/**
 * {@link Coord}s assign `x` coordinates to every node, while
 * respecting the {@link SugiSeparation}.
 *
 * @packageDocumentation
 */
import type { SugiNode, SugiSeparation } from "../sugify";
/**
 * an operator that assigns coordinates to layered {@link SugiNode}s
 *
 * This function must assign each node an `x` coordinate, and return the width
 * of the layout. The `x` coordinates should satisfy the
 * {@link SugiSeparation}, and all be between zero and the returned width.
 *
 * @example
 *
 * In order to illustrate what it might look like, below we demonstrate a
 * coordinate operator that assigns an x attached to the nodes themselves. If
 * the node is a dummy node (e.g. a point on an edge between two nodes), then
 * instead we average the coordinate. Note that this isn't compliant since it
 * might not respect `sep`, and is therefore only an illustration.
 *
 * ```ts
 * customCoord<N extends { x: number }, L>(layers: SugiNode<N, L>[][], sep: SugiSeparation<N, L>): number {
 *     // determine span of xs
 *     let min = Infinity;
 *     let max = -Infinity;
 *     for (const layer of layers) {
 *         for (const node of layer) {
 *             const { data } = node;
 *             const x = node.x = data.role === "node" ? data.node.data.x : (data.link.source.data.x + data.link.target.data.x) / 2;
 *             min = Math.min(min, x - sep(undefined, node));
 *             max = Math.max(max, x + sep(node, undefined));
 *         }
 *     }
 *     // assign xs
 *     for (const node of dag) {
 *         node.x = -= min;
 *     }
 *     return max - min;
 * }
 * ```
 */
export interface Coord<in NodeDatum = never, in LinkDatum = never> {
    /**
     * assign coordinates to a layered graph
     *
     * @param layers - a layered graph of sugiyama nodes
     * @param sep - how much horizontal separation should exist between nodes
     * @returns width - the total width of the layout
     */
    <N extends NodeDatum, L extends LinkDatum>(layers: SugiNode<N, L>[][], sep: SugiSeparation<N, L>): number;
    /**
     * This sentinel field is so that typescript can infer the types of NodeDatum
     * and LinkDatum, because the extra generics make it otherwise hard to infer.
     * It's a function to keep the same variance.
     *
     * @internal
     */
    __sentinel__?: (_: NodeDatum, __: LinkDatum) => void;
}