import type { ErrorReport } from "../../../protocol/error";
import type { ProgressEvent } from "../../../protocol/progress";
import type {
  AssetRequestResult,
  MeshGeometryBuffer,
  WebEngineEditCommand,
  WebEngineLODResult,
  WebEngineRequest,
  WebEngineResponse,
  WebEngineResult,
  WebEngineStatus,
} from "../../../protocol/web-engine";
import type { LODGenerationRequest } from "../../../protocol/lod";
import type { SceneSnapshotIR } from "../../../protocol/scene-ir";
import type { SceneDelta } from "../../../protocol/scene-delta";
import type { NonMeshGeometryChunk } from "../../../protocol/nonmesh-binary";
import type { SimplifyResult } from "../../../protocol/simplify";
import type { DepsgraphEvaluationIR } from "../../../protocol/depsgraph";
import type { RenderCapabilityRequest } from "../../../protocol/render-capabilities";
import type { CapabilityGateResult } from "../../../protocol/capability-gates";
import { applyMeshGeometryDelta } from "../../../protocol/mesh-geometry-delta";

interface PendingRequest {
  resolve: (result: WebEngineResult) => void;
  reject: (error: ErrorReport) => void;
  onProgress?: (progress: ProgressEvent) => void;
  timer: ReturnType<typeof setTimeout>;
}

export interface WebEngineClientOptions {
  timeoutMs?: number;
  workerFactory?: () => Worker;
}

const defaultWorkerFactory = () =>
  new Worker(new URL("../workers/web-engine.worker.ts", import.meta.url), { type: "module" });

export interface BlendOpenResult {
  status: WebEngineStatus;
  snapshot: SceneSnapshotIR;
  geometryBuffers: MeshGeometryBuffer[];
  nonMeshGeometryBuffers?: NonMeshGeometryChunk[];
  simplify?: SimplifyResult;
}

export class WebEngineClient {
  private readonly timeoutMs: number;
  private readonly workerFactory: () => Worker;
  private worker: Worker | null = null;
  private requestCounter = 0;
  private pending = new Map<string, PendingRequest>();
  private geometryBuffers: MeshGeometryBuffer[] = [];
  private nonMeshGeometryBuffers: NonMeshGeometryChunk[] = [];

  constructor(options: WebEngineClientOptions = {}) {
    this.timeoutMs = options.timeoutMs ?? 30_000;
    this.workerFactory = options.workerFactory ?? defaultWorkerFactory;
  }

  async init(): Promise<WebEngineStatus> {
    return (await this.request({ type: "init" })).status;
  }

  async openBlend(buffer: ArrayBuffer, onProgress?: (progress: ProgressEvent) => void): Promise<BlendOpenResult> {
    if (buffer.byteLength === 0) {
      throw this.report("INVALID_ARGUMENT", "无法打开空的 .blend 文件", true);
    }
    const result = await this.request({ type: "openBlend", buffer }, [buffer], onProgress);
    if (!result.snapshot) throw this.report("BLEND_READ_FAILED", "WebEngine 未返回 SceneIR", true);
    this.geometryBuffers = result.geometryBuffers ?? [];
    this.nonMeshGeometryBuffers = result.nonMeshGeometryBuffers ?? [];
    return { status: result.status, snapshot: result.snapshot, geometryBuffers: [...this.geometryBuffers], nonMeshGeometryBuffers: [...this.nonMeshGeometryBuffers] };
  }

  async snapshot(): Promise<BlendOpenResult> {
    const result = await this.request({ type: "snapshot" });
    if (!result.snapshot) throw this.report("INVALID_ARGUMENT", "WebEngine 未返回 SceneIR", true);
    this.geometryBuffers = result.geometryBuffers ?? this.geometryBuffers;
    this.nonMeshGeometryBuffers = result.nonMeshGeometryBuffers ?? this.nonMeshGeometryBuffers;
    return { status: result.status, snapshot: result.snapshot, geometryBuffers: [...this.geometryBuffers], nonMeshGeometryBuffers: [...this.nonMeshGeometryBuffers] };
  }

  async delta(): Promise<{ status: WebEngineStatus; delta: SceneDelta }> {
    const result = await this.request({ type: "delta" });
    if (!result.delta) throw this.report("INVALID_ARGUMENT", "WebEngine 未返回 SceneDelta", true);
    return { status: result.status, delta: result.delta };
  }

  async applyCommand(payload: WebEngineEditCommand): Promise<BlendOpenResult & { delta: SceneDelta }> {
    const result = await this.request({ type: "applyCommand", payload });
    if (!result.snapshot || !result.delta) throw this.report("INVALID_ARGUMENT", "WebEngine 未返回命令结果", true);
    this.geometryBuffers = result.geometryDelta
      ? applyMeshGeometryDelta(this.geometryBuffers, result.geometryDelta)
      : result.geometryBuffers ?? this.geometryBuffers;
    this.nonMeshGeometryBuffers = result.nonMeshGeometryBuffers ?? this.nonMeshGeometryBuffers;
    return {
      status: result.status,
      snapshot: result.snapshot,
      geometryBuffers: [...this.geometryBuffers],
      nonMeshGeometryBuffers: [...this.nonMeshGeometryBuffers],
      delta: result.delta,
      simplify: result.simplify,
    };
  }

