import React, { useEffect, useRef, useState } from 'react';
import { useAuth } from '../context/AuthContext';
import { API_BASE_URL } from '../config';

function normalizeExternalUrl(raw) {
  if (!raw) return '';
  const s = String(raw).trim();
  if (!s) return '';
  // already absolute
  if (/^https?:\/\//i.test(s)) return s;
  // protocol-relative
  if (s.startsWith('//')) return `https:${s}`;
  // common "missing scheme" cases from DB/meta
  if (s.startsWith('img.youtube.com/')) return `https://${s}`;
  if (s.startsWith('www.youtube.com/')) return `https://${s}`;
  if (s.startsWith('youtube.com/')) return `https://${s}`;
  return s; // leave as-is (could be relative path on same origin)
}

export default function AiNewsPage() {
  const { user } = useAuth();
  const [news, setNews] = useState([]);
  const [newsOffset, setNewsOffset] = useState(0);
  const [newsLoading, setNewsLoading] = useState(false);
  const [showNewsEditor, setShowNewsEditor] = useState(false);
  const [newsUrl, setNewsUrl] = useState('');
  const contentRef = useRef(null);
  const sentinelRef = useRef(null);

  useEffect(() => {
    (async () => {
      await loadNews(0, false);
      // 최초 로드 후 최신 위치로 한 번 스크롤
      requestAnimationFrame(() => {
        const el = contentRef.current;
        if (el) el.scrollTop = el.scrollHeight;
      });
    })();
  }, []);

  // IntersectionObserver로 상단 도달 시 로드
  useEffect(() => {
    const observer = new IntersectionObserver(
      (entries) => {
        if (entries[0].isIntersecting && !newsLoading) {
          loadNews(newsOffset, true);
        }
      },
      { root: contentRef.current, threshold: 0.1 }
    );
    if (sentinelRef.current) observer.observe(sentinelRef.current);
    return () => observer.disconnect();
  }, [newsOffset, newsLoading]);

  const loadNews = async (offset = 0, prepend = false) => {
    if (newsLoading) return;
    setNewsLoading(true);
    try {
      const res = await fetch(`${API_BASE_URL}/community/ai_news?offset=${offset}&limit=10`);
      if (!res.ok) return;
      const data = await res.json();
      const items = (data.items || []).reverse();
      if (prepend) {
        const el = contentRef.current;
        const prevH = el ? el.scrollHeight : document.documentElement.scrollHeight;
        setNews((prev) => [...items, ...prev]);
        setTimeout(() => {
          if (el) {
            el.scrollTop = el.scrollHeight - prevH;
          } else {
            const newH = document.documentElement.scrollHeight;
            window.scrollTo(0, newH - prevH);
          }
        }, 0);
      } else {
        setNews(items);
        setTimeout(() => {
          const el = contentRef.current;
          if (el) el.scrollTop = el.scrollHeight; else window.scrollTo(0, document.documentElement.scrollHeight);
        }, 0);
      }
      const nextOffset = data.nextOffset || 0;
      setNewsOffset(nextOffset);
      return nextOffset;
    } finally {
      setNewsLoading(false);
    }
  };

  // 기존 스크롤 보정 루프 제거 – IntersectionObserver 사용

  const submitNews = async () => {
    if (!newsUrl.trim()) return;
    await fetch(`${API_BASE_URL}/community/ai_news`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ url: newsUrl, author_id: String(user?.user_id || ''), author_email: user?.email || null }),
    });
    setShowNewsEditor(false);
    setNewsUrl('');
    loadNews(0);
  };

  return (
    <section className="page page-ai-news" style={{ flex: 1, display: 'flex', flexDirection: 'column' }}>
      <div className="section" style={{ paddingBottom: 8 }}>
        <div className="section-head" style={{ marginBottom: 0 }}>
          <h2 className="section-title">인사이트</h2>
          <p className="section-desc">업계 동향/레퍼런스 링크를 모아두고, 팀/고객과 빠르게 공유합니다.</p>
        </div>
      </div>
      <main className="community-content" ref={contentRef} style={{ overflowY: 'auto', flex: 1 }}>
        <div ref={sentinelRef} />
        <div style={{ padding: '0 20px 50px 20px' }}>
          {news.map((n) => (
            <div key={n.id} className="card" style={{ marginBottom: 12 }}>
              <div style={{ display: 'flex', gap: 12 }}>
                {n.meta?.image ? (
                  <img
                    src={normalizeExternalUrl(n.meta.image)}
                    alt="thumb"
                    style={{ width: 96, height: 96, objectFit: 'cover', borderRadius: 8 }}
                    referrerPolicy="no-referrer"
                  />
                ) : null}
                <div style={{ flex: 1 }}>
                  <a
                    href={normalizeExternalUrl(n.meta?.url || n.url)}
                    target="_blank"
                    rel="noreferrer"
                    style={{ fontWeight: 600, color: '#1976d2', textDecoration: 'none' }}
                  >
                    {n.meta?.title || n.url}
                  </a>
                  <div style={{ marginTop: 6, color: '#555', lineHeight: 1.5 }}>{n.meta?.description}</div>
                  <div style={{ marginTop: 6, color: '#999', fontSize: '.9rem' }}>{new Date(n.created_at).toISOString().slice(0, 10)}</div>
                </div>
              </div>
            </div>
          ))}
        </div>
        {newsLoading && (
          <div className="loading-overlay">
            <span className="loading-text">뉴스 로딩중</span>
            <span className="loading-dots">
              <span className="loading-dot"></span>
              <span className="loading-dot"></span>
              <span className="loading-dot"></span>
            </span>
          </div>
        )}
        {user && !showNewsEditor && (
          <button
            onClick={() => setShowNewsEditor(true)}
            className="btn btn-primary"
            style={{ position: 'fixed', right: 24, bottom: 24, zIndex: 1000 }}
          >
            뉴스등록
          </button>
        )}
        {showNewsEditor && user && (
          <div
            style={{ position: 'fixed', right: 24, bottom: 84, zIndex: 1001, width: 'min(560px, calc(100vw - 40px))', background: '#fff', border: '1px solid #ffd6c2', borderRadius: 12, padding: 12, boxShadow: '0 6px 18px rgba(0,0,0,.15)' }}
          >
            <input
              value={newsUrl}
              onChange={(e) => setNewsUrl(e.target.value)}
              placeholder="뉴스 URL을 입력하세요"
              style={{ width: 'calc(100% - 25px)', marginBottom: 8, padding: '10px 12px', borderRadius: 8, border: '1px solid #ffd6c2' }}
              onKeyDown={(e) => {
                if (e.key === 'Enter') {
                  e.preventDefault();
                  submitNews();
                }
              }}
            />
            <div style={{ display: 'flex', gap: 8, justifyContent: 'flex-end' }}>
              <button
                onClick={() => {
                  setShowNewsEditor(false);
                  setNewsUrl('');
                }}
                style={{ background: '#fff', border: '1px solid #ddd', padding: '8px 12px', borderRadius: 8 }}
              >
                취소
              </button>
              <button onClick={submitNews} style={{ background: '#ff9800', color: '#fff', border: 'none', padding: '8px 12px', borderRadius: 8 }}>등록</button>
            </div>
          </div>
        )}
      </main>
    </section>
  );
}