import React, { useRef, useCallback } from "react"
import { useVirtualizer, VirtualItem } from "@tanstack/react-virtual"
import { Link as LinkSchema, Section as SectionSchema, Topic } from "@/lib/schema"
import { LinkItem } from "./partials/link-item"
import { useAccountOrGuest } from "@/lib/providers/jazz-provider"

export type FlattenedItem = { type: "link"; data: LinkSchema | null } | { type: "section"; data: SectionSchema | null }

interface TopicDetailListProps {
	items: FlattenedItem[]
	topic: Topic
	activeIndex: number
	setActiveIndex: (index: number) => void
}

export function TopicDetailList({ items, topic, activeIndex, setActiveIndex }: TopicDetailListProps) {
	const { me } = useAccountOrGuest({ root: { personalLinks: [] } })
	const personalLinks = !me || me._type === "Anonymous" ? undefined : me.root.personalLinks

	const parentRef = useRef<HTMLDivElement>(null)

	const virtualizer = useVirtualizer({
		count: items.length,
		getScrollElement: () => parentRef.current,
		estimateSize: () => 44,
		overscan: 5
	})

	const renderItem = useCallback(
		(virtualRow: VirtualItem) => {
			const item = items[virtualRow.index]

			if (item.type === "section") {
				return (
					<div
						key={virtualRow.key}
						data-index={virtualRow.index}
						ref={virtualizer.measureElement}
						className="flex flex-col"
					>
						<div className="flex items-center gap-4 px-6 py-2 max-lg:px-4">
							<p className="text-foreground text-sm font-medium">{item.data?.title}</p>
							<div className="flex-1 border-b" />
						</div>
					</div>
				)
			}

			if (item.data?.id) {
				return (
					<LinkItem
						key={virtualRow.key}
						data-index={virtualRow.index}
						ref={virtualizer.measureElement}
						topic={topic}
						link={item.data as LinkSchema}
						isActive={activeIndex === virtualRow.index}
						index={virtualRow.index}
						setActiveIndex={setActiveIndex}
						personalLinks={personalLinks}
					/>
				)
			}

			return null
		},
		[items, topic, activeIndex, setActiveIndex, virtualizer, personalLinks]
	)

	return (
		<div ref={parentRef} className="flex-1 overflow-auto">
			<div
				style={{
					height: `${virtualizer.getTotalSize()}px`,
					width: "100%",
					position: "relative"
				}}
			>
				<div
					style={{
						position: "absolute",
						top: 0,
						left: 0,
						width: "100%",
						transform: `translateY(${virtualizer.getVirtualItems()[0]?.start ?? 0}px)`
					}}
				>
					{virtualizer.getVirtualItems().map(renderItem)}
				</div>
			</div>
		</div>
	)
}