'use client';

import DeleteChat from '@/components/DeleteChat';
import { formatTimeDifference } from '@/lib/utils';
import {
  ClockIcon,
  FileText,
  Globe2Icon,
  MessagesSquare,
  Search,
  Filter,
} from 'lucide-react';
import Link from 'next/link';
import { useEffect, useMemo, useState } from 'react';
import { useTranslation } from '@/lib/localization/context';

export interface Chat {
  id: string;
  title: string;
  createdAt: string;
  sources: string[];
  files: { fileId: string; name: string }[];
}

const SOURCE_KEYS = ['web', 'academic', 'discussions'] as const;
type SourceKey = (typeof SOURCE_KEYS)[number];

type FilesFilter = 'all' | 'with' | 'without';

const Page = () => {
  const { t } = useTranslation();
  const [chats, setChats] = useState<Chat[]>([]);
  const [loading, setLoading] = useState(true);
  const [searchQuery, setSearchQuery] = useState('');
  const [sourceFilter, setSourceFilter] = useState<SourceKey | 'all'>('all');
  const [filesFilter, setFilesFilter] = useState<FilesFilter>('all');

  useEffect(() => {
    const fetchChats = async () => {
      setLoading(true);

      const token =
        typeof window !== 'undefined'
          ? localStorage.getItem('auth_token') ?? localStorage.getItem('access_token')
          : null;

      try {
        if (token) {
          const res = await fetch('/api/v1/library/threads', {
            headers: { Authorization: `Bearer ${token}` },
          });
          if (res.ok) {
            const data = await res.json();
            setChats(data.chats ?? []);
            setLoading(false);
            return;
          }
        }
        const { getGuestChats } = await import('@/lib/guest-storage');
        const guestChats = getGuestChats();
        setChats(
          guestChats.map((c) => ({
            id: c.id,
            title: c.title,
            createdAt: c.createdAt,
            sources: c.sources,
            files: c.files,
          })),
        );
      } catch {
        setChats([]);
      } finally {
        setLoading(false);
      }
    };

    fetchChats();
  }, []);

  useEffect(() => {
    const onMigrated = () => {
      const token =
        typeof window !== 'undefined'
          ? localStorage.getItem('auth_token') ?? localStorage.getItem('access_token')
          : null;
      if (token) {
        fetch('/api/v1/library/threads', {
          headers: { Authorization: `Bearer ${token}` },
        })
          .then((r) => r.json())
          .then((data) => setChats(data.chats ?? []))
          .catch(() => setChats([]));
      }
    };
    window.addEventListener('gooseek:guest-migrated', onMigrated);
    return () => window.removeEventListener('gooseek:guest-migrated', onMigrated);
  }, []);

  const filteredChats = useMemo(() => {
    return chats.filter((chat) => {
      const matchesSearch =
        !searchQuery.trim() ||
        chat.title.toLowerCase().includes(searchQuery.trim().toLowerCase());

      const matchesSource =
        sourceFilter === 'all' ||
        chat.sources.some((s) => s === sourceFilter);

      const matchesFiles =
        filesFilter === 'all' ||
        (filesFilter === 'with' && chat.files.length > 0) ||
        (filesFilter === 'without' && chat.files.length === 0);

      return matchesSearch && matchesSource && matchesFiles;
    });
  }, [chats, searchQuery, sourceFilter, filesFilter]);

  return (
    <div>
      <div className="flex flex-col pt-10 border-b border-light-200/20 dark:border-dark-200/20 pb-6 px-2">
        <div className="flex flex-col lg:flex-row lg:items-end lg:justify-between gap-3">
          <div className="flex items-center justify-center">
            <MessagesSquare size={45} className="mb-2.5" />
            <div className="flex flex-col">
              <h1 className="text-5xl font-normal p-2 pb-0">
                {t('nav.messageHistory')}
              </h1>
              <div className="px-2 text-sm text-black/60 dark:text-white/60 text-center lg:text-left">
                Past chats, sources, and uploads.
              </div>
            </div>
          </div>

