// RSS / Atom / JSON Feed / 自定义 JSON 解析
// 迁自 check-feeds.js 的 parseFeedXml / parseJsonFeed / parseCustomJson 等。

export interface Article {
  title: string;
  link: string;
  pubDate: string;
  author: string;
  feedTitle: string;
}

export interface FeedConfig {
  url: string;
  feedTitle?: string;
  format?: string;
  path?: string;
  proxy?: boolean;
  mapping?: Record<string, string>;
}

export interface ParsedFeed {
  feedTitle: string;
  articles: Article[];
}

function extractTag(xml: string, tag: string): string {
  const regex = new RegExp(`<${tag}[^>]*>([\\s\\S]*?)<\\/${tag}>`, 'i');
  const match = xml.match(regex);
  return match ? match[1] : '';
}

function decodeXml(str: string): string {
  return str
    .replace(/<!\[CDATA\[([\s\S]*?)\]\]>/g, '$1')
    .replace(/&amp;/g, '&')
    .replace(/&lt;/g, '<')
    .replace(/&gt;/g, '>')
    .replace(/&quot;/g, '"')
    .replace(/&apos;/g, "'");
}

export function parseDate(val: unknown): string | null {
  if (!val) return null;
  if (typeof val === 'number') {
    const d = new Date(val > 9999999999 ? val : val * 1000);
    return isNaN(d.getTime()) ? null : d.toISOString();
  }
  const str = String(val).trim();
  if (!str) return null;
  const d = new Date(str);
  if (isNaN(d.getTime())) return null;
  try {
    return d.toISOString();
  } catch {
    return null;
  }
}

export function parseFeedXml(xml: string, feedUrl: string): ParsedFeed {
  const articles: Article[] = [];
  let feedTitle = '';

  const titleMatch = xml.match(/<title[^>]*>([\s\S]*?)<\/title>/);
  if (titleMatch) feedTitle = decodeXml(titleMatch[1]).trim();

  const itemRegex = /<item[\s>]?>([\s\S]*?)<\/item>/gi;
  const entryRegex = /<entry[\s>]?>([\s\S]*?)<\/entry>/gi;

  const parseItem = (itemXml: string) => {
    const title = extractTag(itemXml, 'title');
    let link = '';

    const rssLink = extractTag(itemXml, 'link');
    if (rssLink) link = rssLink;

    const atomLinkMatch = itemXml.match(/<link[^>]+href=["']([^"']+)["'][^>]*>/i);
    if (atomLinkMatch && atomLinkMatch[1]) link = atomLinkMatch[1];

    const altLinkMatch = itemXml.match(
      /<link[^>]+rel=["']alternate["'][^>]+href=["']([^"']+)["']/i,
    );
    if (altLinkMatch) link = altLinkMatch[1];

    const pubDate =
      extractTag(itemXml, 'pubDate') ||
      extractTag(itemXml, 'published') ||
      extractTag(itemXml, 'updated') ||
      extractTag(itemXml, 'dc:date') ||
      extractTag(itemXml, 'lastBuildDate') ||
      extractTag(itemXml, 'date') ||
      extractTag(itemXml, 'modified') ||
      extractTag(itemXml, 'created');

    const author = extractTag(itemXml, 'dc:creator') || extractTag(itemXml, 'author') || '';
    const authorName = author.replace(/<name>([\s\S]*?)<\/name>/gi, '$1').trim();

    if (title && link) {
      articles.push({
        title: decodeXml(title).trim(),
        link: link.trim(),
        pubDate: parseDate(pubDate) || new Date().toISOString(),
        author: decodeXml(authorName).trim(),
        feedTitle: feedTitle || feedUrl,
      });
    }
  };

  let match: RegExpExecArray | null;
  while ((match = itemRegex.exec(xml)) !== null) parseItem(match[1]);
  while ((match = entryRegex.exec(xml)) !== null) parseItem(match[1]);

  return { feedTitle, articles };
}

export function parseJsonFeed(json: any, feedUrl: string): ParsedFeed {
  const articles: Article[] = [];
  const feedTitle = json.title || feedUrl;
  const items = json.items || [];

  for (const item of items) {
    const title = item.title || '';
    const link = item.url || item.id || '';
    const pubDate =
      item.date_published || item.date_modified || item.date || item.published || item.modified || item.created_at || item.createdAt || item.pubDate || item.timestamp || null;
    const author = Array.isArray(item.authors)
      ? item.authors.map((a: any) => a.name).join(', ')
      : item.author?.name || item.author || '';

    if (title && link) {
      articles.push({
        title: title.trim(),
        link: link.trim(),
        pubDate: parseDate(pubDate) || new Date().toISOString(),
        author: typeof author === 'string' ? author.trim() : '',
        feedTitle,
      });
    }
  }

  return { feedTitle, articles };
}

function getNestedValue(obj: any, path?: string): unknown {
  if (!obj || !path) return undefined;
  return path.split('.').reduce((o: any, key) => o?.[key], obj);
}

export function parseCustomJson(json: any, config: FeedConfig): ParsedFeed {
  const articles: Article[] = [];
  const mapping = config.mapping || {};
  const path = config.path || '';

  let data: any = json;
  if (path) {
    for (const key of path.split('.')) {
      if (data && typeof data === 'object') data = data[key];
    }
  }

  const items = Array.isArray(data) ? data : [];

  const titleKey = mapping.title || 'title';
  const linkKey = mapping.link || 'link';
  const pubDateKey = mapping.pubDate || 'pubDate';
  const authorKey = mapping.author || 'author';
  const feedTitleKey = mapping.feedTitle || 'feedTitle';

  for (const item of items) {
    const title = getNestedValue(item, titleKey) || '';
    const link = getNestedValue(item, linkKey) || getNestedValue(item, 'url') || '';
    const pubDate =
      getNestedValue(item, pubDateKey) ||
      getNestedValue(item, 'publishedAt') ||
      getNestedValue(item, 'createdAt') ||
      getNestedValue(item, 'created_at') ||
      getNestedValue(item, 'date') ||
      getNestedValue(item, 'published') ||
      getNestedValue(item, 'updatedAt') ||
      getNestedValue(item, 'timestamp') ||
      getNestedValue(item, 'datePublished') ||
      getNestedValue(item, 'dateModified') ||
      null;
    const author = getNestedValue(item, authorKey) || '';
    const feedTitle = getNestedValue(item, feedTitleKey) || config.feedTitle || config.url || '';

    if (title && link) {
      articles.push({
        title: String(title).trim(),
        link: String(link).trim(),
        pubDate: parseDate(pubDate) || new Date().toISOString(),
        author: String(typeof author === 'object' ? '' : author).trim(),
        feedTitle: String(feedTitle),
      });
    }
  }

  return { feedTitle: config.feedTitle || config.url || '', articles };
}

export function isJsonResponse(text: string, contentType: string): boolean {
  if (contentType?.includes('json')) return true;
  try {
    const parsed = JSON.parse(text);
    return typeof parsed === 'object' && parsed !== null;
  } catch {
    return false;
  }
}