#include <stdio.h>
#include "spi_nb.h"
#include "hardware/gpio.h"
#include "hardware/structs/spi.h"
#include "hardware/spi.h"
#include "hardware/regs/dreq.h"

#define SPI_ERR_TRANSMIT_FIFO_FULL 1
#define SPI_OK 0
#define SPI_BUSY 1
#define SPI_IDLE 0


#define PIN_CS 1


static inline void cs_select() {
    asm volatile("nop \n nop \n nop");
    gpio_put(PIN_CS, 0);  // Active low
    asm volatile("nop \n nop \n nop");
}

static inline void cs_deselect() {
    asm volatile("nop \n nop \n nop");
    gpio_put(PIN_CS, 1);
    asm volatile("nop \n nop \n nop");
}

int spi_nb_read_register_8bits(spi_inst_t * spi, uint16_t spi_slave_register, uint8_t *buffer, uint8_t nb_data_to_read){
    uint16_t dummy_buffer[8]={0, 0, 0, 0,0, 0, 0, 0};
    uint8_t nb_data_read;
    static enum {
        INIT,
        WAIT_SPI_IDLE,
        SEND_REGISTER_ADRESS,
        WAIT_SENDING_DATA,
        SEND_DUMMY_DATA,
        WAIT_RECIEVING_DATA,
        READ_DATA,
        
        SPI_IN_ERROR,
    }status=INIT;

    switch(status){
        case INIT:
            cs_select();
        case WAIT_SPI_IDLE:
            if(spi_nb_busy(spi) == SPI_IDLE){
                status = SEND_REGISTER_ADRESS;
                puts("SEND_REGISTER_ADRESS");
            }
            break;
        
        case SEND_REGISTER_ADRESS:
            spi_slave_register = spi_slave_register | 0x80 | 0X40;
            if(spi_nb_write_data(spi, &spi_slave_register, 1) == SPI_OK){
                status = WAIT_SENDING_DATA;
                puts("WAIT_SENDING_DATA");
            }else{
                status = SPI_IN_ERROR;
            }
            break;
        
        case WAIT_SENDING_DATA:
            if(!spi_nb_busy(spi)){
                spi_nb_flush_recieve_fifo(spi);
                status = SEND_DUMMY_DATA;
                puts("SEND_DUMMY_DATA");
            }
            break;

        case SEND_DUMMY_DATA:
            if(spi_nb_write_data(spi, dummy_buffer, nb_data_to_read) == SPI_OK){
                status = WAIT_RECIEVING_DATA;
                puts("WAIT_RECIEVING_DATA");
            }else{
                status = SPI_IN_ERROR;
            }
            break;

        case WAIT_RECIEVING_DATA:
            if(!spi_nb_busy(spi)){
                status = READ_DATA;
                puts("READ_DATA");
            }
            break;

        case READ_DATA:
            cs_deselect();
            nb_data_read = spi_nb_read_data_8bits(spi, buffer);
            if(nb_data_read == nb_data_to_read){
                puts("SPI_SUCCESS");
                status = INIT;
                return SPI_SUCCESS;
            }
            puts("SPI_FAILED");
            status = SPI_IN_ERROR;
            return SPI_FAILED;
            break;
        
        case SPI_IN_ERROR:
            puts("SPI_IN_ERROR");
            spi_nb_flush_recieve_fifo(spi);
            cs_deselect();
            status = INIT;
            return SPI_FAILED;
            break;
    }
    return SPI_IN_PROGRESS;

}

/// @brief Tell if the SPI is busy
/// @param spi SPI device to use (spi0 or spi1)
/// @return SPI_BUSY of SPI_IDLE
int spi_nb_busy(spi_inst_t * spi){
    return (spi_get_hw(spi)->sr & SPI_SSPSR_BSY_BITS);
}


/// @brief Empty SPI Recieve FIFO
/// @param spi SPI device to use (spi0 or spi1)
void spi_nb_flush_recieve_fifo(spi_inst_t * spi){
    uint16_t dummy;
    while(spi_get_hw(spi)->sr & SPI_SSPSR_RNE_BITS){
        dummy = spi_get_hw(spi)->dr;
    }
}

/// @brief read the SPI Recieve FIFO
/// @param spi SPI device to use (spi0 or spi1)
/// @param buffer To store data recieved
/// @return Number of byte read
uint8_t spi_nb_read_data_8bits(spi_inst_t * spi, uint8_t * buffer){
    uint8_t index = 0;
    char debug[2]="x";
    while(spi_get_hw(spi)->sr & SPI_SSPSR_RNE_BITS){
        buffer[index] = (uint8_t)spi_get_hw(spi)->dr & SPI_SSPDR_DATA_BITS;
        debug[0] = buffer[index];
        puts(debug);
        index++;
    }
    return index;

}

/// @brief Write severals byte to the SPI Transmit FIFO
/// @param spi SPI device to use (spi0 or spi1)
/// @param buffer data to transmit
/// @param size size of the data to transmit
/// @return SPI_OK or SPI_ERR_TRANSMIT_FIFO_FULL
inline int spi_nb_write_data(spi_inst_t * spi, uint16_t * buffer, uint8_t size){
    int statu_spi = SPI_OK;
    uint8_t index=0;
    do
    {
        statu_spi = spi_nb_write_byte(spi, buffer[index]);
        index++;
    } while ( (statu_spi == SPI_OK) && (index < size));
    return statu_spi;
}

/// @brief Write one "byte", 4 to 16 bits to the SPI Transmit FIFO.
/// @param spi 
/// @param data : Data to send
/// @return SPI_OK if Ok, SPI_ERR_TRANSMIT_FIFO_FULL if fifo is full
int spi_nb_write_byte(spi_inst_t * spi, uint16_t data){
    if(spi_get_hw(spi)->sr & SPI_SSPSR_TNF_BITS){
        spi_get_hw(spi)->dr = data;
        return SPI_OK;
    }
    return SPI_ERR_TRANSMIT_FIFO_FULL;
}