/*
 * Copyright 2011-2013 Blender Foundation
 *
 * 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.
 */

#include "stdosl.h"

float safe_divide(float a, float b)
{
  return (b != 0.0) ? a / b : 0.0;
}

float safe_modulo(float a, float b)
{
  return (b != 0.0) ? fmod(a, b) : 0.0;
}

float fract(float a)
{
  return a - floor(a);
}

/* Adapted from godotengine math_funcs.h. */
float wrap(float value, float max, float min)
{
  float range = max - min;
  return (range != 0.0) ? value - (range * floor((value - min) / range)) : min;
}

/* See: https://www.iquilezles.org/www/articles/smin/smin.htm. */
float smoothmin(float a, float b, float c)
{
  if (c != 0.0) {
    float h = max(c - abs(a - b), 0.0) / c;
    return min(a, b) - h * h * h * c * (1.0 / 6.0);
  }
  else {
    return min(a, b);
  }
}

float pingpong(float a, float b)
{
  return (b != 0.0) ? abs(fract((a - b) / (b * 2.0)) * b * 2.0 - b) : 0.0;
}

float safe_sqrt(float a)
{
  return (a > 0.0) ? sqrt(a) : 0.0;
}

float safe_log(float a, float b)
{
  return (a > 0.0 && b > 0.0) ? log(a) / log(b) : 0.0;
}

/* OSL asin, acos, and pow functions are safe by default. */
shader node_math(string type = "add",
                 float Value1 = 0.5,
                 float Value2 = 0.5,
                 float Value3 = 0.5,
                 output float Value = 0.0)
{
  if (type == "add")
    Value = Value1 + Value2;
  else if (type == "subtract")
    Value = Value1 - Value2;
  else if (type == "multiply")
    Value = Value1 * Value2;
  else if (type == "divide")
    Value = safe_divide(Value1, Value2);
  else if (type == "power")
    Value = pow(Value1, Value2);
  else if (type == "logarithm")
    Value = safe_log(Value1, Value2);
  else if (type == "sqrt")
    Value = safe_sqrt(Value1);
  else if (type == "inversesqrt")
    Value = inversesqrt(Value1);
  else if (type == "absolute")
    Value = fabs(Value1);
  else if (type == "radians")
    Value = radians(Value1);
  else if (type == "degrees")
    Value = degrees(Value1);
  else if (type == "minimum")
    Value = min(Value1, Value2);
  else if (type == "maximum")
    Value = max(Value1, Value2);
  else if (type == "less_than")
    Value = Value1 < Value2;
  else if (type == "greater_than")
    Value = Value1 > Value2;
  else if (type == "round")
    Value = floor(Value1 + 0.5);
  else if (type == "floor")
    Value = floor(Value1);
  else if (type == "ceil")
    Value = ceil(Value1);
  else if (type == "fraction")
    Value = Value1 - floor(Value1);
  else if (type == "modulo")
    Value = safe_modulo(Value1, Value2);
  else if (type == "trunc")
    Value = trunc(Value1);
  else if (type == "snap")
    Value = floor(safe_divide(Value1, Value2)) * Value2;
  else if (type == "wrap")
    Value = wrap(Value1, Value2, Value3);
  else if (type == "pingpong")
    Value = pingpong(Value1, Value2);
  else if (type == "sine")
    Value = sin(Value1);
  else if (type == "cosine")
    Value = cos(Value1);
  else if (type == "tangent")
    Value = tan(Value1);
  else if (type == "sinh")
    Value = sinh(Value1);
  else if (type == "cosh")
    Value = cosh(Value1);
  else if (type == "tanh")
    Value = tanh(Value1);
  else if (type == "arcsine")
    Value = asin(Value1);
  else if (type == "arccosine")
    Value = acos(Value1);
  else if (type == "arctangent")
    Value = atan(Value1);
  else if (type == "arctan2")
    Value = atan2(Value1, Value2);
  else if (type == "sign")
    Value = sign(Value1);
  else if (type == "exponent")
    Value = exp(Value1);
  else if (type == "compare")
    Value = ((Value1 == Value2) || (abs(Value1 - Value2) <= max(Value3, 1e-5))) ? 1.0 : 0.0;
  else if (type == "multiply_add")
    Value = Value1 * Value2 + Value3;
  else if (type == "smoothmin")
    Value = smoothmin(Value1, Value2, Value3);
  else if (type == "smoothmax")
    Value = -(smoothmin(-Value1, -Value2, Value3));
  else
    warning("%s", "Unknown math operator!");
}