/*
Copyright 2022, Savanni D'Gerinel <savanni@luminescent-dreams.com>

This file is part of Savanni's AVR library.

Lumeto 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.

Lumeto 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 Lumeto. If not, see <https://www.gnu.org/licenses/>.
*/


#include <rfm.h>
#include <stdio.h>

#define REG_FIFO                0x00
#define REG_OP_MODE             0x01
#define REG_DATA_MODUL          0x02
#define REG_BITRATE_MSB         0x03
#define REG_BITRATE_LSB         0x04
#define REG_FDEV_MSB            0x05
#define REG_FDEV_LSB            0x06
#define REG_VERSION             0x10
#define REG_PA_LEVEL            0x11
#define REG_RXBW                0x19
#define REG_AFCBW               0x1a
#define REG_RSSI_CONFIG         0x23
#define REG_RSSI_VALUE          0x24
#define REG_DIO_MAPPING1        0x25
#define REG_IRQ_FLAGS1          0x27
#define REG_IRQ_FLAGS2          0x28
#define REG_RSSI_THRESH         0x29
#define REG_PREAMBLE_MSB        0x2c
#define REG_PREAMBLE_LSB        0x2d
#define REG_SYNC_CONFIG         0x2e
#define REG_SYNC_VALUE1         0x2f
#define REG_PACKET_CONFIG1      0x37
#define REG_FIFO_THRESH         0x3c
#define REG_TEST_PA1            0x5a
#define REG_TEST_PA2            0x5c
#define REG_TEST_DAGC           0x6f

#define PA1_LOW_POWER           0x55
#define PA1_HIGH_POWER          0x5D
#define PA2_LOW_POWER           0x70
#define PA2_HIGH_POWER          0x7C

void _rfm_write(rfm_t *rfm, uint8_t reg, uint8_t *data, size_t length) {
    spi_acquire(&rfm->spi);
    spi_transceive(&rfm->spi, _BV(7) | reg);
    for (size_t i = 0; i < length; i++) {
        spi_transceive(&rfm->spi, data[i]);
    }
    spi_release(&rfm->spi);
}

void _rfm_read(rfm_t *rfm, uint8_t reg, uint8_t *data, size_t length) {
    spi_acquire(&rfm->spi);
    spi_transceive(&rfm->spi, reg);
    for (size_t i = 0; i < length; i++) {
        data[i] = spi_transceive(&rfm->spi, 0);
    }
    spi_release(&rfm->spi);
}

void _rfm_set_low_power(rfm_t *rfm) {
    _rfm_write(rfm, REG_TEST_PA1, (uint8_t [1]){ PA1_LOW_POWER }, 1);
    _rfm_write(rfm, REG_TEST_PA2, (uint8_t [1]){ PA2_LOW_POWER }, 1);
}

void _rfm_set_high_power(rfm_t *rfm) {
    _rfm_write(rfm, REG_TEST_PA1, (uint8_t [1]){ PA1_HIGH_POWER }, 1);
    _rfm_write(rfm, REG_TEST_PA2, (uint8_t [1]){ PA2_HIGH_POWER }, 1);
}

void rfm_init(rfm_t *rfm, uint8_t *sync_word, size_t length, rfm_error_e *error) {
    if (!error) return;

    spi_initialize(&rfm->spi);
    dio_set_direction(&rfm->irq, LINE_IN);
    dio_set_direction(&rfm->reset, LINE_OUT);

    rfm_reset(rfm);
    rfm_sleep(rfm);

    uint8_t version;
    _rfm_read(rfm, REG_VERSION, &version, 1);
    if (version != 0x24) {
        *error = radio_not_found;
        return;
    }

    // RadioHead packet format
    // 4 bytes preamble (done automatically)
    // 2 Sync words 2d, d4 (configured here, but done automatically)
    // 2 CRC CCITT octets computed on the header, length, and data (wat?)
    // 0 to 60 bytes of data
    // RSSI Threshhold -114dbm
    // No RFM69HCW adress filtering. Payload has custom headers.

    _rfm_write(rfm, REG_FIFO_THRESH, (uint8_t [1]){ 0x8f }, 1);
    _rfm_write(rfm, REG_RSSI_THRESH, (uint8_t [1]){ 0xe4 }, 1);

    // Fading margin improvement (3.4.4). Improved Margin, LowBeta off
    _rfm_write(rfm, REG_TEST_DAGC, (uint8_t [1]){ 0x30 }, 1);

    _rfm_set_low_power(rfm);

    uint8_t syncconfig;
    _rfm_read(rfm, REG_SYNC_CONFIG, &syncconfig, 1);
    uint8_t word_base = REG_SYNC_VALUE1;
    for (int i = 0; i < length; i++) {
        _rfm_write(rfm, word_base + i, &sync_word[i], 1);
    }
    syncconfig &= ~0b00111000;
    syncconfig |= (length - 1) << 3;
    _rfm_write(rfm, REG_SYNC_CONFIG, &syncconfig, 1);

