#include "Copter.h"

#if MODE_GUIDED_ENABLED == ENABLED

/*
 * Init and run calls for guided flight mode
 */

#ifndef GUIDED_LOOK_AT_TARGET_MIN_DISTANCE_CM
 # define GUIDED_LOOK_AT_TARGET_MIN_DISTANCE_CM     500     // point nose at target if it is more than 5m away
#endif

#define GUIDED_POSVEL_TIMEOUT_MS    3000    // guided mode's position-velocity controller times out after 3seconds with no new updates
#define GUIDED_ATTITUDE_TIMEOUT_MS  1000    // guided mode's attitude controller times out after 1 second with no new updates

static Vector3p guided_pos_target_cm;       // position target (used by posvel controller only)
bool guided_pos_terrain_alt;                // true if guided_pos_target_cm.z is an alt above terrain
static Vector3f guided_vel_target_cms;      // velocity target (used by pos_vel_accel controller and vel_accel controller)
static Vector3f guided_accel_target_cmss;   // acceleration target (used by pos_vel_accel controller vel_accel controller and accel controller)
static uint32_t update_time_ms;             // system time of last target update to pos_vel_accel, vel_accel or accel controller

struct {
    uint32_t update_time_ms;
    float roll_cd;
    float pitch_cd;
    float yaw_cd;
    float yaw_rate_cds;
    float climb_rate_cms;   // climb rate in cms.  Used if use_thrust is false
    float thrust;           // thrust from -1 to 1.  Used if use_thrust is true
    bool use_yaw_rate;
    bool use_thrust;
} static guided_angle_state;

struct Guided_Limit {
    uint32_t timeout_ms;  // timeout (in seconds) from the time that guided is invoked
    float alt_min_cm;   // lower altitude limit in cm above home (0 = no limit)
    float alt_max_cm;   // upper altitude limit in cm above home (0 = no limit)
    float horiz_max_cm; // horizontal position limit in cm from where guided mode was initiated (0 = no limit)
    uint32_t start_time;// system time in milliseconds that control was handed to the external computer
    Vector3f start_pos; // start position as a distance from home in cm.  used for checking horiz_max limit
} guided_limit;

// init - initialise guided controller
bool ModeGuided::init(bool ignore_checks)
{
    // start in velaccel control mode
    velaccel_control_start();
    guided_vel_target_cms.zero();
    guided_accel_target_cmss.zero();
    send_notification = false;
    return true;
}

// run - runs the guided controller
// should be called at 100hz or more
void ModeGuided::run()
{
    // call the correct auto controller
    switch (guided_mode) {

    case SubMode::TakeOff:
        // run takeoff controller
        takeoff_run();
        break;

    case SubMode::WP:
        // run position controller
        pos_control_run();
        if (send_notification && wp_nav->reached_wp_destination()) {
            send_notification = false;
            gcs().send_mission_item_reached_message(0);
        }
        break;

    case SubMode::Accel:
        accel_control_run();
        break;

    case SubMode::VelAccel:
        velaccel_control_run();
        break;

    case SubMode::PosVelAccel:
        posvelaccel_control_run();
        break;

    case SubMode::Angle:
        angle_control_run();
        break;
    }
 }

bool ModeGuided::allows_arming(AP_Arming::Method method) const
{
    // always allow arming from the ground station
    if (method == AP_Arming::Method::MAVLINK) {
        return true;
    }

    // optionally allow arming from the transmitter
    return (copter.g2.guided_options & (uint32_t)Options::AllowArmingFromTX) != 0;
};

// do_user_takeoff_start - initialises waypoint controller to implement take-off
bool ModeGuided::do_user_takeoff_start(float takeoff_alt_cm)
{
    guided_mode = SubMode::TakeOff;

    // initialise wpnav destination
    Location target_loc = copter.current_loc;
    Location::AltFrame frame = Location::AltFrame::ABOVE_HOME;
    if (wp_nav->rangefinder_used_and_healthy() &&
            wp_nav->get_terrain_source() == AC_WPNav::TerrainSource::TERRAIN_FROM_RANGEFINDER &&
            takeoff_alt_cm < copter.rangefinder.max_distance_cm_orient(ROTATION_PITCH_270)) {
        // can't takeoff downwards
        if (takeoff_alt_cm <= copter.rangefinder_state.alt_cm) {
            return false;
        }
        frame = Location::AltFrame::ABOVE_TERRAIN;
    }
    target_loc.set_alt_cm(takeoff_alt_cm, frame);

    if (!wp_nav->set_wp_destination_loc(target_loc)) {
        // failure to set destination can only be because of missing terrain data
        AP::logger().Write_Error(LogErrorSubsystem::NAVIGATION, LogErrorCode::FAILED_TO_SET_DESTINATION);
        // failure is propagated to GCS with NAK
        return false;
    }

    // initialise yaw
    auto_yaw.set_mode(AUTO_YAW_HOLD);

    // clear i term when we're taking off
    set_throttle_takeoff();

    // get initial alt for WP_NAVALT_MIN
    auto_takeoff_set_start_alt();

    return true;
}

// initialise position controller
void ModeGuided::pva_control_start()
{
    // initialise horizontal speed, acceleration
    pos_control->set_max_speed_accel_xy(wp_nav->get_default_speed_xy(), wp_nav->get_wp_acceleration());
    pos_control->set_correction_speed_accel_xy(wp_nav->get_default_speed_xy(), wp_nav->get_wp_acceleration());

