'use client';

import { useEffect, useMemo, useRef, useState } from 'react';
import { Check, Copy, ExternalLink, Instagram, LineChart, Linkedin, QrCode, Send, X } from 'lucide-react';
import { Dialog, DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle } from '@/components/ui/Dialog';
import { Button } from '@/components/ui/Button';
import { useCsrf } from '@/hooks/useCsrf';
import { useTranslation } from '@/hooks/useTranslation';
import { showToast } from '@/components/ui/Toast';
import { roundedChartPath } from '@/lib/rounded-chart-path';

type Channel = 'x' | 'instagram';
type Card = { language: 'en' | 'de'; qrTitle: string; label: string; title: string; totalScans?: number; totalUniqueScans: number; milestoneThreshold: number; trend: { points: Array<{ at: string; total: number }>; startLabel: string; endLabel: string; target: number; ceiling: number } | null };
type ChannelOption = { channel: Channel; available: boolean; defaultHandle: string; head: string; tail: string; mentionWord: string };
type PostState = { channel: string; status: string; postUrl: string | null; error: string | null };
type Milestone = { id: string; qrTitle: string; threshold: number; shareUrl: string; language: 'en' | 'de'; card: Card; promptStatus: string; channels: ChannelOption[]; posts: PostState[] };
type BrandState = { promptStatus: string; selfSharedAt: string | null; posts: PostState[] };

const CHANNEL_LABELS: Record<Channel, string> = { x: 'X', instagram: 'Instagram' };

function Trend({ trend, locale }: { trend: NonNullable<Card['trend']>; locale: 'en' | 'de' }) {
  const ceiling = trend.target <= 5 ? 5 : trend.target * 1.25;
  const ticks = trend.target <= 5
    ? [1, 2, 3, 4, 5]
    : Array.from({ length: 5 }, (_, index) => trend.target * (index + 1) / 4);
  const first = new Date(trend.points[0].at).getTime();
  const last = Math.max(new Date(trend.points[trend.points.length - 1].at).getTime(), first + 1);
  const chartPoints = trend.points.map(point => {
    const x = 60 + ((new Date(point.at).getTime() - first) / (last - first)) * 410;
    const y = 142 - (point.total / ceiling) * 126;
    return { x, y };
  });
  const path = roundedChartPath(chartPoints, 18);
  const endPoint = chartPoints[chartPoints.length - 1] || { x: 470, y: 142 };
  const number = new Intl.NumberFormat(locale === 'de' ? 'de-DE' : 'en-US', { maximumFractionDigits: 2 });
  return <svg viewBox="0 0 480 184" className="w-full" role="img" aria-label="Cumulative unique scan trend">
    {ticks.map(tick => {
      const y = 142 - (tick / ceiling) * 126;
      return <g key={tick}><text x="48" y={y + 4} textAnchor="end" fontSize="11" fontWeight={tick === trend.target ? 700 : 500} fill={tick === trend.target ? '#0256ff' : '#64748b'}>{number.format(tick)}</text><line x1="60" x2="470" y1={y} y2={y} stroke={tick === trend.target ? '#bfdbfe' : '#e2e8f0'} strokeWidth={tick === trend.target ? 1.6 : 1} /></g>;
    })}
    <path d={path} fill="none" stroke="#0256ff" strokeWidth="3.5" strokeLinejoin="round" strokeLinecap="round" />
    <circle cx={endPoint.x} cy={endPoint.y} r="4.5" fill="#ffffff" stroke="#0256ff" strokeWidth="3" />
    <text x="60" y="176" fontSize="11" fontWeight="600" fill="#45617f">{trend.startLabel}</text>
    <text x="470" y="176" textAnchor="end" fontSize="11" fontWeight="600" fill="#45617f">{trend.endLabel}</text>
  </svg>;
}

async function copyShareText(text: string) {
  try {
    await navigator.clipboard.writeText(text);
    return;
  } catch {
    const textarea = document.createElement('textarea');
    textarea.value = text;
    textarea.style.position = 'fixed';
    textarea.style.opacity = '0';
    document.body.appendChild(textarea);
    textarea.focus();
    textarea.select();
    const copied = document.execCommand('copy');
    textarea.remove();
    if (!copied) throw new Error('Copying is blocked by this browser');
  }
}

