/**
 * Data access layer for Letters.
 *
 * Provides queries for browsing letters by year, recipient, and location.
 * Calls the BFF API for all data access (no direct Prisma usage).
 *
 * Recipients are stored as an array (e.g., ["Mukunda", "Janaki"]).
 * The recipient list aggregates individual names across all letters,
 * and searching for "Mukunda" finds all letters where Mukunda is
 * ANY recipient (individual or group).
 */

import { bff, bffList } from "@/lib/bff";

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

export type LetterSummary = {
  slug: string;
  recipients: string[];
  recipientDisplay: string;
  date: string | null;
  year: number | null;
  month: number | null;
  location: string | null;
};

export type LetterFull = {
  slug: string;
  recipients: string[];
  recipientDisplay: string;
  date: string | null;
  dateRef: string | null;
  year: number | null;
  month: number | null;
  day: number | null;
  location: string | null;
  salutation: string | null;
  paragraphs: string[];
};

export type YearGroup = {
  year: number;
  count: number;
};

export type RecipientGroup = {
  name: string;
  count: number;
};

export type LocationGroup = {
  name: string;
  count: number;
};

// ---------------------------------------------------------------------------
// BFF response types (snake_case from Go)
// ---------------------------------------------------------------------------

type BffLetterSummary = {
  slug: string;
  recipients: string[];
  recipient_display: string;
  date: string | null;
  year: number | null;
  month: number | null;
  location: string | null;
};

type BffLetterFull = {
  slug: string;
  recipients: string[];
  recipient_display: string;
  date: string | null;
  date_ref: string | null;
  year: number | null;
  month: number | null;
  day: number | null;
  location: string | null;
  salutation: string | null;
  paragraphs: string[];
};

type BffAggregation = {
  _id: string | number;
  count: number;
};

// ---------------------------------------------------------------------------
// 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, "");
  return clean;
}

// ---------------------------------------------------------------------------
// Mappers (BFF snake_case → frontend camelCase)
// ---------------------------------------------------------------------------

function mapLetterSummary(item: BffLetterSummary): LetterSummary {
  return {
    slug: item.slug,
    recipients: item.recipients ?? [],
    recipientDisplay: item.recipient_display ?? "",
    date: item.date ?? null,
    year: item.year ?? null,
    month: item.month ?? null,
    location: item.location ?? null,
  };
}

function mapLetterFull(item: BffLetterFull): LetterFull {
  return {
    slug: item.slug,
    recipients: item.recipients ?? [],
    recipientDisplay: item.recipient_display ?? "",
    date: item.date ?? null,
    dateRef: item.date_ref ?? null,
    year: item.year ?? null,
    month: item.month ?? null,
    day: item.day ?? null,
    location: item.location ?? null,
    salutation: item.salutation ?? null,
    paragraphs: (item.paragraphs ?? []).map(sanitizeHtml),
  };
}

function mapYearGroup(item: BffAggregation): YearGroup {
  return { year: Number(item._id), count: item.count };
}

function mapRecipientGroup(item: BffAggregation): RecipientGroup {
  return { name: String(item._id), count: item.count };
}

function mapLocationGroup(item: BffAggregation): LocationGroup {
  return { name: String(item._id), count: item.count };
}

// ---------------------------------------------------------------------------
// Index / overview queries
// ---------------------------------------------------------------------------

export async function getLetterYears(): Promise<YearGroup[]> {
  const raw = await bffList<BffAggregation>("/letters/years", {
    tags: ["letters"],
  });
  return raw
    .map(mapYearGroup)
    .filter((g) => g.year >= 1940 && g.year <= 1980)
    .sort((a, b) => a.year - b.year);
}

/**
 * Get all unique individual recipients with letter counts.
 *
 * Each letter has a `recipients` array (e.g., ["Mukunda", "Janaki"]).
 * The BFF aggregation endpoint already aggregates across all letters so
 * that "Mukunda" appears once with count = total letters where Mukunda
 * is ANY recipient.
 */
export async function getLetterRecipients(): Promise<RecipientGroup[]> {
  const raw = await bffList<BffAggregation>("/letters/recipients", {
    tags: ["letters"],
  });
  return raw.map(mapRecipientGroup).sort((a, b) => b.count - a.count);
}

export async function getLetterLocations(): Promise<LocationGroup[]> {
  const raw = await bffList<BffAggregation>("/letters/locations", {
    tags: ["letters"],
  });
  return raw.map(mapLocationGroup).sort((a, b) => b.count - a.count);
}

// ---------------------------------------------------------------------------
// Letter list queries
// ---------------------------------------------------------------------------

export async function getLettersByYear(year: number): Promise<LetterSummary[]> {
  const raw = await bffList<BffLetterSummary>(`/letters/year/${year}`, {
    tags: ["letters"],
  });
  return raw.map(mapLetterSummary);
}

/**
 * Get all letters where the given name is ANY recipient.
 *
 * The BFF endpoint handles the array-contains matching server-side.
 * Searching for "Mukunda" returns letters addressed to:
 *   - "Mukunda" (individual)
 *   - "Mukunda, Janaki" (group containing Mukunda)
 *   - "Yamuna, Mukunda, Syamasundara" (group containing Mukunda)
 */
export async function getLettersByRecipient(
  recipient: string,
): Promise<LetterSummary[]> {
  const encoded = encodeURIComponent(recipient);
  const raw = await bffList<BffLetterSummary>(`/letters/recipient/${encoded}`, {
    tags: ["letters"],
  });
  return raw.map(mapLetterSummary);
}

export async function getLettersByLocation(
  location: string,
): Promise<LetterSummary[]> {
  const encoded = encodeURIComponent(location);
  const raw = await bffList<BffLetterSummary>(`/letters/location/${encoded}`, {
    tags: ["letters"],
  });
  return raw.map(mapLetterSummary);
}

// ---------------------------------------------------------------------------
// Single letter
// ---------------------------------------------------------------------------

export async function getLetter(slug: string): Promise<LetterFull | null> {
  const letter = await bff<BffLetterFull>(`/letters/${slug}`, {
    tags: ["letters"],
  });
  if (!letter) return null;
  return mapLetterFull(letter);
}

// ---------------------------------------------------------------------------
// Navigation helpers
// ---------------------------------------------------------------------------

export async function getAdjacentLetters(
  slug: string,
  year: number | null,
): Promise<{ prev: LetterSummary | null; next: LetterSummary | null }> {
  if (!year) return { prev: null, next: null };

  const letters = await getLettersByYear(year);
  const idx = letters.findIndex((l) => l.slug === slug);

  return {
    prev: idx > 0 ? letters[idx - 1] : null,
    next: idx < letters.length - 1 ? letters[idx + 1] : null,
  };
}

export async function getTotalLetterCount(): Promise<number> {
  const result = await bff<{ count: number }>("/letters", {
    tags: ["letters"],
  });
  return result?.count ?? 0;
}