/**
 * Data access layer for Vaiśiṣṭyāṣṭakam (VA).
 *
 * Reads from MongoDB via Prisma.
 * VA is a poetic work with 8 chapters (Vaiśiṣṭyas) and no intro segments.
 *
 * Collections used:
 *   - book_meta (via Prisma BookMeta model)
 *   - prose_chapters (via Prisma ProseChapter model)
 */

import { prisma } from "@/lib/db";
import type { JsonValue } from "@prisma/client/runtime/library";

// ---------------------------------------------------------------------------
// Constants
// ---------------------------------------------------------------------------

const BOOK = "va";

/** Volume sentinel for books without volumes. */
const NO_VOLUME = 0;

// ---------------------------------------------------------------------------
// Types
// ---------------------------------------------------------------------------

export type VaMeta = {
  book: string;
  title: string;
  author: string;
  year: number;
  description: string;
  totalChapters: number;
  chapters: VaChapterEntry[];
};

export type VaChapterEntry = {
  number: number;
  title: string;
};

export type VaChapter = {
  book: string;
  chapter: number | null;
  title: string;
  type: string;
  slug?: string;
  paragraphs: string[];
};

/** Used in sidebar / table-of-contents navigation. */
export type VaSidebarItem = {
  slug: string;
  label: string;
  type: string;
  chapter: number | null;
};

// ---------------------------------------------------------------------------
// HTML sanitisation
// ---------------------------------------------------------------------------

function sanitizeHtml(html: string): string {
  let clean = html.replace(/<script[\s>][\s\S]*?<\/script>/gi, "");
  clean = clean.replace(/<style[\s>][\s\S]*?<\/style>/gi, "");
  clean = clean.replace(/<iframe[\s>][\s\S]*?<\/iframe>/gi, "");
  clean = clean.replace(
    /<\/?(?:script|style|iframe|object|embed|form|input|textarea|select|button)[^>]*>/gi,
    "",
  );
  clean = clean.replace(/\s+on\w+\s*=\s*(?:"[^"]*"|'[^']*'|[^\s>]+)/gi, "");
  clean = clean.replace(/href\s*=\s*"javascript:[^"]*"/gi, 'href=""');
  clean = clean.replace(/href\s*=\s*'javascript:[^']*'/gi, "href=''");
  return clean;
}

function normalizeParagraphs(paragraphs: string[] | JsonValue): string[] {
  let result: string[];

  if (typeof paragraphs === "string") {
    try {
      const parsed = JSON.parse(paragraphs);
      result = Array.isArray(parsed) ? parsed : [paragraphs];
    } catch {
      result = [paragraphs];
    }
  } else if (Array.isArray(paragraphs)) {
    result = paragraphs as string[];
  } else {
    result = [];
  }

  return result.map(sanitizeHtml);
}

// ---------------------------------------------------------------------------
// Book meta
// ---------------------------------------------------------------------------

export async function getVaMeta(): Promise<VaMeta | null> {
  const meta = await prisma.bookMeta.findUnique({ where: { book: BOOK } });
  if (!meta) return null;
  return meta.data as unknown as VaMeta;
}

// ---------------------------------------------------------------------------
// Chapters
// ---------------------------------------------------------------------------

export async function getVaChapter(
  chapterNum: number,
): Promise<VaChapter | null> {
  if (chapterNum < 1 || chapterNum > 8 || !Number.isInteger(chapterNum)) {
    return null;
  }

  const doc = await prisma.proseChapter.findUnique({
    where: {
      book_volume_slug: {
        book: BOOK,
        volume: NO_VOLUME,
        slug: String(chapterNum),
      },
    },
  });
  if (!doc) return null;

  return {
    book: doc.book,
    chapter: doc.chapter,
    title: doc.title,
    type: doc.type,
    slug: doc.slug,
    paragraphs: normalizeParagraphs(doc.paragraphs),
  };
}

// ---------------------------------------------------------------------------
// Unified content accessor
// ---------------------------------------------------------------------------

export async function getVaContent(
  slug: string,
): Promise<VaChapter | null> {
  const num = Number(slug);
  if (!Number.isNaN(num) && Number.isInteger(num) && num >= 1 && num <= 8) {
    return getVaChapter(num);
  }
  return null;
}

// ---------------------------------------------------------------------------
// Sidebar navigation
// ---------------------------------------------------------------------------

export async function getVaSidebarItems(): Promise<VaSidebarItem[]> {
  const meta = await getVaMeta();
  if (!meta) return [];

  return meta.chapters.map((ch) => ({
    slug: String(ch.number),
    label: `${ch.number}. ${ch.title}`,
    type: "chapter",
    chapter: ch.number,
  }));
}