/*
   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/>.
 */
#pragma once

/*
  AP_Radio implementation for CC2500 2.4GHz radio.

  With thanks to cleanflight and betaflight projects
 */

#include "AP_Radio_config.h"

#if AP_RADIO_BK2425_ENABLED

#include "AP_Radio_backend.h"

#include "hal.h"
#include "telem_structure.h"
#include "driver_bk2425.h"

#define BEKEN_MAX_CHANNELS 16
// Documentation of the expected RSSI values. These are determined by the Cypress chip.
enum {
    BK_RSSI_MIN = 0, // Minimum value for RSSI
    BK_RSSI_DEFAULT = 16, // The default value for RSSI for chips that do not support it.
    BK_RSSI_MAX = 31 // Maximum value for RSSI
};

// This helper struct estimates the times (in microseconds) between packets,
// according to the STM32 clock which may well be 2% different from the STM8 clock.
// For instance it may be 5108 instead of the nominal 5000 microseconds.
struct SyncTiming {
    enum { TARGET_DELTA_RX = 5000,               // Nominal 5ms between packets is expected
           SLOP_DELTA_RX = TARGET_DELTA_RX / 10,    // +/- 500us i.e. 10% skew each way is accepted.
           DIFF_DELTA_RX = TARGET_DELTA_RX / 100
         }; // Two consequetive deltas must be very close together (50us)
    uint32_t packet_timer; // Time we last received a valid control packet
    uint32_t rx_time_us; // Time we last received a packet
    uint32_t tx_time_us; // Time we last finished transmitting a packet
    uint32_t delta_rx_time_us; // Time between last rx packets
    uint32_t last_delta_rx_time_us; // previous version of the delta
    uint32_t sync_time_us; // Estimate of base time in microseconds between packets. 5000 +/- 500
    SyncTiming() : // Constructor to setup sensible initial conditions
        delta_rx_time_us(TARGET_DELTA_RX),
        last_delta_rx_time_us(TARGET_DELTA_RX),
        sync_time_us(TARGET_DELTA_RX)
    {}
    void Rx(uint32_t when); // Adjust the timing based on a new packet
};

// Helper struct for synchronising channels when we change hopping table (e.g. learn of a WiFi channel change).
struct SyncChannel {
    enum { countdown_invalid = 0 }; // When countdown is this value, no change is pending
    uint8_t channel; // Index within the channel hopping sequence. Corresponds to txChannel on the button board
    uint8_t lastchan; // Last requested index, if it is a factory test channel.
    uint8_t countdown; // How many packet slots until a pending table change occurs?
    uint8_t countdown_chan; // Which channel do we jump to when the table change happens?
    uint8_t hopping_current; // Which alternative channels are we on now
    uint8_t hopping_wanted; //  Which alternative channels will we be on when Tx changes over?
    uint8_t hopping_countdown; // How many packet slots until a pending table change occurs?
    SyncChannel() : // Constructor to setup sensible initial conditions
        channel(0),
        lastchan(0),
        countdown(countdown_invalid),
        countdown_chan(0),
        hopping_current(0),
        hopping_wanted(0),
        hopping_countdown(countdown_invalid)
    {}
    void SetChannelIfSafe(uint8_t chan); // Check if valid channel index; we have received a packet describing the current channel index
    void SetChannel(uint8_t chan) // Already safe. We have received a packet describing the current channel index
    {
        channel = chan;
    }
    void SetCountdown(uint8_t cnt, uint8_t nextCh) // We receive a countdown to a non-normal channel change in the future
    {
        countdown = cnt;
        countdown_chan = nextCh;
    }
    void SetHopping(uint8_t cnt, uint8_t nextHopping) // We receive a countdown to a change in the adaptive table in the future/now
    {
        hopping_countdown = cnt;
        hopping_wanted = nextHopping;
        if (cnt == 0) {
            hopping_current = nextHopping;
        }
    }
    void NextChannel(void); // Step through the channels normally (taking countdowns into account)
    void SafeTable(void); // Give up on this WiFi table as packets have not been received
};

