#include "Vehicle.h"

void burnStartTimeCalc(struct Vehicle &);
void thrustSelection(struct Vehicle &, int t);
void lqrCalc(struct Vehicle &);
void TVC(struct Vehicle &);
void vehicleDynamics(struct Vehicle &, struct Vehicle &, int t);
void write2CSV(struct Vehicle &, std::fstream &outfile, int t);
double derivative(double x2, double x1, double dt);
double integral(double x2, double x1, double dt);

// Any parameters that are constants should be declared here instead of buried
// in code
double const dt = 0.001;
double const g = -9.81;

bool sim(struct Vehicle &State, struct Vehicle &PrevState) {

  // defining a few random values here cause I'm lazy
  State.burnElapsed = 2000;
  State.mass = State.massInitial;
  PrevState.thrust = 0.0;

  burnStartTimeCalc(State);

  // Deleting any previous output file
  if (remove("simOut.csv") != 0)
    perror("Error deleting file");
  else
    puts("File successfully deleted");

  // Define and open output file "simOut.csv"
  std::fstream outfile;
  outfile.open("simOut.csv", std::ios::app);

  // Output file header. These are the variables that we output - useful for
  // debugging
  outfile
      << "t, x, y, z, vx, vy, vz, ax, ay, az, yaw, pitch, roll, yawdot, "
         "pitchdot, rolldot, yawddot, pitchddot, rollddot, I11, I22, I33, "
         "I11dot, I22dot, I33dot, Servo1, Servo2, m, thrust, burnElapsed, Fz, "
         "LQRx, LQRy"
      << std::endl;

  int t = 0;

  // Start Sim
  do {
    thrustSelection(State, t);
    lqrCalc(State);
    TVC(State);
    vehicleDynamics(State, PrevState, t);
    write2CSV(State, outfile, t);
    t++;
  } while ((State.z > 0.0) || (State.thrust > 1.0));

  outfile.close();

  bool returnValue;

  if (abs(State.vz) < 5) {
    if ((abs(State.yaw) < 5) && (abs(State.pitch) < 5)) {
      returnValue = 1;
    } else {
      returnValue = 0;
    }
  } else {
    returnValue = 0;
  }

  return returnValue;
}

void burnStartTimeCalc(struct Vehicle &State) {
  double velocity = State.vz;
  double h = 0;

  double a, j, mass, thrust;

  // Piecewise functions for F15 thrust curve
  for (double i = 0.148; i < 3.450; i = i + dt) {
    mass = State.massInitial - i * State.mdot;

    if ((i > 0.147) && (i < 0.420))
      thrust = 65.165 * i - 2.3921;

    else if ((i > 0.419) && (i < 3.383))
      thrust = 0.8932 * pow(i, 6) - 11.609 * pow(i, 5) + 60.739 * pow(i, 4) -
               162.99 * pow(i, 3) + 235.6 * pow(i, 2) - 174.43 * i + 67.17;

    else if ((i > 3.382) && (i < 3.46))
      thrust = -195.78 * i + 675.11;

    velocity = (((thrust / mass) + g) * dt) + velocity;
    h = velocity * dt + h;
  }

  State.z = h + (pow(velocity, 2) / (2 * -g)); // starting height
  State.burnVelocity = velocity;               // terminal velocity

  double burnStartTime = State.burnVelocity / -g;
  State.simTime = (State.burntime + burnStartTime) * 1000;
}

void thrustSelection(struct Vehicle &State, int t) {

  if (State.burnElapsed != 2000) {
    // determine where in the thrust curve we're at based on elapsed burn time
    // as well as current mass
    State.burnElapsed = (t - State.burnStart) / 1000;
    State.mass = State.massInitial - (State.mdot * State.burnElapsed);
  }

  else if (abs(State.burnVelocity + State.vz) < .001) {
    // Start burn
    State.burnStart = t;
    State.burnElapsed = 0;
  }

  else
    State.burnElapsed = 2000; // arbitrary number to ensure we don't burn

  if ((State.burnElapsed > 0.147) && (State.burnElapsed < 0.420))
    State.thrust = 65.165 * State.burnElapsed - 2.3921;

  else if ((State.burnElapsed > 0.419) && (State.burnElapsed < 3.383))
    State.thrust = 0.8932 * pow(State.burnElapsed, 6) -
                   11.609 * pow(State.burnElapsed, 5) +
                   60.739 * pow(State.burnElapsed, 4) -
                   162.99 * pow(State.burnElapsed, 3) +
                   235.6 * pow(State.burnElapsed, 2) -
                   174.43 * State.burnElapsed + 67.17;

  else if ((State.burnElapsed > 3.382) && (State.burnElapsed < 3.46))
    State.thrust = -195.78 * State.burnElapsed + 675.11;
}

void lqrCalc(struct Vehicle &State) {

  State.I11 = State.mass * ((1 / 12) * pow(State.vehicleHeight, 2) +
                            pow(State.vehicleRadius, 2) / 4);
  State.I22 = State.mass * ((1 / 12) * pow(State.vehicleHeight, 2) +
                            pow(State.vehicleRadius, 2) / 4);
  State.I33 = State.mass * 0.5 * pow(State.vehicleRadius, 2);