export function SocialMilestoneDialog() {
  const { fetchWithCsrf } = useCsrf();
  const { locale } = useTranslation();
  const [milestone, setMilestone] = useState<Milestone | null>(null);
  const [withName, setWithName] = useState(false);
  const [handles, setHandles] = useState<Record<string, string>>({});
  const [selected, setSelected] = useState<Channel[]>([]);
  const [saving, setSaving] = useState<'brand' | 'self' | 'copy' | 'instagram' | null>(null);
  const [brand, setBrand] = useState<BrandState | null>(null);
  const loadedMilestone = useRef(false);

  useEffect(() => {
    if (loadedMilestone.current) return;
    loadedMilestone.current = true;
    fetch(`/api/social-milestones?locale=${locale}`).then(async response => {
      if (response.ok) {
        const next = (await response.json()).milestone as Milestone | null;
        setMilestone(next);
        if (next) setBrand({ promptStatus: next.promptStatus, selfSharedAt: null, posts: next.posts || [] });
      }
    }).catch(() => undefined);
  }, [locale]);
  useEffect(() => {
    if (!milestone) return;
    setHandles(Object.fromEntries(milestone.channels.map(option => [option.channel, option.defaultHandle])));
    // Instagram stays unticked on purpose: consent for one channel is not
    // consent for the next, so the second one has to be an actual decision.
    setSelected(milestone.channels.filter(option => option.available && option.channel === 'x').map(option => option.channel));
  }, [milestone]);

  const posts = brand?.posts || [];
  const postFor = (channel: Channel) => posts.find(post => post.channel === channel);
  const pending = posts.some(post => ['approved', 'processing'].includes(post.status));
  useEffect(() => {
    if (!milestone || !pending) return;
    const poll = async () => {
      const response = await fetch(`/api/social-milestones/${milestone.id}`);
      if (response.ok) setBrand((await response.json()).milestone);
    };
    const timer = window.setInterval(poll, 3000);
    void poll();
    return () => window.clearInterval(timer);
  }, [milestone, pending]);

  const german = milestone?.language === 'de';
  const copy = german
    ? { heading: 'Ein echter Erfolg', subtitle: 'hat einen Scan-Meilenstein erreicht.', consent: 'Darf QR Master diesen Erfolg auf den eigenen Kanälen veröffentlichen?', name: 'Meinen Handle nennen', decline: 'Nicht jetzt', self: 'Selbst teilen', approve: 'Von QR Master posten', queued: 'Wird veröffentlicht …', posted: 'Veröffentlicht', failed: 'Veröffentlichung fehlgeschlagen' }
    : { heading: 'A real milestone', subtitle: 'just reached a scan milestone.', consent: 'May QR Master publish this success on its own channels?', name: 'Mention my handle', decline: 'Not now', self: 'Share myself', approve: 'Post from QR Master', queued: 'Publishing …', posted: 'Published', failed: 'Publishing failed' };

  const optionFor = (channel: Channel) => milestone?.channels.find(option => option.channel === channel);
  const mentionOf = (channel: Channel) => {
    const option = optionFor(channel);
    const handle = (handles[channel] || '').trim().replace(/^@/, '');
    return option && withName && handle ? `\n\n${option.mentionWord} @${handle}.` : '';
  };
  /** Without the channel suffix - used where the share URL is added by hand. */
  const composeBody = (channel: Channel) => {
    const option = optionFor(channel);
    return option ? `${option.head}${mentionOf(channel)}` : '';
  };
  // Head + mention + tail is exactly how the server assembles the consent text.
  const compose = (channel: Channel) => {
    const option = optionFor(channel);
    return option ? `${composeBody(channel)}${option.tail}` : '';
  };
  const previews = useMemo(
    () => selected.map(channel => ({ channel, text: compose(channel) })),
    // eslint-disable-next-line react-hooks/exhaustive-deps
    [selected, handles, withName, milestone],
  );

