import {useQuery, useQueryClient} from "@tanstack/react-query";
import firestore from "@react-native-firebase/firestore";
import {useAuthContext} from "@/contexts/AuthContext";
import {useAtomValue} from "jotai";
import {isFamilyViewAtom} from "@/components/pages/calendar/atoms";
import {colorMap} from "@/constants/colorMap";
import {useEffect, useRef} from "react";

const createEventHash = (event: any): string => {
    const str = `${event.startDate?.seconds || ''}-${event.endDate?.seconds || ''}-${
        event.title || ''
    }-${event.location || ''}-${event.allDay ? 'true' : 'false'}`;

    let hash = 0;
    for (let i = 0; i < str.length; i++) {
        const char = str.charCodeAt(i);
        hash = ((hash << 5) - hash) + char;
        hash = hash & hash;
    }
    return hash.toString(36);
};

export const useGetEvents = () => {
    const {user, profileData} = useAuthContext();
    const isFamilyView = useAtomValue(isFamilyViewAtom);
    const queryClient = useQueryClient();
    const lastSyncTimestamp = useRef<number>(0);

    useEffect(() => {
        if (!profileData?.familyId) return;

        const unsubscribe = firestore()
            .collection('Households')
            .where("familyId", "==", profileData.familyId)
            .onSnapshot((snapshot) => {
                snapshot.docChanges().forEach((change) => {
                    if (change.type === 'modified') {
                        const data = change.doc.data();
                        if (data?.lastSyncTimestamp) {
                            const newTimestamp = data.lastSyncTimestamp.seconds;
                            if (newTimestamp > lastSyncTimestamp.current) {
                                lastSyncTimestamp.current = newTimestamp;
                                queryClient.invalidateQueries({queryKey: ["events", user?.uid, isFamilyView]});
                            }
                        }
                    }
                });
            }, console.error);

        return unsubscribe;
    }, [profileData?.familyId, user?.uid, isFamilyView, queryClient]);

    return useQuery({
        queryKey: ["events", user?.uid, isFamilyView],
        queryFn: async () => {
            const db = firestore();
            const userId = user?.uid;
            const familyId = profileData?.familyId;

            const eventsQuery = db.collection("Events");
            let constraints = [];

            if (isFamilyView) {
                constraints = [
                    eventsQuery
                        .where("familyId", "==", familyId)
                        .where("private", "==", false),
                    eventsQuery
                        .where("creatorId", "==", userId),
                    eventsQuery
                        .where("attendees", "array-contains", userId)
                ];
            } else {
                constraints = [
                    eventsQuery.where("creatorId", "==", userId),
                    eventsQuery.where("attendees", "array-contains", userId)
                ];
            }

            const snapshots = await Promise.all(
                constraints.map(query => query.get())
            );

            const uniqueEvents = new Map();
            const processedHashes = new Set();
            const creatorIds = new Set();

            snapshots.forEach(snapshot => {
                snapshot.docs.forEach(doc => {
                    const event = doc.data();
                    const hash = createEventHash(event);

                    if (!processedHashes.has(hash)) {
                        processedHashes.add(hash);
                        creatorIds.add(event.creatorId);
                        uniqueEvents.set(doc.id, event);
                    }
                });
            });

            const creatorIdsArray = Array.from(creatorIds);
            const creatorProfiles = new Map();

            for (let i = 0; i < creatorIdsArray.length; i += 10) {
                const chunk = creatorIdsArray.slice(i, i + 10);
                const profilesSnapshot = await db
                    .collection("Profiles")
                    .where(firestore.FieldPath.documentId(), "in", chunk)
                    .get();

                profilesSnapshot.docs.forEach(doc => {
                    creatorProfiles.set(doc.id, doc.data()?.eventColor || colorMap.pink);
                });
            }

            return Array.from(uniqueEvents.entries()).map(([id, event]) => {
                const startSeconds = event.startDate.seconds;
                const endSeconds = event.endDate.seconds;

                return {
                    ...event,
                    id,
                    start: event.allDay
                        ? new Date(new Date(startSeconds * 1000).setHours(0, 0, 0, 0))
                        : new Date(startSeconds * 1000),
                    end: event.allDay
                        ? new Date(new Date(endSeconds * 1000).setHours(0, 0, 0, 0))
                        : new Date(endSeconds * 1000),
                    hideHours: event.allDay,
                    eventColor: creatorProfiles.get(event.creatorId) || colorMap.pink,
                    notes: event.notes
                };
            });
        },
        staleTime: 5 * 60 * 1000,
        gcTime: Infinity,
        placeholderData: (previousData) => previousData,
    });
};