    _rfm_write(rfm, REG_PREAMBLE_MSB, (uint8_t [1]){ 0 }, 1);
    _rfm_write(rfm, REG_PREAMBLE_LSB, (uint8_t [1]){ 4 }, 1);

    // Datamodul: CONFIG_FSK (Packet mode, FSK, no shaping: 0b00000000
    // BitRateMSB: 0x00
    // BitRateLSB: 0x80 (oscillator 32,000,000 / bitrate 250kbps = 128 (0x80))
    // FDEVMSB: 0x10
    // FDEVLSB: 0x00
    // RXBW: 0xe0
    // AFCBW: 0xe0
    // PacketConfig1: CONFIG_WHITE (variable packet format, whitening on, crc on, no address filtering)

    _rfm_write(rfm, REG_DATA_MODUL, (uint8_t [1]){ 0 }, 1);
    _rfm_write(rfm, REG_BITRATE_MSB, (uint8_t [1]){ 0 }, 1);
    _rfm_write(rfm, REG_BITRATE_LSB, (uint8_t [1]){ 0x80 }, 1);
    _rfm_write(rfm, REG_FDEV_MSB, (uint8_t [1]){ 0x10 }, 1);
    _rfm_write(rfm, REG_FDEV_LSB, (uint8_t [1]){ 0x00 }, 1);
    _rfm_write(rfm, REG_RXBW, (uint8_t [1]){ 0xe0 }, 1);
    _rfm_write(rfm, REG_AFCBW, (uint8_t [1]){ 0xe0 }, 1);
    _rfm_write(rfm, REG_PACKET_CONFIG1, (uint8_t [1]){ 0b10110000 }, 1);

    // set power level 13dbm
    // This is super complicated. Dig through the RadioHead library and the documentation and make things better.
    _rfm_write(rfm, REG_PA_LEVEL, (uint8_t [1]){ 0b11000000 | 31 }, 1);
}

uint8_t sync_word(rfm_t *rfm, uint8_t sync_word[8]) {
    uint8_t length;

    _rfm_read(rfm, REG_SYNC_CONFIG, &length, 1);
    length = (length >> 2) & 0b00000111;
    uint8_t word_base = REG_SYNC_VALUE1;
    for (int i = 0; i < length; i++) {
        _rfm_read(rfm, word_base + i, &sync_word[i], 1);
    }

    return length;
}

void rfm_reset(rfm_t *rfm) {
    dio_set(&rfm->reset, 1);
    _delay_us(100);
    dio_set(&rfm->reset, 0);
    _delay_us(5);
}

void rfm_packet_format(rfm_t *rfm, packet_format_e format, size_t length) {
    switch (format) {
        case unlimited:
            _rfm_write(rfm, 0x37, (uint8_t [1]){ 0 }, 1);
            _rfm_write(rfm, 0x38, (uint8_t [1]){ 0 }, 1);
            break;
        case fixed:
            _rfm_write(rfm, 0x37, (uint8_t [1]){ 0 }, 1);
            _rfm_write(rfm, 0x38, (uint8_t [1]){ length }, 1);
            break;
        case variable:
            _rfm_write(rfm, 0x37, (uint8_t [1]){ _BV(7) }, 1);
            _rfm_write(rfm, 0x38, (uint8_t [1]){ 0 }, 1);
            break;
    }
}

void rfm_sleep(rfm_t *rfm) {
    rfm_set_mode(rfm, (op_mode_t){ .listen_on = false, .mode = sleep });
}

void rfm_standby(rfm_t *rfm) {
    rfm_set_mode(rfm, (op_mode_t){ .listen_on = false, .mode = standby });
}

void rfm_listen(rfm_t *rfm) {
    rfm_set_mode(rfm, (op_mode_t){ .listen_on = true, .mode = standby });
}

void rfm_transmit(rfm_t *rfm, uint8_t *data, uint8_t length) {
    rfm_set_mode(rfm, (op_mode_t){ .listen_on = false, .mode = standby });
    _rfm_set_low_power(rfm);
    _rfm_write(rfm, REG_FIFO, &length, 1);
    _rfm_write(rfm, REG_FIFO, data, length);
    _rfm_write(rfm, REG_DIO_MAPPING1, (uint8_t [1]){ 0x00 }, 1);
    rfm_set_mode(rfm, (op_mode_t){ .listen_on = false, .mode = tx });
}

void rfm_receive_mode(rfm_t *rfm) {
    _rfm_write(rfm, REG_DIO_MAPPING1, (uint8_t [1]){ _BV(6) }, 1);
    rfm_set_mode(rfm, (op_mode_t){ .listen_on = false, .mode = rx });
}

