/*
 * Copyright (C) 2016  Intel Corporation. All rights reserved.
 *
 * This file 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 file 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_HAL/AP_HAL.h>
#include <AP_SerialManager/AP_SerialManager.h>
#include <ctype.h>
#include "AP_RangeFinder_NanoRadar_MR72.h"

#define MAXSONAR_SERIAL_LV_BAUD_RATE 9600

extern const AP_HAL::HAL &hal;

static const uint8_t crc8_table[] = {
    0x00, 0x07, 0x0e, 0x09, 0x1c, 0x1b, 0x12, 0x15, 0x38, 0x3f, 0x36, 0x31,
    0x24, 0x23, 0x2a, 0x2d, 0x70, 0x77, 0x7e, 0x79, 0x6c, 0x6b, 0x62, 0x65,
    0x48, 0x4f, 0x46, 0x41, 0x54, 0x53, 0x5a, 0x5d, 0xe0, 0xe7, 0xee, 0xe9,
    0xfc, 0xfb, 0xf2, 0xf5, 0xd8, 0xdf, 0xd6, 0xd1, 0xc4, 0xc3, 0xca, 0xcd,
    0x90, 0x97, 0x9e, 0x99, 0x8c, 0x8b, 0x82, 0x85, 0xa8, 0xaf, 0xa6, 0xa1,
    0xb4, 0xb3, 0xba, 0xbd, 0xc7, 0xc0, 0xc9, 0xce, 0xdb, 0xdc, 0xd5, 0xd2,
    0xff, 0xf8, 0xf1, 0xf6, 0xe3, 0xe4, 0xed, 0xea, 0xb7, 0xb0, 0xb9, 0xbe,
    0xab, 0xac, 0xa5, 0xa2, 0x8f, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9d, 0x9a,
    0x27, 0x20, 0x29, 0x2e, 0x3b, 0x3c, 0x35, 0x32, 0x1f, 0x18, 0x11, 0x16,
    0x03, 0x04, 0x0d, 0x0a, 0x57, 0x50, 0x59, 0x5e, 0x4b, 0x4c, 0x45, 0x42,
    0x6f, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7d, 0x7a, 0x89, 0x8e, 0x87, 0x80,
    0x95, 0x92, 0x9b, 0x9c, 0xb1, 0xb6, 0xbf, 0xb8, 0xad, 0xaa, 0xa3, 0xa4,
    0xf9, 0xfe, 0xf7, 0xf0, 0xe5, 0xe2, 0xeb, 0xec, 0xc1, 0xc6, 0xcf, 0xc8,
    0xdd, 0xda, 0xd3, 0xd4, 0x69, 0x6e, 0x67, 0x60, 0x75, 0x72, 0x7b, 0x7c,
    0x51, 0x56, 0x5f, 0x58, 0x4d, 0x4a, 0x43, 0x44, 0x19, 0x1e, 0x17, 0x10,
    0x05, 0x02, 0x0b, 0x0c, 0x21, 0x26, 0x2f, 0x28, 0x3d, 0x3a, 0x33, 0x34,
    0x4e, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5c, 0x5b, 0x76, 0x71, 0x78, 0x7f,
    0x6a, 0x6d, 0x64, 0x63, 0x3e, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2c, 0x2b,
    0x06, 0x01, 0x08, 0x0f, 0x1a, 0x1d, 0x14, 0x13, 0xae, 0xa9, 0xa0, 0xa7,
    0xb2, 0xb5, 0xbc, 0xbb, 0x96, 0x91, 0x98, 0x9f, 0x8a, 0x8d, 0x84, 0x83,
    0xde, 0xd9, 0xd0, 0xd7, 0xc2, 0xc5, 0xcc, 0xcb, 0xe6, 0xe1, 0xe8, 0xef,
    0xfa, 0xfd, 0xf4, 0xf3};
/* 
   The constructor also initialises the rangefinder. Note that this
   constructor is not called until detect() returns true, so we
   already know that we should setup the rangefinder
*/
AP_RangeFinder_NanoRadar_MR72::AP_RangeFinder_NanoRadar_MR72(RangeFinder::RangeFinder_State &_state,
                                                             AP_RangeFinder_Params &_params,
                                                             uint8_t serial_instance) : AP_RangeFinder_Backend(_state, _params)
{
    const AP_SerialManager &serial_manager = AP::serialmanager();
    uart = serial_manager.find_serial(AP_SerialManager::SerialProtocol_Rangefinder, serial_instance);
    if (uart != nullptr)
    {
        uart->begin(serial_manager.find_baudrate(AP_SerialManager::SerialProtocol_Rangefinder, serial_instance));
    }
}

