"use client";

import { useState, useEffect } from "react";
import { format, isToday, isTomorrow, addDays } from "date-fns";
import { fr } from "date-fns/locale";
import { CalendarIcon, ChevronRight } from "lucide-react";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { Button } from "@/components/ui/button";
import Link from "next/link";
import { useSession } from "next-auth/react";

type Event = {
  id: string;
  title: string;
  start: Date;
  end: Date;
  isAllDay: boolean;
  calendarId: string;
  calendarName?: string;
  calendarColor?: string;
};

export function CalendarWidget() {
  const { data: session, status } = useSession();
  const [events, setEvents] = useState<Event[]>([]);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    if (status === "loading") {
      return;
    }

    if (status !== "authenticated" || !session) {
      setLoading(false);
      return;
    }

    const fetchUpcomingEvents = async () => {
      try {
        setLoading(true);
        
        const response = await fetch('/api/calendars');

        if (!response.ok) {
          throw new Error("Impossible de charger les événements");
        }

        const calendarsData = await response.json();
        
        if (!Array.isArray(calendarsData)) {
          throw new Error("Format de données invalide");
        }

        const now = new Date();
        now.setHours(0, 0, 0, 0);
        
        const allEvents = calendarsData.flatMap((calendar) => {
          return (calendar.events || []).map((event: { 
            id: string; 
            title: string; 
            start: string; 
            end: string; 
            isAllDay: boolean; 
            calendarId: string; 
          }) => {
            const startDate = new Date(event.start);
            const endDate = new Date(event.end);
            return {
              id: event.id,
              title: event.title,
              start: startDate,
              end: endDate,
              isAllDay: event.isAllDay,
              calendarId: event.calendarId,
              calendarColor: calendar.color,
              calendarName: calendar.name
            };
          });
        });

        const upcomingEvents = allEvents
          .filter(event => event.start >= now)
          .sort((a, b) => a.start.getTime() - b.start.getTime())
          .slice(0, 5);

        setEvents(upcomingEvents);
        setError(null);
      } catch (err) {
        setError("Impossible de charger les événements à venir");
      } finally {
        setLoading(false);
      }
    };

    fetchUpcomingEvents();

    const intervalId = setInterval(fetchUpcomingEvents, 300000);

    return () => clearInterval(intervalId);
  }, [session, status]);

  const formatEventDate = (date: Date, isAllDay: boolean) => {
    let dateString = "";

    if (isToday(date)) {
      dateString = "Aujourd'hui";
    } else if (isTomorrow(date)) {
      dateString = "Demain";
    } else {
      dateString = format(date, "EEEE d MMMM", { locale: fr });
    }

    if (!isAllDay) {
      dateString += ` · ${format(date, "HH:mm", { locale: fr })}`;
    }

    return dateString;
  };

  return (
    <Card className='transition-transform duration-500 ease-in-out transform hover:scale-105'>
      <CardHeader className='flex flex-row items-center justify-between pb-2'>
        <CardTitle className='text-lg font-medium'>
          Événements à venir
        </CardTitle>
        <Link href='/calendar' passHref>
          <Button variant='ghost' size='sm' className='h-8 w-8 p-0'>
            <ChevronRight className='h-4 w-4' />
            <span className='sr-only'>Voir le calendrier</span>
          </Button>
        </Link>
      </CardHeader>
      <CardContent className='pb-3'>
        {loading ? (
          <div className='flex items-center justify-center py-4'>
            <div className='h-4 w-4 animate-spin rounded-full border-2 border-primary border-t-transparent' />
            <span className='ml-2 text-sm text-muted-foreground'>
              Chargement...
            </span>
          </div>
        ) : error ? (
          <p className='text-sm text-red-500'>{error}</p>
        ) : events.length === 0 ? (
          <p className='text-sm text-muted-foreground py-2'>
            Aucun événement à venir cette semaine
          </p>
        ) : (
          <div className='space-y-3'>
            {events.map((event) => (
              <div
                key={event.id}
                className='flex items-start space-x-3 rounded-md border border-muted p-2'
              >
                <div
                  className='h-3 w-3 flex-shrink-0 rounded-full mt-1'
                  style={{ backgroundColor: event.calendarColor || "#0082c9" }}
                />
                <div className='flex-1 min-w-0'>
                  <h5
                    className='text-sm font-medium truncate'
                    title={event.title}
                  >
                    {event.title}
                  </h5>
                  <div className='flex items-center text-xs text-muted-foreground mt-1'>
                    <CalendarIcon className='h-3 w-3 mr-1' />
                    <span>{formatEventDate(event.start, event.isAllDay)}</span>
                  </div>
                </div>
              </div>
            ))}
            <Link href='/calendar' passHref>
              <Button
                size='sm'
                className='w-full transition-all ease-in-out duration-500 bg-muted text-black hover:text-white hover:bg-primary'
              >
                Voir tous les événements
              </Button>
            </Link>
          </div>
        )}
      </CardContent>
    </Card>
  );
}