/*
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "AP_Beacon_SITL.h"

#if AP_BEACON_SITL_ENABLED

#include <AP_HAL/AP_HAL.h>

#include <stdio.h>

extern const AP_HAL::HAL& hal;

#define NUM_BEACONS 4
/*
 *  Define a rectangular pattern of beacons with the pattern centroid located at the beacon origin as defined by the following params:
 *
 * BCN_ALT - Height above the WGS-84 geoid (m)
 * BCN_LATITUDE - WGS-84 latitude (deg)
 * BCN_LONGITUDE - WGS-84 longitude (deg)
 *
 * The spacing between beacons in the North/South and East/West directions is defined by the following parameters:
 */
#define BEACON_SPACING_NORTH 10.0
#define BEACON_SPACING_EAST 20.0

// The centroid of the pattern can be moved using using the following parameters:
#define ORIGIN_OFFSET_NORTH 2.5 // shifts beacon pattern centroid North (m)
#define ORIGIN_OFFSET_EAST 5.0 // shifts beacon pattern centroid East (m)

// constructor
AP_Beacon_SITL::AP_Beacon_SITL(AP_Beacon &frontend) :
    AP_Beacon_Backend(frontend),
    sitl(AP::sitl())
{
}

// return true if sensor is basically healthy (we are receiving data)
bool AP_Beacon_SITL::healthy()
{
    // healthy if we have parsed a message within the past 300ms
    return ((AP_HAL::millis() - last_update_ms) < AP_BEACON_TIMEOUT_MS);
}

// update the state of the sensor
void AP_Beacon_SITL::update(void)
{
    uint32_t now = AP_HAL::millis();
    if (now - last_update_ms < 10) {
        return;
    }

    uint8_t beacon_id = next_beacon;
    next_beacon = (next_beacon+1) % NUM_BEACONS;

    // truth location of the flight vehicle
    Location current_loc;
    current_loc.lat = sitl->state.latitude * 1.0e7f;
    current_loc.lng = sitl->state.longitude * 1.0e7f;
    current_loc.alt = sitl->state.altitude * 1.0e2;

    // where the beacon system origin is located
    Location beacon_origin;
    beacon_origin.lat = get_beacon_origin_lat() * 1.0e7f;
    beacon_origin.lng = get_beacon_origin_lon() * 1.0e7f;
    beacon_origin.alt = get_beacon_origin_alt() * 1.0e2;

    // position of each beacon
    Location beacon_loc = beacon_origin;
    switch (beacon_id) {
    case 0:
        // NE corner
        beacon_loc.offset(ORIGIN_OFFSET_NORTH + BEACON_SPACING_NORTH/2, ORIGIN_OFFSET_EAST + BEACON_SPACING_EAST/2);
        break;
    case 1:
        // SE corner
        beacon_loc.offset(ORIGIN_OFFSET_NORTH - BEACON_SPACING_NORTH/2, ORIGIN_OFFSET_EAST + BEACON_SPACING_EAST/2);
        break;
    case 2:
        // SW corner
        beacon_loc.offset(ORIGIN_OFFSET_NORTH - BEACON_SPACING_NORTH/2, ORIGIN_OFFSET_EAST - BEACON_SPACING_EAST/2);
        break;
    case 3:
        // NW corner
        beacon_loc.offset(ORIGIN_OFFSET_NORTH + BEACON_SPACING_NORTH/2, ORIGIN_OFFSET_EAST - BEACON_SPACING_EAST/2);
        break;
    }

    const Vector2f beac_diff = beacon_origin.get_distance_NE(beacon_loc);
    const Vector2f veh_diff = beacon_origin.get_distance_NE(current_loc);

    Vector3f veh_pos3d(veh_diff.x, veh_diff.y, (beacon_origin.alt - current_loc.alt)*1.0e-2f);
    Vector3f beac_pos3d(beac_diff.x, beac_diff.y, (beacon_loc.alt - beacon_origin.alt)*1.0e-2f);
    Vector3f beac_veh_offset = veh_pos3d - beac_pos3d;

    set_beacon_position(beacon_id, beac_pos3d);
    set_beacon_distance(beacon_id, beac_veh_offset.length());
    set_vehicle_position(veh_pos3d, 0.5f);
    last_update_ms = now;
}

#endif // AP_BEACON_SITL_ENABLED