/* 
   detect if a MaxSonar rangefinder is connected. We'll detect by
   trying to take a reading on Serial. If we get a result the sensor is
   there.
*/
bool AP_RangeFinder_NanoRadar_MR72::detect(uint8_t serial_instance)
{
    return AP::serialmanager().find_serial(AP_SerialManager::SerialProtocol_Rangefinder, serial_instance) != nullptr;
}

// read - return last value measured by sensor
bool AP_RangeFinder_NanoRadar_MR72::get_reading(uint16_t &reading_cm)
{
    if (uart == nullptr)
    {
        return false;
    }

    uint8_t frameOK = 0;
    uint16_t Range = 0; //雷达实测距离
    int16_t nbytes = uart->available();

    while (nbytes-- > 0)
    {
        // uint8_t c = uart->read();
        // gcs().send_text(MAV_SEVERITY_INFO, "getc 0x%02x",c);
        if (uart->read() == Head1)
        { //判断数据包帧头0x54
            string[0] = Head1;
            // gcs().send_text(MAV_SEVERITY_INFO, "getc 0x%02x",string[0]);
            if (uart->read() == Head2)
            { //判断数据包帧头0X48
                string[1] = Head2;
                // gcs().send_text(MAV_SEVERITY_INFO, "getc 0x%02x",string[1]);
                for (int i = 2; i < 19; i++)
                { //存储数据到数组
                    string[i] = uart->read();
                    // gcs().send_text(MAV_SEVERITY_INFO, "%02d: 0x%02x",i,string[i]);
                }
                CheckSum = crc_crc8(string,18);
                // gcs().send_text(MAV_SEVERITY_INFO, "crc 0x%02x, rec:0x%02x",CheckSum,string[18]);
                if (string[18] == CheckSum)
                { //按照协议对收到的数据进行校验
                    frameOK = 1;
                    Range = (string[2] * 256 + string[3]); //cm
                    // gcs().send_text(MAV_SEVERITY_INFO, "range: %dcm",Range);
                    // testdata = (string[8]*256+string[9]);
                }
            }
        }
    }

    if (frameOK == 0)
    {
        return false;
    }

    if (Range != 0)
    {
        reading_cm = Range;
    }
    return true;
}

/* 
   update the state of the sensor
*/
void AP_RangeFinder_NanoRadar_MR72::update(void)
{
    if (get_reading(state.distance_cm))
    {
        // update range_valid state based on distance measured
        state.last_reading_ms = AP_HAL::millis();
        update_status();
    }
    else if (AP_HAL::millis() - state.last_reading_ms > 500)
    {
        set_status(RangeFinder::RangeFinder_NoData);
    }
}

/*
crc8 from trone driver by Luis Rodrigues
*/
uint8_t AP_RangeFinder_NanoRadar_MR72::crc_crc8(const uint8_t *p, uint8_t len)
{
    uint16_t i;
    uint16_t crc = 0x0;
    while (len--)
    {
        i = (crc ^ *p++) & 0xFF;
        crc = (crc8_table[i] ^ (crc << 8)) & 0xFF;
    }
    return crc & 0xFF;
}