import Tree from 'rc-tree';
import type { DataNode, EventDataNode } from 'rc-tree/lib/interface';
import { type Key, useMemo, useState } from 'react';
import { useNavigate } from 'react-router';
import type { MultiLang } from '../../config';
import Functions from '../../functions';
import IndexUtil, { INDEX_ID_PUBLIC, type Index } from '../lib/IndexUtil';
import styles from './IndexTree.module.css';

interface Props {
    lang: MultiLang;
}

interface TreeData {
    elements: DataNode[];
    expandableKeys: string[];
    defaultExpandedKeys: string[];
}

const load = (lang: MultiLang): TreeData => {
    const expandableKeys: string[] = [];
    const defaultExpandedKeys: string[] = [];
    const makeTreeNode = (index: Index, depth: number): DataNode => {
        const title = Functions.mlang(index.title, lang) + (index.numOfItems > 0 ? ` (${index.numOfItems})` : '');
        const children = IndexUtil.getChildren(index.id);
        if (children.length === 0) {
            return { key: String(index.id), title: title };
        }
        const childTreeNodes = children.map((value: Index) => makeTreeNode(value, depth + 1));
        if (depth < 1) {
            defaultExpandedKeys.push(String(index.id));
        }
        expandableKeys.push(String(index.id));
        return { key: String(index.id), title: title, children: childTreeNodes };
    };
    const elements: DataNode[] = [];
    const index = IndexUtil.get(INDEX_ID_PUBLIC);
    if (index !== null) {
        elements.push(makeTreeNode(index, 0));
    }
    return { elements, expandableKeys, defaultExpandedKeys };
};

const toStringKeys = (keys: Key[]): string[] => keys.map((key) => (typeof key === 'string' ? key : String(key)));

const IndexTree = (props: Props) => {
    const { lang } = props;
    const data = useMemo(() => load(lang), [lang]);
    const [expandedKeys, setExpandedKeys] = useState<string[]>(data.defaultExpandedKeys);
    const navigate = useNavigate();

    const handleExpand = (
        keys: Key[],
        _info: { node: EventDataNode<DataNode>; expanded: boolean; nativeEvent: MouseEvent }
    ) => {
        setExpandedKeys(toStringKeys(keys));
    };

    const handleSelect = (
        selectedKeys: Key[],
        _info: {
            event: 'select';
            selected: boolean;
            node: EventDataNode<DataNode>;
            selectedNodes: DataNode[];
            nativeEvent: MouseEvent;
        }
    ) => {
        const selectedKey = selectedKeys[0] ?? 0;
        const key = typeof selectedKey === 'string' ? parseInt(selectedKey, 10) : Number(selectedKey);
        void navigate(IndexUtil.getUrl(key));
    };

    return (
        <div className={styles.container}>
            <button type="button" className={styles.formButton} onClick={() => setExpandedKeys(data.expandableKeys)}>
                open all
            </button>
            <button type="button" className={styles.formButton} onClick={() => setExpandedKeys([])}>
                close all
            </button>
            <Tree
                className={styles.indexTree}
                expandedKeys={expandedKeys}
                selectedKeys={[]}
                onExpand={handleExpand}
                onSelect={handleSelect}
                showIcon={false}
                treeData={data.elements}
            />
        </div>
    );
};

export default IndexTree;