'use client';

import { useEffect, useMemo, useState } from 'react';
import Link from 'next/link';
import { ArrowRight, Download, Monitor, ShieldCheck, Smartphone, Sparkles } from 'lucide-react';
import { BrandLogo } from '@/components/id/brand-logo';
import { usePublicSettings } from '@/components/id/public-settings-provider';
import { Button } from '@/components/ui/button';
import {
  AppRelease,
  AppReleasePlatform,
  buildAppReleaseDownloadUrl,
  fetchPublicAppReleases
} from '@/lib/api';

function formatBytes(value: string) {
  const size = Number(value);
  if (!Number.isFinite(size) || size <= 0) return '—';
  const units = ['Б', 'КБ', 'МБ', 'ГБ'];
  let amount = size;
  let unit = 0;
  while (amount >= 1024 && unit < units.length - 1) {
    amount /= 1024;
    unit += 1;
  }
  return `${amount.toFixed(amount >= 10 || unit === 0 ? 0 : 1)} ${units[unit]}`;
}

function formatDate(value: string) {
  return new Intl.DateTimeFormat('ru-RU', {
    day: '2-digit',
    month: 'long',
    year: 'numeric'
  }).format(new Date(value));
}

const platformCards: Array<{
  platform: AppReleasePlatform;
  slug: 'android' | 'windows';
  title: string;
  subtitle: string;
  icon: typeof Smartphone;
  gradient: string;
}> = [
  {
    platform: 'ANDROID',
    slug: 'android',
    title: 'Android',
    subtitle: 'Скачайте APK для телефона или планшета',
    icon: Smartphone,
    gradient: 'from-[#34c759] to-[#0f9d58]'
  },
  {
    platform: 'WINDOWS',
    slug: 'windows',
    title: 'Windows',
    subtitle: 'Установщик для компьютера',
    icon: Monitor,
    gradient: 'from-[#3390ec] to-[#1d4ed8]'
  }
];

export default function DownloadsPage() {
  const { projectName } = usePublicSettings();
  const [releases, setReleases] = useState<AppRelease[]>([]);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    void (async () => {
      try {
        const response = await fetchPublicAppReleases();
        setReleases(response.releases ?? []);
      } finally {
        setLoading(false);
      }
    })();
  }, []);

  const latestByPlatform = useMemo(() => {
    const map = new Map<AppReleasePlatform, AppRelease>();
    for (const release of releases) {
      if (!map.has(release.platform)) {
        map.set(release.platform, release);
      }
    }
    return map;
  }, [releases]);

  const historyByPlatform = useMemo(() => ({
    ANDROID: releases.filter((item) => item.platform === 'ANDROID'),
    WINDOWS: releases.filter((item) => item.platform === 'WINDOWS')
  }), [releases]);

  return (
    <main className="min-h-screen bg-[linear-gradient(180deg,#f7f9fc_0%,#ffffff_42%,#f4f7fb_100%)]">
      <div className="mx-auto max-w-6xl px-4 py-10 sm:px-6 lg:py-14">
        <div className="mb-10 flex flex-wrap items-center justify-between gap-4">
          <BrandLogo />
          <Button variant="outline" className="rounded-full" asChild>
            <Link href="/auth/login">Войти в аккаунт</Link>
          </Button>
        </div>

        <section className="relative overflow-hidden rounded-[32px] border border-[#e8edf5] bg-white px-6 py-10 shadow-[0_24px_80px_rgba(31,36,48,0.08)] sm:px-10 sm:py-12">
          <div className="absolute -right-16 -top-16 h-56 w-56 rounded-full bg-[#eef4ff] blur-3xl" />
          <div className="absolute -bottom-20 left-10 h-48 w-48 rounded-full bg-[#e8f8ee] blur-3xl" />
          <div className="relative max-w-3xl">
            <div className="mb-4 inline-flex items-center gap-2 rounded-full bg-[#eef4ff] px-3 py-1 text-sm font-medium text-[#3390ec]">
              <Sparkles className="h-4 w-4" />
              Официальные сборки {projectName}
            </div>
            <h1 className="text-4xl font-semibold tracking-tight text-[#1f2430] sm:text-5xl">
              Скачайте приложение
            </h1>
            <p className="mt-4 max-w-2xl text-base leading-relaxed text-[#667085] sm:text-lg">
              Актуальные версии для Android и Windows. Каждый релиз подписан SHA-256 — мобильное приложение может
              автоматически проверять обновления по коду версии.
            </p>
          </div>
        </section>

        <section className="mt-8 grid gap-5 lg:grid-cols-2">
          {platformCards.map((card) => {
            const latest = latestByPlatform.get(card.platform);
            const Icon = card.icon;
            return (
              <div
                key={card.platform}
                className="overflow-hidden rounded-[28px] border border-[#eceef4] bg-white shadow-[0_18px_50px_rgba(31,36,48,0.06)]"
              >
                <div className={`bg-gradient-to-br ${card.gradient} px-6 py-8 text-white`}>
                  <div className="flex items-center gap-3">
                    <div className="flex h-14 w-14 items-center justify-center rounded-2xl bg-white/15 backdrop-blur">
                      <Icon className="h-7 w-7" />
                    </div>
                    <div>
                      <h2 className="text-2xl font-semibold">{card.title}</h2>
                      <p className="mt-1 text-sm text-white/85">{card.subtitle}</p>
                    </div>
                  </div>
                </div>

