import { useEffect, useRef, useState } from 'react';
import { createPortal } from 'react-dom';
import { buildChatSavePreviewFrameUrl, downloadChatMessageDocx, quickShareFromChat } from '../api/client';

type SharePhase =
  | { kind: 'idle' }
  | { kind: 'loading' }
  | { kind: 'done'; publicUrl: string }
  | { kind: 'error'; message: string };

type ExportPhase =
  | { kind: 'idle' }
  | { kind: 'image-loading' }
  | { kind: 'docx-loading' }
  | { kind: 'error'; message: string };

function appendLongImageDownloadParam(url: string) {
  const next = new URL(url, window.location.href);
  next.searchParams.set('download', 'long-image');
  return next.toString();
}

function triggerUrlDownload(url: string) {
  const link = document.createElement('a');
  link.href = url;
  link.download = '';
  document.body.appendChild(link);
  link.click();
  link.remove();
}

function downloadBlob(blob: Blob, filename: string) {
  const url = URL.createObjectURL(blob);
  const link = document.createElement('a');
  link.href = url;
  link.download = filename;
  document.body.appendChild(link);
  link.click();
  link.remove();
  window.setTimeout(() => URL.revokeObjectURL(url), 60_000);
}

export function ChatSharePreviewModal({
  sessionId,
  messageId,
  selectedLinkIndex = 0,
  onClose,
  onSave,
}: {
  sessionId: string;
  messageId: string;
  selectedLinkIndex?: number;
  onClose: () => void;
  onSave?: () => void;
}) {
  const [phase, setPhase] = useState<SharePhase>({ kind: 'idle' });
  const [exportPhase, setExportPhase] = useState<ExportPhase>({ kind: 'idle' });
  const [copied, setCopied] = useState(false);
  const copyTimer = useRef<ReturnType<typeof setTimeout> | null>(null);

  const previewUrl = buildChatSavePreviewFrameUrl({ sessionId, messageId, selectedLinkIndex });

  useEffect(() => {
    const prev = document.body.style.overflow;
    document.body.style.overflow = 'hidden';
    return () => { document.body.style.overflow = prev; };
  }, []);

  useEffect(() => {
    const onKey = (e: KeyboardEvent) => { if (e.key === 'Escape') onClose(); };
    window.addEventListener('keydown', onKey);
    return () => window.removeEventListener('keydown', onKey);
  }, [onClose]);

  useEffect(() => () => { if (copyTimer.current) clearTimeout(copyTimer.current); }, []);

  const share = async () => {
    if (phase.kind === 'loading') return;
    setPhase({ kind: 'loading' });
    try {
      const result = await quickShareFromChat({ sessionId, messageId, selectedLinkIndex });
      setPhase({ kind: 'done', publicUrl: result.publicUrl });
    } catch (err) {
      setPhase({ kind: 'error', message: err instanceof Error ? err.message : '公开分享失败，请重试' });
    }
  };

  const ensurePublicUrl = async () => {
    if (phase.kind === 'done') return phase.publicUrl;
    setPhase({ kind: 'loading' });
    const result = await quickShareFromChat({ sessionId, messageId, selectedLinkIndex });
    setPhase({ kind: 'done', publicUrl: result.publicUrl });
    return result.publicUrl;
  };

  const downloadImage = async () => {
    if (exportPhase.kind === 'image-loading' || exportPhase.kind === 'docx-loading') return;
    setExportPhase({ kind: 'image-loading' });
    try {
      const publicUrl = await ensurePublicUrl();
      triggerUrlDownload(appendLongImageDownloadParam(publicUrl));
      setExportPhase({ kind: 'idle' });
    } catch (err) {
      setExportPhase({ kind: 'error', message: err instanceof Error ? err.message : '长图下载失败，请重试' });
      setPhase((current) => (current.kind === 'loading' ? { kind: 'idle' } : current));
    }
  };

  const downloadDocx = async () => {
    if (exportPhase.kind === 'image-loading' || exportPhase.kind === 'docx-loading') return;
    setExportPhase({ kind: 'docx-loading' });
    try {
      const result = await downloadChatMessageDocx({ sessionId, messageId, selectedLinkIndex });
      downloadBlob(result.blob, result.filename);
      setExportPhase({ kind: 'idle' });
    } catch (err) {
      setExportPhase({ kind: 'error', message: err instanceof Error ? err.message : '文档下载失败，请重试' });
    }
  };

  const copy = async (url: string) => {
    try {
      await navigator.clipboard.writeText(url);
      setCopied(true);
      if (copyTimer.current) clearTimeout(copyTimer.current);
      copyTimer.current = setTimeout(() => setCopied(false), 2000);
    } catch { /* ignore */ }
  };

  const handleSave = () => {
    onClose();
    onSave?.();
  };

  return createPortal(
    <div className="chat-share-preview-overlay" role="dialog" aria-modal="true" aria-label="页面预览">
      <div className="chat-share-preview-header">
        <span className="chat-share-preview-title">页面预览</span>
        <button type="button" className="chat-share-preview-close" onClick={onClose} aria-label="关闭">✕</button>
      </div>
      <div className="chat-share-preview-body">
        <iframe src={previewUrl} title="页面预览" sandbox="allow-same-origin allow-scripts allow-popups allow-downloads" className="chat-share-preview-frame" />

        <div className="chat-share-side-actions">
          {phase.kind === 'done' ? (
            <div className="chat-share-result-card">
              <p className="chat-share-result-label">✅ 已公开！</p>
              <button type="button" className="chat-share-result-copy" onClick={() => void copy(phase.publicUrl)}>
                {copied ? '已复制 ✓' : '复制链接'}
              </button>
              <a href={phase.publicUrl} target="_blank" rel="noreferrer" className="chat-share-result-open">
                打开页面 →
              </a>
            </div>
          ) : (
            <button
              type="button"
              className={`chat-share-side-btn chat-share-side-btn-primary${phase.kind === 'loading' ? ' is-loading' : ''}`}
              disabled={phase.kind === 'loading'}
              onClick={() => void share()}
              title="将页面转为公开链接，私有图片自动转为公开地址"
            >
              {phase.kind === 'loading' ? '处理中…' : '公开分享'}
            </button>
          )}
          {phase.kind === 'error' && <p className="chat-share-side-error">{phase.message}</p>}
          {onSave && (
            <button type="button" className="chat-share-side-btn" onClick={handleSave}>
              保存页面
            </button>
          )}
          <button
            type="button"
            className="chat-share-side-btn"
            disabled={exportPhase.kind === 'image-loading' || exportPhase.kind === 'docx-loading'}
            onClick={() => void downloadImage()}
          >
            {exportPhase.kind === 'image-loading' ? '生成图片…' : '下载图片'}
          </button>
          <button
            type="button"
            className="chat-share-side-btn"
            disabled={exportPhase.kind === 'image-loading' || exportPhase.kind === 'docx-loading'}
            onClick={() => void downloadDocx()}
          >
            {exportPhase.kind === 'docx-loading' ? '生成文档…' : '保存文档'}
          </button>
          {exportPhase.kind === 'error' && <p className="chat-share-side-error">{exportPhase.message}</p>}
        </div>
      </div>
    </div>,
    document.body,
  );
}