#include "battery.h"
#include "ti/driverlib/dl_i2c.h"
#include "ti/driverlib/m0p/dl_core.h"
#include "ti_msp_dl_config.h"
#include <adc.h>
#include <stdint.h>
#include <stdio.h>

volatile bool gRxComplete;
volatile bool gTxComplete;
uint8_t gTxPacket[I2C_TX_MAX_PACKET_SIZE];
uint8_t gRxPacket[I2C_RX_MAX_PACKET_SIZE];

uint32_t gTxADClen, gTxADCcount;
uint32_t gRxADClen, gRxADCcount;
static ADC_PARAMS adc_params;
static ADC_MeasurementState adc_state = ADC_STATE_CONFIGURE;

uint8_t ADC_ConstructConfigBytes(ADC_PARAMS params) {

  uint8_t config = 0;

  config |= ((params.channel) << 5); // Channel Selection (Bits 6-5)

  config |= (1 << 4); // One-Shot Mode

  switch (params.resolution) {
  case 12:
    config |= (0b00 << 2);
    break;
  case 14:
    config |= (0b01 << 2);
    break;
  case 16:
    config |= (0b10 << 2);
    break;
  default:
    printf("ERROR: Invalid Resolution!\n");
    return 0;
  }

  switch (params.gain) {
  case 1:
    config |= (0b00);
    break;
  case 2:
    config |= (0b01);
    break;
  case 4:
    config |= (0b10);
    break;
  default:
    printf("ERROR: Invalid Gain!\n");
    return 0;
  }

  return config;
}

/* Tansmit Data from MCU to ADC:  Function to SET configuration to ADC over
 * I2C*/

void ADC_SetConfigurationBytes(ADC_PARAMS params) {
  // **Construct Configuration Byte**
  uint8_t config_byte = ADC_ConstructConfigBytes(params);

  // Wait for I2C Bus to be Free**
  while (DL_I2C_getControllerStatus(I2C_controller_INST) &
         DL_I2C_CONTROLLER_STATUS_BUSY_BUS)
    ;

  // **Start I2C Write Transaction**
  // Prepare TX Buffer:
  gTxPacket[0] = config_byte;
  gTxADClen = 1;
  gTxADCcount = 0;
  gTxComplete = false;

  DL_I2C_flushControllerTXFIFO(I2C_controller_INST);
  DL_I2C_fillControllerTXFIFO(I2C_controller_INST, (uint8_t *)&gTxPacket, 1);
  DL_I2C_startControllerTransfer(I2C_controller_INST, ADC_TARGET_BASE_ADDRESS,
                                 DL_I2C_CONTROLLER_DIRECTION_TX, gTxADClen);
  // DL_I2C_enableInterrupt(I2C_controller_INST,
  //                        DL_I2C_INTERRUPT_CONTROLLER_TXFIFO_TRIGGER);
  //  while(!gTxComplete);
  //   **Ensure STOP Condition is Sent**
  while (DL_I2C_getControllerStatus(I2C_controller_INST) &
         DL_I2C_CONTROLLER_STATUS_BUSY_BUS)
    ;
  // printf("Configuration Sent Successfully for 0x%X!\n", config_byte);
}

/*
READY BIT:
    This bit is the data ready flag. In read mode, this bit indicates if the
output register has been updated with a latest conversion result. In One-Shot
Conversion mode, writing this bit to “1” initiates a new conversion.

    1= Output Register has not been updated
    0= Output Register has been updated

*/

bool ADC_CheckReadyBit(uint8_t slot_id, ADC_PARAMS params) {
  // Buffer for ADC data (MSB, LSB, Config Byte)
  uint8_t adc_data[3];
  uint8_t adc_address = ADC_TARGET_BASE_ADDRESS + slot_id;
  printf("Reading ADC Data from MCP3428 for channel: %u\n", params.channel);
  gRxADClen = 3;
  gRxADCcount = 0;
  gRxComplete = false;

  DL_I2C_startControllerTransfer(I2C_controller_INST, adc_address,
                                 DL_I2C_CONTROLLER_DIRECTION_RX, gRxADClen);
  DL_I2C_enableInterrupt(I2C_controller_INST,
                         DL_I2C_INTERRUPT_CONTROLLER_RXFIFO_TRIGGER);
  while (DL_I2C_getControllerStatus(I2C_controller_INST) &
         DL_I2C_CONTROLLER_STATUS_BUSY_BUS)
    ;
  while (!gRxComplete)
    ;

  uint8_t config_adc_byte = gRxPacket[2];

