#include "mcp3550.h"
#include "mcp23018.h"
#include "driver/gpio.h"
#include <esp_timer.h>


#define TAG_MICS "MICS_ADC"
#define MCP3550_SPS 3.75f
#define MCP3550_CONVERSION_MS ((int)(1000.0f / MCP3550_SPS)) // ~267ms
#define MCP3550_TIMEOUT_MS 400

#define ADC_COUNT 4
const uint8_t adc_cs_pins[ADC_COUNT] = {
    MCP_CS_ADC_NH3, MCP_CS_ADC_CO, MCP_CS_ADC_NO2, MCP_CS_ADC_UVC
};


spi_device_handle_t mcp3550_handle;

void mcp3550_spi_init()
{
    spi_device_interface_config_t devcfg = {
        .clock_speed_hz = 100000,
        .mode = 0,
        .spics_io_num = -1, // We handle CS manually
        .queue_size = 1,
    };

    ESP_ERROR_CHECK(spi_bus_add_device(SPI2_HOST, &devcfg, &mcp3550_handle));

    // Set MISO pin for input (needed for polling)
    gpio_set_direction(MCP3550_MISO_GPIO, GPIO_MODE_INPUT);
    mcp23018_set_pin(MCP23018_DEV_HANDLE, MCP_MICS_POWER, 1); // CS HIGH
}


int32_t mcp3550_read(uint8_t cs_pin)
{
    uint8_t rx_buf[4] = {0}; // 25 bits fits in 4 bytes

    int64_t start = esp_timer_get_time(); // in microseconds
    while (true) {
        mcp23018_set_pin(MCP23018_DEV_HANDLE, cs_pin, 0); // CS LOW

        spi_transaction_t trans = {
            .length = 25,
            .rx_buffer = rx_buf,
        };

        esp_err_t err = spi_device_transmit(mcp3550_handle, &trans);

        mcp23018_set_pin(MCP23018_DEV_HANDLE, cs_pin, 1); // CS HIGH

        if (err != ESP_OK) {
            ESP_LOGE(TAG_MICS, "SPI transmit failed on CS pin %u", cs_pin);
            return INT32_MIN;
        }

        bool dr = (rx_buf[0] & 0x80) != 0;
        if (!dr) break;

        if ((esp_timer_get_time() - start) > (MCP3550_TIMEOUT_MS * 1000)) {
            ESP_LOGW(TAG_MICS, "Timeout waiting for DR=0 on CS pin %u", cs_pin);
            return INT32_MIN;
        }

        vTaskDelay(pdMS_TO_TICKS(10)); // Wait before retrying
    }

    // Combine 22-bit result (drop DR + status bits)
    uint32_t raw = ((rx_buf[0] & 0x3F) << 16) | (rx_buf[1] << 8) | rx_buf[2];

    // Sign-extend 22-bit value
    int32_t value = raw;
    if (value & (1 << 21)) value |= 0xFFC00000;

    return value;
}


float mcp3550_to_voltage(int32_t value, float vref)
{
    return ((float)value / (1 << 21)) * vref;
}

mics_adc_data_t mcp3550_read_all(float vref)
{
    mics_adc_data_t data;
    int32_t raw[ADC_COUNT];
    float volts[ADC_COUNT];

    for (int i = 0; i < ADC_COUNT; i++) {
        raw[i] = mcp3550_read(adc_cs_pins[i]);
        vTaskDelay(pdMS_TO_TICKS(10)); // Wait before retrying
        volts[i] = mcp3550_to_voltage(raw[i], vref);
    }

    data.raw_nh3 = raw[0]; data.volts_nh3 = volts[0];
    data.raw_co  = raw[1]; data.volts_co  = volts[1];
    data.raw_no2 = raw[2]; data.volts_no2 = volts[2];
    data.raw_uvc = raw[3]; data.volts_uvc = volts[3];

    return data;
}

void log_mics_adc_values(mics_adc_data_t *data)
{
    ESP_LOGI(TAG_MICS,
             "ADC Readings:\n"
             "  NH3  -> Raw: %8d, Voltage: %7.6f V\n"
             "  CO   -> Raw: %8d, Voltage: %7.6f V\n"
             "  NO2  -> Raw: %8d, Voltage: %7.6f V\n"
             "  UVC  -> Raw: %8d, Voltage: %7.6f V",
             data->raw_nh3, data->volts_nh3,
             data->raw_co,  data->volts_co,
             data->raw_no2, data->volts_no2,
             data->raw_uvc, data->volts_uvc);
}