#include "spi_manager.h"
#include <Arduino.h>
#include <avr/io.h>

// =====================================================
// SPI MANAGER — SPI0 DEFAULT MUX
//   PA1=MOSI (pin 20)  PA2=MISO (pin 1)
//   PA3=SCK  (pin  2)  PA4=CS   (pin 5, software)
// No PORTMUX remapping required.
// =====================================================

void SPI_Init(void) {
    pinMode(SPI_MOSI_PIN,   OUTPUT);
    pinMode(SPI_MISO_PIN,   INPUT);
    pinMode(SPI_SCK_PIN,    OUTPUT);
    pinMode(SPI_CS_CAN_PIN, OUTPUT);
    digitalWrite(SPI_CS_CAN_PIN, HIGH);     // CS inactive

    // Default SPI0 MUX is already PA1/PA2/PA3.
    PORTMUX.SPIROUTEA = PORTMUX_SPI0_DEFAULT_gc;

    SPI0.CTRLA = SPI_MASTER_bm
               | SPI_PRESC_DIV4_gc;    // 20 MHz / 4 = 5 MHz

    SPI0.CTRLB = SPI_MODE_0_gc
               | SPI_SSD_bm;           // Software SS

    SPI0.CTRLA |= SPI_ENABLE_bm;
}

void SPI_CS_Assert(void) {
    digitalWrite(SPI_CS_CAN_PIN, LOW);
}

void SPI_CS_Deassert(void) {
    digitalWrite(SPI_CS_CAN_PIN, HIGH);
}

uint8_t SPI_TransferByte(uint8_t txByte) {
    SPI0.DATA = txByte;
    while (!(SPI0.INTFLAGS & SPI_IF_bm)) { /* wait */ }
    return SPI0.DATA;
}

void SPI_TransferBuffer(const uint8_t *txBuf, uint8_t *rxBuf, uint16_t len) {
    for (uint16_t i = 0; i < len; i++) {
        uint8_t tx = (txBuf != nullptr) ? txBuf[i] : 0x00;
        uint8_t rx = SPI_TransferByte(tx);
        if (rxBuf != nullptr) rxBuf[i] = rx;
    }
}

void SPI_Write(const uint8_t *data, uint16_t len) {
    SPI_CS_Assert();
    SPI_TransferBuffer(data, nullptr, len);
    SPI_CS_Deassert();
}

void SPI_Read(uint8_t *buf, uint16_t len) {
    SPI_CS_Assert();
    SPI_TransferBuffer(nullptr, buf, len);
    SPI_CS_Deassert();
}