#include <stdio.h>
#include <stdint.h>

#include "driver/gpio.h"
#include "driver/i2c.h"
#include "esp_err.h"
#include "esp_log.h"
#include "freertos/portmacro.h"
#include "hal/i2c_types.h"

/* DAC Peripheral Config */
#define DAC_SCL_PIN 12
#define DAC_SDA_PIN 13
#define DAC_LDAC_PIN 14

#define DAC_ADDR 0x64 /* I2C Address of DAC */
#define DAC_VREF 0x00 /* Use Vdd as reference voltage */
#define DAC_PD 0x00 /* Full power mode */
#define DAC_GAIN 0x00 /* Since we use external Vref, this doesn't matter */

#define ACK_EN 0x1 /* Enable i2c acknowledgment check */
#define ACK_DIS 0x0 /* Disable i2c acknowledgment check */
#define ACK_VAL 0x0  /* i2c acknowledgment value */
#define NACK_VAL 0x1 /* i2c negative-acknowledgment value */

static const i2c_port_t I2C_MASTER_PORT = 0;

static const char *TAG = "EERG";


/* Initialize and configure I2C DAC */
static void dac_init(void)
{
  ESP_LOGI(TAG, "Initializing DAC I2C connection");

  /* Configure µC as I2C master */
  i2c_config_t i2c_conf = {
    .mode = I2C_MODE_MASTER,
    .scl_io_num = DAC_SCL_PIN,
    .sda_io_num = DAC_SDA_PIN,
    .master.clk_speed = 400000 /* 400kHz for i2c fast mode */

  };
  i2c_param_config(I2C_MASTER_PORT, &i2c_conf);

  /* Install i2c driver */
  ESP_ERROR_CHECK(i2c_driver_install(I2C_MASTER_PORT, i2c_conf.mode, 0, 0, 0));

  /* Setup LDAC pin with GPIO. Tied low */
  gpio_reset_pin(DAC_LDAC_PIN);
  gpio_set_direction(DAC_LDAC_PIN, GPIO_MODE_OUTPUT);
  gpio_set_level(DAC_LDAC_PIN, 0);
}

/* Tests for acknowledgment of i2c DAC. Return ESP_OK if so */
static esp_err_t dac_ack_test(void)
{
  ESP_LOGI(TAG, "Testing I2C DAC");
  /* Create i2c command handle */
  i2c_cmd_handle_t cmd = i2c_cmd_link_create();
  i2c_master_start(cmd);
  i2c_master_write_byte(cmd, (DAC_ADDR << 1) | I2C_MASTER_READ, ACK_EN); /* R/W byte is LSB of DAC address */
  i2c_master_stop(cmd);
  esp_err_t ret = i2c_master_cmd_begin(I2C_MASTER_PORT, cmd, 1000 / portTICK_PERIOD_MS);
  i2c_cmd_link_delete(cmd);

  return ret;
}

static esp_err_t dac_out_test(void)
{
  esp_err_t ret;
  uint16_t test_value = 0; /* The value sent to DAC input registers */
  i2c_cmd_handle_t cmd;

  for (uint16_t i = 0; i < 4096; i++){

    test_value = i;

    cmd = i2c_cmd_link_create();
    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, (DAC_ADDR << 1) | I2C_MASTER_WRITE, ACK_EN); /* R/W byte is LSB of DAC address */
    i2c_master_write_byte(cmd, 0x50, ACK_EN); /* Multi-write to all channels */

    /* For each channel [A-D] write 2 bytes to input register */
    /* V_ref + PD1 + PD0 + Gx + D11-D8 | D7-D0 */
    for (uint8_t i = 0; i < 4; i++) {
      uint8_t bytes[2];
      bytes[0] = ((uint8_t) DAC_VREF << 7) | ((uint8_t) DAC_PD << 5) | ((uint8_t) DAC_GAIN << 4) | (test_value >> 8);
      bytes[1] = test_value;
      i2c_master_write_byte(cmd, bytes[0], ACK_EN);
      i2c_master_write_byte(cmd, bytes[1], ACK_EN);
    }

    i2c_master_stop(cmd);

    /* Issue the multi-write command */
    /* TODO need to create array of returns and check them for error */
    ret = i2c_master_cmd_begin(I2C_MASTER_PORT, cmd, 1000 / portTICK_PERIOD_MS);
    i2c_cmd_link_delete(cmd);
  }
  return ret;
}

/* Main application entrance */
void app_main(void)
{
  /* Initialize and configure I2C DAC */
  dac_init();

  /* Test DAC */
  esp_err_t ret = dac_ack_test();
  if (ret != ESP_OK){
    ESP_LOGE(TAG, "Failed to initialize DAC");
  } else {
    ESP_LOGI(TAG, "Sucessfully initialized DAC");
  }

  /* Loop to test DAC output */
  while (1) {
    dac_out_test();
  }
}