                <div className="space-y-5 px-6 py-6">
                  {loading ? (
                    <p className="text-sm text-[#667085]">Проверяем доступные версии...</p>
                  ) : latest ? (
                    <>
                      <div>
                        <p className="text-sm text-[#667085]">Последняя версия</p>
                        <div className="mt-2 flex flex-wrap items-center gap-2">
                          <span className="text-2xl font-semibold text-[#1f2430]">v{latest.version}</span>
                          <span className="rounded-full bg-[#eef4ff] px-2.5 py-1 text-xs font-medium text-[#3390ec]">
                            build {latest.versionCode}
                          </span>
                        </div>
                        <p className="mt-2 text-sm text-[#667085]">
                          {formatBytes(latest.fileSize)} · {formatDate(latest.createdAt)}
                        </p>
                      </div>

                      {latest.releaseNotes ? (
                        <p className="rounded-2xl bg-[#f8f9fb] px-4 py-3 text-sm leading-relaxed text-[#1f2430]">
                          {latest.releaseNotes}
                        </p>
                      ) : null}

                      <div className="flex flex-col gap-3 sm:flex-row">
                        <Button className="flex-1 rounded-xl" asChild>
                          <a href={`/downloads/${card.slug}`}>
                            <Download className="mr-2 h-4 w-4" />
                            Скачать последнюю
                          </a>
                        </Button>
                        <Button variant="outline" className="flex-1 rounded-xl" asChild>
                          <a href={buildAppReleaseDownloadUrl(card.platform, latest.id)}>
                            Прямая ссылка
                            <ArrowRight className="ml-2 h-4 w-4" />
                          </a>
                        </Button>
                      </div>
                    </>
                  ) : (
                    <p className="text-sm text-[#667085]">Сборка для этой платформы пока не опубликована.</p>
                  )}
                </div>
              </div>
            );
          })}
        </section>

        <section className="mt-10 grid gap-6 lg:grid-cols-2">
          {platformCards.map((card) => {
            const history = historyByPlatform[card.platform];
            return (
              <div key={`history-${card.platform}`} className="rounded-[24px] border border-[#eceef4] bg-white p-6 shadow-sm">
                <h3 className="text-xl font-semibold">История версий · {card.title}</h3>
                <div className="mt-4 space-y-3">
                  {loading ? (
                    <p className="text-sm text-[#667085]">Загружаем список версий...</p>
                  ) : history.length ? (
                    history.map((release, index) => (
                      <div
                        key={release.id}
                        className="flex flex-wrap items-center justify-between gap-3 rounded-2xl bg-[#f8f9fb] px-4 py-3"
                      >
                        <div>
                          <div className="flex items-center gap-2">
                            <span className="font-medium text-[#1f2430]">v{release.version}</span>
                            <span className="text-xs text-[#667085]">build {release.versionCode}</span>
                            {index === 0 ? (
                              <span className="rounded-full bg-[#e8f8ee] px-2 py-0.5 text-[11px] font-medium text-[#1a7f37]">
                                Актуальная
                              </span>
                            ) : null}
                          </div>
                          <p className="mt-1 text-xs text-[#667085]">
                            {formatDate(release.createdAt)} · {formatBytes(release.fileSize)}
                          </p>
                        </div>
                        <Button variant="outline" size="sm" className="rounded-xl" asChild>
                          <a href={buildAppReleaseDownloadUrl(card.platform, release.id)}>Скачать</a>
                        </Button>
                      </div>
                    ))
                  ) : (
                    <p className="text-sm text-[#667085]">Версии пока не опубликованы.</p>
                  )}
                </div>
              </div>
            );
          })}
        </section>

        <section className="mt-10 rounded-[24px] border border-[#eceef4] bg-white p-6 shadow-sm">
          <div className="flex items-start gap-3">
            <div className="flex h-11 w-11 shrink-0 items-center justify-center rounded-2xl bg-[#eef4ff] text-[#3390ec]">
              <ShieldCheck className="h-5 w-5" />
            </div>
            <div>
              <h3 className="text-lg font-semibold">Проверка обновлений в приложении</h3>
              <p className="mt-2 text-sm leading-relaxed text-[#667085]">
                Мобильный клиент может запрашивать{' '}
                <code className="rounded bg-[#f4f5f8] px-1.5 py-0.5">GET /idp-api/releases/check?platform=ANDROID&amp;versionCode=...</code>{' '}
                и сравнивать SHA-256 перед установкой. Постоянные ссылки на последнюю версию:
                <span className="mt-2 block font-medium text-[#1f2430]">/downloads/android</span>
                <span className="block font-medium text-[#1f2430]">/downloads/windows</span>
              </p>
            </div>
          </div>
        </section>
      </div>
    </main>
  );
}