          <div className="flex items-center justify-center lg:justify-end gap-2 text-xs text-black/60 dark:text-white/60">
            <span className="inline-flex items-center gap-1 rounded-full border border-black/20 dark:border-white/20 px-2 py-0.5">
              <MessagesSquare size={14} />
              {loading && chats.length === 0
                ? '—'
                : `${chats.length} ${chats.length === 1 ? 'chat' : 'chats'}`}
            </span>
          </div>
        </div>
      </div>

      {(chats.length > 0 || loading) && (
        <div className="sticky top-0 z-10 flex flex-row flex-wrap items-center gap-2 pt-4 pb-2 px-2 bg-light-primary dark:bg-dark-primary border-b border-light-200/20 dark:border-dark-200/20">
          <div className="relative flex-1 min-w-[140px]">
            <Search
              size={18}
              className="absolute left-3 top-1/2 -translate-y-1/2 text-black/40 dark:text-white/40"
            />
            <input
              type="text"
              value={searchQuery}
              onChange={(e) => setSearchQuery(e.target.value)}
              placeholder={t('app.searchPlaceholder')}
              className="w-full pl-10 pr-4 py-2.5 text-sm bg-light-secondary dark:bg-dark-secondary border border-light-200 dark:border-dark-200 rounded-xl placeholder:text-black/40 dark:placeholder:text-white/40 text-black dark:text-white focus:outline-none focus:border-light-300 dark:focus:border-dark-300 transition-colors"
            />
          </div>
          <div className="flex flex-wrap items-center gap-2 shrink-0">
            <Filter size={16} className="text-black/50 dark:text-white/50" />
              <select
                value={sourceFilter}
                onChange={(e) =>
                  setSourceFilter(e.target.value as SourceKey | 'all')
                }
                className="text-xs py-1.5 px-3 rounded-lg bg-light-secondary dark:bg-dark-secondary border border-light-200 dark:border-dark-200 text-black dark:text-white focus:outline-none focus:ring-2 focus:ring-[#EA580C]/30"
              >
                <option value="all">{t('library.filterSourceAll')}</option>
                <option value="web">{t('library.filterSourceWeb')}</option>
                <option value="academic">{t('library.filterSourceAcademic')}</option>
                <option value="discussions">{t('library.filterSourceSocial')}</option>
              </select>
              <select
                value={filesFilter}
                onChange={(e) => setFilesFilter(e.target.value as FilesFilter)}
                className="text-xs py-1.5 px-3 rounded-lg bg-light-secondary dark:bg-dark-secondary border border-light-200 dark:border-dark-200 text-black dark:text-white focus:outline-none focus:ring-2 focus:ring-[#EA580C]/30"
              >
                <option value="all">{t('library.filterFilesAll')}</option>
                <option value="with">{t('library.filterFilesWith')}</option>
                <option value="without">{t('library.filterFilesWithout')}</option>
              </select>
          </div>
        </div>
      )}

