import { useMemo } from 'react';
import { format, startOfWeek, addDays, isSameDay, isBefore, startOfDay } from 'date-fns';
import type { UpcomingItem } from '@/types';
import { cn } from '@/lib/utils';

interface WeekTimelineProps {
  items: UpcomingItem[];
}

const typeColors: Record<string, string> = {
  todo: 'bg-blue-400',
  event: 'bg-purple-400',
  reminder: 'bg-orange-400',
};

export default function WeekTimeline({ items }: WeekTimelineProps) {
  const today = useMemo(() => startOfDay(new Date()), []);
  const weekStart = useMemo(() => startOfWeek(today, { weekStartsOn: 1 }), [today]);

  const days = useMemo(() => {
    return Array.from({ length: 7 }, (_, i) => {
      const date = addDays(weekStart, i);
      const dayItems = items.filter((item) => {
        const itemDate = item.datetime ? new Date(item.datetime) : new Date(item.date);
        return isSameDay(startOfDay(itemDate), date);
      });
      return {
        date,
        key: format(date, 'yyyy-MM-dd'),
        dayName: format(date, 'EEE'),
        dayNum: format(date, 'd'),
        isToday: isSameDay(date, today),
        isPast: isBefore(date, today),
        items: dayItems,
      };
    });
  }, [weekStart, today, items]);

  return (
    <div className="flex items-stretch gap-2">
      {days.map((day) => (
        <div
          key={day.key}
          className={cn(
            'flex-1 flex flex-col items-center gap-1.5 rounded-lg py-3 px-2 transition-all duration-200 border',
            day.isToday
              ? 'bg-accent/10 border-accent/30 shadow-[0_0_12px_hsl(var(--accent-color)/0.15)]'
              : day.isPast
                ? 'border-transparent opacity-50'
                : 'border-transparent hover:border-border/50'
          )}
        >
          <span
            className={cn(
              'text-[11px] font-medium uppercase tracking-wider',
              day.isToday ? 'text-accent' : 'text-muted-foreground'
            )}
          >
            {day.dayName}
          </span>
          <span
            className={cn(
              'font-heading text-lg font-semibold leading-none',
              day.isToday ? 'text-accent' : 'text-foreground'
            )}
          >
            {day.dayNum}
          </span>
          <div className="flex items-center gap-1 mt-0.5 min-h-[8px]">
            {day.items.slice(0, 4).map((item) => (
              <div
                key={`${item.type}-${item.id}`}
                className={cn(
                  'w-1.5 h-1.5 rounded-full',
                  !item.color && (typeColors[item.type] || 'bg-muted-foreground')
                )}
                style={item.color ? { backgroundColor: item.color } : undefined}
              />
            ))}
            {day.items.length > 4 && (
              <span className="text-[9px] text-muted-foreground font-medium">
                +{day.items.length - 4}
              </span>
            )}
          </div>
        </div>
      ))}
    </div>
  );
}