import { HELP_CENTER_SEED_ARTICLES, HELP_CENTER_SEED_CATEGORIES } from '~/data/help-center-seed';

export type HelpArticle = {
  id: string;
  slug: string;
  title: string;
  summary: string;
  categoryKey: string;
  category: string;
  role: 'ALL' | 'company' | 'jobSeeker' | 'professional' | 'customer' | 'platform';
  tags: string[];
  updatedAt: string;
  content: string;
};

export type HelpCategory = {
  id: string;
  key: string;
  title: string;
};

// ── API fetchers ──────────────────────────────────────────────────────────────

export async function fetchHelpCenterArticles(input: {
  role?: string;
  categoryKey?: string;
  q?: string;
}): Promise<HelpArticle[]> {
  const params = new URLSearchParams();
  if (input.role && input.role !== 'ALL') params.set('role', input.role);
  if (input.categoryKey) params.set('category', input.categoryKey);
  if (input.q) params.set('q', input.q);

  try {
    const res = await fetch(`/api/kb/articles?${params.toString()}`);
    if (!res.ok) return filterArticles(HELP_CENTER_SEED_ARTICLES as HelpArticle[], input);
    const data = await res.json();
    const raw: any[] = Array.isArray(data) ? data : (data.articles ?? []);
    let items = raw.map(normalizeArticle);

    // Fallback: when backend search returns sparse/empty data, apply local filtering
    // so users can still find articles by simple keywords.
    if (input.q && items.length === 0) {
      const allRes = await fetch('/api/kb/articles');
      if (allRes.ok) {
        const allData = await allRes.json();
        const allRaw: any[] = Array.isArray(allData) ? allData : (allData.articles ?? []);
        items = allRaw.map(normalizeArticle);
      }
    }

    if (items.length === 0) {
      items = HELP_CENTER_SEED_ARTICLES as HelpArticle[];
    }

    return filterArticles(items, input);
  } catch {
    return filterArticles(HELP_CENTER_SEED_ARTICLES as HelpArticle[], input);
  }
}

export async function fetchHelpCenterCategories(): Promise<HelpCategory[]> {
  try {
    const res = await fetch('/api/kb/categories');
    if (!res.ok) return HELP_CENTER_SEED_CATEGORIES;
    const data = await res.json();
    const raw: any[] = Array.isArray(data) ? data : (data.categories ?? []);
    const mapped = raw.map((c) => ({
      id: c.id,
      key: c.slug ?? c.key,
      title: c.name ?? c.title,
    }));
    return mapped.length > 0 ? mapped : HELP_CENTER_SEED_CATEGORIES;
  } catch {
    return HELP_CENTER_SEED_CATEGORIES;
  }
}

export async function fetchArticleBySlug(slug: string): Promise<HelpArticle | null> {
  try {
    const res = await fetch(`/api/kb/articles/${slug}`);
    if (!res.ok) return (HELP_CENTER_SEED_ARTICLES as HelpArticle[]).find((a) => a.slug === slug) ?? null;
    const data = await res.json();
    const normalized = normalizeArticle(data);
    if (!normalized.slug) {
      return (HELP_CENTER_SEED_ARTICLES as HelpArticle[]).find((a) => a.slug === slug) ?? null;
    }
    return normalized;
  } catch {
    return (HELP_CENTER_SEED_ARTICLES as HelpArticle[]).find((a) => a.slug === slug) ?? null;
  }
}

export async function fetchRelatedArticles(input: {
  article: HelpArticle;
  limit?: number;
}): Promise<HelpArticle[]> {
  try {
    const res = await fetch('/api/kb/articles');
    if (!res.ok) return pickRelated(HELP_CENTER_SEED_ARTICLES as HelpArticle[], input.article, input.limit ?? 4);
    const data = await res.json();
    const raw: any[] = Array.isArray(data) ? data : (data.articles ?? []);
    const all = raw.map(normalizeArticle);
    if (all.length === 0) return pickRelated(HELP_CENTER_SEED_ARTICLES as HelpArticle[], input.article, input.limit ?? 4);
    return pickRelated(all, input.article, input.limit ?? 4);
  } catch {
    return pickRelated(HELP_CENTER_SEED_ARTICLES as HelpArticle[], input.article, input.limit ?? 4);
  }
}

// ── Normalizer ────────────────────────────────────────────────────────────────

function normalizeArticle(raw: any): HelpArticle {
  return {
    id: raw.id ?? '',
    slug: raw.slug ?? '',
    title: raw.title ?? '',
    summary: raw.summary ?? raw.content?.slice(0, 160) ?? '',
    categoryKey: raw.categoryKey ?? raw.category_key ?? raw.categorySlug ?? '',
    category: raw.category ?? raw.categoryKey ?? '',
    role: (raw.role ?? 'ALL') as HelpArticle['role'],
    tags: Array.isArray(raw.tags) ? raw.tags : [],
    updatedAt: raw.updatedAt ?? raw.updated_at ?? new Date().toISOString(),
    content: raw.content ?? raw.body ?? '',
  };
}

// ── Legacy sync shims (kept for any remaining call sites) ─────────────────────
// These return empty data synchronously — pages should use the async fetch* functions above.

export function listHelpCenterArticles(_input: { role?: string; categoryKey?: string; q?: string }): HelpArticle[] {
  return [];
}

export function listHelpCenterCategories(): HelpCategory[] {
  return [];
}

export function getArticleBySlug(_slug: string): HelpArticle | null {
  return null;
}

function articleMatchesQuery(article: HelpArticle, needle: string): boolean {
  const haystack = [article.title, article.summary, article.content, article.category, article.categoryKey, article.tags.join(' ')].join(' ').toLowerCase();
  return haystack.includes(needle);
}

function filterArticles(items: HelpArticle[], input: { role?: string; categoryKey?: string; q?: string }): HelpArticle[] {
  let filtered = items;

  if (input.role && input.role !== 'ALL') {
    const roleNeedle = input.role.toLowerCase();
    filtered = filtered.filter((a) => a.role === 'ALL' || String(a.role).toLowerCase() === roleNeedle);
  }

  if (input.categoryKey) {
    const needle = input.categoryKey.toLowerCase();
    filtered = filtered.filter((a) => [a.categoryKey, a.category].some((v) => (v || '').toLowerCase().includes(needle)));
  }

  if (input.q) {
    const needle = input.q.toLowerCase();
    filtered = filtered.filter((a) => articleMatchesQuery(a, needle));
  }

  return filtered;
}

function pickRelated(allItems: HelpArticle[], current: HelpArticle, limit: number): HelpArticle[] {
  const all = allItems.filter((a) => a.slug !== current.slug);
  const sameCategory = all.filter((a) => {
    const left = `${a.categoryKey}|${a.category}`.toLowerCase();
    const right = `${current.categoryKey}|${current.category}`.toLowerCase();
    return left && right && left === right;
  });
  const fallback = all.filter((a) => !sameCategory.some((x) => x.slug === a.slug));
  return [...sameCategory, ...fallback].slice(0, limit);
}