import { fetchApi, type FetchInit } from '@libs/fetch';
import { Plugin } from '@/types/plugin';
import { NovelStatus } from '@libs/novelStatus';
import { storage } from '@libs/storage';

// Reads EPUB series from a self-hosted Kavita server. Each LNReader chapter is
// one EPUB page (spine item), named from the book's table of contents.

type Library = { id: number; type: number };
type Series = { id: number; name: string; libraryId: number };
type SearchResult = {
  series?: { seriesId: number; name: string; libraryId: number }[];
};
type Volume = {
  name: string;
  chapters: { id: number; title: string; pages: number }[];
};
type TocItem = { title: string; page: number; children?: TocItem[] };
type Metadata = {
  summary?: string;
  genres?: { title: string }[];
  writers?: { name: string }[];
  publicationStatus?: number;
};

const BOOK_LIBRARY_TYPES = new Set([2, 4]); // Book, LightNovel
const STATUS: Record<number, string> = {
  0: NovelStatus.Ongoing,
  1: NovelStatus.OnHiatus,
  2: NovelStatus.Completed,
  3: NovelStatus.Cancelled,
  4: NovelStatus.Completed,
};
const PAGE_SIZE = 20;

class KavitaPlugin implements Plugin.PluginBase {
  id = 'kavita';
  name = 'Kavita';
  icon = 'src/multi/kavita/icon.png';
  version = '1.0.0';
  site = 'https://www.kavitareader.com';

  pluginSettings = {
    url: { value: '', label: 'Server URL (e.g. https://novel.example.com)' },
    apiKey: { value: '', label: 'API key (Kavita: Settings → Account)' },
  };

  token?: string;

  get base(): string {
    const url = String(storage.get('url') || '')
      .trim()
      .replace(/\/+$/, '');
    if (!url)
      throw new Error('Set the Kavita server URL in the plugin settings');
    return url;
  }

  get apiKey(): string {
    const key = String(storage.get('apiKey') || '').trim();
    if (!key) throw new Error('Set your Kavita API key in the plugin settings');
    return key;
  }

  async authenticate(): Promise<string> {
    const res = await fetchApi(
      `${this.base}/api/Plugin/authenticate?apiKey=${encodeURIComponent(this.apiKey)}&pluginName=LNReader`,
      { method: 'POST' },
    );
    if (!res.ok)
      throw new Error(`Kavita login failed (${res.status}); check the API key`);
    this.token = (await res.json()).token;
    return this.token!;
  }

  async request(
    path: string,
    init: FetchInit = {},
    retry = true,
  ): Promise<Response> {
    const token = this.token || (await this.authenticate());
    const res = await fetchApi(`${this.base}/api/${path}`, {
      ...init,
      headers: {
        'Authorization': `Bearer ${token}`,
        'Content-Type': 'application/json',
        ...(init.headers as Record<string, string>),
      },
    });
    if (res.status === 401 && retry) {
      this.token = undefined;
      return this.request(path, init, false);
    }
    if (!res.ok) throw new Error(`Kavita ${res.status} for ${path}`);
    return res;
  }

  json = async <T>(path: string, init?: FetchInit): Promise<T> =>
    (await this.request(path, init)).json();

  async bookLibraryIds(): Promise<number[]> {
    const libs = await this.json<Library[]>('Library/libraries');
    return libs.filter(l => BOOK_LIBRARY_TYPES.has(l.type)).map(l => l.id);
  }

  cover = (seriesId: number) =>
    `${this.base}/api/image/series-cover?seriesId=${seriesId}&apiKey=${encodeURIComponent(this.apiKey)}`;

  toItem = (s: { id: number; name: string }): Plugin.NovelItem => ({
    name: s.name,
    path: String(s.id),
    cover: this.cover(s.id),
  });

