import { useCallback, useEffect, useState } from 'react';
import { Link } from 'react-router-dom';
import { ArrowLeft, Info, Sparkles } from 'lucide-react';
import { api } from '@/api';
import { Button } from '@/components/ui/button';
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';

export default function AboutPage() {
  const [about, setAbout] = useState(null);
  const [loading, setLoading] = useState(true);

  const load = useCallback(async () => {
    setLoading(true);
    try {
      setAbout(await api.about());
    } finally {
      setLoading(false);
    }
  }, []);

  useEffect(() => { load(); }, [load]);

  const stack = about?.stack || {};

  return (
    <div className="min-h-screen bg-[radial-gradient(circle_at_top_left,oklch(var(--primary)/0.10),transparent_34rem),linear-gradient(180deg,oklch(var(--background)),oklch(var(--muted)/0.28))] px-4 py-8 text-foreground sm:px-6">
      <main className="mx-auto w-full max-w-3xl space-y-5">
        <Button asChild variant="ghost" size="sm" className="-ml-2">
          <Link to="/login">
            <ArrowLeft className="h-3.5 w-3.5" />
            Back
          </Link>
        </Button>

        <Card className="border-border/70 bg-card/95 shadow-sm">
          <CardHeader>
            <div className="mb-2 flex h-10 w-10 items-center justify-center rounded-xl border border-border/70 bg-primary/10 text-primary">
              <Info className="h-5 w-5" />
            </div>
            <CardTitle className="text-2xl">{about?.name || 'BillTracker'}</CardTitle>
            <CardDescription>
              {loading ? 'Loading app information...' : about?.description}
            </CardDescription>
          </CardHeader>
          <CardContent className="space-y-5">
            <div className="grid gap-3 sm:grid-cols-3">
              <div className="rounded-xl border border-border/70 bg-background/65 p-4">
                <p className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">Version</p>
                <p className="mt-1 font-mono text-lg font-bold">v{about?.version || '...'}</p>
              </div>
              <div className="rounded-xl border border-border/70 bg-background/65 p-4">
                <p className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">Backend</p>
                <p className="mt-1 text-sm font-semibold">{stack.backend || 'Node.js / Express'}</p>
              </div>
              <div className="rounded-xl border border-border/70 bg-background/65 p-4">
                <p className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">Storage</p>
                <p className="mt-1 text-sm font-semibold">{stack.database || 'SQLite'}</p>
              </div>
            </div>

            <div className="rounded-xl border border-border/70 bg-muted/35 p-4">
              <div className="flex items-start gap-3">
                <Sparkles className="mt-0.5 h-4 w-4 shrink-0 text-primary" />
                <div>
                  <p className="text-sm font-semibold">Produced with AI assistance</p>
                  <p className="mt-1 text-sm leading-6 text-muted-foreground">
                    BillTracker is self-hosted software for personal bill planning and history. This product was produced with the assistance of AI.
                  </p>
                </div>
              </div>
            </div>

            <div className="flex flex-col gap-2 sm:flex-row">
              <Button asChild>
                <Link to="/release-notes">Release Notes</Link>
              </Button>
              <Button asChild variant="outline">
                <Link to="/login">Sign In</Link>
              </Button>
            </div>
          </CardContent>
        </Card>
      </main>
    </div>
  );
}