    // initialize vertical speeds and acceleration
    pos_control->set_max_speed_accel_z(wp_nav->get_default_speed_down(), wp_nav->get_default_speed_up(), wp_nav->get_accel_z());
    pos_control->set_correction_speed_accel_z(wp_nav->get_default_speed_down(), wp_nav->get_default_speed_up(), wp_nav->get_accel_z());

    // initialise velocity controller
    pos_control->init_z_controller();
    pos_control->init_xy_controller();

    // initialise yaw
    auto_yaw.set_mode_to_default(false);
}

// initialise guided mode's position controller
void ModeGuided::pos_control_start()
{
    // set to position control mode
    guided_mode = SubMode::WP;

    // initialise position controller
    pva_control_start();
}

// initialise guided mode's velocity controller
void ModeGuided::accel_control_start()
{
    // set guided_mode to velocity controller
    guided_mode = SubMode::Accel;

    // initialise position controller
    pva_control_start();
}

// initialise guided mode's velocity and acceleration controller
void ModeGuided::velaccel_control_start()
{
    // set guided_mode to velocity controller
    guided_mode = SubMode::VelAccel;

    // initialise position controller
    pva_control_start();
}

// initialise guided mode's position, velocity and acceleration controller
void ModeGuided::posvelaccel_control_start()
{
    // set guided_mode to velocity controller
    guided_mode = SubMode::PosVelAccel;

    // initialise position controller
    pva_control_start();
}

bool ModeGuided::is_taking_off() const
{
    return guided_mode == SubMode::TakeOff;
}

// initialise guided mode's angle controller
void ModeGuided::angle_control_start()
{
    // set guided_mode to velocity controller
    guided_mode = SubMode::Angle;

    // set vertical speed and acceleration limits
    pos_control->set_max_speed_accel_z(wp_nav->get_default_speed_down(), wp_nav->get_default_speed_up(), wp_nav->get_accel_z());
    pos_control->set_correction_speed_accel_z(wp_nav->get_default_speed_down(), wp_nav->get_default_speed_up(), wp_nav->get_accel_z());

    // initialise the vertical position controller
    if (!pos_control->is_active_z()) {
        pos_control->init_z_controller();
    }

    // initialise targets
    guided_angle_state.update_time_ms = millis();
    guided_angle_state.roll_cd = ahrs.roll_sensor;
    guided_angle_state.pitch_cd = ahrs.pitch_sensor;
    guided_angle_state.yaw_cd = ahrs.yaw_sensor;
    guided_angle_state.climb_rate_cms = 0.0f;
    guided_angle_state.yaw_rate_cds = 0.0f;
    guided_angle_state.use_yaw_rate = false;

    // pilot always controls yaw
    auto_yaw.set_mode(AUTO_YAW_HOLD);
}

// set_destination - sets guided mode's target destination
// Returns true if the fence is enabled and guided waypoint is within the fence
// else return false if the waypoint is outside the fence
bool ModeGuided::set_destination(const Vector3f& destination, bool use_yaw, float yaw_cd, bool use_yaw_rate, float yaw_rate_cds, bool relative_yaw, bool terrain_alt)
{
#if AC_FENCE == ENABLED
    // reject destination if outside the fence
    const Location dest_loc(destination, terrain_alt ? Location::AltFrame::ABOVE_TERRAIN : Location::AltFrame::ABOVE_ORIGIN);
    if (!copter.fence.check_destination_within_fence(dest_loc)) {
        AP::logger().Write_Error(LogErrorSubsystem::NAVIGATION, LogErrorCode::DEST_OUTSIDE_FENCE);
        // failure is propagated to GCS with NAK
        return false;
    }
#endif

    // ensure we are in position control mode
    if (guided_mode != SubMode::WP) {
        pos_control_start();
    }

    // initialise terrain following if needed
    if (terrain_alt) {
        // get current alt above terrain
        float origin_terr_offset;
        if (!wp_nav->get_terrain_offset(origin_terr_offset)) {
            // if we don't have terrain altitude then stop
            init(true);
            return false;
        }
        // convert origin to alt-above-terrain if necessary
        if (!guided_pos_terrain_alt) {
            // new destination is alt-above-terrain, previous destination was alt-above-ekf-origin
            pos_control->set_pos_offset_z_cm(origin_terr_offset);
        }
    } else {
        pos_control->set_pos_offset_z_cm(0.0);
    }

    // set yaw state
    set_yaw_state(use_yaw, yaw_cd, use_yaw_rate, yaw_rate_cds, relative_yaw);

    // set position target and zero velocity and acceleration
    guided_pos_target_cm = destination.topostype();
    guided_pos_terrain_alt = terrain_alt;
    guided_vel_target_cms.zero();
    guided_accel_target_cmss.zero();
    update_time_ms = millis();

    // log target
    copter.Log_Write_GuidedTarget(guided_mode, guided_pos_target_cm.tofloat(), guided_pos_terrain_alt, guided_vel_target_cms, guided_accel_target_cmss);

    send_notification = true;

    return true;
}

bool ModeGuided::get_wp(Location& destination)
{
    if (guided_mode != SubMode::WP) {
        return false;
    }
    destination = Location(guided_pos_target_cm.tofloat(), guided_pos_terrain_alt ? Location::AltFrame::ABOVE_TERRAIN : Location::AltFrame::ABOVE_ORIGIN);
    return true;
}