  async popularNovels(
    pageNo: number,
    { showLatestNovels }: Plugin.PopularNovelsOptions,
  ): Promise<Plugin.NovelItem[]> {
    const libraries = await this.bookLibraryIds();
    if (!libraries.length) return [];
    const series = await this.json<Series[]>(
      `Series/all-v2?PageNumber=${pageNo}&PageSize=${PAGE_SIZE}`,
      {
        method: 'POST',
        body: JSON.stringify({
          statements: [
            { comparison: 5, field: 19, value: libraries.join(',') },
          ],
          combination: 1,
          // LastChapterAdded (newest first) for "latest", otherwise by name.
          sortOptions: showLatestNovels
            ? { sortField: 4, isAscending: false }
            : { sortField: 1, isAscending: true },
          limitTo: 0,
        }),
      },
    );
    return series.map(this.toItem);
  }

  async searchNovels(
    searchTerm: string,
    pageNo: number,
  ): Promise<Plugin.NovelItem[]> {
    if (pageNo > 1) return [];
    const [libraries, result] = await Promise.all([
      this.bookLibraryIds(),
      this.json<SearchResult>(
        `Search/search?queryString=${encodeURIComponent(searchTerm)}&includeChapterAndFiles=false`,
      ),
    ]);
    return (result.series || [])
      .filter(s => libraries.includes(s.libraryId))
      .map(s => this.toItem({ id: s.seriesId, name: s.name }));
  }

  async parseNovel(novelPath: string): Promise<Plugin.SourceNovel> {
    const [series, meta, volumes] = await Promise.all([
      this.json<Series>(`Series/${novelPath}`),
      this.json<Metadata>(`Series/metadata?seriesId=${novelPath}`),
      this.json<Volume[]>(`Series/volumes?seriesId=${novelPath}`),
    ]);

    const books = volumes.flatMap(v => v.chapters);
    const chapters: Plugin.ChapterItem[] = [];
    for (const book of books) {
      const toc = await this.json<TocItem[]>(`Book/${book.id}/chapters`);
      const titles = new Map<number, string>();
      const walk = (items: TocItem[]) =>
        items.forEach(item => {
          if (!titles.has(item.page)) titles.set(item.page, item.title);
          if (item.children?.length) walk(item.children);
        });
      walk(toc);

      const prefix = books.length > 1 ? `${book.title} - ` : '';
      let part = 0;
      for (let page = 0; page < book.pages; page++) {
        const title = titles.get(page);
        chapters.push({
          name: prefix + (title || `Part ${++part}`),
          path: `${book.id}/${page}`,
          chapterNumber: chapters.length + 1,
        });
      }
    }

    return {
      path: novelPath,
      name: series.name,
      cover: this.cover(series.id),
      author: meta.writers?.map(w => w.name).join(', '),
      genres: meta.genres?.map(g => g.title).join(', '),
      summary: meta.summary?.replace(/<[^>]+>/g, '').trim(),
      status:
        meta.publicationStatus !== undefined
          ? STATUS[meta.publicationStatus] || NovelStatus.Unknown
          : NovelStatus.Unknown,
      chapters,
    };
  }

  async parseChapter(chapterPath: string): Promise<string> {
    const [bookId, page] = chapterPath.split('/');
    const html = await (
      await this.request(`Book/${bookId}/book-page?page=${page}`)
    ).text();
    const protocol = this.base.startsWith('http://') ? 'http:' : 'https:';
    return (
      html
        // Kavita's reader stylesheet forces its own colours; let LNReader theme the text.
        .replace(/<style[\s\S]*?<\/style>/gi, '')
        // Resource URLs are protocol-relative (//host/api/book/...).
        .replace(/((?:src|href|xlink:href)=["'])\/\//g, `$1${protocol}//`)
    );
  }

  resolveUrl = (path: string, isNovel?: boolean) => {
    const base = String(storage.get('url') || this.site).replace(/\/+$/, '');
    return isNovel
      ? `${base}/library/0/series/${path}`
      : `${base}/library/0/series/0/book/${path.split('/')[0]}`;
  };
}

export default new KavitaPlugin();