import 'dart:math';

import 'package:energy_bilance/models/EnergyBilanceModel.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  EnergyBilanceModel model = EnergyBilanceModel();

  const double startHeight = 10;
  const double endHeight = 20;

  const double startVelocity = 0;
  const double endVelocity = 100;

  const double weight = 50;

  const double gravity = 9.81;

  const double waterHeatCapacity = 4.181; //unit: J / (g * C°)
  const double ironHeatCapacity = 0.439; //unit: J / (g * C°)

  resetModel() {
    model.setWeight(0);
    model.setStartVelocity(0);
    model.setEndVelocity(0);
    model.setStartHeight(0);
    model.setEndHeight(0);
  }

  group("Testing EnergyBilanceModel", () {
    test("initial calculations", () {
      expect(0, model.potentialEnergy);
      expect(0, model.kineticEnergy);
      expect(0, model.deltaVelocity);
      expect(0, model.deltaHeight);

      expect(0, model.amountOfGlowingIronInKg);
      expect(0, model.amountOfBoilingWaterInL);

      resetModel();
    });
    test("deltaHeight", () {
      model.setStartHeight(startHeight);
      model.setEndHeight(endHeight);
      expect(endHeight - startHeight, model.deltaHeight);

      resetModel();
    });
    test("deltaVelocity", () {
      model.setStartVelocity(startVelocity);
      model.setEndVelocity(endVelocity);
      expect(endVelocity - startVelocity, model.deltaVelocity);

      resetModel();
    });
    test("potentialEnergy", () {
      model.setStartHeight(startHeight);
      model.setEndHeight(endHeight);

      //without weight
      expect(0, model.potentialEnergy);

      model.setWeight(weight);
      expect(weight * gravity * model.deltaHeight, model.potentialEnergy);

      //kinetic energy should still be zero
      expect(0, model.kineticEnergy);
      resetModel();
    });
    test("kineticEnergy", () {
      resetModel();
      model.setStartVelocity(startVelocity);
      model.setEndVelocity(endVelocity);

      //without weight
      expect(0, model.kineticEnergy);

      model.setWeight(weight);
      expect(weight * pow(model.deltaVelocity, 2) / 2, model.kineticEnergy);

      //kinetic energy should still be zero
      expect(0, model.potentialEnergy);
      resetModel();
    });
    test("amountOfBoilingWaterInL", () {

      model.setWeight(weight);
      model.setStartVelocity(startVelocity);
      model.setEndVelocity(endVelocity);

      double shouldAmountWithKineticEnergy = (model.potentialEnergy + model.kineticEnergy) / waterHeatCapacity / 80 / 1000;
      expect(shouldAmountWithKineticEnergy, model.amountOfBoilingWaterInL);
      resetModel();

      model.setWeight(weight);
      model.setStartHeight(startHeight);
      model.setEndHeight(endHeight);

      double shouldAmountWithPotentialEnergy = (model.potentialEnergy + model.kineticEnergy) / waterHeatCapacity / 80 / 1000;
      expect(shouldAmountWithPotentialEnergy, model.amountOfBoilingWaterInL);

      model.setStartVelocity(startVelocity);
      model.setEndVelocity(endVelocity);

      double shouldAmountWithBoth = (model.potentialEnergy + model.kineticEnergy) / waterHeatCapacity / 80 / 1000;
      expect(shouldAmountWithBoth, model.amountOfBoilingWaterInL);

      resetModel();

    });
    test("amountOfGlowingIronInKg", () {

      model.setWeight(weight);
      model.setStartVelocity(startVelocity);
      model.setEndVelocity(endVelocity);

      double shouldAmountWithKineticEnergy = (model.potentialEnergy + model.kineticEnergy) / ironHeatCapacity / 680 / 1000;
      expect(shouldAmountWithKineticEnergy, model.amountOfGlowingIronInKg);
      resetModel();

      model.setWeight(weight);
      model.setStartHeight(startHeight);
      model.setEndHeight(endHeight);

      double shouldAmountWithPotentialEnergy = (model.potentialEnergy + model.kineticEnergy) / ironHeatCapacity / 680 / 1000;
      expect(shouldAmountWithPotentialEnergy, model.amountOfGlowingIronInKg);

      model.setStartVelocity(startVelocity);
      model.setEndVelocity(endVelocity);

      double shouldAmountWithBoth = (model.potentialEnergy + model.kineticEnergy) / ironHeatCapacity / 680 / 1000;
      expect(shouldAmountWithBoth, model.amountOfGlowingIronInKg);

      resetModel();
    });
  });
}