/**
 * @license
 * Copyright 2018 Google Inc. All Rights Reserved.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * =============================================================================
 */

import * as broadcast_util from '../../ops/broadcast_util';
import {sizeFromShape} from '../../util';
import {getChannels} from '../packing_util';

import {GPGPUProgram} from './gpgpu_math';
import {getCoordsDataType} from './shader_compiler';

const CHECK_NAN_SNIPPET = `
  result.r = isNaN.r > 0. ? NAN : result.r;
  result.g = isNaN.g > 0. ? NAN : result.g;
  result.b = isNaN.b > 0. ? NAN : result.b;
  result.a = isNaN.a > 0. ? NAN : result.a;
`;

// We do the same as in ./binaryop_gpu, with vec4 and ivec4.
// On Linux, the vectorized implementation produces NaNs when a and b are 0.
export const DIV = `
  // vec4 one = vec4(equal(a, b));
  // return one + (vec4(1.0) - one) * a / b;
  vec4 result = a / b;
  if(a.x == b.x) {
    result.x = 1.;
  }
  if(a.y == b.y) {
    result.y = 1.;
  }
  if(a.z == b.z) {
    result.z = 1.;
  }
  if(a.w == b.w) {
    result.w = 1.;
  }

  return result;
`;

export const INT_DIV = `
  ivec4 ia = round(a);
  ivec4 ib = round(b);
  bvec4 cond = notEqual(ib, ivec4(0));
  ivec4 result = ivec4(0);
  vec4 s = sign(a) * sign(b);

  // Windows (D3D) wants guaranteed non-zero int division at compile-time.
  if (cond[0]) {
    result[0] = idiv(ia[0], ib[0], s[0]);
  }
  if (cond[1]) {
    result[1] = idiv(ia[1], ib[1], s[1]);
  }
  if (cond[2]) {
    result[2] = idiv(ia[2], ib[2], s[2]);
  }
  if (cond[3]) {
    result[3] = idiv(ia[3], ib[3], s[3]);
  }
  return vec4(result);
`;

export const POW = `
  // isModRound1 has 1 for components with round(mod(b, 2.0)) == 1, 0 otherwise.
  vec4 isModRound1 = vec4(equal(round(mod(b, 2.0)), ivec4(1)));
  vec4 multiplier = sign(a) * isModRound1 + (vec4(1.0) - isModRound1);
  vec4 result = multiplier * pow(abs(a), b);

  // Ensure that a^0 = 1, including 0^0 = 1 as this correspond to TF and JS
  bvec4 isExpZero = equal(b, vec4(0.0));
  result.r = isExpZero.r ? 1.0 : result.r;
  result.g = isExpZero.g ? 1.0 : result.g;
  result.b = isExpZero.b ? 1.0 : result.b;
  result.a = isExpZero.a ? 1.0 : result.a;

  vec4 isNaN = vec4(lessThan(a, vec4(0.0))) * vec4(lessThan(floor(b), b));
  ` +
    CHECK_NAN_SNIPPET + `
  return result;
`;

export const PRELU = `
  vec4 aLessThanZero = vec4(lessThan(a, vec4(0.)));
  return (aLessThanZero * (b * a)) + ((vec4(1.0) - aLessThanZero) * a);
`;

export const ELU_DER = `
  vec4 bGTEZero = vec4(greaterThanEqual(b, vec4(0.)));
  return (bGTEZero * a) + ((vec4(1.0) - bGTEZero) * (a * (b + vec4(1.0))));
`;

export const ATAN2 = `
  vec4 result = atan(a, b);
  vec4 isNaN = min(vec4(isnan(a)) + vec4(isnan(b)), vec4(1.0));
  ` +
    CHECK_NAN_SNIPPET + `
  return result;
`;

export const EQUAL = `
  return vec4(equal(a, b));
`;

export const NOT_EQUAL = `
  return vec4(notEqual(a, b));
`;

export const LESS = `
  return vec4(lessThan(a, b));
`;

export const LESS_EQUAL = `
  return vec4(lessThanEqual(a, b));
`;

export const GREATER = `
  return vec4(greaterThan(a, b));
`;

export const GREATER_EQUAL = `
  return vec4(greaterThanEqual(a, b));
`;

export const LOGICAL_AND = `
  return vec4(
    vec4(greaterThanEqual(a, vec4(1.0))) *
    vec4(greaterThanEqual(b, vec4(1.0))));
`;

export const LOGICAL_OR = `
  return min(
    vec4(greaterThanEqual(a, vec4(1.0))) +
    vec4(greaterThanEqual(b, vec4(1.0))),
    vec4(1.0));
`;

export const MAX = `
  vec4 result = vec4(max(a, b));
  vec4 isNaN = min(vec4(isnan(a)) + vec4(isnan(b)), vec4(1.0));
  ` +
    CHECK_NAN_SNIPPET + `
  return result;
`;

export const MIN = `
  vec4 result = vec4(min(a, b));
  vec4 isNaN = min(vec4(isnan(a)) + vec4(isnan(b)), vec4(1.0));
  ` +
    CHECK_NAN_SNIPPET + `
  return result;
`;

export const MOD = `
  vec4 result = mod(a, b);
  vec4 isNaN = vec4(equal(b, vec4(0.0)));
  ` +
    CHECK_NAN_SNIPPET + `
  return result;
`;

export class BinaryOpPackedProgram implements GPGPUProgram {
  variableNames = ['A', 'B'];
  outputShape: number[];
  userCode: string;
  supportsBroadcasting = true;
  packedInputs = true;
  packedOutput = true;

  constructor(
      op: string, aShape: number[], bShape: number[],
      checkOutOfBounds = false) {
    this.outputShape =
        broadcast_util.assertAndGetBroadcastShape(aShape, bShape);
    const rank = this.outputShape.length;
    let checkOutOfBoundsString = '';
    if (checkOutOfBounds) {
      if (rank === 0 || sizeFromShape(this.outputShape) === 1) {
        checkOutOfBoundsString = `
          result.y = 0.;
          result.z = 0.;
          result.w = 0.;
        `;
      } else {
        const dtype = getCoordsDataType(rank);
        checkOutOfBoundsString = `
          ${dtype} coords = getOutputCoords();
        `;
        if (rank === 1) {
          checkOutOfBoundsString += `
            result.y = (coords + 1) >= ${this.outputShape[0]} ? 0. : result.y;
            result.z = 0.;
            result.w = 0.;
          `;
        } else {
          const channels = getChannels('coords', rank);
          checkOutOfBoundsString += `
            bool nextRowOutOfBounds =
              (${channels[rank - 2]} + 1) >= ${this.outputShape[rank - 2]};
            bool nextColOutOfBounds =
              (${channels[rank - 1]} + 1) >= ${this.outputShape[rank - 1]};
            result.y = nextColOutOfBounds ? 0. : result.y;
            result.z = nextRowOutOfBounds ? 0. : result.z;
            result.w = nextColOutOfBounds || nextRowOutOfBounds ? 0. : result.w;
          `;
        }
      }
    }

    this.userCode = `
      vec4 binaryOperation(vec4 a, vec4 b) {
        ${op}
      }

      void main() {
        vec4 a = getAAtOutCoords();
        vec4 b = getBAtOutCoords();

        vec4 result = binaryOperation(a, b);
        ${checkOutOfBoundsString}

        setOutput(result);
      }
    `;
  }
}