import { CircularProgress, List, ListItem, Box, useTheme, Pagination } from "@mui/material";
import { useEffect, useState } from "react";
import TicketCard from "./TicketCard";
import { useSnackbar } from "notistack";
import { apiRequestHandler } from "@utils/api/apiRequestHandler";
import { ApiError, Ticket } from "@utils/api/types";


const TICKETS_PER_PAGE = 10;

export default function TicketList() {
    const theme = useTheme();
    const { enqueueSnackbar } = useSnackbar();
    const [tickets, setTickets] = useState<Ticket[]>([]);
    const [ticketCount, setTicketCount] = useState<number | null>(null);
    const [currentPage, setCurrentPage] = useState<number>(0);
    const [isLoading, setIsLoading] = useState<boolean>(false);

    useEffect(function fetchTickets() {
        setIsLoading(true);
        const abortController = new AbortController();

        apiRequestHandler
            .getTickets({ amt: TICKETS_PER_PAGE, page: currentPage, srch: "", status: "open" }, abortController.signal)
            .then((result) => {
                if (result instanceof ApiError) {
                    enqueueSnackbar(`Error: ${result.message}`);
                } else if (result instanceof Error) {
                    console.log(result);
                } else {
                    setTickets(result.data);
                    setTicketCount(result.count);
                    setIsLoading(false);
                }
            });

        return () => {
            abortController.abort();
        };
    }, [currentPage, enqueueSnackbar]);

    useEffect(function subscribeToTickets() {
        const unsubscribe = apiRequestHandler.subscribeToAllTickets({
            onMessage(event) {
                console.log("SSE received:", event.data);
                try {
                    const newTicket = JSON.parse(event.data) as Ticket;
                    const existingTicketIndex = tickets.findIndex((ticket) => ticket.id === newTicket.id);
                    if (existingTicketIndex !== -1) {
                        setTickets((prevTickets) => {
                            const newTickets = prevTickets.slice();
                            newTickets.splice(existingTicketIndex, 1, newTicket);
                            return newTickets;
                        });
                        return;
                    }
                    setTickets((prevTickets) => [newTicket, ...prevTickets.slice(0, TICKETS_PER_PAGE - 1)]);
                } catch (error) {
                    console.log("SSE is not JSON", error);
                }
            },
            onError(event) {
                console.log("SSE Error:", event);
            },
        });

        return () => {
            unsubscribe();
        };
    }, [tickets]);

    return (
        <Box
            sx={{
                display: "flex",
                gap: "40px",
                flexDirection: "column",
            }}
        >
            <List
                sx={{
                    p: 0,
                    display: "flex",
                    flexDirection: "column",
                    gap: "40px",
                    opacity: isLoading ? 0.4 : 1,
                    transitionProperty: "opacity",
                    transitionDuration: "200ms",
                }}
            >
                {tickets.map((ticket) => (
                    <ListItem key={ticket.id} disablePadding>
                        <TicketCard
                            name={ticket.title}
                            body={ticket.top_message.message}
                            time={new Date(ticket.updated_at).toLocaleDateString()}
                            ticketId={ticket.id}
                        />
                    </ListItem>
                ))}
                {isLoading && (
                    <Box
                        sx={{
                            position: "absolute",
                            width: "100%",
                            height: "100%",
                            minHeight: "80px",
                            display: "flex",
                            alignItems: "center",
                            justifyContent: "center",
                        }}
                    >
                        <CircularProgress sx={{ color: theme.palette.brightPurple.main }} size={60} />
                    </Box>
                )}
            </List>
            {ticketCount !== null && ticketCount > TICKETS_PER_PAGE && (
                <Pagination
                    count={Math.ceil(ticketCount / TICKETS_PER_PAGE)}
                    page={currentPage + 1}
                    onChange={(e, value) => setCurrentPage(value - 1)}
                    sx={{ alignSelf: "center" }}
                />
            )}
        </Box>
    );
}