      {loading && chats.length === 0 ? (
        <div className="pt-6 pb-28 px-2">
          <div className="rounded-2xl border border-light-200 dark:border-dark-200 overflow-hidden bg-light-primary dark:bg-dark-primary">
            {[1, 2, 3, 4].map((i) => (
              <div
                key={i}
                className="flex flex-col gap-2 p-4 border-b border-light-200 dark:border-dark-200 last:border-b-0"
              >
                <div className="h-5 w-3/4 rounded bg-light-200 dark:bg-dark-200 animate-pulse" />
                <div className="flex gap-2 mt-2">
                  <div className="h-4 w-16 rounded bg-light-200 dark:bg-dark-200 animate-pulse" />
                  <div className="h-4 w-24 rounded bg-light-200 dark:bg-dark-200 animate-pulse" />
                </div>
              </div>
            ))}
          </div>
        </div>
      ) : chats.length === 0 ? (
        <div className="flex flex-col items-center justify-center min-h-[70vh] px-2 text-center">
          <div className="flex items-center justify-center w-12 h-12 rounded-2xl border border-light-200 dark:border-dark-200 bg-light-secondary dark:bg-dark-secondary">
            <MessagesSquare className="text-black/70 dark:text-white/70" />
          </div>
          <p className="mt-2 text-black/70 dark:text-white/70 text-sm">
            No chats found.
          </p>
          <p className="mt-1 text-black/70 dark:text-white/70 text-sm">
            <Link href="/" className="text-[#EA580C]">
              Start a new chat
            </Link>{' '}
            to see it listed here.
          </p>
        </div>
      ) : filteredChats.length === 0 ? (
        <div className="flex flex-col items-center justify-center min-h-[50vh] px-2 text-center">
          <p className="text-black/70 dark:text-white/70 text-sm">
            {t('library.noResults')}
          </p>
          <button
            type="button"
            onClick={() => {
              setSearchQuery('');
              setSourceFilter('all');
              setFilesFilter('all');
            }}
            className="mt-2 text-sm text-[#EA580C] hover:underline"
          >
            {t('library.clearFilters')}
          </button>
        </div>
      ) : (
        <div className="pt-6 pb-28 px-2">
          <div className="rounded-2xl border border-light-200 dark:border-dark-200 overflow-hidden bg-light-primary dark:bg-dark-primary">
            {filteredChats.map((chat, index) => {
              const sourcesLabel =
                chat.sources.length === 0
                  ? null
                  : chat.sources.length <= 2
                    ? chat.sources
                        .map((s) => s.charAt(0).toUpperCase() + s.slice(1))
                        .join(', ')
                    : `${chat.sources
                        .slice(0, 2)
                        .map((s) => s.charAt(0).toUpperCase() + s.slice(1))
                        .join(', ')} + ${chat.sources.length - 2}`;

              return (
                <div
                  key={chat.id}
                  className={
                    'group flex flex-col gap-2 p-4 hover:bg-light-secondary dark:hover:bg-dark-secondary transition-colors duration-200 ' +
                    (index !== chats.length - 1
                      ? 'border-b border-light-200 dark:border-dark-200'
                      : '')
                  }
                >
                  <div className="flex items-start justify-between gap-3">
                    <Link
                      href={`/c/${chat.id}`}
                      className="flex-1 text-black dark:text-white text-base lg:text-lg font-medium leading-snug line-clamp-2 group-hover:text-[#EA580C] transition duration-200"
                      title={chat.title}
                    >
                      {chat.title}
                    </Link>
                    <div className="pt-0.5 shrink-0">
                      <DeleteChat
                        chatId={chat.id}
                        chats={chats}
                        setChats={setChats}
                      />
                    </div>
                  </div>

                  <div className="flex flex-wrap items-center gap-2 text-black/70 dark:text-white/70">
                    <span className="inline-flex items-center gap-1 text-xs">
                      <ClockIcon size={14} />
                      {formatTimeDifference(new Date(), chat.createdAt)} Ago
                    </span>

                    {sourcesLabel && (
                      <span className="inline-flex items-center gap-1 text-xs border border-black/20 dark:border-white/20 rounded-full px-2 py-0.5">
                        <Globe2Icon size={14} />
                        {sourcesLabel}
                      </span>
                    )}
                    {chat.files.length > 0 && (
                      <span className="inline-flex items-center gap-1 text-xs border border-black/20 dark:border-white/20 rounded-full px-2 py-0.5">
                        <FileText size={14} />
                        {chat.files.length}{' '}
                        {chat.files.length === 1 ? 'file' : 'files'}
                      </span>
                    )}
                  </div>
                </div>
              );
            })}
          </div>
        </div>
      )}
    </div>
  );
};

export default Page;