#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/i2c.h"
#include "bme68x.h"

/* ----- I2C pins (ESP-01S: SDA=GPIO0, SCL=GPIO2) ----- */
#define I2C_PORT        I2C_NUM_0
#define I2C_SDA_PIN     0
#define I2C_SCL_PIN     2
#define I2C_TIMEOUT_MS  1000

/* BME68x address: SDO=GND -> LOW(0x76), SDO=VCC -> HIGH(0x77) */
#define BME68X_ADDR     BME68X_I2C_ADDR_LOW

/* --------- ESP8266 I2C init (note: clk_stretch_tick field) --------- */
static void i2c_init(void)
{
    i2c_config_t conf = {
        .mode = I2C_MODE_MASTER,
        .sda_io_num = I2C_SDA_PIN,
        .scl_io_num = I2C_SCL_PIN,
        .sda_pullup_en = GPIO_PULLUP_ENABLE,
        .scl_pullup_en = GPIO_PULLUP_ENABLE,
        .clk_stretch_tick = 300,  // reasonable default on ESP8266
    };
    i2c_param_config(I2C_PORT, &conf);
    i2c_driver_install(I2C_PORT, conf.mode);  // ESP8266 signature: (port, mode)
}

/* ------------- BME68x I2C read/write helpers ------------- */
static int8_t bme68x_i2c_read(uint8_t reg, uint8_t *data, uint32_t len, void *intf_ptr)
{
    uint8_t addr = *(uint8_t *)intf_ptr;  // 7-bit address
    i2c_cmd_handle_t cmd = i2c_cmd_link_create();

    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, (addr << 1) | I2C_MASTER_WRITE, true);
    i2c_master_write_byte(cmd, reg, true);

    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, (addr << 1) | I2C_MASTER_READ, true);
    if (len > 1) i2c_master_read(cmd, data, len - 1, I2C_MASTER_ACK);
    i2c_master_read_byte(cmd, data + len - 1, I2C_MASTER_NACK);
    i2c_master_stop(cmd);

    esp_err_t ret = i2c_master_cmd_begin(I2C_PORT, cmd, I2C_TIMEOUT_MS / portTICK_PERIOD_MS);
    i2c_cmd_link_delete(cmd);
    return (ret == ESP_OK) ? BME68X_OK : BME68X_E_COM_FAIL;
}

static int8_t bme68x_i2c_write(uint8_t reg, const uint8_t *data, uint32_t len, void *intf_ptr)
{
    uint8_t addr = *(uint8_t *)intf_ptr;
    i2c_cmd_handle_t cmd = i2c_cmd_link_create();

    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, (addr << 1) | I2C_MASTER_WRITE, true);
    i2c_master_write_byte(cmd, reg, true);
    i2c_master_write(cmd, (uint8_t*)data, len, true);
    i2c_master_stop(cmd);

    esp_err_t ret = i2c_master_cmd_begin(I2C_PORT, cmd, I2C_TIMEOUT_MS / portTICK_PERIOD_MS);
    i2c_cmd_link_delete(cmd);
    return (ret == ESP_OK) ? BME68X_OK : BME68X_E_COM_FAIL;
}

static void bme68x_delay_us(uint32_t period_us, void *intf_ptr)
{
    (void)intf_ptr;
    /* Delay granularity is ms on FreeRTOS; round up */
    vTaskDelay((period_us + 999) / 1000 / portTICK_PERIOD_MS);
}

/* ----------------------- App ----------------------- */
void app_main(void)
{
    i2c_init();

    struct bme68x_dev dev = {0};
    uint8_t i2c_addr = BME68X_ADDR;

    dev.intf = BME68X_I2C_INTF;
    dev.read = bme68x_i2c_read;
    dev.write = bme68x_i2c_write;
    dev.delay_us = bme68x_delay_us;
    dev.intf_ptr = &i2c_addr;

    if (bme68x_init(&dev) != BME68X_OK) {
        printf("BME68x init failed\n");
        return;
    }

    /* Oversampling + filter */
    struct bme68x_conf conf = {
        .os_hum = BME68X_OS_2X,
        .os_temp = BME68X_OS_8X,
        .os_pres = BME68X_OS_4X,
        .filter = BME68X_FILTER_SIZE_3,
        .odr = BME68X_ODR_NONE
    };
    if (bme68x_set_conf(&conf, &dev) != BME68X_OK) {
        printf("set_conf failed\n");
        return;
    }

    /* Gas heater config for one-shot */
    struct bme68x_heatr_conf hconf = {
        .enable = BME68X_ENABLE,
        .heatr_temp = 320,    // °C
        .heatr_dur = 150      // ms
    };
    if (bme68x_set_heatr_conf(BME68X_FORCED_MODE, &hconf, &dev) != BME68X_OK) {
        printf("set_heatr_conf failed\n");
        return;
    }

    while (1) {
        if (bme68x_set_op_mode(BME68X_FORCED_MODE, &dev) != BME68X_OK) {
            printf("set_op_mode failed\n");
            vTaskDelay(pdMS_TO_TICKS(1000));
            continue;
        }

        /* Calculate measurement duration and wait */
        uint32_t dur_us = bme68x_get_meas_dur(BME68X_FORCED_MODE, &conf, &dev) + (hconf.heatr_dur * 1000);
        bme68x_delay_us(dur_us, NULL);

        struct bme68x_data data;
        uint8_t n_fields = 0;

        if (bme68x_get_data(BME68X_FORCED_MODE, &data, &n_fields, &dev) == BME68X_OK && n_fields > 0) {
            /* Note: API returns fixed-point values; divide per defs */
            float temp_c = data.temperature / 100.0f;   // °C
            float press_hpa = data.pressure / 100.0f;   // hPa
            float hum_pct = data.humidity / 1000.0f;    // %RH
            float gas_kohm = data.gas_resistance / 1000.0f;

            printf("T=%.2f °C  RH=%.2f %%  P=%.2f hPa  Gas=%.2f kΩ\n",
                   temp_c, hum_pct, press_hpa, gas_kohm);
        } else {
            printf("read failed\n");
        }

        vTaskDelay(pdMS_TO_TICKS(2000));
    }
}