// This helper struct determines which physical channels are better
struct SyncAdaptive {
    uint32_t missed[CHANNEL_FCC_HIGH+1]; // Missed
    uint32_t rx[CHANNEL_FCC_HIGH+1]; // Received
    uint8_t hopping; // Currently wanted hopping state. Send this to the tx.
    SyncAdaptive() : // Constructor to setup sensible initial conditions
        hopping(0)
    {}
    void Miss(uint8_t channel);
    void Get(uint8_t channel);
    void Invalidate()
    {
        hopping = 0;    // e.g. if we have jumped tables
    }
};

// Support OTA upload. Assumes that mavlink offsets go from zero upwards contiguously
struct FwUpload {
    enum { SZ_BUFFER = 128 }; // Must be a power of two
    mavlink_channel_t chan; // Reference for talking to mavlink subsystem
    uint8_t counter; // Used to throttle the upload, to prevent starvation of telemetry
    enum telem_type fw_type; // Whether we are uploading program code or a test tune

    // Data that is reset by reset()
    bool need_ack; // When true, we need to talk to mavlink subsystem (ask for more firmware)
    uint32_t added;  // The number of bytes added to the queue
    uint32_t sent;   // The number of bytes sent to the tx
    uint32_t acked;  // The number of bytes acked by the tx
    bool rx_ack;     // True each time we receive a non-zero ack from the tx
    bool rx_reboot;  // True when we are in the rebooting process
    uint8_t pending_data[SZ_BUFFER]; // Pending data (from mavlink packets) circular buffer
    uint8_t pending_head; // Where mavlink packets are added (relative to pending_data[0])
    uint8_t pending_tail; // Where DFU packets are taken from (relative to pending_data[0])
    uint16_t file_length; // The length of the file, six more than the value stored in the first 16 bit word
    uint16_t file_length_round; // file_length rounded up to 0x80

    // Helper functions
    uint8_t pending_length()
    {
        return (pending_head - pending_tail) & (SZ_BUFFER-1);
    }
    uint8_t free_length()
    {
        return SZ_BUFFER - 1 - pending_length();    // Do not fill in the last byte in the circular buffer
    }
    void queue(const uint8_t *pSrc, uint8_t len); // Assumes sufficient room has been checked for
    void dequeue(uint8_t *pDst, uint8_t len); // Assumes sufficient data has been checked for
    void reset()
    {
        file_length = file_length_round = 0;
        added = sent = acked = 0;
        pending_head = pending_tail = 0;
        rx_reboot = rx_ack = need_ack = false;
    }
};

// Main class for receiving (and replying) to Beken radio packets
class AP_Radio_beken : public AP_Radio_backend
{
public:
    // Override base class functions
    AP_Radio_beken(AP_Radio &radio); // Normal constructore
    bool init(void) override; // initialise the radio
    bool reset(void) override; // reset the radio
    bool send(const uint8_t *pkt, uint16_t len) override; // send a packet
    void start_recv_bind(void) override; // start bind process as a receiver
    uint32_t last_recv_us(void) override; // return time in microseconds of last received R/C packet
    uint8_t num_channels(void) override; // return number of input channels
    uint16_t read(uint8_t chan) override; // return current "PWM" (value) of a channel
    void handle_data_packet(mavlink_channel_t chan, const mavlink_data96_t &m) override; // handle a data96 mavlink packet for fw upload
    void update(void) override; // update status

    uint32_t get_tx_version(void) override   // get TX fw version
    {
        // pack date into 16 bits for vendor_id in AUTOPILOT_VERSION
        return (uint16_t(tx_date.firmware_year)<<12) + (uint16_t(tx_date.firmware_month)<<8) + tx_date.firmware_day;
    }
    const AP_Radio::stats &get_stats(void) override; // get radio statistics structure

