#include "battery.h"
#include "system.h"
#include "gpio.h"
#include "esp_log.h"
#include "esp_adc/adc_oneshot.h"
#include "esp_adc/adc_cali.h"
#include "esp_adc/adc_cali_scheme.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"

static const char *TAG = "battery";

static adc_oneshot_unit_handle_t adc1_handle = NULL;
static adc_cali_handle_t adc1_cali_handle = NULL;
static bool adc_calibration_enabled = false;

// ADC Calibration initialization
static bool adc_calibration_init(adc_unit_t unit, adc_channel_t channel, adc_atten_t atten, adc_cali_handle_t *out_handle)
{
    adc_cali_handle_t handle = NULL;
    esp_err_t ret = ESP_FAIL;
    bool calibrated = false;

#if ADC_CALI_SCHEME_CURVE_FITTING_SUPPORTED
    if (!calibrated) {
        ESP_LOGI(TAG, "Calibration scheme: Curve Fitting");
        adc_cali_curve_fitting_config_t cali_config = {
            .unit_id = unit,
            .chan = channel,
            .atten = atten,
            .bitwidth = BATTERY_ADC_WIDTH,
        };
        ret = adc_cali_create_scheme_curve_fitting(&cali_config, &handle);
        if (ret == ESP_OK) {
            calibrated = true;
        }
    }
#endif

#if ADC_CALI_SCHEME_LINE_FITTING_SUPPORTED
    if (!calibrated) {
        ESP_LOGI(TAG, "Calibration scheme: Line Fitting");
        adc_cali_line_fitting_config_t cali_config = {
            .unit_id = unit,
            .atten = atten,
            .bitwidth = BATTERY_ADC_WIDTH,
        };
        ret = adc_cali_create_scheme_line_fitting(&cali_config, &handle);
        if (ret == ESP_OK) {
            calibrated = true;
        }
    }
#endif

    *out_handle = handle;
    if (ret == ESP_OK) {
        ESP_LOGI(TAG, "ADC calibration successful");
    } else {
        ESP_LOGW(TAG, "ADC calibration failed: %s", esp_err_to_name(ret));
    }
    return calibrated;
}

esp_err_t battery_init(void)
{
    esp_err_t ret;

    // Configure ADC1 oneshot mode
    adc_oneshot_unit_init_cfg_t init_config = {
        .unit_id = ADC_UNIT_1,
    };
    ret = adc_oneshot_new_unit(&init_config, &adc1_handle);
    if (ret != ESP_OK) {
        ESP_LOGE(TAG, "Failed to initialize ADC unit: %s", esp_err_to_name(ret));
        return ret;
    }

    // Configure ADC channel
    adc_oneshot_chan_cfg_t config = {
        .bitwidth = BATTERY_ADC_WIDTH,
        .atten = BATTERY_ADC_ATTEN,
    };
    ret = adc_oneshot_config_channel(adc1_handle, BATTERY_ADC_CHANNEL, &config);
    if (ret != ESP_OK) {
        ESP_LOGE(TAG, "Failed to configure ADC channel: %s", esp_err_to_name(ret));
        return ret;
    }

    // Initialize calibration
    adc_calibration_enabled = adc_calibration_init(ADC_UNIT_1, BATTERY_ADC_CHANNEL,
                                                    BATTERY_ADC_ATTEN, &adc1_cali_handle);

    ESP_LOGI(TAG, "Battery monitoring initialized on GPIO34 (ADC1_CH6)");
    return ESP_OK;
}

int battery_read_raw(void)
{
    int adc_raw = 0;
    esp_err_t ret = adc_oneshot_read(adc1_handle, BATTERY_ADC_CHANNEL, &adc_raw);
    if (ret != ESP_OK) {
        ESP_LOGE(TAG, "Failed to read ADC: %s", esp_err_to_name(ret));
        return -1;
    }
    return adc_raw;
}

int battery_read_voltage_mv(void)
{
    int voltage_mv = 0;
    int adc_sum = 0;
    int valid_samples = 0;

    // Take multiple samples and average
    for (int i = 0; i < BATTERY_SAMPLES; i++) {
        int adc_raw = battery_read_raw();
        if (adc_raw >= 0) {
            adc_sum += adc_raw;
            valid_samples++;
        }
        vTaskDelay(pdMS_TO_TICKS(1)); // Small delay between samples
    }

    if (valid_samples == 0) {
        ESP_LOGE(TAG, "No valid ADC samples");
        return -1;
    }

    int adc_avg = adc_sum / valid_samples;

    // Convert to voltage using calibration if available
    if (adc_calibration_enabled) {
        esp_err_t ret = adc_cali_raw_to_voltage(adc1_cali_handle, adc_avg, &voltage_mv);
        if (ret != ESP_OK) {
            ESP_LOGW(TAG, "Calibration conversion failed, using raw calculation");
            adc_calibration_enabled = false; // Disable for future reads
        }
    }

    // Fallback to manual calculation if calibration not available
    if (!adc_calibration_enabled) {
        // Simple linear conversion for 12-bit ADC with 12dB attenuation
        // Approximate range: 0-3300mV for 0-4095 raw values
        voltage_mv = (adc_avg * 3300) / 4095;
    }

    // Apply voltage divider ratio to get actual battery voltage
    voltage_mv = (int)(voltage_mv * BATTERY_VOLTAGE_DIVIDER_RATIO);

    return voltage_mv;
}

int battery_get_percentage(void)
{
    int voltage_mv = battery_read_voltage_mv();

    if (voltage_mv < 0) {
        return -1;
    }

    // Clamp to min/max range
    if (voltage_mv >= BATTERY_VOLTAGE_MAX) {
        return 100;
    }
    if (voltage_mv <= BATTERY_VOLTAGE_MIN) {
        return 0;
    }

    // Linear interpolation between min and max
    int percentage = ((voltage_mv - BATTERY_VOLTAGE_MIN) * 100) /
                     (BATTERY_VOLTAGE_MAX - BATTERY_VOLTAGE_MIN);

    return percentage;
}

// Battery monitoring task
static void battery_monitoring_task(void *pvParameters)
{
    ESP_LOGI(TAG, "Battery monitoring task started");

    while (1) {
        int voltage_mv = battery_read_voltage_mv();
        int percentage = battery_get_percentage();

        if (voltage_mv >= 0 && percentage >= 0) {
            // Update system state with battery info
            system_setBatteryVoltage(voltage_mv);
            system_setBatteryPercentage(percentage);

            ESP_LOGI(TAG, "Battery: %d mV (%d%%)", voltage_mv, percentage);
        } else {
            ESP_LOGW(TAG, "Failed to read battery voltage");
        }

        // Read battery every 30 seconds
        vTaskDelay(pdMS_TO_TICKS(30000));
    }
}

void battery_start_monitoring_task(void)
{
    xTaskCreate(battery_monitoring_task, "battery_task", 3072, NULL, 5, NULL);
    ESP_LOGI(TAG, "Battery monitoring task created");
}