/**
 * Data access layer for Śrī Brahma-saṁhitā (BS).
 *
 * Reads from MongoDB via Prisma.
 * BS has BOTH verses (in the `verses` collection)
 * AND prose intro segments (in the `prose_chapters` collection).
 *
 * Verses were seeded with:
 *   - book: "bs", division: null
 *   - chapter = text number (1-62)
 *   - verse = always 1
 *
 * Intro segments were seeded with:
 *   - book: "bs", volume: 0, type: "intro-segment"
 *   - slugs like "intro-introduction", "intro-foreword"
 */

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

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

const BOOK = "bs";
const NO_VOLUME = 0;

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

const TEXT_TITLES: Record<number, string> = {
  1: "Text 1",
  2: "Text 2",
  3: "Text 3",
  4: "Text 4",
  5: "Text 5",
  6: "Text 6",
  7: "Text 7",
  8: "Text 8",
  9: "Text 9",
  10: "Text 10",
  11: "Text 11",
  12: "Text 12",
  13: "Text 13",
  14: "Text 14",
  15: "Text 15",
  16: "Text 16",
  17: "Text 17",
  18: "Text 18",
  19: "Text 19",
  20: "Text 20",
  21: "Text 21",
  22: "Text 22",
  23: "Text 23",
  24: "Text 24",
  25: "Text 25",
  26: "Text 26",
  27: "Text 27",
  28: "Text 28",
  29: "Text 29",
  30: "Text 30",
  31: "Text 31",
  32: "Text 32",
  33: "Text 33",
  34: "Text 34",
  35: "Text 35",
  36: "Text 36",
  37: "Text 37",
  38: "Text 38",
  39: "Text 39",
  40: "Text 40",
  41: "Text 41",
  42: "Text 42",
  43: "Text 43",
  44: "Text 44",
  45: "Text 45",
  46: "Text 46",
  47: "Text 47",
  48: "Text 48",
  49: "Text 49",
  50: "Text 50",
  51: "Text 51",
  52: "Text 52",
  53: "Text 53",
  54: "Text 54",
  55: "Text 55",
  56: "Text 56",
  57: "Text 57",
  58: "Text 58",
  59: "Text 59",
  60: "Text 60",
  61: "Text 61",
  62: "Text 62",
};

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

export type BsMeta = {
  book: string;
  title: string;
  author: string;
  year: number;
  description: string;
  totalTexts: number;
  texts: BsTextEntry[];
};

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

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

export type BsVerse = {
  book: string;
  book_title: string;
  text: number; // 1-62
  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 BsSidebarItem = {
  /** URL-safe slug: "intro-introduction", "intro-foreword", "1" … "62" */
  slug: string;
  /** Human-readable label for the sidebar */
  label: string;
  /** "intro-segment" | "verse" */
  type: string;
  /** Text number for verses, or null for intro segments */
  text: number | null;
};

// ---------------------------------------------------------------------------
// HTML sanitisation (mirrors lib/iso.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 (string[] from Prisma) via normalizeParagraphs. */
function normalizePurport(purport: string[] | JsonValue): string[] {
  return normalizeParagraphs(purport);
}

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

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

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

/**
 * All intro segments, ordered by their `order` field.
 */
export async function getBsIntroSegments(): Promise<BsIntroSegment[]> {
  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-introduction" (URL slug) and "introduction" (raw slug).
 */
export async function getBsIntroSegment(
  slug: string,
): Promise<BsIntroSegment | 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 (from verses collection)
// ---------------------------------------------------------------------------

/**
 * A single verse/text by slug.
 *
 * - "1"-"62" → chapter=1–62, verse=1
 *
 * Verse stored as chapter=text_number, verse=1 in the verses collection.
 */
export async function getBsVerse(slug: string): Promise<BsVerse | null> {
  const num = Number(slug);
  if (!Number.isInteger(num) || num < 1 || num > 62) return null;
  const textNum = num;

  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-introduction"  → intro segment
 *   "intro-foreword"      → intro segment
 *   "1" … "62"            → verse (text)
 */
export async function getBsContent(
  slug: string,
): Promise<BsVerse | BsIntroSegment | null> {
  if (slug.startsWith("intro-")) {
    return getBsIntroSegment(slug);
  }

  const num = Number(slug);
  if (!Number.isNaN(num) && Number.isInteger(num) && num >= 1 && num <= 62) {
    return getBsVerse(String(num));
  }

  return null;
}

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

/**
 * Build the full sidebar navigation list.
 *
 * Order: Introduction → Foreword → Texts 1-62
 */
export async function getBsSidebarItems(): Promise<BsSidebarItem[]> {
  const items: BsSidebarItem[] = [];

  // 1. Introduction intro segment
  items.push({
    slug: "intro-introduction",
    label: "Introduction",
    type: "intro-segment",
    text: null,
  });

  // 2. Foreword intro segment
  items.push({
    slug: "intro-foreword",
    label: "Foreword",
    type: "intro-segment",
    text: null,
  });

  // 3. Texts 1-62 (verses)
  for (let i = 1; i <= 62; i++) {
    items.push({
      slug: String(i),
      label: `${i}. ${TEXT_TITLES[i]}`,
      type: "verse",
      text: i,
    });
  }

  return items;
}