import { CSSProperties, ReactNode, useState } from 'react';

import { NavbarItem } from '../components/navbar';

import KeyboardArrowDownRoundedIcon from '@material-ui/icons/KeyboardArrowDownRounded';
import RemoveRoundedIcon from '@material-ui/icons/RemoveRounded';

export interface chapter {
	name: string;
	sectionLink?: string;
	children?: Array<chapter>;
}

function NavbarChapter(props: {
	level: number;
	chapter: chapter;
	children?: ReactNode;
}) {
	var [collapsed, setCollapsed] = useState(true);

	var icon = <div className={'collapseIcon' + (collapsed ? '' : ' collapsed')}>
		{props.chapter.children?.length > 0
			? <KeyboardArrowDownRoundedIcon />
			: <RemoveRoundedIcon />}
	</div>;

	var classes = [
		'chapter',
		`indentLevel${props.level}`,
	];
	!collapsed && classes.push('childrenCollapsed');

	var outercss = /* { "--children-height": 0 + "px" } */ {} as CSSProperties;

	return <NavbarItem
		icon={icon}
		classList={classes}
		title={props.chapter.name}
		onIconClick={() => props.chapter.children?.length > 0 && setCollapsed(!collapsed)}
		href={props.chapter.sectionLink}
		key={(() => Math.round(Math.random() * 1e12))()}
		style={{
			marginLeft: 12 * props.level,
		}}
		outerStyle={outercss}
	>
		{props.children}
	</NavbarItem>;
}

class Chapter {
	constructor(public chapters: Array<chapter>, public level: number) {}
	render() {
		return <div className='chapterChildren'>
			{this.chapters?.map(chapter => {
				return <NavbarChapter level={this.level} chapter={chapter}>
					{new Chapter(chapter.children, this.level + 1).render()}
				</NavbarChapter>;
			})}
		</div>;
	}
}

export default function Chapters(props: {
	chapters: Array<chapter>;
}) {
	return new Chapter(props.chapters, 0).render();
}