  async previewCommand(payload: Extract<WebEngineEditCommand, { type: "previewDecimateMesh" }>): Promise<BlendOpenResult> {
    const result = await this.request({ type: "applyCommand", payload });
    if (!result.snapshot) throw this.report("INVALID_ARGUMENT", "WebEngine 未返回预览结果", true);
    return { status: result.status, snapshot: result.snapshot, geometryBuffers: result.geometryBuffers ?? [], nonMeshGeometryBuffers: result.nonMeshGeometryBuffers ?? [], simplify: result.simplify };
  }

  async generateLOD(payload: LODGenerationRequest): Promise<{ status: WebEngineStatus; lod: WebEngineLODResult }> {
    const result = await this.request({ type: "generateLOD", payload });
    if (!result.lod) throw this.report("INVALID_ARGUMENT", "WebEngine 未返回 LOD 结果", true);
    return { status: result.status, lod: result.lod };
  }

  async requestAsset(assetId: string): Promise<AssetRequestResult> {
    if (!assetId) throw this.report("INVALID_ARGUMENT", "Asset ID 不能为空", true);
    const result = await this.request({ type: "requestAsset", assetId });
    if (!result.asset) throw this.report("INVALID_ARGUMENT", "WebEngine 未返回资产结果", true);
    return result.asset;
  }

  async queryRenderCapability(request: RenderCapabilityRequest): Promise<CapabilityGateResult> {
    const result = await this.request({ type: "queryRenderCapability", request });
    if (!result.capabilityGate) throw this.report("CAPABILITY_MISSING", "WebEngine 未返回渲染能力门", true);
    return result.capabilityGate;
  }

  async queryNonMeshCapability(dataId: string): Promise<CapabilityGateResult> {
    const result = await this.request({ type: "queryNonMeshCapability", dataId });
    if (!result.capabilityGate) throw this.report("CAPABILITY_MISSING", "WebEngine did not return the non-mesh capability gate", true);
    return result.capabilityGate;
  }

  async evaluateDepsgraph(): Promise<{ status: WebEngineStatus; depsgraph: DepsgraphEvaluationIR }> {
    const result = await this.request({ type: "evaluateDepsgraph" });
    if (!result.depsgraph) throw this.report("CAPABILITY_MISSING", "WebEngine 未返回 Blender Depsgraph 结果", true);
    return { status: result.status, depsgraph: result.depsgraph };
  }

  async saveBlend(): Promise<ArrayBuffer> {
    const result = await this.request({ type: "saveBlend" });
    if (!result.blend) throw this.report("BLEND_WRITE_FAILED", "WebEngine 未返回 .blend 数据", true);
    return result.blend;
  }

  terminate(): void {
    this.failPending(this.report("WORKER_TERMINATED", "WebEngineWorker 已关闭", true));
    this.worker?.terminate();
    this.worker = null;
    this.geometryBuffers = [];
    this.nonMeshGeometryBuffers = [];
  }

  private start(): Worker {
    if (this.worker) return this.worker;
    const worker = this.workerFactory();
    worker.onmessage = (event: MessageEvent<WebEngineResponse>) => this.handleResponse(event.data);
    worker.onerror = (event) => {
      this.failPending(this.report("WORKER_TERMINATED", event.message || "WebEngineWorker 发生异常", true));
    };
    this.worker = worker;
    return worker;
  }

  private request(
    command: WebEngineRequest["command"],
    transfer: Transferable[] = [],
    onProgress?: (progress: ProgressEvent) => void,
  ): Promise<WebEngineResult> {
    const worker = this.start();
    const requestId = `web-engine-${++this.requestCounter}`;
    const request = { requestId, command } as WebEngineRequest;
    return new Promise<WebEngineResult>((resolve, reject) => {
      const timer = setTimeout(() => {
        this.pending.delete(requestId);
        reject(this.report("WORKER_TERMINATED", `WebEngine 请求超时: ${command.type}`, true));
      }, this.timeoutMs);
      this.pending.set(requestId, { resolve, reject, onProgress, timer });
      worker.postMessage(request, transfer);
    });
  }

  private handleResponse(response: WebEngineResponse): void {
    const pending = this.pending.get(response.requestId);
    if (!pending) return;
    if (response.kind === "progress") {
      pending.onProgress?.(response.progress);
      return;
    }
    this.pending.delete(response.requestId);
    clearTimeout(pending.timer);
    if (response.ok) pending.resolve(response.result);
    else pending.reject(response.error);
  }

  private failPending(error: ErrorReport): void {
    for (const pending of this.pending.values()) {
      clearTimeout(pending.timer);
      pending.reject(error);
    }
    this.pending.clear();
  }

  private report(code: ErrorReport["code"], message: string, recoverable: boolean): ErrorReport {
    return { code, severity: "error", message, recoverable };
  }
}