// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.

import {Env} from 'onnxruntime-common';

import type {OrtWasmModule} from '../wasm-types';
import {DataType, getTensorElementSize} from '../wasm-common';

import {WebGpuBackend} from './backend-webgpu';
import {LOG_DEBUG} from './log';
import {TensorView} from './tensor-view';
import {ShapeUtil} from './util';
import {AdapterInfo, ComputeContext, ComputeContextInputsOutputsMapping, ProgramInfo} from './webgpu/types';

/* eslint-disable no-bitwise */

class TensorViewImpl implements TensorView {
  constructor(
      private module: OrtWasmModule, public readonly dataType: number, public readonly data: number,
      public readonly dims: readonly number[]) {}

  getFloat32Array(): Float32Array {
    if (this.dataType !== DataType.float) {
      throw new Error('Invalid data type');
    }
    const elementCount = ShapeUtil.size(this.dims);
    return elementCount === 0 ? new Float32Array() :
                                new Float32Array(this.module.HEAP8.buffer, this.data, elementCount);
  }

  getBigInt64Array(): BigInt64Array {
    if (this.dataType !== DataType.int64) {
      throw new Error('Invalid data type');
    }
    const elementCount = ShapeUtil.size(this.dims);
    return elementCount === 0 ? new BigInt64Array() :
                                new BigInt64Array(this.module.HEAP8.buffer, this.data, elementCount);
  }

  getInt32Array(): Int32Array {
    if (this.dataType !== DataType.int32) {
      throw new Error('Invalid data type');
    }
    const elementCount = ShapeUtil.size(this.dims);
    return elementCount === 0 ? new Int32Array() : new Int32Array(this.module.HEAP8.buffer, this.data, elementCount);
  }

  reshape(newDims: readonly number[]): TensorView {
    if (ShapeUtil.size(newDims) !== ShapeUtil.size(this.dims)) {
      throw new Error('Invalid new shape');
    }
    return new TensorViewImpl(this.module, this.dataType, this.data, newDims);
  }
}

class ComputeContextImpl implements ComputeContext {
  readonly adapterInfo: AdapterInfo;
  readonly opKernelContext: number;
  readonly inputs: readonly TensorView[];
  readonly outputCount: number;
  get kernelCustomData(): {[key: string]: unknown} {
    return this.backend.currentKernelCustomData;
  }
  get customDataBuffer(): Uint8Array {
    return this.module.HEAPU8.subarray(this.customDataOffset, this.customDataOffset + this.customDataSize);
  }
  private customDataOffset = 0;
  private customDataSize = 0;
  constructor(private module: OrtWasmModule, private backend: WebGpuBackend, contextDataOffset: number) {
    this.adapterInfo = backend.adapterInfo;
    const heapU32 = module.HEAPU32;

    // extract context data
    let dataIndex = (contextDataOffset >>> 2);
    this.opKernelContext = heapU32[dataIndex++];
    const inputCount = heapU32[dataIndex++];
    this.outputCount = heapU32[dataIndex++];
    this.customDataOffset = heapU32[dataIndex++];
    this.customDataSize = heapU32[dataIndex++];

    const inputs: TensorView[] = [];
    for (let i = 0; i < inputCount; i++) {
      const dataType = heapU32[dataIndex++];
      const data = heapU32[dataIndex++];
      const dim = heapU32[dataIndex++];
      const dims: number[] = [];
      for (let d = 0; d < dim; d++) {
        dims.push(heapU32[dataIndex++]);
      }
      inputs.push(new TensorViewImpl(module, dataType, data, dims));
    }
    this.inputs = inputs;
  }

  getMaxComputeWorkgroupSizes(): [number, number, number] {
    return [
      this.backend.device.limits.maxComputeWorkgroupSizeX, this.backend.device.limits.maxComputeWorkgroupSizeY,
      this.backend.device.limits.maxComputeWorkgroupSizeZ
    ];
  }

  getMaxComputeWorkgroupStoragesize(): number {
    return this.backend.device.limits.maxComputeWorkgroupStorageSize;
  }

  compute(program: ProgramInfo, inputsOutputsMapping?: ComputeContextInputsOutputsMapping): TensorView[] {
    // prepare inputs. inputs should always be valid data.
    const mappedInputs =
        inputsOutputsMapping?.inputs?.map(i => typeof i === 'number' ? this.inputs[i] : i) ?? this.inputs;
    // prepare outputs.
    const outputIndices = inputsOutputsMapping?.outputs ?? [];
    const createKernelOutput = (index: number, dataType: number, dims: readonly number[]): TensorView =>
        new TensorViewImpl(this.module, dataType, this.output(index, dims), dims);
    const createTemporaryOutput = (dataType: number, dims: readonly number[]): TensorView => {
      const elementSize = getTensorElementSize(dataType);
      if (!elementSize) {
        throw new Error(`Unsupported data type: ${dataType}`);
      }
      const bufferSize = elementSize * ShapeUtil.size(dims);
      const gpuDataId = bufferSize > 0 ? this.backend.gpuDataManager.create(bufferSize).id : 0;
      return new TensorViewImpl(this.module, dataType, gpuDataId, dims);
    };
    return this.backend.run(
        program, mappedInputs, outputIndices, createKernelOutput, createTemporaryOutput, this.outputCount);
  }

