// import dagre from '@dagrejs/dagre'
import dagre from 'dagre'
import { Position, useVueFlow } from '@vue-flow/core'
import { ref } from 'vue'

/**
 * Composable to run the layout algorithm on the graph.
 * It uses the `dagre` library to calculate the layout of the nodes and edges.
 */
export function useLayout() {
	const { findNode } = useVueFlow()

	const graph = ref(new dagre.graphlib.Graph())

	const previousDirection = ref('LR')

	function layout(nodes, edges, direction = 'LR') {
		// 验证和规范化方向参数
		const validDirections = ['TB', 'BT', 'LR', 'RL']
		const layoutDirection = validDirections.includes(direction) ? direction : 'LR'

		// we create a new graph instance, in case some nodes/edges were removed, otherwise dagre would act as if they were still there
		const dagreGraph = new dagre.graphlib.Graph()

		graph.value = dagreGraph

		dagreGraph.setDefaultEdgeLabel(() => ({}))

		// 根据方向判断是否为水平布局
		const isHorizontal = layoutDirection === 'LR' || layoutDirection === 'RL'
		dagreGraph.setGraph({ rankdir: layoutDirection })

		previousDirection.value = layoutDirection

		for (const node of nodes) {
			// if you need width+height of nodes for your layout, you can use the dimensions property of the internal node (`GraphNode` type)
			const graphNode = findNode(node.id)

			dagreGraph.setNode(node.id, { width: graphNode.dimensions.width || 150, height: graphNode.dimensions.height || 50 })
		}

		for (const edge of edges) {
			dagreGraph.setEdge(edge.source, edge.target)
		}

		dagre.layout(dagreGraph)

		// set nodes with updated positions
		return nodes.map((node) => {
			const nodeWithPosition = dagreGraph.node(node.id)

			// 根据方向动态计算连接点位置
			let targetPosition, sourcePosition
			switch (layoutDirection) {
				case 'BT': // 从上到下 (Top to Bottom)
					targetPosition = Position.Bottom   // 目标节点连接点在下方
					sourcePosition = Position.Top // 源节点连接点在上方
					break
				case 'TB': // 从下到上 (Bottom to Top)
					targetPosition = Position.Top   // 目标节点连接点在上方
					sourcePosition = Position.Bottom // 源节点连接点在下方
					break
				case 'LR': // 从左到右 (Left to Right)
					targetPosition = Position.Left
					sourcePosition = Position.Right
					break
				case 'RL': // 从右到左 (Right to Left)
					targetPosition = Position.Right
					sourcePosition = Position.Left
					break
				default:
					targetPosition = Position.Top
					sourcePosition = Position.Bottom
			}

			return {
				...node,
				targetPosition,
				sourcePosition,
				position: { x: nodeWithPosition.x, y: nodeWithPosition.y },
			}
		})
	}

	return { graph, layout, previousDirection }
}