  // Paste in Values from gainCalc.m
  double K11 = 39.54316;
  double K12 = 0.00000;
  double K13 = -0.00000;
  double K14 = 39.55769;
  double K15 = 0.00000;
  double K16 = 0.00000;
  double K21 = 0.00000;
  double K22 = 39.54316;
  double K23 = 0.00000;
  double K24 = 0.00000;
  double K25 = 39.55769;
  double K26 = 0.00000;
  double K31 = 0.00000;
  double K32 = 0.00000;
  double K33 = 39.54316;
  double K34 = 0.00000;
  double K35 = 0.00000;
  double K36 = 39.54394;

  // changing gain exponent drastically changes results of LQR
  double gain = 0.25 * pow(10, -4);

  // Matrix Multiply K with [YPR/2; w123] column vector and divide by moment arm
  State.LQRx =
      gain *
      ((K12 * State.pitch) / 2 + K15 * State.pitchdot + (K13 * State.roll) / 2 +
       K16 * State.rolldot + (K11 * State.yaw) / 2 + K14 * State.yawdot) /
      -State.momentArm;
  State.LQRy =
      gain *
      ((K22 * State.pitch) / 2 + K25 * State.pitchdot + (K23 * State.roll) / 2 +
       K26 * State.rolldot + (K21 * State.yaw) / 2 + K24 * State.yawdot) /
      -State.momentArm;

  // LQR Force limiter X
  if (State.LQRx > State.thrust)
    State.LQRx = State.thrust;
  else if (State.LQRx < -1 * State.thrust)
    State.LQRx = -1 * State.thrust;

  // LQR Force limiter Y
  if (State.LQRy > State.thrust)
    State.LQRy = State.thrust;
  else if (State.LQRy < -1 * State.thrust)
    State.LQRy = -1 * State.thrust;
}

void TVC(struct Vehicle &State) {
  if (State.thrust < 1) {
    // Define forces and moments for t = 0
    State.Fx = 0;
    State.Fy = 0;
    State.Fz = g * State.massInitial;

    State.momentX = 0;
    State.momentY = 0;
    State.momentZ = 0;
  } else {
    // Convert servo position to degrees for comparison to max allowable
    State.xServoDegs = (180 / M_PI) * asin(State.LQRx / State.thrust);

    // Servo position limiter
    if (State.xServoDegs > State.maxServo)
      State.xServoDegs = State.maxServo;
    else if (State.xServoDegs < -1 * State.maxServo)
      State.xServoDegs = -1 * State.maxServo;

    // Convert servo position to degrees for comparison to max allowable
    State.yServoDegs = (180 / M_PI) * asin(State.LQRy / State.thrust);

    // Servo position limiter
    if (State.yServoDegs > State.maxServo)
      State.yServoDegs = State.maxServo;
    else if (State.yServoDegs < -1 * State.maxServo)
      State.yServoDegs = -1 * State.maxServo;

    // Vector math to aqcuire thrust vector components
    State.Fx = State.thrust * sin(State.xServoDegs * (M_PI / 180));
    State.Fy = State.thrust * sin(State.yServoDegs * (M_PI / 180));
    State.Fz =
        sqrt(pow(State.thrust, 2) - (pow(State.Fx, 2) + pow(State.Fy, 2))) +
        (State.mass * g);

    // Calculate moment created by Fx and Fy
    State.momentX = State.Fx * State.momentArm;
    State.momentY = State.Fy * State.momentArm;
    State.momentZ = 0;
  }
}

void vehicleDynamics(Vehicle &State, Vehicle &PrevState, int t) {
  // Idot
  if (t < 1) {
    State.I11dot = 0;
    State.I22dot = 0;
    State.I33dot = 0;
  } else {
    State.I11dot = derivative(State.I11, PrevState.I11, State.stepSize);
    State.I22dot = derivative(State.I22, PrevState.I22, State.stepSize);
    State.I33dot = derivative(State.I33, PrevState.I33, State.stepSize);
  }

  // pdot, qdot, rdot
  State.yawddot = (State.momentX - State.I11dot * State.yawdot +
                   State.I22 * State.pitchdot * State.rolldot -
                   State.I33 * State.pitchdot * State.rolldot) /
                  State.I11;
  State.pitchddot = (State.momentY - State.I22dot * State.pitchdot -
                     State.I11 * State.rolldot * State.yawdot +
                     State.I33 * State.rolldot * State.yawdot) /
                    State.I22;
  State.rollddot = (State.momentZ - State.I33dot * State.rolldot +
                    State.I11 * State.pitchdot * State.yawdot -
                    State.I22 * State.pitchdot * State.yawdot) /
                   State.I33;

  if (t < 1) {
    State.x = 0;
    State.y = 0;

