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

import { DataType } from '../../../wasm-common';
import { TensorView } from '../../tensor-view';
import { BroadcastUtil, ShapeUtil } from '../../util';
import { ComputeContext, ProgramInfo, ProgramUniform } from '../types';

import { createMatmulProgramInfo } from './3rd-party/matmul_packed_webgpu';
import {
  createTensorShapeVariables,
  getBroadcastDims,
  getMaxComponents,
  IndicesHelper,
  inputVariable,
  internalVariable,
  outputVariable,
  ShaderHelper,
  tensorTypeToWsglStorageType,
  UniformsArrayType,
} from './common';
import {
  appendActivationUniforms,
  appendActivationUniformsData,
  getActivationSnippet,
  InternalActivationAttributes,
} from './fuse-utils';

export const createNaiveMatmulProgramInfo = (
  inputs: readonly TensorView[],
  activationAttributes: InternalActivationAttributes,
  outputShape: readonly number[],
  reshapedOutputShape?: readonly number[],
  isChannelsLast = false /* only used for conv2dByMatMul*/,
  squeezeOutputShapeFunction?: (shape: readonly number[]) => number[],
): ProgramInfo => {
  const aShape = inputs[0].dims;
  const bShape = inputs[1].dims;

  const M = aShape[aShape.length - 2];
  const N = bShape[bShape.length - 1];
  const K = aShape[aShape.length - 1];
  const components = getMaxComponents(N);
  const aComponents = getMaxComponents(K);
  const outputNumber = getMaxComponents(M);
  const outputSize = ShapeUtil.size(outputShape) / components / outputNumber;
  const hasBias = inputs.length > 2;
  const outerDims = reshapedOutputShape ? reshapedOutputShape.slice(0, -2) : outputShape.slice(0, -2);
  const batchSize = ShapeUtil.size(outerDims);
  const outputShapeInShader = [batchSize, M, N];

  const programUniforms: ProgramUniform[] = [
    { type: DataType.uint32, data: outputSize },
    { type: DataType.uint32, data: M },
    { type: DataType.uint32, data: N },
    { type: DataType.uint32, data: K },
  ];
  appendActivationUniformsData(activationAttributes, programUniforms);
  programUniforms.push(...createTensorShapeVariables(outerDims, aShape, bShape));
  if (hasBias) {
    programUniforms.push(...createTensorShapeVariables(inputs[2].dims));
  }
  programUniforms.push(...createTensorShapeVariables(outputShapeInShader));

  const getShaderSource = (shaderHelper: ShaderHelper) => {
    const batchDims = internalVariable('batch_dims', inputs[0].dataType, outerDims.length);
    const a = inputVariable('a', inputs[0].dataType, aShape.length, aComponents);
    const b = inputVariable('b', inputs[1].dataType, bShape.length, components);
    const output = outputVariable('output', inputs[0].dataType, outputShapeInShader.length, components);
    const baseType = tensorTypeToWsglStorageType(output.type.tensor);
    const applyActivation = getActivationSnippet(activationAttributes, output.type.value, baseType);
    const inputVariables = [a, b];
    let processBias = '';
    if (hasBias) {
      const biasComponents = isChannelsLast ? components : 1;
      inputVariables.push(inputVariable('bias', inputs[2].dataType, inputs[2].dims.length, biasComponents));
      processBias = `${
        isChannelsLast ? `value += bias[col / ${biasComponents}];` : `value += ${output.type.value}(bias[row + i]);`
      }`;
    }

    const outerDimsA = aShape.slice(0, -2);
    const outerDimsB = bShape.slice(0, -2);
    const broadCastADims = getBroadcastDims(outerDimsA, outerDims);
    const broadCastBDims = getBroadcastDims(outerDimsB, outerDims);
    const uniforms: UniformsArrayType = [
      { name: 'output_size', type: 'u32' },
      { name: 'M', type: 'u32' },
      { name: 'N', type: 'u32' },
      { name: 'K', type: 'u32' },
    ];
    appendActivationUniforms(activationAttributes, uniforms);