  const update = async (action: 'approve_brand' | 'self_share' | 'decline' | 'opt_out', extra?: Record<string, unknown>) => {
    if (!milestone) return null;
    const response = await fetchWithCsrf(`/api/social-milestones/${milestone.id}`, {
      method: 'PATCH',
      body: JSON.stringify({ action, withName, handles, channels: selected, language: milestone.language, ...extra }),
    });
    const result = await response.json();
    if (!response.ok) throw new Error(result.error || 'Could not save your choice');
    return result;
  };
  const prepareSelfShare = async () => {
    const result = await update('self_share');
    const shareUrl = `${result.shareUrl}?v=${result.shareVersion}`;
    setBrand(result.milestone);
    return {
      shareUrl,
      // 4:5 is the tallest ratio Instagram accepts and the one that keeps the
      // numbers readable in a phone feed.
      imageUrl: `${result.shareUrl}/og?format=portrait&v=${result.shareVersion}`,
      text: `${composeBody('x')}\n\n${shareUrl}`,
    };
  };
  const shareSelf = async (network: 'x' | 'linkedin') => {
    if (!milestone) return;
    // LinkedIn's public share dialog accepts only a URL. Start copying the
    // prepared commentary while this click still owns browser focus, then
    // open the LinkedIn share dialog after public-share consent is persisted.
    const commentary = composeBody('x');
    const linkedinCopy = network === 'linkedin'
      ? copyShareText(commentary).then(() => true).catch(() => false)
      : Promise.resolve(true);
    // Open synchronously from the user gesture. Awaiting the API first can make
    // LinkedIn treat the new window as a blocked popup.
    const shareWindow = window.open('about:blank', '_blank');
    if (shareWindow) shareWindow.opener = null;
    setSaving('self');
    try {
      const { shareUrl, text } = await prepareSelfShare();
      const copied = await linkedinCopy;
      const targetUrl = network === 'x'
        ? `https://x.com/intent/post?text=${encodeURIComponent(text)}`
        : `https://www.linkedin.com/sharing/share-offsite/?url=${encodeURIComponent(shareUrl)}`;
      if (shareWindow) shareWindow.location.href = targetUrl;
      else window.location.assign(targetUrl);
      showToast(network === 'linkedin'
        ? copied
          ? (german ? 'LinkedIn-Text kopiert. Jetzt nur noch einfügen.' : 'LinkedIn text copied. Paste it into the composer.')
          : (german ? 'LinkedIn ist geöffnet. Bitte nutze „Text kopieren“ im QR-Master-Fenster.' : 'LinkedIn is open. Please use “Copy text” in the QR Master window.')
        : 'X share composer opened.', copied ? 'success' : 'error');
    } catch (error) { shareWindow?.close(); showToast(error instanceof Error ? error.message : 'Could not prepare this share', 'error'); }
    finally { setSaving(null); }
  };
  // Instagram has no composer a website can prefill: there is no intent URL,
  // and the story deep links need a native pasteboard the browser cannot
  // reach. What is left is the system share sheet on a phone, and a download
  // plus the caption in the clipboard everywhere else.
  const shareInstagram = async () => {
    if (!milestone) return;
    setSaving('instagram');
    try {
      const caption = compose('instagram');
      const { imageUrl } = await prepareSelfShare();
      const response = await fetch(imageUrl);
      if (!response.ok) throw new Error(german ? 'Das Meilenstein-Bild konnte nicht geladen werden.' : 'Could not load the milestone image');
      const blob = await response.blob();
      const file = new File([blob], 'qr-master-milestone.png', { type: blob.type || 'image/png' });
      const copied = await copyShareText(caption).then(() => true).catch(() => false);
      if (navigator.canShare?.({ files: [file] })) {
        try {
          await navigator.share({ files: [file], text: caption });
          return;
        } catch (error) {
          // Sheet dismissed on purpose - do not push a download nobody asked for.
          if (error instanceof Error && error.name === 'AbortError') return;
        }
      }
      const objectUrl = URL.createObjectURL(blob);
      const link = document.createElement('a');
      link.href = objectUrl;
      link.download = file.name;
      link.click();
      URL.revokeObjectURL(objectUrl);
      showToast(copied
        ? (german ? 'Bild geladen, Text kopiert. Beides in Instagram einfügen.' : 'Image downloaded, caption copied. Add both in Instagram.')
        : (german ? 'Bild geladen. Bitte „Nur Text kopieren“ für die Bildunterschrift nutzen.' : 'Image downloaded. Use “Copy text only” for the caption.'),
        copied ? 'success' : 'error');
    } catch (error) {
      showToast(error instanceof Error ? error.message : 'Could not prepare this share', 'error');
    } finally {
      setSaving(null);
    }
  };
  const copyLinkedInText = async () => {
    setSaving('copy');
    try {
      const { text } = await prepareSelfShare();
      await copyShareText(text);
      showToast(german ? 'LinkedIn-Text kopiert.' : 'LinkedIn post text copied.', 'success');
    } catch (error) {
      showToast(error instanceof Error ? error.message : 'Could not copy the LinkedIn text', 'error');
    } finally { setSaving(null); }
  };
  const approveBrand = async () => {
    setSaving('brand');
    try {
      const result = await update('approve_brand');
      setBrand(result.milestone);
      showToast(copy.queued, 'success');
    } catch (error) { showToast(error instanceof Error ? error.message : 'Could not save your choice', 'error'); }
    finally { setSaving(null); }
  };
  const dismiss = async (action: 'decline' | 'opt_out') => {
    try { await update(action); setMilestone(null); } catch (error) { showToast(error instanceof Error ? error.message : 'Could not save your choice', 'error'); }
  };
  const optOut = () => {
    const message = german
      ? 'Meilenstein-Hinweise dauerhaft ausblenden? Du kannst sie später in den Einstellungen wieder aktivieren.'
      : 'Turn off milestone prompts? You can enable them again later in Settings.';
    if (window.confirm(message)) void dismiss('opt_out');
  };
  const toggleChannel = (channel: Channel) => {
    setSelected(current => current.includes(channel) ? current.filter(entry => entry !== channel) : [...current, channel]);
  };

