/*
References:
https://stackoverflow.com/questions/246127/why-is-volatile-needed-in-c
*/

#include "i2c_target.h"
#include "src/battery_data/battery.h"
#include "ti/driverlib/dl_i2c.h"
#include <stdio.h>
#include <string.h>
#include "src/peripherals/dac/dac.h"
#include <inttypes.h>
#include "src/config.h"
#include "ti_msp_dl_config.h"
#include "src/peripherals/temp/tmp1075.h"

/**
 * Dynamic addressing function
 * 1. set resistor to pullup
 * 2. measure gpio:
 *   is it up, set the address +0, else set it +1
 * 3. disable the pullup again, so there is no current wasted
 */
void initialize_target_address() {
    uint8_t add = 0;
    if (DL_GPIO_readPins(GPIOS_PORT, GPIOS_ADDR_PIN)) {
        add = 1;
        addr_offset = 4;
    }
    DL_I2C_setTargetOwnAddress(I2C_target_INST, I2C_TARGET_BASE_ADDRESS+add);
    DL_I2C_enableTargetOwnAddress(I2C_target_INST);
}

/*Function to Rx and Tx data from Target to Controller*/
// The code has multiple i2c instances (multiple MCUs connected) from which we
// need to select the right one, passing a pointer as an argument

int8_t mcu_i2c_handle(I2C_Regs *i2c) {
    if (DL_I2C_isTargetRXFIFOEmpty(i2c)) {
      return -1;
    }
        
    uint8_t receivedByte = DL_I2C_receiveTargetData(i2c);
    uint8_t receivedCommand = (receivedByte & 0x0F);
    uint8_t slot = ((receivedByte & 0xF0) >> 4);

    if (receivedCommand == CMD_GET_MEASUREMENT) {
        DL_I2C_flushTargetTXFIFO(i2c);
        DL_I2C_fillTargetTXFIFO(i2c, (uint8_t *)&battery_slots[slot].measurement, 8);
    } else if (receivedCommand == CMD_SET_CURRENT) {
        return slot;
    } else if (receivedCommand == CMD_CLEAR_ERR) {
        if (slot > NUM_SLOTS) {
            DL_I2C_flushTargetTXFIFO(i2c);
            return -1;
        }
        *battery_slots[slot].state = SLOT_STATE_OK;
    }
    DL_I2C_flushTargetRXFIFO(i2c);
    return -1;
}

void mcu_i2c_handle_read(I2C_Regs *i2c, uint8_t slot) {
    // Read incoming bytes from the Controller:
        uint8_t rx_index = 0;
        uint8_t rx_buffer[2] = {0x00, 0x00};
        while (rx_index < 2) {
            // TODO: Need to have a workaround, currently the code is getting stuck on
            // the first trigger and provides result on the second trigger
            if (!DL_I2C_isTargetRXFIFOEmpty(i2c)) {
                rx_buffer[rx_index] = DL_I2C_receiveTargetData(i2c);
                rx_index++;
            }
        }
        if (rx_index != 2) {
#ifdef DEBUG_TARGET
            printf("ERROR: Incomplete I2C Rx: received %d bytes\n", rx_index);
#endif
            DL_I2C_flushTargetRXFIFO(i2c);
            rx_index = 0;
            return;
        }
        battery_slots[slot].set_current = *((int16_t*)(&rx_buffer[0]));
        
#ifdef DEBUG_TARGET
        printf("Slot id: %d, Current: %d mA (Bytes 0x%02X 0x%02X)\n", slot, battery_slots[slot].set_current, rx_buffer[0], rx_buffer[1]);
#endif
        /*
        // This code is for debugging:
        // you can shoot directly code to the DAC / PWM for debugging
        if (battery_slots[slot].set_current >= 0) {
            DAC_SingleWrite(slot, battery_slots[slot].set_current);
        } else if (battery_slots[slot].set_current < 0) {
            DL_TimerG_setCaptureCompareValue(PWM_0_INST, -1*battery_slots[slot].set_current, DL_TIMER_CC_1_INDEX);

        } else {
            // do nothing, charge or discharge
#ifdef DEBUG_TARGET
            printf("state is idle");
#else
            ;
#endif
        } */
}