import { Highlight, Category, FavoritePaper } from '../types';

const KEYS = {
  highlights: 'arxiv_explorer_highlights',
  categories: 'arxiv_explorer_categories',
  favorites: 'arxiv_explorer_favorites',
  cachedSections: 'arxiv_explorer_sections_cache',
};

function loadJson<T>(key: string, fallback: T): T {
  try {
    const data = localStorage.getItem(key);
    return data ? JSON.parse(data) : fallback;
  } catch {
    return fallback;
  }
}

function saveJson<T>(key: string, data: T) {
  try {
    localStorage.setItem(key, JSON.stringify(data));
  } catch (e) {
    console.warn('Failed to save to localStorage:', e);
  }
}

// ==================== Highlights ====================
export function getHighlights(): Highlight[] {
  return loadJson<Highlight[]>(KEYS.highlights, []);
}

export function addHighlight(highlight: Omit<Highlight, 'id' | 'timestamp'>): Highlight {
  const highlights = getHighlights();
  const newHighlight: Highlight = {
    ...highlight,
    id: `hl_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`,
    timestamp: Date.now(),
  };
  highlights.unshift(newHighlight);
  saveJson(KEYS.highlights, highlights);
  return newHighlight;
}

export function removeHighlight(id: string) {
  const highlights = getHighlights().filter((h) => h.id !== id);
  saveJson(KEYS.highlights, highlights);
}

// ==================== Categories ====================
const defaultCategories: Category[] = [
  { id: 'uncategorized', name: '未分类 / Uncategorized', color: '#6b7280' },
];

export function getCategories(): Category[] {
  return loadJson<Category[]>(KEYS.categories, defaultCategories);
}

export function addCategory(name: string, color: string): Category {
  const categories = getCategories();
  const newCat: Category = {
    id: `cat_${Date.now()}_${Math.random().toString(36).substr(2, 6)}`,
    name,
    color,
  };
  categories.push(newCat);
  saveJson(KEYS.categories, categories);
  return newCat;
}

export function removeCategory(id: string) {
  if (id === 'uncategorized') return;
  const categories = getCategories().filter((c) => c.id !== id);
  saveJson(KEYS.categories, categories);
  // Move papers in deleted category to uncategorized
  const favorites = getFavorites();
  favorites.forEach((f) => {
    if (f.categoryId === id) f.categoryId = 'uncategorized';
  });
  saveJson(KEYS.favorites, favorites);
}

export function updateCategory(id: string, name: string, color: string) {
  const categories = getCategories().map((c) =>
    c.id === id ? { ...c, name, color } : c
  );
  saveJson(KEYS.categories, categories);
}

// ==================== Favorites ====================
export function getFavorites(): FavoritePaper[] {
  return loadJson<FavoritePaper[]>(KEYS.favorites, []);
}

export function addFavorite(
  paperId: string,
  paperTitle: string,
  paperAuthors: string[],
  categoryId: string = 'uncategorized'
): FavoritePaper {
  const favorites = getFavorites();
  const existing = favorites.find((f) => f.paperId === paperId);
  if (existing) return existing;
  const fav: FavoritePaper = {
    paperId,
    paperTitle,
    paperAuthors,
    categoryId,
    timestamp: Date.now(),
  };
  favorites.unshift(fav);
  saveJson(KEYS.favorites, favorites);
  return fav;
}

export function removeFavorite(paperId: string) {
  const favorites = getFavorites().filter((f) => f.paperId !== paperId);
  saveJson(KEYS.favorites, favorites);
}

export function moveFavoriteToCategory(paperId: string, categoryId: string) {
  const favorites = getFavorites().map((f) =>
    f.paperId === paperId ? { ...f, categoryId } : f
  );
  saveJson(KEYS.favorites, favorites);
}

export function isFavorited(paperId: string): boolean {
  return getFavorites().some((f) => f.paperId === paperId);
}

// ==================== Section Cache ====================
interface CachedSections {
  [arxivId: string]: {
    introduction?: string;
    relatedWork?: string;
    methods?: string;
    references?: Array<{ key: string; number: string; text: string; arxivId?: string }>;
    timestamp: number;
  };
}

export function getCachedSections(arxivId: string) {
  const cache = loadJson<CachedSections>(KEYS.cachedSections, {});
  const entry = cache[arxivId];
  if (entry && Date.now() - entry.timestamp < 7 * 24 * 60 * 60 * 1000) {
    return entry;
  }
  return null;
}

export function setCachedSections(
  arxivId: string,
  data: {
    introduction?: string;
    relatedWork?: string;
    methods?: string;
    references?: Array<{ key: string; number: string; text: string; arxivId?: string }>;
  }
) {
  const cache = loadJson<CachedSections>(KEYS.cachedSections, {});
  // Limit cache size
  const keys = Object.keys(cache);
  if (keys.length > 100) {
    const sorted = keys.sort((a, b) => (cache[a].timestamp || 0) - (cache[b].timestamp || 0));
    sorted.slice(0, 20).forEach((k) => delete cache[k]);
  }
  cache[arxivId] = { ...data, timestamp: Date.now() };
  saveJson(KEYS.cachedSections, cache);
}