    // Extra public functions
    void set_wifi_channel(uint8_t channel) override
    {
        t_status.wifi_chan = channel;    // set the 2.4GHz wifi channel used by companion computer, so it can be avoided
    }

private:
    // Static functions, for interrupt support
    static void irq_handler_thd(void* arg);
    static void trigger_irq_radio_event(void);
    static void trigger_timeout_event(virtual_timer_t* vt, void *arg);

    //  Private functions
    void radio_init(void);
    uint8_t ProcessPacket(const uint8_t* packet, uint8_t rxaddr);
    uint8_t ProcessBindPacket(const packetFormatRx * rx);
    void BadDroneId(void); // The tx we are listening to wants to talk to another drone
    void setChannel(uint8_t channel);
    void nextChannel(uint8_t skip);
    uint16_t calc_crc(uint8_t *data, uint8_t len);
    void irq_handler(uint32_t when);
    void irq_timeout(uint32_t when);
    void save_bind_info(void);
    bool load_bind_info(void);
    void UpdateFccScan(void);
    bool UpdateTxData(void);
    void map_stick_mode(void); // Support mode1,2,3,4 for stick mapping
    void update_SRT_telemetry(void);
    void check_fw_ack(void);

    // Static data, for interrupt support
    friend class SyncChannel; // For DebugPrintf support
    static AP_Radio_beken *radio_singleton; // Singleton pointer to the Beken radio instance
    static thread_t *_irq_handler_ctx;
    static virtual_timer_t timeout_vt;
    static uint32_t isr_irq_time_us; // Time the Beken IRQ was last triggered, in the handler interrupts (in microseconds)
    static uint32_t isr_timeout_time_us; // Time the timeout was last triggered (copied from irq_time_us via irq_when_us) (in microseconds)
    static uint32_t next_switch_us; // Time when we next want to switch radio channels (in microseconds)
    static uint32_t bind_time_ms; // Rough time in ms (milliseconds) when the last BIND command was received

    // Class data
    AP_HAL::OwnPtr<AP_HAL::SPIDevice> dev; // Low level support of SPI device
    HAL_Semaphore sem;  // semaphore between ISR and main thread to protect fwupload

    AP_Radio::stats stats; // Radio stats (live) for the current time-period
    AP_Radio::stats last_stats; // Radio stats (snapshot) for the previous time-period
    uint16_t pwm_channels[BEKEN_MAX_CHANNELS]; // Channel data
    uint8_t chan_count; // Number of valid channels

    Radio_Beken beken; // The low level class for communicating to the Beken chip
    SyncChannel syncch; // Index within the channel hopping sequence. Corresponds to txChannel on the button board
    static SyncTiming synctm; // Timing between packets, according to the local clock (not the tx clock).
    uint32_t already_bound; // True when we have received packets from a tx after bootup. Prevent auto-binding to something else.
    FwUpload fwupload; // Support OTA upload
    SyncAdaptive adaptive; // Support adaptive hopping
    struct {
        uint8_t firmware_year;
        uint8_t firmware_month;
        uint8_t firmware_day;
    } tx_date;

    // Bind structure saved to storage
    static const uint16_t bind_magic = 0x120a;
    struct PACKED bind_info {
        uint16_t magic;
        uint8_t bindTxId[5]; // The transmission address I last used
    };

    // Received
    struct telem_status t_status; // Keep track of certain data that can be sent as telemetry to the tx.
    uint32_t last_pps_ms; // Timestamp of the last PPS (packets per second) calculation, in milliseconds.
    uint32_t tx_pps; // Last telemetry PPS received from Tx
    uint32_t have_tx_pps; // 0=never received, 1=received at least one, 2=received recently
    uint32_t valid_connection; // Take some time before admitting to ardupilot we have a connection
    uint32_t telem_send_count; // How many telemetry packets have i sent?

    // Parameters
    ITX_SPEED spd; // Speed of radio modulation.
    uint8_t myDroneId[4]; // CRC of the flight boards UUID, to inform the tx
};

#endif // AP_RADIO_BK2425_ENABLED