import { api } from "@fileone/convex/api"
import type { Doc, Id } from "@fileone/convex/dataModel"
import * as Err from "@fileone/convex/error"
import {
	type DirectoryHandle,
	type FileSystemHandle,
	isSameHandle,
} from "@fileone/convex/filesystem"
import { useMutation } from "@tanstack/react-query"
import { useMutation as useContextMutation } from "convex/react"
import type { PrimitiveAtom } from "jotai"
import { useSetAtom, useStore } from "jotai"
import { useState } from "react"
import { toast } from "sonner"

export interface FileDragInfo {
	source: FileSystemHandle
	items: FileSystemHandle[]
}

export interface UseFileDropOptions {
	destItem: DirectoryHandle | null
	dragInfoAtom: PrimitiveAtom<FileDragInfo | null>
	onDropSuccess?: (
		items: Id<"files">[],
		targetDirectory: Doc<"directories">,
	) => void
}

export interface UseFileDropReturn {
	isDraggedOver: boolean
	dropHandlers: {
		onDrop: (e: React.DragEvent) => void
		onDragOver: (e: React.DragEvent) => void
		onDragLeave: () => void
	}
}

export function useFileDrop({
	destItem,
	dragInfoAtom,
}: UseFileDropOptions): UseFileDropReturn {
	const [isDraggedOver, setIsDraggedOver] = useState(false)
	const setDragInfo = useSetAtom(dragInfoAtom)
	const store = useStore()

	const { mutate: moveDroppedItems } = useMutation({
		mutationFn: useContextMutation(api.filesystem.moveItems),
		onSuccess: ({
			moved,
			errors,
		}: {
			moved: FileSystemHandle[]
			errors: Err.ApplicationErrorData[]
		}) => {
			const conflictCount = errors.reduce((acc, error) => {
				if (error.code === Err.Code.Conflict) {
					return acc + 1
				}
				return acc
			}, 0)
			if (conflictCount > 0) {
				toast.warning(
					`${moved.length} items moved${conflictCount > 0 ? `, ${conflictCount} conflicts` : ""}`,
				)
			} else {
				toast.success(`${moved.length} items moved!`)
			}
		},
	})

	const handleDrop = (_e: React.DragEvent) => {
		const dragInfo = store.get(dragInfoAtom)
		if (dragInfo && destItem) {
			const items = dragInfo.items.filter(
				(item) => !isSameHandle(item, destItem),
			)
			if (items.length > 0) {
				moveDroppedItems({
					targetDirectory: destItem,
					items,
				})
			}
		}
		setIsDraggedOver(false)
		setDragInfo(null)
	}

	const handleDragOver = (e: React.DragEvent) => {
		const dragInfo = store.get(dragInfoAtom)
		if (dragInfo && destItem) {
			e.preventDefault()
			e.dataTransfer.dropEffect = "move"
			setIsDraggedOver(true)
		} else {
			e.dataTransfer.dropEffect = "none"
		}
	}

	const handleDragLeave = () => {
		setIsDraggedOver(false)
	}

	return {
		isDraggedOver,
		dropHandlers: {
			onDrop: handleDrop,
			onDragOver: handleDragOver,
			onDragLeave: handleDragLeave,
		},
	}
}