// sets guided mode's target from a Location object
// returns false if destination could not be set (probably caused by missing terrain data)
// or if the fence is enabled and guided waypoint is outside the fence
bool ModeGuided::set_destination(const Location& dest_loc, bool use_yaw, float yaw_cd, bool use_yaw_rate, float yaw_rate_cds, bool relative_yaw)
{
#if AC_FENCE == ENABLED
    // reject destination outside the fence.
    // Note: there is a danger that a target specified as a terrain altitude might not be checked if the conversion to alt-above-home fails
    if (!copter.fence.check_destination_within_fence(dest_loc)) {
        AP::logger().Write_Error(LogErrorSubsystem::NAVIGATION, LogErrorCode::DEST_OUTSIDE_FENCE);
        // failure is propagated to GCS with NAK
        return false;
    }
#endif

    // ensure we are in position control mode
    if (guided_mode != SubMode::WP) {
        pos_control_start();
    }

    // set yaw state
    set_yaw_state(use_yaw, yaw_cd, use_yaw_rate, yaw_rate_cds, relative_yaw);

    // set position target and zero velocity and acceleration
    Vector3f pos_target_f;
    bool terrain_alt;
    if (!wp_nav->get_vector_NEU(dest_loc, pos_target_f, terrain_alt)) {
        return false;
    }

    // initialise terrain following if needed
    if (terrain_alt) {
        // get current alt above terrain
        float origin_terr_offset;
        if (!wp_nav->get_terrain_offset(origin_terr_offset)) {
            // if we don't have terrain altitude then stop
            init(true);
            return false;
        }
        // convert origin to alt-above-terrain if necessary
        if (!guided_pos_terrain_alt) {
            // new destination is alt-above-terrain, previous destination was alt-above-ekf-origin
            pos_control->set_pos_offset_z_cm(origin_terr_offset);
        }
    } else {
        pos_control->set_pos_offset_z_cm(0.0);
    }

    guided_pos_target_cm = pos_target_f.topostype();
    guided_pos_terrain_alt = terrain_alt;
    guided_vel_target_cms.zero();
    guided_accel_target_cmss.zero();

    // log target
    copter.Log_Write_GuidedTarget(guided_mode, Vector3f(dest_loc.lat, dest_loc.lng, dest_loc.alt), guided_pos_terrain_alt, guided_vel_target_cms, guided_accel_target_cmss);

    send_notification = true;

    return true;
}

// set_velaccel - sets guided mode's target velocity and acceleration
void ModeGuided::set_accel(const Vector3f& acceleration, bool use_yaw, float yaw_cd, bool use_yaw_rate, float yaw_rate_cds, bool relative_yaw, bool log_request)
{
    // check we are in velocity control mode
    if (guided_mode != SubMode::Accel) {
        accel_control_start();
    }

    // set yaw state
    set_yaw_state(use_yaw, yaw_cd, use_yaw_rate, yaw_rate_cds, relative_yaw);

    // set velocity and acceleration targets and zero position
    guided_pos_target_cm.zero();
    guided_pos_terrain_alt = false;
    guided_vel_target_cms.zero();
    guided_accel_target_cmss = acceleration;
    update_time_ms = millis();

    // log target
    if (log_request) {
        copter.Log_Write_GuidedTarget(guided_mode, guided_pos_target_cm.tofloat(), guided_pos_terrain_alt, guided_vel_target_cms, guided_accel_target_cmss);
    }
}

// set_velocity - sets guided mode's target velocity
void ModeGuided::set_velocity(const Vector3f& velocity, bool use_yaw, float yaw_cd, bool use_yaw_rate, float yaw_rate_cds, bool relative_yaw, bool log_request)
{
    set_velaccel(velocity, Vector3f(), use_yaw, yaw_cd, use_yaw_rate, yaw_rate_cds, relative_yaw, log_request);
}

// set_velaccel - sets guided mode's target velocity and acceleration
void ModeGuided::set_velaccel(const Vector3f& velocity, const Vector3f& acceleration, bool use_yaw, float yaw_cd, bool use_yaw_rate, float yaw_rate_cds, bool relative_yaw, bool log_request)
{
    // check we are in velocity control mode
    if (guided_mode != SubMode::VelAccel) {
        velaccel_control_start();
    }

    // set yaw state
    set_yaw_state(use_yaw, yaw_cd, use_yaw_rate, yaw_rate_cds, relative_yaw);

    // set velocity and acceleration targets and zero position
    guided_pos_target_cm.zero();
    guided_pos_terrain_alt = false;
    guided_vel_target_cms = velocity;
    guided_accel_target_cmss = acceleration;
    update_time_ms = millis();

    // log target
    if (log_request) {
        copter.Log_Write_GuidedTarget(guided_mode, guided_pos_target_cm.tofloat(), guided_pos_terrain_alt, guided_vel_target_cms, guided_accel_target_cmss);
    }
}

