import { UnseenItemsEvent, UnseenResetCategoryComposer, UnseenResetItemsComposer } from '@nitrots/nitro-renderer';
import { useCallback, useMemo, useState } from 'react';
import { useBetween } from 'use-between';
import { SendMessageComposer } from '../../api';
import { useMessageEvent } from '../events';

const sendResetCategoryMessage = (category: number) => SendMessageComposer(new UnseenResetCategoryComposer(category));
const sendResetItemsMessage = (category: number, itemIds: number[]) => SendMessageComposer(new UnseenResetItemsComposer(category, ...itemIds));

const useInventoryUnseenTrackerState = () =>
{
    const [ unseenItems, setUnseenItems ] = useState<Map<number, number[]>>(new Map());

    const getCount = useCallback((category: number) => (unseenItems.get(category)?.length || 0), [ unseenItems ]);

    const getFullCount = useMemo(() =>
    {
        let count = 0;

        for(const key of unseenItems.keys()) count += getCount(key);

        return count;
    }, [ unseenItems, getCount ]);

    const resetCategory = useCallback((category: number) =>
    {
        let didReset = true;

        setUnseenItems(prevValue =>
        {
            if(!prevValue.has(category))
            {
                didReset = false;

                return prevValue;
            }

            const newValue = new Map(prevValue);

            newValue.delete(category);

            sendResetCategoryMessage(category);

            return newValue;
        });

        return didReset;
    }, []);

    const resetItems = useCallback((category: number, itemIds: number[]) =>
    {
        let didReset = true;

        setUnseenItems(prevValue =>
        {
            if(!prevValue.has(category))
            {
                didReset = false;

                return prevValue;
            }

            const newValue = new Map(prevValue);
            const existing = newValue.get(category);

            // Replace the per-category array instead of splicing the one still
            // referenced by the previous Map, and filter (an absent id used to
            // splice(indexOf=-1) and drop the wrong last element).
            if(existing) newValue.set(category, existing.filter(id => !itemIds.includes(id)));

            sendResetItemsMessage(category, itemIds);

            return newValue;
        });

        return didReset;
    }, []);

    const isUnseen = useCallback((category: number, itemId: number) =>
    {
        if(!unseenItems.has(category)) return false;

        const items = unseenItems.get(category);

        return (items.indexOf(itemId) >= 0);
    }, [ unseenItems ]);

    const removeUnseen = useCallback((category: number, itemId: number) =>
    {
        setUnseenItems(prevValue =>
        {
            if(!prevValue.has(category)) return prevValue;

            const newValue = new Map(prevValue);
            const items = newValue.get(category);

            // Clone the array rather than splicing the one shared with prevValue.
            if(items && items.indexOf(itemId) >= 0) newValue.set(category, items.filter(id => id !== itemId));

            return newValue;
        });
    }, []);

    useMessageEvent<UnseenItemsEvent>(UnseenItemsEvent, event =>
    {
        const parser = event.getParser();

        setUnseenItems(prevValue =>
        {
            const newValue = new Map(prevValue);

            for(const category of parser.categories)
            {
                // Clone the existing array so we never push into the one still
                // referenced by the previous (shallow-copied) Map.
                const merged = [ ...(newValue.get(category) ?? []) ];

                const itemIds = parser.getItemsByCategory(category);

                for(const itemId of itemIds) if(merged.indexOf(itemId) === -1) merged.push(itemId);

                newValue.set(category, merged);
            }

            return newValue;
        });
    });

    return { getCount, getFullCount, resetCategory, resetItems, isUnseen, removeUnseen };
};

export const useInventoryUnseenTracker = () => useBetween(useInventoryUnseenTrackerState);