import ELK, { ElkNode } from "elkjs/lib/elk.bundled.js";
import { Unit, Behaviour } from "@incgame/engine";

const elk = new ELK();

const UNIT_WIDTH = 200;
const NODE_HEIGHT = 150;

export type GraphNode = {
    position: { x: number, y: number };
    kind: 'behaviour';
    entity: Behaviour;
}

export async function build2dNodes(units: Unit[], area: { width: number, height: number, padding: number }): Promise<GraphNode[]> {
    const entitiesById = new Map(units.map((unit) => [unit.behaviour.id, unit.behaviour]));

    const graph: ElkNode = {
        id: "root",
        layoutOptions: {
            "elk.algorithm": "layered",
            "elk.direction": "LEFT",
            "elk.spacing.nodeNode": "100",
            "elk.layered.spacing.nodeNodeBetweenLayers": "100",
        },
        children: units.map((unit) => ({
            id: unit.behaviour.id,
            width: UNIT_WIDTH,
            height: NODE_HEIGHT,
        })),
        edges: units.flatMap((node) =>
            node.behaviour.inputLinks.map((link, idx) => ({
                id: `${node.behaviour.id}->${link.target}.${idx}`,
                sources: [node.behaviour.id],
                targets: [link.target],
            }))
        ),
    };

    const layout = await elk.layout(graph);

    return (layout.children ?? []).map((child) => ({
        position: {
            x: (child.x ?? 0) + area.padding,
            y: (child.y ?? 0) + area.padding,
        },
        kind: 'behaviour',
        entity: entitiesById.get(child.id)!,
    }));
}