// set_destination_posvel - set guided mode position and velocity target
bool ModeGuided::set_destination_posvel(const Vector3f& destination, const Vector3f& velocity, bool use_yaw, float yaw_cd, bool use_yaw_rate, float yaw_rate_cds, bool relative_yaw)
{
    set_destination_posvelaccel(destination, velocity, Vector3f(), use_yaw, yaw_cd, use_yaw_rate, yaw_rate_cds, relative_yaw);
    return true;
}

// set_destination_posvelaccel - set guided mode position, velocity and acceleration target
bool ModeGuided::set_destination_posvelaccel(const Vector3f& destination, const Vector3f& velocity, const Vector3f& acceleration, bool use_yaw, float yaw_cd, bool use_yaw_rate, float yaw_rate_cds, bool relative_yaw)
{
#if AC_FENCE == ENABLED
    // reject destination if outside the fence
    const Location dest_loc(destination, Location::AltFrame::ABOVE_ORIGIN);
    if (!copter.fence.check_destination_within_fence(dest_loc)) {
        AP::logger().Write_Error(LogErrorSubsystem::NAVIGATION, LogErrorCode::DEST_OUTSIDE_FENCE);
        // failure is propagated to GCS with NAK
        return false;
    }
#endif

    // check we are in velocity control mode
    if (guided_mode != SubMode::PosVelAccel) {
        posvelaccel_control_start();
    }

    // set yaw state
    set_yaw_state(use_yaw, yaw_cd, use_yaw_rate, yaw_rate_cds, relative_yaw);

    update_time_ms = millis();
    guided_pos_target_cm = destination.topostype();
    guided_pos_terrain_alt = false;
    guided_vel_target_cms = velocity;
    guided_accel_target_cmss = acceleration;

    // log target
    copter.Log_Write_GuidedTarget(guided_mode, guided_pos_target_cm.tofloat(), guided_pos_terrain_alt, guided_vel_target_cms, guided_accel_target_cmss);
    return true;
}

// returns true if GUIDED_OPTIONS param suggests SET_ATTITUDE_TARGET's "thrust" field should be interpreted as thrust instead of climb rate
bool ModeGuided::set_attitude_target_provides_thrust() const
{
    return ((copter.g2.guided_options.get() & uint32_t(Options::SetAttitudeTarget_ThrustAsThrust)) != 0);
}

// returns true if GUIDED_OPTIONS param suggests SET_ATTITUDE_TARGET's "thrust" field should be interpreted as thrust instead of climb rate
bool ModeGuided:: stabilizing_pos_xy() const
{
    return !((copter.g2.guided_options.get() & uint32_t(Options::DoNotStabilizePositionXY)) != 0);
}

// returns true if GUIDED_OPTIONS param suggests SET_ATTITUDE_TARGET's "thrust" field should be interpreted as thrust instead of climb rate
bool ModeGuided:: stabilizing_vel_xy() const
{
    return !((copter.g2.guided_options.get() & uint32_t(Options::DoNotStabilizeVelocityXY)) != 0);
}

// set guided mode angle target and climbrate
void ModeGuided::set_angle(const Quaternion &q, float climb_rate_cms_or_thrust, bool use_yaw_rate, float yaw_rate_rads, bool use_thrust)
{
    // check we are in velocity control mode
    if (guided_mode != SubMode::Angle) {
        angle_control_start();
    }

    // convert quaternion to euler angles
    q.to_euler(guided_angle_state.roll_cd, guided_angle_state.pitch_cd, guided_angle_state.yaw_cd);
    guided_angle_state.roll_cd = ToDeg(guided_angle_state.roll_cd) * 100.0f;
    guided_angle_state.pitch_cd = ToDeg(guided_angle_state.pitch_cd) * 100.0f;
    guided_angle_state.yaw_cd = wrap_180_cd(ToDeg(guided_angle_state.yaw_cd) * 100.0f);
    guided_angle_state.yaw_rate_cds = ToDeg(yaw_rate_rads) * 100.0f;
    guided_angle_state.use_yaw_rate = use_yaw_rate;

    guided_angle_state.use_thrust = use_thrust;
    if (use_thrust) {
        guided_angle_state.thrust = climb_rate_cms_or_thrust;
        guided_angle_state.climb_rate_cms = 0.0f;
    } else {
        guided_angle_state.thrust = 0.0f;
        guided_angle_state.climb_rate_cms = climb_rate_cms_or_thrust;
    }

    guided_angle_state.update_time_ms = millis();

    // log target
    copter.Log_Write_GuidedTarget(guided_mode,
                           Vector3f(guided_angle_state.roll_cd, guided_angle_state.pitch_cd, guided_angle_state.yaw_cd),
                           false,
                           Vector3f(0.0f, 0.0f, climb_rate_cms_or_thrust), Vector3f());
}

// takeoff_run - takeoff in guided mode
//      called by guided_run at 100hz or more
void ModeGuided::takeoff_run()
{
    auto_takeoff_run();
    if (wp_nav->reached_wp_destination()) {
#if LANDING_GEAR_ENABLED == ENABLED
        // optionally retract landing gear
        copter.landinggear.retract_after_takeoff();
#endif

        // switch to position control mode but maintain current target
        const Vector3f target = pos_control->get_pos_target_cm().tofloat();
        set_destination(target, false, 0, false, 0, false, wp_nav->origin_and_destination_are_terrain_alt());
    }
}

