#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/gpio.h"
#include "esp_adc/adc_oneshot.h"

// ---------------- Pin configuration -------------
#define LED_RED     13
#define LED_BLUE    8

#define ADC_CH_X    ADC_CHANNEL_3   // Joystick X-axis - GPIO 4
#define ADC_CH_Y    ADC_CHANNEL_4   // Joystick Y-axis - GPIO 5

// ---------------- Joystick thresholds ----------------
#define ADC_BITS        12
#define ADC_MAX         ((1 << ADC_BITS) - 1) // 4095 for 12 bits
#define CENTER          2048                  // joystick center (approx half)
#define DEADZONE        400                 // ignore small variations
#define SAMPLES         8                     // average this many samples

// ---------------- Zones ------------------------------
#define ZONE_NONE       0
#define ZONE_RED_1S     1
#define ZONE_RED_3S     2
#define ZONE_BLUE_1S    3
#define ZONE_BLUE_3S    4

// ADC1 handle (created in adc_oneshot_setup and used everywhere)
static adc_oneshot_unit_handle_t adc1_handle = NULL;

// ================== Function Declarations =====================
void init_output(gpio_num_t pin);
void leds_off();
void blink_led_period(gpio_num_t pin, int period_ms);

void blink_red_1s();
void blink_red_3s();
void blink_blue_1s();
void blink_blue_3s();

void adc_oneshot_setup();
int  adc_read_avg(adc_channel_t ch, int samples);
int  select_zone(int x, int y);

// ============================= Main ========================================
void app_main() {
    init_output(LED_RED);
    init_output(LED_BLUE);
    leds_off();

    adc_oneshot_setup();

    while (1) {
        int x = adc_read_avg(ADC_CH_X, SAMPLES);
        int y = adc_read_avg(ADC_CH_Y, SAMPLES);

        printf("x=%d y=%d\n", x, y);

        int z = select_zone(x, y);

        switch (z) {
            case ZONE_RED_1S:   blink_red_1s();  break;
            case ZONE_RED_3S:   blink_red_3s();  break;
            case ZONE_BLUE_1S:  blink_blue_1s(); break;
            case ZONE_BLUE_3S:  blink_blue_3s(); break;
            default:
                leds_off();
                vTaskDelay(pdMS_TO_TICKS(60));
                break;
        }
    }
}

// ========================= Function Definitions ============================

/*
Function name- init_output
Description-  Configure a GPIO as output; disable pulls and interrupts for clean drive.
Parameters-   pin (gpio_num_t): GPIO to configure
return type-  none
*/
void init_output(gpio_num_t pin) {
    gpio_set_direction(pin, GPIO_MODE_OUTPUT);
    gpio_pullup_dis(pin);
    gpio_pulldown_dis(pin);
    gpio_intr_disable(pin);
}

/*
Function name- leds_off
Description-  Turn both LEDs off.
Parameters-   none
return type-  none
*/
void leds_off() {
    gpio_set_level(LED_RED, 0);
    gpio_set_level(LED_BLUE, 0);
}

/*
Function name- blink_led_period
Description-  Blink a given GPIO with the specified period (ms), 50% duty.
Parameters-   pin (gpio_num_t), period_ms (int)
return type-  none
*/
void blink_led_period(gpio_num_t pin, int period_ms) {
    gpio_set_level(pin, 1);
    vTaskDelay(pdMS_TO_TICKS(period_ms / 2));
    gpio_set_level(pin, 0);
    vTaskDelay(pdMS_TO_TICKS(period_ms / 2));
}

/*
Function name- blink_red_1s
Description-  Blink RED LED with 1 second period.
Parameters-   none
return type-  none
*/
void blink_red_1s()  { blink_led_period(LED_RED, 1000); }

/*
Function name- blink_red_3s
Description-  Blink RED LED with 3 second period.
Parameters-   none
return type-  none
*/
void blink_red_3s()  { blink_led_period(LED_RED, 3000); }

/*
Function name- blink_blue_1s
Description-  Blink BLUE LED with 1 second period.
Parameters-   none
return type-  none
*/
void blink_blue_1s() { blink_led_period(LED_BLUE, 1000); }

/*
Function name- blink_blue_3s
Description-  Blink BLUE LED with 3 second period.
Parameters-   none
return type-  none
*/
void blink_blue_3s() { blink_led_period(LED_BLUE, 3000); }

/*
Function name- adc_oneshot_setup
Description-  Create ADC1 oneshot unit and configure X/Y channels (12-bit, 11 dB).
Parameters-   none
return type-  none
*/
void adc_oneshot_setup() {
    adc_oneshot_unit_init_cfg_t unit_cfg = {
        .unit_id = ADC_UNIT_1
    };
    adc_oneshot_new_unit(&unit_cfg, &adc1_handle);

    adc_oneshot_chan_cfg_t chan_cfg = {
        .bitwidth = ADC_BITWIDTH_12,
        .atten    = ADC_ATTEN_DB_11
    };
    adc_oneshot_config_channel(adc1_handle, ADC_CH_X, &chan_cfg);
    adc_oneshot_config_channel(adc1_handle, ADC_CH_Y, &chan_cfg);
}

/*
Function name- adc_read_avg
Description-  Read 'samples' oneshot ADC values from channel 'ch' and return the average.
Parameters-   ch (adc_channel_t), samples (int)
return type-  int (average raw ADC count)
*/
int adc_read_avg(adc_channel_t ch, int samples) {
    long sum = 0;
    for (int i = 0; i < samples; ++i) {
        int raw = 0;
        adc_oneshot_read(adc1_handle, ch, &raw);
        sum += raw;
        vTaskDelay(pdMS_TO_TICKS(2));  // small pause for stability
    }
    return (int)(sum / samples);
}

/*
Function name- select_zone
Description-  Map joystick X/Y positions to a zone label using center + deadzone.
Parameters-   x (int), y (int)
return type-  int (ZONE_* constant)
*/
int select_zone(int x, int y) {
//To have consistent output behavior on each axis, we map the actions of the LEDs to one axis for each colour. (JI - 2024-09-01)
    if (x > CENTER + DEADZONE) return ZONE_BLUE_1S;   // right
    if (x < CENTER - DEADZONE) return ZONE_BLUE_3S;  // left
    if (y > CENTER + DEADZONE) return ZONE_RED_1S;   // up
    if (y < CENTER - DEADZONE) return ZONE_RED_3S;  // down
    return ZONE_NONE;                                // centered
}