import { VertexBuffer } from "../../Meshes/buffer";
import { Nullable } from "../../types";
import { WebGPUCacheRenderPipeline } from "./webgpuCacheRenderPipeline";

class NodeState {
    public values: { [name: number]: NodeState };
    public pipeline: GPURenderPipeline;

    constructor() {
        this.values = {};
    }

    public count(): [number, number] {
        let countNode = 0, countPipeline = this.pipeline ? 1 : 0;
        for (const value in this.values) {
            const node = this.values[value];
            const [childCountNodes, childCoundPipeline] = node!.count();
            countNode += childCountNodes;
            countPipeline += childCoundPipeline;
            countNode++;
        }
        return [countNode, countPipeline];
    }
}

/** @hidden */
export class WebGPUCacheRenderPipelineTree extends WebGPUCacheRenderPipeline {

    private static _Cache: NodeState = new NodeState();

    private _nodeStack: NodeState[];

    public static GetNodeCounts(): { nodeCount: number, pipelineCount: number } {
        const counts = WebGPUCacheRenderPipelineTree._Cache.count();

        return { nodeCount: counts[0], pipelineCount: counts[1] };
    }

    constructor(device: GPUDevice, emptyVertexBuffer: VertexBuffer) {
        super(device, emptyVertexBuffer);
        this._nodeStack = [];
        this._nodeStack[0] = WebGPUCacheRenderPipelineTree._Cache;
    }

    protected _getRenderPipeline(param: { token: any, pipeline: Nullable<GPURenderPipeline> }): void {
        let node = this._nodeStack[this._stateDirtyLowestIndex];
        for (let i = this._stateDirtyLowestIndex; i < this._states.length; ++i) {
            let nn: NodeState | undefined = node!.values[this._states[i]];
            if (!nn) {
                nn = new NodeState();
                node!.values[this._states[i]] = nn;
            }
            node = nn;
            this._nodeStack[i + 1] = node;
        }

        param.token = node;
        param.pipeline = node.pipeline;
    }

    protected _setRenderPipeline(param: { token: NodeState, pipeline: Nullable<GPURenderPipeline> }): void {
        param.token.pipeline = param.pipeline!;
    }
}