import dagre from "dagre";

export const NODE_W = 150;
export const NODE_H = 54;

/**
 * dagre 自动布局，返回带 position 的 nodes
 * @param {Array} nodes Vue Flow 节点（id 必须为字符串）
 * @param {Array} edges Vue Flow 边
 * @param {Object} opts { rankdir: TB|BT|LR|RL, nodeW, nodeH }
 */
export function layoutGraph(nodes, edges, opts = {}) {
	const { rankdir = "TB", nodeW = NODE_W, nodeH = NODE_H } = opts;
	const g = new dagre.graphlib.Graph();
	g.setGraph({ rankdir, nodesep: 30, ranksep: 56, marginx: 20, marginy: 20 });
	g.setDefaultEdgeLabel(() => ({}));
	nodes.forEach((n) => g.setNode(n.id, { width: nodeW, height: nodeH }));
	edges.forEach((e) => g.setEdge(e.source, e.target));
	dagre.layout(g);
	return nodes.map((n) => {
		const gn = g.node(n.id);
		return { ...n, position: { x: gn.x - nodeW / 2, y: gn.y - nodeH / 2 } };
	});
}