#include "quartic_model.h"
#include "../../shared/poincare_helpers.h"
#include <math.h>
#include <assert.h>
#include "../../poincare/include/poincare_layouts.h"

using namespace Poincare;
using namespace Shared;

namespace Regression {

ExpressionLayout * QuarticModel::layout() {
  static ExpressionLayout * layout = nullptr;
  if (layout == nullptr) {
    const ExpressionLayout * layoutChildren[] = {
      CharLayoutRef('a', KDText::FontSize::Small),
      CharLayoutRef(Ion::Charset::MiddleDot, KDText::FontSize::Small),
      CharLayoutRef('X', KDText::FontSize::Small),
      VerticalOffsetLayoutRef(
          CharLayoutRef('4', KDText::FontSize::Small),
          VerticalOffsetLayoutNode::Type::Superscript
        ),
      CharLayoutRef('+', KDText::FontSize::Small),
      CharLayoutRef('b', KDText::FontSize::Small),
      CharLayoutRef(Ion::Charset::MiddleDot, KDText::FontSize::Small),
      CharLayoutRef('X', KDText::FontSize::Small),
      VerticalOffsetLayoutRef(
          CharLayoutRef('3', KDText::FontSize::Small),
          VerticalOffsetLayoutNode::Type::Superscript
        ),
      CharLayoutRef('+', KDText::FontSize::Small),
      CharLayoutRef('c', KDText::FontSize::Small),
      CharLayoutRef(Ion::Charset::MiddleDot, KDText::FontSize::Small),
      CharLayoutRef('X', KDText::FontSize::Small),
      VerticalOffsetLayoutRef(
          CharLayoutRef('2', KDText::FontSize::Small),
          VerticalOffsetLayoutNode::Type::Superscript
        ),
      CharLayoutRef('+', KDText::FontSize::Small),
      CharLayoutRef('d', KDText::FontSize::Small),
      CharLayoutRef(Ion::Charset::MiddleDot, KDText::FontSize::Small),
      CharLayoutRef('X', KDText::FontSize::Small),
      CharLayoutRef('+', KDText::FontSize::Small),
      CharLayoutRef('e', KDText::FontSize::Small),
    };
    layout = HorizontalLayoutRef(layoutChildren, 20);
  }
  return layout;
}

Expression * QuarticModel::simplifiedExpression(double * modelCoefficients, Poincare::Context * context) {
  double a = modelCoefficients[0];
  double b = modelCoefficients[1];
  double c = modelCoefficients[2];
  double d = modelCoefficients[3];
  double e = modelCoefficients[4];
  Expression * ax4Expression = new Multiplication(
      new Decimal(a),
      new Power(
        new Symbol('x'),
        new Decimal(4.0),
        false),
      false);
  Expression * bx3Expression = new Multiplication(
      new Decimal(b),
      new Power(
        new Symbol('x'),
        new Decimal(3.0),
        false),
      false);
  Expression * cx2Expression = new Multiplication(
    new Decimal(c),
    new Power(
      new Symbol('x'),
      new Decimal(2.0),
      false),
    false);
  Expression * dxExpression = new Multiplication(
    new Decimal(d),
    new Symbol('x'),
    false);
  Expression * eExpression = new Decimal(e);
  Expression * const operands[] = {ax4Expression, bx3Expression, cx2Expression, dxExpression, eExpression};
  Expression * result = new Addition(operands, 5, false);
  PoincareHelpers::Simplify(&result, *context);
  return result;
}

double QuarticModel::evaluate(double * modelCoefficients, double x) const {
  double a = modelCoefficients[0];
  double b = modelCoefficients[1];
  double c = modelCoefficients[2];
  double d = modelCoefficients[3];
  double e = modelCoefficients[4];
  return a*x*x*x*x+b*x*x*x+c*x*x+d*x+e;
}

double QuarticModel::partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const {
  if (derivateCoefficientIndex == 0) {
    // Derivate: x^4
    return x*x*x*x;
  }
  if (derivateCoefficientIndex == 1) {
    // Derivate: x^3
    return x*x*x;
  }
  if (derivateCoefficientIndex == 2) {
    // Derivate: x^2
    return x*x;
  }
  if (derivateCoefficientIndex == 3) {
    // Derivate: x
    return x;
  }
  if (derivateCoefficientIndex == 4) {
    // Derivate: 1
    return 1;
  }
  assert(false);
  return 0.0;
}

}