import { useState, useEffect } from 'react';
import { format } from 'date-fns';
import { useNavigate } from 'react-router-dom';
import { Calendar } from 'lucide-react';
import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
import { cn } from '@/lib/utils';

interface DashboardEvent {
  id: number;
  title: string;
  start_datetime: string;
  end_datetime: string;
  all_day: boolean;
  color?: string;
  is_starred?: boolean;
}

interface CalendarWidgetProps {
  events: DashboardEvent[];
}

function getEventTimeState(event: DashboardEvent, now: Date) {
  if (event.all_day) return 'all-day' as const;
  const start = new Date(event.start_datetime).getTime();
  const end = new Date(event.end_datetime).getTime();
  const current = now.getTime();
  if (current >= end) return 'past' as const;
  if (current >= start && current < end) return 'current' as const;
  return 'future' as const;
}

function getProgressPercent(event: DashboardEvent, now: Date): number {
  if (event.all_day) return 0;
  const start = new Date(event.start_datetime).getTime();
  const end = new Date(event.end_datetime).getTime();
  if (end <= start) return 0;
  const current = now.getTime();
  if (current >= end) return 100;
  if (current <= start) return 0;
  return Math.round(((current - start) / (end - start)) * 100);
}

export default function CalendarWidget({ events }: CalendarWidgetProps) {
  const navigate = useNavigate();
  const todayStr = format(new Date(), 'yyyy-MM-dd');
  const [clientNow, setClientNow] = useState(() => new Date());

  useEffect(() => {
    const interval = setInterval(() => setClientNow(new Date()), 60_000);
    return () => clearInterval(interval);
  }, []);

  const hasCurrentEvent = events.some((e) => getEventTimeState(e, clientNow) === 'current');

  return (
    <Card className={cn('hover:shadow-lg hover:shadow-accent/5 hover:border-accent/20 transition-all duration-200', hasCurrentEvent && 'animate-card-breathe')}>
      <CardHeader>
        <CardTitle className="flex items-center gap-2">
          <div className="p-1.5 rounded-md bg-purple-500/10">
            <Calendar className="h-4 w-4 text-purple-400" />
          </div>
          Today's Events
        </CardTitle>
      </CardHeader>
      <CardContent>
        {events.length === 0 ? (
          <div className="flex flex-col items-center justify-center py-6 gap-2">
            <div className="rounded-full bg-muted p-4">
              <Calendar className="h-8 w-8 text-muted-foreground" />
            </div>
            <p className="text-sm text-muted-foreground">Enjoy the free time</p>
          </div>
        ) : (
          <div className="space-y-0.5">
            {events.map((event) => {
              const timeState = getEventTimeState(event, clientNow);
              const progress = getProgressPercent(event, clientNow);
              const isCurrent = timeState === 'current';
              const isPast = timeState === 'past';

              return (
                <div
                  key={event.id}
                  onClick={() => navigate('/calendar', { state: { date: todayStr, view: 'timeGridDay', eventId: event.id } })}
                  className={cn(
                    'flex items-center gap-2 py-1.5 rounded-md hover:bg-card-elevated transition-colors duration-150 cursor-pointer relative pl-3.5',
                    isCurrent && 'bg-accent/[0.05]',
                    isPast && 'opacity-50'
                  )}
                >
                  {/* Time progress bar — always rendered for consistent layout */}
                  <div
                    className="absolute left-0 top-1 bottom-1 w-0.5 rounded-full overflow-hidden"
                    style={{ backgroundColor: event.all_day ? 'transparent' : 'hsl(var(--border))' }}
                  >
                    {!event.all_day && (
                      <div
                        className={cn('w-full rounded-full transition-all duration-1000', isPast && 'opacity-50')}
                        style={{
                          height: `${progress}%`,
                          backgroundColor: event.color || 'hsl(var(--accent-color))',
                        }}
                      />
                    )}
                  </div>
                  <div
                    className="w-1.5 h-1.5 rounded-full shrink-0"
                    style={{ backgroundColor: event.color || 'hsl(var(--primary))' }}
                  />
                  <span className="text-[11px] text-muted-foreground shrink-0 whitespace-nowrap tabular-nums">
                    {event.all_day
                      ? 'All day'
                      : `${format(new Date(event.start_datetime), 'h:mm a')} – ${format(new Date(event.end_datetime), 'h:mm a')}`}
                  </span>
                  <span className="text-sm font-medium truncate">{event.title}</span>
                </div>
              );
            })}
          </div>
        )}
      </CardContent>
    </Card>
  );
}