'use client';

import { ArrowLeft, BarChart3 } from 'lucide-react';
import { useTranslations } from 'next-intl';
import { useEffect } from 'react';
import { ComparisonStatsBanner } from '@/components/comparison/comparison-stats';
import { ComparisonTable } from '@/components/comparison/comparison-table';
import { Button } from '@/components/ui/button';
import { Link } from '@/i18n/navigation';
import { fetchListingsForComparison } from '@/lib/comparison-api';
import { useComparisonStore, computeComparisonStats, MIN_COMPARE } from '@/lib/comparison-store';

export default function ComparePage() {
  const t = useTranslations('compare');
  const selectedIds = useComparisonStore((s) => s.selectedIds);
  const listings = useComparisonStore((s) => s.listings);
  const isLoading = useComparisonStore((s) => s.isLoading);
  const error = useComparisonStore((s) => s.error);
  const setListings = useComparisonStore((s) => s.setListings);
  const setLoading = useComparisonStore((s) => s.setLoading);
  const setError = useComparisonStore((s) => s.setError);
  const removeFromCompare = useComparisonStore((s) => s.removeFromCompare);
  const clearAll = useComparisonStore((s) => s.clearAll);

  useEffect(() => {
    if (selectedIds.length < MIN_COMPARE) return;

    let cancelled = false;

    async function load() {
      setLoading(true);
      try {
        const data = await fetchListingsForComparison(selectedIds);
        if (!cancelled) {
          setListings(data);
        }
      } catch {
        if (!cancelled) {
          setError(t('loadError'));
        }
      }
    }

    void load();
    return () => {
      cancelled = true;
    };
  }, [selectedIds.join(',')]);

  const stats = computeComparisonStats(listings);

  // Empty state — not enough listings selected
  if (selectedIds.length < MIN_COMPARE) {
    return (
      <div className="mx-auto max-w-7xl px-4 py-16">
        <div className="flex flex-col items-center justify-center text-center">
          <BarChart3 className="mb-4 h-16 w-16 text-muted-foreground/50" />
          <h1 className="text-2xl font-bold">{t('title')}</h1>
          <p className="mt-2 text-muted-foreground">{t('emptyState')}</p>
          <Link href="/search" className="mt-6">
            <Button className="gap-2">
              <ArrowLeft className="h-4 w-4" />
              {t('goToSearch')}
            </Button>
          </Link>
        </div>
      </div>
    );
  }

  // Loading state
  if (isLoading) {
    return (
      <div className="mx-auto max-w-7xl px-4 py-16">
        <div className="flex min-h-[400px] items-center justify-center">
          <div className="h-8 w-8 animate-spin rounded-full border-4 border-primary border-t-transparent" />
        </div>
      </div>
    );
  }

  // Error state
  if (error) {
    return (
      <div className="mx-auto max-w-7xl px-4 py-16">
        <div className="flex flex-col items-center justify-center gap-3 text-muted-foreground">
          <p className="text-lg font-medium">{error}</p>
          <Button variant="outline" size="sm" onClick={() => window.location.reload()}>
            {t('retry')}
          </Button>
        </div>
      </div>
    );
  }

  return (
    <div className="mx-auto max-w-7xl px-4 py-8">
      {/* Header */}
      <div className="mb-6 flex flex-col gap-4 sm:flex-row sm:items-center sm:justify-between">
        <div>
          <h1 className="text-2xl font-bold">{t('title')}</h1>
          <p className="mt-1 text-sm text-muted-foreground">
            {t('subtitle', { count: listings.length })}
          </p>
        </div>
        <div className="flex gap-2">
          <Link href="/search">
            <Button variant="outline" size="sm" className="gap-1">
              <ArrowLeft className="h-4 w-4" />
              {t('addMore')}
            </Button>
          </Link>
          <Button variant="ghost" size="sm" onClick={clearAll}>
            {t('clearAll')}
          </Button>
        </div>
      </div>

      {/* Stats summary */}
      {stats && (
        <div className="mb-6">
          <ComparisonStatsBanner stats={stats} />
        </div>
      )}

      {/* Comparison table */}
      <ComparisonTable listings={listings} onRemove={removeFromCompare} />
    </div>
  );
}