    const getIndices = (variable: IndicesHelper, broadCastDims: number[]) => {
      const rank = variable.rank;
      const name = variable.name;
      if (rank === 2) {
        return `var ${name}_indices = ${variable.type.indices}(0u, 0u);`;
      }
      const batchRank = batchDims.rank;
      let resStr = `var ${name}_indices: ${variable.type.indices};`;
      for (let i = rank - 2 - 1, j = batchRank - 1; i >= 0; i--, j--) {
        resStr += `\n${name}_indices[${i}] = ${batchRank > 1 ? `batch_indices[${j}]` : 'batch_indices'};`;
      }
      broadCastDims.forEach((i) => {
        resStr += `\n${name}_indices[${i}] = 0;`;
      });
      resStr += `${name}_indices[${rank - 2}] = 0u;
                     ${name}_indices[${rank - 1}] = 0u;`;
      return resStr;
    };

    const calcResult = (): string => {
      let calcStr = `var a_data: ${a.type.value};`;
      for (let i = 0; i < aComponents; i++) {
        calcStr += `
              let b_data${i} = b[(b_offset + (k + ${i}) * uniforms.N + col) / ${components}];`;
      }
      for (let i = 0; i < outputNumber; i++) {
        calcStr += `a_data = a[(a_offset + (row + ${i}) * uniforms.K + k) / ${aComponents}];`;

        for (let j = 0; j < aComponents; j++) {
          calcStr += `
            values[${i}] = fma(${b.type.value}(a_data${aComponents === 1 ? '' : `[${j}]`}), b_data${j}, values[${i}]);\n`;
        }
      }
      return calcStr;
    };

    return `
  ${shaderHelper
    .registerUniforms(uniforms)
    .registerInternalVariables(batchDims)
    .declareVariables(...inputVariables, output)}
  ${shaderHelper.mainStart()}
    ${shaderHelper.guardAgainstOutOfBoundsWorkgroupSizes('uniforms.output_size')}
    let col = (global_idx % (uniforms.N / ${components})) * ${components};
    var index1 = global_idx / (uniforms.N / ${components});
    let stride1 = uniforms.M / ${outputNumber};
    let row = (index1 % stride1) * ${outputNumber};
    let batch = index1 / stride1;

    ${outputShape.length === 2 ? '' : `let batch_indices = ${batchDims.offsetToIndices('batch')};`}
    ${getIndices(a, broadCastADims)}
    let a_offset = ${a.indicesToOffset('a_indices')};
    ${getIndices(b, broadCastBDims)}
    let b_offset = ${b.indicesToOffset('b_indices')};
    var values: array<${output.type.value}, ${outputNumber}>;
    for (var k: u32 = 0u; k < uniforms.K; k = k + ${aComponents}) {
      ${calcResult()}
    }
    for (var i = 0u; i < ${outputNumber}u; i++) {
      var value = values[i];
      ${processBias}
      ${applyActivation}
      let cur_indices = ${output.type.indices}(batch, row + i, col);
      let offset = ${output.indicesToOffset('cur_indices')};
      ${output.setByOffset(`offset / ${components}`, 'value')};
    }
  }
  `;
  };
  return {
    name: 'MatMulNaive',
    shaderCache: {
      hint: `${activationAttributes.activation};${components};${aComponents};${outputNumber};${isChannelsLast}`,
      inputDependencies: hasBias ? ['rank', 'rank', 'rank'] : ['rank', 'rank'],
    },
    getRunData: () => ({
      outputs: [
        {
          dims: squeezeOutputShapeFunction ? squeezeOutputShapeFunction(outputShape) : outputShape,
          dataType: inputs[0].dataType,
        },
      ],
      dispatchGroup: { x: Math.ceil(outputSize / 64 /* workgroup size */) },
      programUniforms,
    }),
    getShaderSource,
  };
};

const validateInputs = (inputs: readonly TensorView[]): void => {
  if (!inputs || inputs.length !== 2) {
    throw new Error('MatMul requires 2 inputs.');
  }

  if (inputs[0].dims[inputs[0].dims.length - 1] !== inputs[1].dims[inputs[1].dims.length - 2]) {
    throw new Error('shared dimension does not match.');
  }
};

export const matMul = (context: ComputeContext): void => {
  validateInputs(context.inputs);
  const outputShape = BroadcastUtil.calcShape(context.inputs[0].dims, context.inputs[1].dims, true);
  if (!outputShape) {
    throw new Error("Can't use matmul on the given tensors");
  }
  const N = outputShape[outputShape.length - 1];
  const K = context.inputs[0].dims[context.inputs[0].dims.length - 1];
  if (N < 8 && K < 8) {
    context.compute(createNaiveMatmulProgramInfo(context.inputs, { activation: '' }, outputShape));
  } else {
    context.compute(createMatmulProgramInfo(context.inputs, { activation: '' }, outputShape));
  }
};