNum, 1);
}

export async function getIsoContent(
  slug: string,
): Promise<IsoVerse | IsoIntroSegment | IsoChapter | null> {
  // Try as verse/mantra first (numeric slug or "invocation")
  if (slug === "invocation" || /^\d+$/.test(slug)) {
    const verse = await getIsoVerse(slug);
    if (verse) return verse;
  }
  // Fall back to prose content (intro segments, etc.)
  return getContent(CODE, slug);
}
export async function getIsoSidebarItems() {
  return getSidebarItems(CODE);
}