  output(index: number, dims: readonly number[]): number {
    const stack = this.module.stackSave();
    try {
      const data = this.module.stackAlloc((1 + dims.length) * 4 /* sizeof(size_t) */);
      let offset = data >> 2;
      this.module.HEAPU32[offset++] = dims.length;
      for (let i = 0; i < dims.length; i++) {
        this.module.HEAPU32[offset++] = dims[i];
      }
      return this.module._JsepOutput!(this.opKernelContext, index, data);
    } catch (e) {
      throw new Error(
          `Failed to generate kernel's output[${index}] with dims [${dims}]. ` +
          'If you are running with pre-allocated output, please make sure the output type/dims are correct. ' +
          `Error: ${e}`);
    } finally {
      this.module.stackRestore(stack);
    }
  }
}

/**
 * Initialize JSEP with WebGPU backend.
 *
 * This function will be called after the WebAssembly module is loaded and initialized ("_OrtInit" is called), once for
 * each of the following EPs if they are specified:
 * - "webgpu"
 * - "webnn"
 *
 * For WebGPU, this function expects:
 *  - WebGPU is enabled in build (BUILD_DEFS.DISABLE_JSEP === false).
 *  - WebGPU is available in current environment. (a valid GPUAdapter is passed in)
 *
 * For WebNN, this function expects:
 * - WebNN is enabled in build (BUILD_DEFS.DISABLE_JSEP === false).
 * - WebNN is available in current environment. (navigator.ml is not undefined)
 *
 * If the WebAssembly module is not built with JSEP support, this function will throw an error. This will invalidate
 * 'webgpu'/'webnn' backend.
 *
 * @param name - the name of the EP, either "webgpu" or "webnn"
 * @param module - the ORT WebAssembly module
 * @param env - the ORT environment variable (ort.env)
 * @param gpuAdapter - the pre-created GPU adapter
 */
export const init =
    async(name: 'webgpu'|'webnn', module: OrtWasmModule, env: Env, gpuAdapter?: GPUAdapter): Promise<void> => {
  const jsepInit = module.jsepInit;
  if (!jsepInit) {
    throw new Error('Failed to initialize JSEP. The WebAssembly module is not built with JSEP support.');
  }

  if (name === 'webgpu') {
    const backend = new WebGpuBackend();
    await backend.initialize(env, gpuAdapter!);

    jsepInit('webgpu', [
      // backend
      backend,

      // jsepAlloc()
      (size: number) => backend.alloc(size),

      // jsepFree()
      (ptr: number) => backend.free(ptr),

      // jsepCopy(src, dst, size, isSourceGpu)
      (src: number, dst: number, size: number, isSourceGpu = false) => {
        if (isSourceGpu) {
          LOG_DEBUG('verbose', () => `[WebGPU] jsepCopyGpuToGpu: src=${src}, dst=${dst}, size=${size}`);
          backend.memcpy(src, dst);
        } else {
          LOG_DEBUG('verbose', () => `[WebGPU] jsepCopyCpuToGpu: dataOffset=${src}, gpuDataId=${dst}, size=${size}`);
          const data = module.HEAPU8.subarray(src >>> 0, (src >>> 0) + size);
          backend.upload(dst, data);
        }
      },

      // jsepCopyAsync(src, dst, size)
      async(gpuDataId: number, dataOffset: number, size: number):
          Promise<void> => {
            LOG_DEBUG(
                'verbose',
                () => `[WebGPU] jsepCopyGpuToCpu: gpuDataId=${gpuDataId}, dataOffset=${dataOffset}, size=${size}`);

            await backend.download(
                gpuDataId, () => module.HEAPU8.subarray(dataOffset >>> 0, (dataOffset >>> 0) + size));
          },

      // jsepCreateKernel
      (kernelType: string, kernelId: number, attribute: unknown) => backend.createKernel(
          kernelType, kernelId, attribute, module.UTF8ToString(module._JsepGetNodeName!(kernelId))),

      // jsepReleaseKernel
      (kernel: number) => backend.releaseKernel(kernel),

      // jsepRun
      (kernel: number, contextDataOffset: number, sessionHandle: number, errors: Array<Promise<string|null>>) => {
        LOG_DEBUG(
            'verbose',
            () => `[WebGPU] jsepRun: sessionHandle=${sessionHandle}, kernel=${kernel}, contextDataOffset=${
                contextDataOffset}`);
        const context = new ComputeContextImpl(module, backend, contextDataOffset);
        return backend.computeKernel(kernel, context, errors);
      },
      // jsepCaptureBegin
      () => backend.captureBegin(),
      // jsepCaptureEnd
      () => backend.captureEnd(),
      // jsepReplay
      () => backend.replay()
    ]);
  } else {
    jsepInit('webnn');
  }
};