  if (!milestone) return null;
  const card = milestone.card;
  const count = card.totalUniqueScans || milestone.threshold;
  const promptStatus = brand?.promptStatus || milestone.promptStatus;
  const brandChannels = milestone.channels.filter(option => option.available);
  // A channel that is already published or in flight cannot be re-approved.
  const canApprove = selected.length > 0 && !selected.some(channel => ['processing', 'posted'].includes(postFor(channel)?.status || ''));
  return <Dialog open onOpenChange={open => !open && setMilestone(null)} containerClassName="max-w-[960px]">
    <DialogContent className="flex max-h-[calc(100dvh-1rem)] w-full max-w-none flex-col overflow-hidden border-slate-200 p-0 shadow-[0_30px_45px_-30px_rgba(50,50,93,0.45)] sm:max-h-[calc(100dvh-1.5rem)]">
      <div className="shrink-0 px-4 py-4 sm:px-6">
        <DialogHeader className="flex-row items-center space-y-0 text-left">
          <div className="mr-3 flex h-10 w-10 shrink-0 items-center justify-center rounded-lg border border-slate-200 bg-white text-[#0256ff] shadow-sm"><QrCode className="h-5 w-5" /></div>
          <div className="min-w-0 flex-1"><DialogTitle className="text-xl font-semibold tracking-[-0.03em] text-[#061b31] sm:text-[22px]">{copy.heading}</DialogTitle><DialogDescription className="truncate pt-1 text-sm text-[#4b5e76]"><strong className="font-medium text-[#061b31]">{milestone.qrTitle}</strong> {copy.subtitle}</DialogDescription></div>
          <button type="button" aria-label={german ? 'Schließen' : 'Close'} onClick={() => setMilestone(null)} className="ml-3 inline-flex h-10 w-10 shrink-0 items-center justify-center rounded-md text-slate-500 transition-colors hover:bg-slate-100 hover:text-slate-800 focus:outline-none focus:ring-2 focus:ring-[#0256ff]"><X className="h-5 w-5" /></button>
        </DialogHeader>
      </div>
      <div className="min-h-0 space-y-4 overflow-y-auto border-y border-slate-100 px-4 py-4 overscroll-contain sm:px-6 md:grid md:grid-cols-[minmax(0,1.12fr)_minmax(320px,0.88fr)] md:gap-6 md:space-y-0">
        <section className="rounded-xl border border-slate-200 bg-white p-4 shadow-[0_14px_28px_-22px_rgba(50,50,93,0.4)]">
          <div className="flex items-center justify-between border-b border-slate-100 pb-3 text-xs"><span className="flex items-center gap-2 font-semibold tracking-wide text-[#061b31]"><img src="/favicon.ico" alt="" className="h-5 w-5" />QR MASTER</span><span className="rounded bg-emerald-50 px-2 py-1 font-medium text-emerald-700"><Check className="mr-1 inline h-3 w-3" />Verified scan milestone</span></div>
          <div className="mt-4 flex items-end justify-between gap-6"><div><div className="text-[10px] font-semibold tracking-[0.1em] text-slate-400">UNIQUE SCANS</div><div className="mt-1 text-5xl font-normal tracking-[-0.04em] tabular-nums text-[#061b31]">{count.toLocaleString(german ? 'de-DE' : 'en-US')}</div></div><div className="pb-1 text-right"><div className="text-[10px] font-semibold tracking-[0.1em] text-slate-400">{german ? 'SCANS INSGESAMT' : 'TOTAL SCANS'}</div><div className="mt-1 text-2xl font-normal tabular-nums text-[#061b31]">{(card.totalScans || count).toLocaleString(german ? 'de-DE' : 'en-US')}</div></div></div>