// pos_control_run - runs the guided position controller
// called from guided_run
void ModeGuided::pos_control_run()
{
    // process pilot's yaw input
    float target_yaw_rate = 0;

    if (!copter.failsafe.radio && use_pilot_yaw()) {
        // get pilot's desired yaw rate
        target_yaw_rate = get_pilot_desired_yaw_rate(channel_yaw->get_control_in());
        if (!is_zero(target_yaw_rate)) {
            auto_yaw.set_mode(AUTO_YAW_HOLD);
        }
    }

    // if not armed set throttle to zero and exit immediately
    if (is_disarmed_or_landed()) {
        make_safe_spool_down();
        return;
    }

    // calculate terrain adjustments
    float terr_offset = 0.0f;
    if (guided_pos_terrain_alt && !wp_nav->get_terrain_offset(terr_offset)) {
        // failure to set destination can only be because of missing terrain data
        copter.failsafe_terrain_on_event();
        return;
    }

    // set motors to full range
    motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::THROTTLE_UNLIMITED);

    // send position and velocity targets to position controller
    guided_accel_target_cmss.zero();
    guided_vel_target_cms.zero();

    // todo: Randy to convert to parameter TERRAIN_MARGIN (in m)
    float TERRAIN_MARGIN = 10;
    float pos_offset_z_buffer = 0.0; // Vertical buffer size in m
    if (guided_pos_terrain_alt) {
        pos_offset_z_buffer = MIN(TERRAIN_MARGIN * 100.0, 0.5 * fabsf(guided_pos_target_cm.z));
    }
    pos_control->input_pos_xyz(guided_pos_target_cm, terr_offset, pos_offset_z_buffer);

    // run position controllers
    pos_control->update_xy_controller();
    pos_control->update_z_controller();

    // call attitude controller
    if (auto_yaw.mode() == AUTO_YAW_HOLD) {
        // roll & pitch from position controller, yaw rate from pilot
        attitude_control->input_thrust_vector_rate_heading(pos_control->get_thrust_vector(), target_yaw_rate);
    } else if (auto_yaw.mode() == AUTO_YAW_RATE) {
        // roll & pitch from position controller, yaw rate from mavlink command or mission item
        attitude_control->input_thrust_vector_rate_heading(pos_control->get_thrust_vector(), auto_yaw.rate_cds());
    } else {
        // roll & pitch from position controller, yaw heading from GCS or auto_heading()
        attitude_control->input_thrust_vector_heading(pos_control->get_thrust_vector(), auto_yaw.yaw(), auto_yaw.rate_cds());
    }
}

// velaccel_control_run - runs the guided velocity controller
// called from guided_run
void ModeGuided::accel_control_run()
{
    // process pilot's yaw input
    float target_yaw_rate = 0;
    if (!copter.failsafe.radio && use_pilot_yaw()) {
        // get pilot's desired yaw rate
        target_yaw_rate = get_pilot_desired_yaw_rate(channel_yaw->get_control_in());
        if (!is_zero(target_yaw_rate)) {
            auto_yaw.set_mode(AUTO_YAW_HOLD);
        }
    }

    // if not armed set throttle to zero and exit immediately
    if (is_disarmed_or_landed()) {
        make_safe_spool_down();
        return;
    }

    // set motors to full range
    motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::THROTTLE_UNLIMITED);

    // set velocity to zero and stop rotating if no updates received for 3 seconds
    uint32_t tnow = millis();
    if (tnow - update_time_ms > GUIDED_POSVEL_TIMEOUT_MS) {
        guided_vel_target_cms.zero();
        guided_accel_target_cmss.zero();
        if (auto_yaw.mode() == AUTO_YAW_RATE) {
            auto_yaw.set_rate(0.0f);
        }
        pos_control->input_vel_accel_xy(guided_vel_target_cms.xy(), guided_accel_target_cmss.xy());
        pos_control->input_vel_accel_z(guided_vel_target_cms.z, guided_accel_target_cmss.z, false);
    } else {
        // update position controller with new target
        pos_control->input_accel_xy(guided_accel_target_cmss);
        if (!stabilizing_vel_xy()) {
            // set position and velocity errors to zero
            pos_control->stop_vel_xy_stabilisation();
        } else if (!stabilizing_pos_xy()) {
            // set position errors to zero
            pos_control->stop_pos_xy_stabilisation();
        }
        pos_control->input_accel_z(guided_accel_target_cmss.z);
    }

    // call velocity controller which includes z axis controller
    pos_control->update_xy_controller();
    pos_control->update_z_controller();

    // call attitude controller
    if (auto_yaw.mode() == AUTO_YAW_HOLD) {
        // roll & pitch from position controller, yaw rate from pilot
        attitude_control->input_thrust_vector_rate_heading(pos_control->get_thrust_vector(), target_yaw_rate);
    } else if (auto_yaw.mode() == AUTO_YAW_RATE) {
        // roll & pitch from position controller, yaw rate from mavlink command or mission item
        attitude_control->input_thrust_vector_rate_heading(pos_control->get_thrust_vector(), auto_yaw.rate_cds());
    } else {
        // roll & pitch from position controller, yaw heading from GCS or auto_heading()
        attitude_control->input_thrust_vector_heading(pos_control->get_thrust_vector(), auto_yaw.yaw(), auto_yaw.rate_cds());
    }
}