  // Ready bit is bit 7
  bool ready = (config_adc_byte & 0x80) == 0;
  printf("Slot: %d | Config Byte: 0x%02X | READY Bit: %d\n", slot_id,
         config_adc_byte, ready);
  return ready;
}

/*
Function to read ADC DATA: This function simply retrieves the ADC raw digital
output as 16-bit signed integer.
* The value returned is not yet converted to VOLTAGE.
* adc_data[2]: Buffer with an array of size 2, to store two bytes of ADC data.
*             Since, the ADC output consists of two 8-bit bytes:
*             - adc_data[0] (MSB)
*             - adc_data[1] (LSB)
* Next, we verify if the the I2C bus is busy using the function in the
driverlib: DL_I2C_get ControllerStatus
*       - Prevents collisions by ensuring no two I2C device is using the same
bus before initializing.
* BEGIN I2C READ operation to request 2 bytes from the ADC->
DL_I2C_startControllerTransfer()
* Parameters:
    - I2C_controller_INST: Refererence to the I2C instance bring used.
    - DEF_TARGET_ADDR_ADC: Address of the ADC
    - DL_I2C_CONTROLLER_DIRECTION_RX: Indicates that we want to receive the data
from ADC
    - 2: Specifies that we expect 2 bytes from the ADC
* WAIT for the data to be received: (DL_I2C_getControllerStatus())
    - Waits until the ADC sends the data over I2C.
    - Ensures that the data transfer is complete before proceeding.
* READ the two bytes of ADc Data:
    - adc_data[0] : MSB
    - adc_data[1] : LSB
    - adc_data[2] : config_bytes
    ADC sends its 16-bit value in two parts over 8-bit I2C data frames.
* COMBINE the two bytes into 16-bit Integer:
    - Shifts the MSB(first byte) left by 8 bits to make space for LSB.
    - Performs a bitwise OR operation to combine MSB and LSB into a single
16-bit number.
* PRINT HEXADEC and DECIMAL format for DEBUGGING.
* Output code is in binary and is proportional to the Input Voltage and PGA
settings.
* From the datasheet:
https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ProductDocuments/DataSheets/22226a.pdf
    - Equation 4.4 is being used to convert the output codes to input voltage

* The ACK bits after conversion is issued by the Master, when the device
receives a READ command, it outputs two data bytes followed by a configuration
register in 16 bit conversion mode the MSB(=sign bit) of the first data type is
D15.

*/

int16_t ADC_ReadData(uint8_t slot_id, ADC_PARAMS params) {

  // Buffer for ADC data (MSB, LSB, Config Byte)
  uint8_t adc_data[3] = {0};
  int16_t raw_adc = 0;
  uint8_t bytes_to_read = 3;
  uint8_t adc_address = ADC_TARGET_BASE_ADDRESS + slot_id;
  // printf("Reading ADC Data from MCP3428 for channel: %u\n", params.channel);

  if (DL_I2C_getControllerStatus(I2C_controller_INST) &
      DL_I2C_CONTROLLER_STATUS_BUSY_BUS) {
    printf("Error: I2C bus stuck! Resetting..\n");
    // DL_I2C_resetControllerTransfer(I2C_controller_INST);
  }

  gRxADClen = bytes_to_read;
  gRxADCcount = 0;
  gRxComplete = false;

  DL_I2C_startControllerTransfer(I2C_controller_INST, adc_address,
                                 DL_I2C_CONTROLLER_DIRECTION_RX, gRxADClen);
  DL_I2C_enableInterrupt(I2C_controller_INST,
                         DL_I2C_INTERRUPT_CONTROLLER_RXFIFO_TRIGGER);
  while (DL_I2C_getControllerStatus(I2C_controller_INST) &
         DL_I2C_CONTROLLER_STATUS_BUSY_BUS)
    ;
  while (!gRxComplete)
    ;

  uint8_t msb = gRxPacket[0];
  uint8_t lsb = gRxPacket[1];
  uint8_t config_adc_byte = gRxPacket[2];

  uint8_t gain_setting = (config_adc_byte & 0x03);
  uint8_t gain_multiplier = (1 << gain_setting); // Gain values: 1, 2, 4, 8

  if (params.resolution == 16) {
    raw_adc = (msb << 8) | lsb;
    if (raw_adc > 32767)
      raw_adc -= 65536;
  } else if (params.resolution == 14) {
    raw_adc = ((msb & 0b00111111) << 8) | lsb;
    if (raw_adc > 8191)
      raw_adc -= 16384;
  } else if (params.resolution == 12) {
    raw_adc = ((msb & 0b00001111) << 8) | lsb;
    if (raw_adc > 2047)
      raw_adc -= 4096;
  }
  printf("Raw ADC Value: 0x%0X (%d)\n", raw_adc, raw_adc);
  return raw_adc;
}

