'use client';

import Link from 'next/link';
import type { Route } from 'next';
import { useParams } from 'next/navigation';
import { useQuery } from '@tanstack/react-query';
import { ArrowRight, Globe } from 'lucide-react';

import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
import { Skeleton } from '@/components/ui/skeleton';
import { apiFetch } from '@/lib/api/client';
import { CountryFlag } from '@/components/shared/country-flag';
import { getCountryName } from '@/lib/i18n/countries';
import { cn } from '@/lib/utils';

interface ClientsByCountryRow {
  country: string;
  count: number;
}

interface ClientsByCountryResponse {
  data: ClientsByCountryRow[];
  total: number;
}

/**
 * Compact ranked-list widget showing the per-country distribution of
 * non-archived clients. Designed to fit the rail tile footprint (no
 * external chart library); the mini-bar per row gives leadership an
 * at-a-glance feel for whether the book is concentrated or diverse.
 *
 * Each row deep-links to `/clients?country=<ISO>` so the rep can drill
 * into a specific market. Country names render via the existing
 * locale-aware helper; unknown ISO codes fall back to the raw code.
 *
 * Variant (b) of the master-doc design - a true choropleth would need
 * a heavier viz lib (react-simple-maps + topojson) and pushes us to
 * the chart-library migration agenda. Variant (a) ships now; the
 * world-map variant can land alongside the recharts→ECharts pass.
 */
export function ClientsByCountryWidget({ limit = 8 }: { limit?: number } = {}) {
  const params = useParams<{ portSlug: string }>();
  const portSlug = params?.portSlug ?? '';

  const { data, isLoading } = useQuery<ClientsByCountryResponse>({
    queryKey: ['dashboard', 'clients-by-country'],
    queryFn: () => apiFetch<ClientsByCountryResponse>('/api/v1/dashboard/clients-by-country'),
    staleTime: 60_000,
  });

  if (isLoading) {
    return (
      <Card>
        <CardHeader>
          <CardTitle className="text-base">Clients by country</CardTitle>
          <CardDescription>Distribution of the active client book.</CardDescription>
        </CardHeader>
        <CardContent className="space-y-2">
          {Array.from({ length: 4 }).map((_, i) => (
            <Skeleton key={i} className="h-6 w-full" aria-hidden />
          ))}
        </CardContent>
      </Card>
    );
  }

  const rows = data?.data ?? [];
  const visibleRows = rows.slice(0, limit);
  const hiddenCount = Math.max(0, rows.length - limit);
  const maxCount = visibleRows.reduce((m, r) => Math.max(m, r.count), 0) || 1;

  return (
    <Card className="h-full flex flex-col">
      <CardHeader>
        <CardTitle className="text-base flex items-center gap-2">
          <Globe className="size-4 text-muted-foreground" aria-hidden />
          Clients by country
        </CardTitle>
        <CardDescription>
          {rows.length === 0
            ? 'No clients with a country recorded yet.'
            : `${data?.total ?? rows.reduce((s, r) => s + r.count, 0)} client${rows.length === 1 ? '' : 's'} across ${rows.length} ${rows.length === 1 ? 'country' : 'countries'}.`}
        </CardDescription>
      </CardHeader>
      <CardContent className="flex-1">
        {rows.length === 0 ? (
          <div className="flex h-32 items-center justify-center text-sm text-muted-foreground">
            Distribution will appear once clients capture a nationality.
          </div>
        ) : (
          <ol className="space-y-1.5">
            {visibleRows.map((row) => {
              const pct = (row.count / maxCount) * 100;
              const name = getCountryName(row.country) || row.country;
              return (
                <li key={row.country}>
                  <Link
                    href={
                      `/${portSlug}/clients?nationality=${encodeURIComponent(row.country)}` as Route
                    }
                    className="group flex items-center justify-between gap-3 rounded-md px-2 py-1.5 -mx-2 hover:bg-foreground/5"
                    title={`${row.count} client${row.count === 1 ? '' : 's'} in ${name}`}
                  >
                    <div className="flex min-w-0 flex-1 items-center gap-2.5">
                      <CountryFlag code={row.country} className="h-3.5 w-5" decorative />
                      <span className="truncate text-sm">{name}</span>
                    </div>
                    {/* Mini bar - same `BerthHeatWidget` idiom: a thin
                        background track with a coloured fill. The count
                        sits on the right so the eye can read both the
                        bar shape and the precise number. */}
                    <div className="flex shrink-0 items-center gap-2">
                      <div className="h-1.5 w-16 overflow-hidden rounded-full bg-muted">
                        <div
                          className={cn('h-full rounded-full bg-brand-500 transition-[width]')}
                          style={{ width: `${pct}%` }}
                          aria-hidden
                        />
                      </div>
                      <span className="w-7 text-right text-xs tabular-nums text-foreground">
                        {row.count}
                      </span>
                    </div>
                  </Link>
                </li>
              );
            })}
            {hiddenCount > 0 ? (
              <li className="border-t pt-2 text-right">
                <Link
                  href={`/${portSlug}/clients/by-country` as Route}
                  className="inline-flex items-center gap-1 text-xs font-medium text-muted-foreground hover:text-foreground"
                >
                  Show all {rows.length} countries
                  <ArrowRight className="size-3" aria-hidden />
                </Link>
              </li>
            ) : null}
          </ol>
        )}
      </CardContent>
    </Card>
  );
}