// velaccel_control_run - runs the guided velocity and acceleration controller
// called from guided_run
void ModeGuided::velaccel_control_run()
{
    // process pilot's yaw input
    float target_yaw_rate = 0;
    if (!copter.failsafe.radio && use_pilot_yaw()) {
        // get pilot's desired yaw rate
        target_yaw_rate = get_pilot_desired_yaw_rate(channel_yaw->get_control_in());
        if (!is_zero(target_yaw_rate)) {
            auto_yaw.set_mode(AUTO_YAW_HOLD);
        }
    }

    // if not armed set throttle to zero and exit immediately
    if (is_disarmed_or_landed()) {
        make_safe_spool_down();
        return;
    }

    // set motors to full range
    motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::THROTTLE_UNLIMITED);

    // set velocity to zero and stop rotating if no updates received for 3 seconds
    uint32_t tnow = millis();
    if (tnow - update_time_ms > GUIDED_POSVEL_TIMEOUT_MS) {
        guided_vel_target_cms.zero();
        guided_accel_target_cmss.zero();
        if (auto_yaw.mode() == AUTO_YAW_RATE) {
            auto_yaw.set_rate(0.0f);
        }
    }

    bool do_avoid = false;
#if AC_AVOID_ENABLED
    // limit the velocity for obstacle/fence avoidance
    copter.avoid.adjust_velocity(guided_vel_target_cms, pos_control->get_pos_xy_p().kP(), pos_control->get_max_accel_xy_cmss(), pos_control->get_pos_z_p().kP(), pos_control->get_max_accel_z_cmss(), G_Dt);
    do_avoid = copter.avoid.limits_active();
#endif

    // update position controller with new target

    if (!stabilizing_vel_xy() && !do_avoid) {
        // set the current commanded xy vel to the desired vel
        guided_vel_target_cms.x = pos_control->get_vel_desired_cms().x;
        guided_vel_target_cms.y = pos_control->get_vel_desired_cms().y;
    }
    pos_control->input_vel_accel_xy(guided_vel_target_cms.xy(), guided_accel_target_cmss.xy());
    if (!stabilizing_vel_xy() && !do_avoid) {
        // set position and velocity errors to zero
        pos_control->stop_vel_xy_stabilisation();
    } else if (!stabilizing_pos_xy() && !do_avoid) {
        // set position errors to zero
        pos_control->stop_pos_xy_stabilisation();
    }
    pos_control->input_vel_accel_z(guided_vel_target_cms.z, guided_accel_target_cmss.z, false);

    // call velocity controller which includes z axis controller
    pos_control->update_xy_controller();
    pos_control->update_z_controller();

    // call attitude controller
    if (auto_yaw.mode() == AUTO_YAW_HOLD) {
        // roll & pitch from position controller, yaw rate from pilot
        attitude_control->input_thrust_vector_rate_heading(pos_control->get_thrust_vector(), target_yaw_rate);
    } else if (auto_yaw.mode() == AUTO_YAW_RATE) {
        // roll & pitch from position controller, yaw rate from mavlink command or mission item
        attitude_control->input_thrust_vector_rate_heading(pos_control->get_thrust_vector(), auto_yaw.rate_cds());
    } else {
        // roll & pitch from position controller, yaw heading from GCS or auto_heading()
        attitude_control->input_thrust_vector_heading(pos_control->get_thrust_vector(), auto_yaw.yaw(), auto_yaw.rate_cds());
    }
}

// posvelaccel_control_run - runs the guided position, velocity and acceleration controller
// called from guided_run
void ModeGuided::posvelaccel_control_run()
{
    // process pilot's yaw input
    float target_yaw_rate = 0;

    if (!copter.failsafe.radio && use_pilot_yaw()) {
        // get pilot's desired yaw rate
        target_yaw_rate = get_pilot_desired_yaw_rate(channel_yaw->get_control_in());
        if (!is_zero(target_yaw_rate)) {
            auto_yaw.set_mode(AUTO_YAW_HOLD);
        }
    }

    // if not armed set throttle to zero and exit immediately
    if (is_disarmed_or_landed()) {
        make_safe_spool_down();
        return;
    }

    // set motors to full range
    motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::THROTTLE_UNLIMITED);

    // set velocity to zero and stop rotating if no updates received for 3 seconds
    uint32_t tnow = millis();
    if (tnow - update_time_ms > GUIDED_POSVEL_TIMEOUT_MS) {
        guided_vel_target_cms.zero();
        guided_accel_target_cmss.zero();
        if (auto_yaw.mode() == AUTO_YAW_RATE) {
            auto_yaw.set_rate(0.0f);
        }
    }

    // send position and velocity targets to position controller
    if (!stabilizing_vel_xy()) {
        // set the current commanded xy pos to the target pos and xy vel to the desired vel
        guided_pos_target_cm.x = pos_control->get_pos_target_cm().x;
        guided_pos_target_cm.y = pos_control->get_pos_target_cm().y;
        guided_vel_target_cms.x = pos_control->get_vel_desired_cms().x;
        guided_vel_target_cms.y = pos_control->get_vel_desired_cms().y;
    } else if (!stabilizing_pos_xy()) {
        // set the current commanded xy pos to the target pos
        guided_pos_target_cm.x = pos_control->get_pos_target_cm().x;
        guided_pos_target_cm.y = pos_control->get_pos_target_cm().y;
    }
    pos_control->input_pos_vel_accel_xy(guided_pos_target_cm.xy(), guided_vel_target_cms.xy(), guided_accel_target_cmss.xy());
    if (!stabilizing_vel_xy()) {
        // set position and velocity errors to zero
        pos_control->stop_vel_xy_stabilisation();
    } else if (!stabilizing_pos_xy()) {
        // set position errors to zero
        pos_control->stop_pos_xy_stabilisation();
    }