    State.ax = 0;
    State.ay = 0;
    State.az = State.Fz / State.massInitial;
  }

  else {
    // p, q, r
    State.yawdot = integral(State.yawddot, PrevState.yawdot, State.stepSize);
    State.pitchdot =
        integral(State.pitchddot, PrevState.pitchdot, State.stepSize);
    State.rolldot = integral(State.rollddot, PrevState.rolldot, State.stepSize);

    // ax ay az
    State.ax = (State.Fx / State.mass) +
               (State.pitchdot * State.vz - State.rolldot * State.vy);
    State.ay = (State.Fy / State.mass) +
               (State.rolldot * State.vx - State.vz * State.yawdot);
    State.az = (State.Fz / State.mass) +
               (State.vy * State.yawdot - State.pitchdot * State.vx);

    // vx vy vz in Body frame
    State.vx = integral(State.ax, PrevState.vx, State.stepSize);
    State.vy = integral(State.ay, PrevState.vy, State.stepSize);
    State.vz = integral(State.az, PrevState.vz, State.stepSize);

    // Xe
    State.x = integral(State.vx, PrevState.x, State.stepSize);
    State.y = integral(State.vy, PrevState.y, State.stepSize);
    State.z = integral(State.vz, PrevState.z, State.stepSize);

    // Euler Angles
    State.phidot = State.yawdot + (State.pitchdot * sin(State.yaw) +
                                   State.rolldot * cos(State.yaw)) *
                                      (sin(State.pitch) / cos(State.pitch));
    State.thetadot =
        State.pitchdot * cos(State.yaw) - State.rolldot * sin(State.pitch);
    State.psidot =
        (State.pitchdot * sin(State.yaw) + State.rolldot * cos(State.yaw)) /
        cos(State.pitch);

    State.yaw = integral(State.phidot, PrevState.yaw, State.stepSize);
    State.pitch = integral(State.thetadot, PrevState.pitch, State.stepSize);
    State.roll = integral(State.psidot, PrevState.roll, State.stepSize);
  }

  PrevState = State;

  /*
  // Set "prev" values for next timestep
  PrevState.I11 = State.I11;
  PrevState.I22 = State.I22;
  PrevState.I33 = State.I33;

  PrevState.yaw = State.yaw;
  PrevState.pitch = State.pitch;
  PrevState.roll = State.roll;

  PrevState.yawdot = State.yawdot;
  PrevState.pitchdot = State.pitchdot;
  PrevState.rolldot = State.rolldot;

  PrevState.yawddot = State.yawddot;
  PrevState.pitchddot = State.pitchddot;
  PrevState.rollddot = State.rollddot;

  PrevState.ax = State.ax;
  PrevState.ay = State.ay;
  PrevState.az = State.az;

  PrevState.vx = State.vx;
  PrevState.vy = State.vy;
  PrevState.vz = State.vz;

  PrevState.x = State.x;
  PrevState.y = State.y;
  PrevState.z = State.z;
  */
}

void write2CSV(struct Vehicle &State, std::fstream &outfile, int t) {
  // writing to output file
  outfile << t << ", ";

  outfile << State.x << ", ";
  outfile << State.y << ", ";
  outfile << State.z << ", ";

  outfile << State.vx << ", ";
  outfile << State.vy << ", ";
  outfile << State.vz << ", ";

  outfile << State.ax << ", ";
  outfile << State.ay << ", ";
  outfile << State.az << ", ";

  outfile << State.yaw * 180 / M_PI << ", ";
  outfile << State.pitch * 180 / M_PI << ", ";
  outfile << State.roll * 180 / M_PI << ", ";

  outfile << State.yawdot * 180 / M_PI << ", ";
  outfile << State.pitchdot * 180 / M_PI << ", ";
  outfile << State.rolldot * 180 / M_PI << ", ";

  outfile << State.yawddot * 180 / M_PI << ", ";
  outfile << State.pitchddot * 180 / M_PI << ", ";
  outfile << State.rollddot * 180 / M_PI << ", ";

  outfile << State.I11 << ", ";
  outfile << State.I22 << ", ";
  outfile << State.I33 << ", ";

  outfile << State.I11dot << ", ";
  outfile << State.I22dot << ", ";
  outfile << State.I33dot << ", ";

  outfile << State.xServoDegs << ", ";
  outfile << State.yServoDegs << ", ";

  outfile << State.mass << ", ";
  outfile << State.thrust << ", ";
  outfile << State.burnElapsed << ", ";
  outfile << State.Fz << ", ";

  outfile << State.LQRx << ", ";
  outfile << State.LQRy << std::endl;
}

double derivative(double x2, double x1, double dt) {
  double dxdt = (x2 - x1) / (dt / 1000);
  return dxdt;
}

double integral(double x, double y, double dt) {
  double integ = (x * dt / 1000) + y;
  return integ;
}