          <div className="mt-3 border-t border-slate-100 pt-3">{card.trend ? <Trend trend={card.trend} locale={milestone.language} /> : <div className="py-8 text-center text-xs text-[#45617f]">{german ? 'Noch keine Verlaufskurve verfügbar.' : 'No scan timeline available yet.'}</div>}</div>
          {card.trend && <div className="mt-1 flex items-center justify-end gap-2 text-[11px] text-[#45617f]"><LineChart className="h-3.5 w-3.5 text-[#0256ff]" />{german ? 'Kumulierte eindeutige Scans' : 'Cumulative unique scans'}</div>}
          <div className="mt-3 truncate border-t border-slate-100 pt-3 text-sm font-medium text-[#061b31]">{card.qrTitle}</div>
        </section>
        <div className="min-w-0 space-y-4 md:pt-1">
          <div>
            <p className="text-sm leading-6 text-[#4b5e76]">{copy.consent}</p>
            <div className="mt-2 flex flex-wrap gap-3">
              {brandChannels.map(option => (
                <label key={option.channel} className="flex cursor-pointer items-center gap-2 rounded-md border border-slate-200 px-3 py-1.5 text-sm font-medium text-slate-700 hover:border-[#0256ff]">
                  <input type="checkbox" checked={selected.includes(option.channel)} onChange={() => toggleChannel(option.channel)} disabled={saving !== null} className="h-4 w-4 rounded border-slate-300 text-[#0256ff] focus:ring-[#0256ff]" />
                  {option.channel === 'instagram' ? <Instagram className="h-3.5 w-3.5" /> : <X className="h-3.5 w-3.5" />}
                  {CHANNEL_LABELS[option.channel]}
                </label>
              ))}
            </div>
            {previews.length === 0
              ? <p className="mt-3 text-xs text-slate-500">{german ? 'Kein Kanal ausgewählt – QR Master veröffentlicht nichts.' : 'No channel selected – QR Master publishes nothing.'}</p>
              : previews.map(preview => (
                <div key={preview.channel} className="mt-3">
                  <div className="text-[11px] font-semibold uppercase tracking-wide text-slate-400">{CHANNEL_LABELS[preview.channel]}</div>
                  <blockquote className="mt-1 max-h-40 overflow-y-auto whitespace-pre-line break-words border-l border-[#0256ff] pl-3 text-sm leading-6 text-[#273951]">{preview.text}</blockquote>
                </div>
              ))}
          </div>
          <div className="space-y-2">
            <label className="flex cursor-pointer items-center gap-3 text-sm font-medium text-slate-700"><input type="checkbox" checked={withName} onChange={event => setWithName(event.target.checked)} disabled={saving !== null} className="h-4 w-4 rounded border-slate-300 text-[#0256ff] focus:ring-[#0256ff]" />{copy.name}</label>
            {withName && selected.map(channel => (
              <input
                key={channel}
                aria-label={`${CHANNEL_LABELS[channel]} handle`}
                value={handles[channel] || ''}
                onChange={event => setHandles(current => ({ ...current, [channel]: event.target.value }))}
                disabled={saving !== null}
                maxLength={channel === 'instagram' ? 31 : 16}
                placeholder={channel === 'instagram' ? '@your.instagram' : '@yourhandle'}
                className="w-full rounded-md border border-slate-200 px-3 py-2 text-sm outline-none focus:border-[#0256ff] focus:ring-2 focus:ring-blue-100"
