import { GpuFragmentParams, KitTexture } from '../contract';

/** The resolver the pass manager passes to `bindInputs`: texture key → bound texture. */
type InputResolver = (key: string) => {
    texture: unknown;
} | undefined;
export interface LateBoundChildInput<TGroups> {
    /**
     * The child's RTT handle. Put it in the compute node's `outputs` so the fragment can sample
     * the same texture (`computeOutputs.childTexture`) instead of RTT-ing the child twice.
     */
    readonly childTexture: KitTexture;
    /** Hand straight to the compute node's `bindInputs`. */
    bindInputs: (resolve: InputResolver) => void;
    /**
     * The bind groups built by `buildGroups`, or `null` while the child RTT is still unallocated.
     * The canonical first line of `getComputeNodes` is `const g = child.bound(); if (!g) return null`.
     */
    bound(): TGroups | null;
    /** Boolean form of {@link bound}, for readability in tests and guards. */
    ready(): boolean;
}
/**
 * Name a compute hook's child input and defer its bind-group construction to `bindInputs`.
 *
 * `buildGroups` receives the resolved child texture — already cast to the type
 * `root.createBindGroup` accepts — and returns whatever collection of bind groups the shader
 * needs (a single group, a `{a, b}` orientation pair, an object of several). It re-runs on every
 * recompose, so anything it allocates must be safe to rebuild.
 *
 * Returns `null` when the node has no child at all, so a child-REQUIRED shader can write
 * `if (!child) return null` and inherit the "no child → no compute" branch.
 *
 * @example
 * const child = createLateBoundChildInput(params, (src) => ({
 *     bg: root.createBindGroup(layout, {src, prev: stateA, next: stateB, params: buf.buffer}),
 * }))
 * if (!child) return null
 * return {
 *     outputs: {childTexture: child.childTexture, display},
 *     bindInputs: child.bindInputs,
 *     getComputeNodes: () => {
 *         const g = child.bound()
 *         if (!g) return null
 *         return [pipeline.with(g.bg)]
 *     },
 * }
 */
export declare function createLateBoundChildInput<TGroups>(params: GpuFragmentParams, buildGroups: (childTexture: never) => TGroups): LateBoundChildInput<TGroups> | null;
export {};
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