    // guided_pos_target z-axis should never be a terrain altitude
    if (guided_pos_terrain_alt) {
        INTERNAL_ERROR(AP_InternalError::error_t::flow_of_control);
    }

    float pz = guided_pos_target_cm.z;
    pos_control->input_pos_vel_accel_z(pz, guided_vel_target_cms.z, guided_accel_target_cmss.z);
    guided_pos_target_cm.z = pz;

    // run position controllers
    pos_control->update_xy_controller();
    pos_control->update_z_controller();

    // call attitude controller
    if (auto_yaw.mode() == AUTO_YAW_HOLD) {
        // roll & pitch from position controller, yaw rate from pilot
        attitude_control->input_thrust_vector_rate_heading(pos_control->get_thrust_vector(), target_yaw_rate);
    } else if (auto_yaw.mode() == AUTO_YAW_RATE) {
        // roll & pitch from position controller, yaw rate from mavlink command or mission item
        attitude_control->input_thrust_vector_rate_heading(pos_control->get_thrust_vector(), auto_yaw.rate_cds());
    } else {
        // roll & pitch from position controller, yaw heading from GCS or auto_heading()
        attitude_control->input_thrust_vector_heading(pos_control->get_thrust_vector(), auto_yaw.yaw(), auto_yaw.rate_cds());
    }
}

// angle_control_run - runs the guided angle controller
// called from guided_run
void ModeGuided::angle_control_run()
{
    // constrain desired lean angles
    float roll_in = guided_angle_state.roll_cd;
    float pitch_in = guided_angle_state.pitch_cd;
    float total_in = norm(roll_in, pitch_in);
    float angle_max = MIN(attitude_control->get_althold_lean_angle_max(), copter.aparm.angle_max);
    if (total_in > angle_max) {
        float ratio = angle_max / total_in;
        roll_in *= ratio;
        pitch_in *= ratio;
    }

    // wrap yaw request
    float yaw_in = wrap_180_cd(guided_angle_state.yaw_cd);
    float yaw_rate_in = guided_angle_state.yaw_rate_cds;

    float climb_rate_cms = 0.0f;
    if (!guided_angle_state.use_thrust) {
        // constrain climb rate
        climb_rate_cms = constrain_float(guided_angle_state.climb_rate_cms, -fabsf(wp_nav->get_default_speed_down()), wp_nav->get_default_speed_up());

        // get avoidance adjusted climb rate
        climb_rate_cms = get_avoidance_adjusted_climbrate(climb_rate_cms);
    }

    // check for timeout - set lean angles and climb rate to zero if no updates received for 3 seconds
    uint32_t tnow = millis();
    if (tnow - guided_angle_state.update_time_ms > GUIDED_ATTITUDE_TIMEOUT_MS) {
        roll_in = 0.0f;
        pitch_in = 0.0f;
        climb_rate_cms = 0.0f;
        yaw_rate_in = 0.0f;
        if (guided_angle_state.use_thrust) {
            // initialise vertical velocity controller
            pos_control->init_z_controller();
            guided_angle_state.use_thrust = false;
        }
    }

    // interpret positive climb rate or thrust as triggering take-off
    const bool positive_thrust_or_climbrate = is_positive(guided_angle_state.use_thrust ? guided_angle_state.thrust : climb_rate_cms);
    if (motors->armed() && positive_thrust_or_climbrate) {
        copter.set_auto_armed(true);
    }

    // if not armed set throttle to zero and exit immediately
    if (!motors->armed() || !copter.ap.auto_armed || (copter.ap.land_complete && !positive_thrust_or_climbrate)) {
        make_safe_spool_down();
        return;
    }

    // TODO: use get_alt_hold_state
    // landed with positive desired climb rate, takeoff
    if (copter.ap.land_complete && (guided_angle_state.climb_rate_cms > 0.0f)) {
        zero_throttle_and_relax_ac();
        motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::THROTTLE_UNLIMITED);
        if (motors->get_spool_state() == AP_Motors::SpoolState::THROTTLE_UNLIMITED) {
            set_land_complete(false);
            set_throttle_takeoff();
        }
        return;
    }

    // set motors to full range
    motors->set_desired_spool_state(AP_Motors::DesiredSpoolState::THROTTLE_UNLIMITED);

    // call attitude controller
    if (guided_angle_state.use_yaw_rate) {
        attitude_control->input_euler_angle_roll_pitch_euler_rate_yaw(roll_in, pitch_in, yaw_rate_in);
    } else {
        attitude_control->input_euler_angle_roll_pitch_yaw(roll_in, pitch_in, yaw_in, true);
    }

    // call position controller
    if (guided_angle_state.use_thrust) {
        attitude_control->set_throttle_out(guided_angle_state.thrust, true, copter.g.throttle_filt);
    } else {
        pos_control->set_pos_target_z_from_climb_rate_cm(climb_rate_cms, false);
        pos_control->update_z_controller();
    }
}