              />
            ))}
          </div>
          <div className="space-y-2"><div className="text-xs font-medium text-slate-500">{copy.self}</div><div className="grid grid-cols-1 gap-2 sm:grid-cols-2 md:grid-cols-1 lg:grid-cols-2"><Button variant="outline" size="sm" className="w-full" onClick={() => shareSelf('x')} disabled={saving !== null}><X className="mr-1.5 h-3.5 w-3.5" />X</Button><Button variant="outline" size="sm" className="w-full" onClick={() => shareSelf('linkedin')} disabled={saving !== null}><Linkedin className="mr-1.5 h-3.5 w-3.5" />{german ? 'Kopieren & LinkedIn' : 'Copy & open LinkedIn'}</Button><Button variant="outline" size="sm" className="w-full" onClick={shareInstagram} disabled={saving !== null}><Instagram className="mr-1.5 h-3.5 w-3.5" />Instagram</Button></div><button type="button" onClick={copyLinkedInText} disabled={saving !== null} className="inline-flex items-center gap-1.5 text-xs font-medium text-[#45617f] underline underline-offset-2 hover:text-[#0256ff] disabled:opacity-50"><Copy className="h-3.5 w-3.5" />{german ? 'Nur Text kopieren' : 'Copy text only'}</button><p className="text-[11px] leading-4 text-slate-500">{german ? 'LinkedIn öffnet den Editor und kopiert den fertigen Text automatisch. Instagram lässt sich nicht vorbefüllen: am Handy öffnet das Teilen-Menü, sonst wird das Bild geladen und der Text kopiert.' : 'LinkedIn opens the composer and copies the finished text automatically. Instagram cannot be prefilled: on a phone the share sheet opens, otherwise the image is downloaded and the caption copied.'}</p></div>
          {posts.filter(post => post.status !== 'revoked').map(post => (
            <div key={post.channel} className={`flex items-start justify-between gap-3 rounded-md px-3 py-2 text-sm ${post.status === 'posted' ? 'bg-emerald-50 text-emerald-800' : post.status === 'failed' ? 'bg-rose-50 text-rose-800' : 'bg-blue-50 text-blue-800'}`}>
              <span>{CHANNEL_LABELS[post.channel as Channel] || post.channel}: {post.status === 'posted' ? copy.posted : post.status === 'failed' ? `${copy.failed}${post.error ? ` – ${post.error}` : ''}` : copy.queued}</span>
              {post.postUrl && <a href={post.postUrl} target="_blank" rel="noreferrer" className="inline-flex shrink-0 items-center gap-1 font-medium underline"><ExternalLink className="h-3.5 w-3.5" />View</a>}
            </div>
          ))}
        </div>
      </div>
      <DialogFooter className="shrink-0 bg-slate-50 px-4 py-3 sm:px-6"><div className="grid w-full grid-cols-2 gap-2 sm:ml-auto sm:flex sm:w-auto sm:flex-wrap sm:justify-end"><Button variant="outline" onClick={() => promptStatus === 'shown' ? dismiss('decline') : setMilestone(null)} disabled={saving !== null}>{copy.decline}</Button><Button variant="primary" onClick={approveBrand} disabled={saving !== null || !canApprove}><Send className="mr-1.5 h-4 w-4" />{pending ? copy.queued : copy.approve}</Button>{promptStatus === 'shown' && <button type="button" className="col-span-2 pt-1 text-xs text-slate-500 underline underline-offset-2 hover:text-slate-700 sm:w-full" onClick={optOut} disabled={saving !== null}>{german ? 'Nicht mehr anzeigen' : 'Do not show again'}</button>}</div></DialogFooter>
    </DialogContent>
  </Dialog>;
}