void rfm_receive(rfm_t *rfm, uint8_t data[66], uint8_t *length) {
    _rfm_write(rfm, REG_DIO_MAPPING1, (uint8_t [1]){ _BV(6) }, 1);
    rfm_set_mode(rfm, (op_mode_t){ .listen_on = false, .mode = rx });
    _rfm_read(rfm, REG_FIFO, length, 1);

    if (*length > 0) {
        _rfm_read(rfm, 0x00, data, *length);
    }
}

uint8_t rfm_temperature(rfm_t *rfm) {
    uint8_t ready = 0;
    uint8_t temp;
    _rfm_write(rfm, 0x4e, (uint8_t [1]){ _BV(3) }, 1);
    _delay_ms(1);

    uint8_t i = 0;
    while (!(ready & _BV(2)) && i < 10) {
        _rfm_read(rfm, 0x4e, &ready, 1);
        i++;
        _delay_us(100);
    }

    _rfm_read(rfm, 0x4f, &temp, 1);

    return temp;
}

op_mode_t rfm_mode(rfm_t *rfm) {
    op_mode_t op_mode = {
        .listen_on = false,
        .mode = sleep,
    };
    uint8_t flags;

    _rfm_read(rfm, 0x01, &flags, 1);
    if (flags & _BV(6)) op_mode.listen_on = 1;
    op_mode.mode = (flags & 0b00011100) >> 2;

    return op_mode;
}

void rfm_set_mode(rfm_t *rfm, op_mode_t mode) {
    op_mode_t current = rfm_mode(rfm);
    uint8_t flags = mode.mode << 2;

    if (mode.listen_on) {
        flags |= _BV(6);
    } else if (current.listen_on) {
        flags |= _BV(5);
        _rfm_write(rfm, REG_OP_MODE, (uint8_t [1]){ flags }, 1);

        flags = flags & ~_BV(5);
    }

    _rfm_write(rfm, REG_OP_MODE, (uint8_t [1]){ flags }, 1);
}

uint8_t rfm_status(rfm_t *rfm) {
    uint8_t status_flag;
    _rfm_read(rfm, 0x28, &status_flag, 1);
    return status_flag;
}

uint32_t rfm_frequency(rfm_t *rfm) {
    uint8_t frequency_bytes[3];
    uint32_t frequency;
    _rfm_read(rfm, 0x07, &frequency_bytes[2], 1);
    _rfm_read(rfm, 0x08, &frequency_bytes[1], 1);
    _rfm_read(rfm, 0x09, &frequency_bytes[0], 1);

    frequency = frequency_bytes[2];
    frequency = frequency << 8;
    frequency += frequency_bytes[1];
    frequency = frequency << 8;
    frequency += frequency_bytes[0];
    return frequency * 61;
}

interrupt_flags_t rfm_interrupts(rfm_t *rfm) {
    uint8_t irq_1;
    uint8_t irq_2;
    interrupt_flags_t flags = {
        .mode_ready = false,
        .rx_ready = false,
        .tx_ready = false,
        .timeout = false,
        .auto_mode = false,
        .sync_addr_match = false,

        .fifo_full = false,
        .fifo_not_empty = false,
        .fifo_level = false,
        .fifo_overrun = false,
        .packet_sent = false,
        .payload_ready = false,
        .crc_ok = false,
    };

    _rfm_read(rfm, REG_IRQ_FLAGS1, &irq_1, 1);
    _rfm_read(rfm, REG_IRQ_FLAGS2, &irq_2, 1);

    if (irq_1 & _BV(7)) flags.mode_ready = true;
    if (irq_1 & _BV(6)) flags.rx_ready = true;
    if (irq_1 & _BV(5)) flags.tx_ready = true;
    if (irq_1 & _BV(2)) flags.timeout = true;
    if (irq_1 & _BV(1)) flags.auto_mode = true;
    if (irq_1 & _BV(0)) flags.sync_addr_match = true;

    if (irq_2 & _BV(7)) flags.fifo_full = true;
    if (irq_2 & _BV(6)) flags.fifo_not_empty = true;
    if (irq_2 & _BV(5)) flags.fifo_level = true;
    if (irq_2 & _BV(4)) flags.fifo_overrun = true;
    if (irq_2 & _BV(3)) flags.packet_sent = true;
    if (irq_2 & _BV(2)) flags.payload_ready = true;
    if (irq_2 & _BV(1)) flags.crc_ok = true;

    return flags;
}

uint8_t rfm_rssi(rfm_t *rfm) {
    uint8_t rssi_reg;
    uint8_t rssi_value;

    _rfm_write(rfm, REG_RSSI_CONFIG, (uint8_t [1]){ _BV(0) }, 1);

    while(!(rssi_reg & _BV(1))) {
        _rfm_read(rfm, REG_RSSI_CONFIG, &rssi_reg, 1);
    }

    _rfm_read(rfm, REG_RSSI_VALUE, &rssi_value, 1);

    return rssi_value;
}