// helper function to update position controller's desired velocity while respecting acceleration limits
void ModeGuided::set_desired_velocity_with_accel_and_fence_limits(const Vector3f& vel_des)
{
}

// helper function to set yaw state and targets
void ModeGuided::set_yaw_state(bool use_yaw, float yaw_cd, bool use_yaw_rate, float yaw_rate_cds, bool relative_angle)
{
    if (use_yaw && relative_angle) {
        auto_yaw.set_fixed_yaw(yaw_cd * 0.01f, 0.0f, 0, relative_angle);
    } else if (use_yaw && use_yaw_rate) {
        auto_yaw.set_yaw_angle_rate(yaw_cd * 0.01f, yaw_rate_cds * 0.01f);
    } else if (use_yaw && !use_yaw_rate) {
        auto_yaw.set_yaw_angle_rate(yaw_cd * 0.01f, 0.0f);
    } else if (use_yaw_rate) {
        auto_yaw.set_rate(yaw_rate_cds);
    }
}

// returns true if pilot's yaw input should be used to adjust vehicle's heading
bool ModeGuided::use_pilot_yaw(void) const
{
    return (copter.g2.guided_options.get() & uint32_t(Options::IgnorePilotYaw)) == 0;
}

// Guided Limit code

// limit_clear - clear/turn off guided limits
void ModeGuided::limit_clear()
{
    guided_limit.timeout_ms = 0;
    guided_limit.alt_min_cm = 0.0f;
    guided_limit.alt_max_cm = 0.0f;
    guided_limit.horiz_max_cm = 0.0f;
}

// limit_set - set guided timeout and movement limits
void ModeGuided::limit_set(uint32_t timeout_ms, float alt_min_cm, float alt_max_cm, float horiz_max_cm)
{
    guided_limit.timeout_ms = timeout_ms;
    guided_limit.alt_min_cm = alt_min_cm;
    guided_limit.alt_max_cm = alt_max_cm;
    guided_limit.horiz_max_cm = horiz_max_cm;
}

// limit_init_time_and_pos - initialise guided start time and position as reference for limit checking
//  only called from AUTO mode's auto_nav_guided_start function
void ModeGuided::limit_init_time_and_pos()
{
    // initialise start time
    guided_limit.start_time = AP_HAL::millis();

    // initialise start position from current position
    guided_limit.start_pos = inertial_nav.get_position();
}

// limit_check - returns true if guided mode has breached a limit
//  used when guided is invoked from the NAV_GUIDED_ENABLE mission command
bool ModeGuided::limit_check()
{
    // check if we have passed the timeout
    if ((guided_limit.timeout_ms > 0) && (millis() - guided_limit.start_time >= guided_limit.timeout_ms)) {
        return true;
    }

    // get current location
    const Vector3f& curr_pos = inertial_nav.get_position();

    // check if we have gone below min alt
    if (!is_zero(guided_limit.alt_min_cm) && (curr_pos.z < guided_limit.alt_min_cm)) {
        return true;
    }

    // check if we have gone above max alt
    if (!is_zero(guided_limit.alt_max_cm) && (curr_pos.z > guided_limit.alt_max_cm)) {
        return true;
    }

    // check if we have gone beyond horizontal limit
    if (guided_limit.horiz_max_cm > 0.0f) {
        float horiz_move = get_horizontal_distance_cm(guided_limit.start_pos, curr_pos);
        if (horiz_move > guided_limit.horiz_max_cm) {
            return true;
        }
    }

    // if we got this far we must be within limits
    return false;
}

const Vector3p &ModeGuided::get_target_pos() const
{
    return guided_pos_target_cm;
}

const Vector3f& ModeGuided::get_target_vel() const
{
    return guided_vel_target_cms;
}

const Vector3f& ModeGuided::get_target_accel() const
{
    return guided_accel_target_cmss;
}

uint32_t ModeGuided::wp_distance() const
{
    switch(guided_mode) {
    case SubMode::WP:
        return norm(guided_pos_target_cm.x - inertial_nav.get_position().x, guided_pos_target_cm.y - inertial_nav.get_position().y);
        break;
    case SubMode::PosVelAccel:
        return pos_control->get_pos_error_xy_cm();
        break;
    default:
        return 0;
    }
}

int32_t ModeGuided::wp_bearing() const
{
    switch(guided_mode) {
    case SubMode::WP:
        return get_bearing_cd(inertial_nav.get_position(), guided_pos_target_cm.tofloat());
        break;
    case SubMode::PosVelAccel:
        return pos_control->get_bearing_to_target_cd();
        break;
    case SubMode::TakeOff:
    case SubMode::Accel:
    case SubMode::VelAccel:
    case SubMode::Angle:
        // these do not have bearings
        return 0;
    }
    // compiler guarantees we don't get here
    return 0.0;
}

float ModeGuided::crosstrack_error() const
{
    switch (guided_mode) {
    case SubMode::WP:
    case SubMode::TakeOff:
    case SubMode::Accel:
    case SubMode::VelAccel:
    case SubMode::PosVelAccel:
    case SubMode::Angle:
        // no track to have a crosstrack to
        return 0;
    }
    // compiler guarantees we don't get here
    return 0;
}

#endif