/**
 * Data access layer for The Nectar of Instruction (NoI).
 *
 * Reads from MongoDB via Prisma.
 * NoI has 11 texts (verses) plus intro segments (front-pages, preface, appendixes).
 *
 * Verses were seeded with:
 *   - book: "noi", division: null
 *   - chapter = text number (1-11)
 *   - verse = always 1
 *
 * Intro segments were seeded with:
 *   - book: "noi", volume: 0, type: "intro-segment"
 *   - slugs like "intro-front-pages", "intro-preface", "intro-appendixes"
 */

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

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

const BOOK = "noi";
const NO_VOLUME = 0;

// ---------------------------------------------------------------------------
// Text title lookup
// ---------------------------------------------------------------------------

const TEXT_TITLES: Record<number, string> = {
  1: "Text One",
  2: "Text Two",
  3: "Text Three",
  4: "Text Four",
  5: "Text Five",
  6: "Text Six",
  7: "Text Seven",
  8: "Text Eight",
  9: "Text Nine",
  10: "Text Ten",
  11: "Text Eleven",
};

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

export type NoiMeta = {
  book: string;
  title: string;
  subtitle: string;
  author: string;
  year: number;
  description: string;
  totalTexts: number;
  texts: NoiTextEntry[];
};

export type NoiTextEntry = {
  number: number;
  title: string;
  slug: string;
};

export type NoiIntroSegment = {
  slug: string;
  title: string;
  type: string;
  book: string;
  order: number;
  paragraphs: string[];
};

export type NoiVerse = {
  book: string;
  book_title: string;
  text: number;
  title: string;
  reference: string;
  devanagari: string;
  transliteration: string;
  synonyms: { word: string; meanings: string[] }[];
  translation: string;
  purport: string[];
};

/** Union type used in sidebar / table-of-contents navigation. */
export type NoiSidebarItem = {
  /** URL-safe slug: "intro-front-pages", "intro-preface", "1", etc. */
  slug: string;
  /** Human-readable label for the sidebar */
  label: string;
  /** "intro-segment" | "verse" */
  type: string;
  /** Text number (1-11), or null for non-verse items */
  text: number | null;
};

// ---------------------------------------------------------------------------
// HTML sanitisation (mirrors lib/iso.ts, lib/nod.ts)
// ---------------------------------------------------------------------------

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;
}

/** Normalize paragraphs — handles both native arrays and stringified JSON. */
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);
}

/** Normalize purport via normalizeParagraphs. */
function normalizePurport(purport: string[] | JsonValue): string[] {
  return normalizeParagraphs(purport);
}

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

/**
 * Book-level metadata (title, author, texts list, etc.)
 */
export async function getNoiMeta(): Promise<NoiMeta | null> {
  const meta = await prisma.bookMeta.findUnique({ where: { book: BOOK } });
  if (!meta) return null;
  return meta.data as unknown as NoiMeta;
}

// ---------------------------------------------------------------------------
// Intro segments (from prose_chapters collection)
// ---------------------------------------------------------------------------

/**
 * All intro segments, ordered by their `order` field.
 */
export async function getNoiIntroSegments(): Promise<NoiIntroSegment[]> {
  const results = await prisma.proseChapter.findMany({
    where: { book: BOOK, volume: NO_VOLUME, type: "intro-segment" },
    orderBy: { order: "asc" },
  });

  return results.map((doc) => ({
    slug: doc.slug,
    title: doc.title,
    type: doc.type,
    book: doc.book,
    order: doc.order,
    paragraphs: normalizeParagraphs(doc.paragraphs),
  }));
}

/**
 * A single intro segment by slug.
 * Accepts both "intro-front-pages" (URL slug) and "front-pages" (raw slug).
 */
export async function getNoiIntroSegment(
  slug: string,
): Promise<NoiIntroSegment | null> {
  // DB stores with "intro-" prefix; accept either form
  const dbSlug = slug.startsWith("intro-") ? slug : `intro-${slug}`;

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

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

// ---------------------------------------------------------------------------
// Verses (texts 1-11, from verses collection)
// ---------------------------------------------------------------------------

/**
 * A single verse/text by slug.
 *
 * - "1"-"11" → chapter=1–11, verse=1
 */
export async function getNoiVerse(slug: string): Promise<NoiVerse | null> {
  const textNum = Number(slug);
  if (!Number.isInteger(textNum) || textNum < 1 || textNum > 11) return null;

  const doc = await prisma.verse.findFirst({
    where: { book: BOOK, division: null, chapter: textNum, verse: 1 },
  });
  if (!doc) return null;

  return {
    book: doc.book,
    book_title: doc.bookTitle,
    text: doc.chapter, // chapter field stores the text number
    title: TEXT_TITLES[doc.chapter] ?? `Text ${doc.chapter}`,
    reference: doc.reference,
    devanagari: doc.devanagari,
    transliteration: doc.transliteration,
    synonyms: doc.synonyms as { word: string; meanings: string[] }[],
    translation: sanitizeHtml(doc.translation),
    purport: normalizePurport(doc.purport),
  };
}

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

/**
 * Get content by URL slug.
 *
 *   "intro-front-pages"    → intro segment
 *   "intro-preface"        → intro segment
 *   "intro-appendixes"     → intro segment
 *   "1" … "11"             → verse/text
 */
export async function getNoiContent(
  slug: string,
): Promise<NoiVerse | NoiIntroSegment | null> {
  if (slug.startsWith("intro-")) {
    return getNoiIntroSegment(slug);
  }

  const num = Number(slug);
  if (!Number.isNaN(num) && Number.isInteger(num) && num >= 1 && num <= 11) {
    return getNoiVerse(String(num));
  }

  return null;
}

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

/**
 * Build the full sidebar navigation list.
 *
 * Order: front-pages → preface → texts 1-11 → appendixes
 */
export async function getNoiSidebarItems(): Promise<NoiSidebarItem[]> {
  const [meta, allDocs] = await Promise.all([
    getNoiMeta(),
    prisma.proseChapter.findMany({
      where: { book: BOOK, volume: NO_VOLUME },
      orderBy: { order: "asc" },
      select: { slug: true, title: true, type: true, chapter: true },
    }),
  ]);

  if (!meta) return [];

  const items: NoiSidebarItem[] = [];

  // 1. Intro segments that come before the texts (front-pages, preface — by order)
  for (const doc of allDocs) {
    if (doc.type === "intro-segment" && doc.slug !== "intro-appendixes") {
      items.push({
        slug: doc.slug,
        label: doc.title,
        type: "intro-segment",
        text: null,
      });
    }
  }

  // 2. Texts 1-11 (from meta.texts)
  for (const t of meta.texts) {
    items.push({
      slug: String(t.number),
      label: `${t.number}. ${t.title}`,
      type: "verse",
      text: t.number,
    });
  }

  // 3. Appendixes intro segment (at the end)
  const appendixes = allDocs.find((d) => d.slug === "intro-appendixes");
  if (appendixes) {
    items.push({
      slug: appendixes.slug,
      label: appendixes.title,
      type: "intro-segment",
      text: null,
    });
  }

  return items;
}