// **Interrupt handler for ADC Read Completion**
void I2C_ADC_IRQHandler(void) {
  if (DL_I2C_getPendingInterrupt(I2C_controller_INST) ==
      DL_I2C_IIDX_CONTROLLER_RXFIFO_TRIGGER) {
    gRxComplete = true;
  }
}

/* Function to Convert ADC Reading to Voltage */
uint16_t ADC_ConvertToVoltage(int16_t adc_value, ADC_PARAMS params) {
  uint16_t measured_voltage = 0;
  uint16_t LSB = 0;
  uint32_t max_adc_value = 1;

  switch (params.resolution) {
  case 12: // 12-bit
    max_adc_value = 4095;
    break;
  case 14: // 14-bit
    max_adc_value = 16383;
    break;
  case 16: // 16-bit
    max_adc_value = 65535;
    break;
  default:
    printf("Error: Unknown ADC Resolution!\n");
    return 0;
  }
  measured_voltage = (((uint32_t)adc_value * ADC_VREF_MV) * 3) / max_adc_value;
  return (uint16_t)measured_voltage;
}

/* Function to Convert ADC Reading to Voltage */
uint16_t ADC_ConvertToCurrent(int16_t adc_value, ADC_PARAMS params) {
  int16_t current_mA = 0;
  // uint8_t r_shunt= 0.1;
  // Convert ADC value to voltage across shunt resistor:
  uint16_t voltage_mV = ADC_ConvertToVoltage(adc_value, params);
  uint8_t gain_multiplier = (1 << (params.gain - 1));
  // Convert voltage drop across shunt resistor to current
  current_mA = (voltage_mV) / (0.1 * gain_multiplier);
  // printf("Converted Current: %d mA.\n", current_mA);
  return (int16_t)current_mA;
}

void Battery_UpdateADCReading(uint8_t slot, uint8_t channel) {
  while (adc_state != ADC_STATE_DONE) {
    switch (adc_state) {

    case ADC_STATE_CONFIGURE:
      adc_params.channel = channel;
      // printf("Channel: %d\n", adc_params.channel);
      adc_params.resolution = 12;
      adc_params.continuous = 1;
      adc_params.gain = 1;
      ADC_SetConfigurationBytes(adc_params);
      adc_state = ADC_STATE_WAIT;
      break;

    case ADC_STATE_WAIT:
      if (ADC_CheckReadyBit(slot, adc_params)) {
        adc_state = ADC_STATE_READ;
      }
      break;

    case ADC_STATE_READ:
      if (channel == 0) {

        int16_t raw_adc_voltage = ADC_ReadData(slot, adc_params);
        batteries[slot].voltage =
            ADC_ConvertToVoltage(raw_adc_voltage, adc_params);
        printf("Battery voltage for slot %d is %u mV.\n", slot,
               batteries[slot].voltage);
        adc_state = ADC_STATE_DONE;

      } else if (channel == 1) {

        int16_t raw_adc_current = ADC_ReadData(slot, adc_params);
        batteries[slot].current =
            ADC_ConvertToCurrent(raw_adc_current, adc_params);
        printf("Battery current for slot %d is %u mA.\n", slot,
               batteries[slot].current);

        adc_state = ADC_STATE_DONE;
      }
      break;
    default:
      channel = 0;
      adc_state = ADC_STATE_CONFIGURE;
      break;
    }
  }

  adc_state = ADC_STATE_CONFIGURE;
}

void Battery_ReadState(uint8_t slot_id) {

  uint16_t voltage_mv = batteries[slot_id].voltage;
  uint16_t min_voltage = batteries[slot_id].min_voltage;
  uint16_t max_voltage = batteries[slot_id].max_voltage;

  /* Changing the battery states based on adc values*/
  if (voltage_mv < 500) {
    batteries[slot_id].state = STATE_EMPTY;
  } else if (voltage_mv >= 500 && voltage_mv < 3000) { //TODO: change the voltage_mv to min_voltage
    batteries[slot_id].state = STATE_BATTERY_DETECTED;
  } else if (voltage_mv >= min_voltage && voltage_mv < max_voltage) {
    batteries[slot_id].state = STATE_MEASUREMENT_IN_PROGRESS;
  }
  // once MCU is done reading ADC:
  else if (adc_state== ADC_STATE_DONE && batteries[slot_id].state== STATE_MEASUREMENT_IN_PROGRESS) {
    batteries[slot_id].state = STATE_MEASUREMENT_DONE;
  } else {
    batteries[slot_id].state = STATE_OVERCHARGING;
  }
}