#include "motion_gesture.h"

#include "ui_nav.h"

#include "esp_log.h"
#include "esp_timer.h"
#include "freertos/FreeRTOS.h"
#include "freertos/queue.h"
#include "freertos/task.h"
#include "lvgl.h"

#include <math.h>

static const char *TAG = "motion";

#define SAMPLE_RATE_HZ           100
#define THRESHOLD_LOW_G          0.6f
#define THRESHOLD_MED_G          0.8f
#define THRESHOLD_HIGH_G         1.0f
#define WINDOW_MS                300
#define MIN_SAMPLES              5
#define COOLDOWN_MS              800
#define CALIBRATION_MS           500

typedef enum {
    GESTURE_IDLE = 0,
    GESTURE_COOLDOWN,
} gesture_state_t;

static QueueHandle_t s_nav_queue;
static bool s_enabled = true;
static float s_threshold = THRESHOLD_MED_G;
static gesture_state_t s_state = GESTURE_IDLE;

static float s_ref_x;
static float s_ref_y;
static float s_ref_z;
static bool s_calibrated;
static int64_t s_cal_start_us;
static int s_cal_count;
static float s_cal_sum_x;
static float s_cal_sum_y;
static float s_cal_sum_z;

static int s_over_count;
static int64_t s_window_start_us;
static int64_t s_cooldown_until_us;

static void nav_handler_task(void *arg)
{
    (void)arg;
    motion_nav_event_t ev;

    while (xQueueReceive(s_nav_queue, &ev, portMAX_DELAY) == pdTRUE) {
        if (ev == MOTION_NAV_NEXT) {
            ui_nav_next();
        }
    }
}

static float magnitude(float ax, float ay, float az)
{
    return sqrtf(ax * ax + ay * ay + az * az);
}

static void post_nav_next(void)
{
    motion_nav_event_t ev = MOTION_NAV_NEXT;
    if (xQueueSend(s_nav_queue, &ev, 0) != pdTRUE) {
        ESP_LOGW(TAG, "nav queue full");
    } else {
        ESP_LOGI(TAG, "Shake detected -> next screen");
    }
}

static void run_calibration(float ax, float ay, float az)
{
    s_cal_sum_x += ax;
    s_cal_sum_y += ay;
    s_cal_sum_z += az;
    s_cal_count++;

    int64_t elapsed_us = esp_timer_get_time() - s_cal_start_us;
    if (elapsed_us >= (int64_t)CALIBRATION_MS * 1000) {
        if (s_cal_count > 0) {
            s_ref_x = s_cal_sum_x / (float)s_cal_count;
            s_ref_y = s_cal_sum_y / (float)s_cal_count;
            s_ref_z = s_cal_sum_z / (float)s_cal_count;
        }
        s_calibrated = true;
        ESP_LOGI(TAG, "Baseline calibrated (ref=%.3f,%.3f,%.3f g)", s_ref_x, s_ref_y,
                 s_ref_z);
    }
}

static void reset_window(void)
{
    s_over_count = 0;
    s_window_start_us = 0;
}

static void process_sample(float ax, float ay, float az)
{
    int64_t now_us = esp_timer_get_time();

    if (!s_calibrated) {
        run_calibration(ax, ay, az);
        return;
    }

    if (s_state == GESTURE_COOLDOWN) {
        if (now_us >= s_cooldown_until_us) {
            s_state = GESTURE_IDLE;
            reset_window();
        }
        return;
    }

    float dx = ax - s_ref_x;
    float dy = ay - s_ref_y;
    float dz = az - s_ref_z;
    float mag = magnitude(dx, dy, dz);

    if (mag > s_threshold) {
        if (s_over_count == 0) {
            s_window_start_us = now_us;
        }
        s_over_count++;

        int64_t window_us = (int64_t)WINDOW_MS * 1000;
        if ((now_us - s_window_start_us) > window_us) {
            s_over_count = 1;
            s_window_start_us = now_us;
        }

        if (s_over_count >= MIN_SAMPLES) {
            if (s_enabled) {
                post_nav_next();
            }
            s_state = GESTURE_COOLDOWN;
            s_cooldown_until_us = now_us + (int64_t)COOLDOWN_MS * 1000;
            reset_window();
        }
    } else if (s_over_count > 0) {
        int64_t window_us = (int64_t)WINDOW_MS * 1000;
        if ((now_us - s_window_start_us) > window_us) {
            reset_window();
        }
    }
}

void motion_gesture_init(motion_nav_cb_t cb)
{
    (void)cb;

    s_nav_queue = xQueueCreate(4, sizeof(motion_nav_event_t));
    xTaskCreate(nav_handler_task, "nav_handler", 2048, NULL, 5, NULL);

    s_cal_start_us = esp_timer_get_time();
    ESP_LOGI(TAG, "Motion gesture ready (calibrating %d ms)", CALIBRATION_MS);
}

void motion_gesture_set_enabled(bool enabled)
{
    s_enabled = enabled;
    ESP_LOGI(TAG, "Shake navigation %s", enabled ? "enabled" : "disabled");
}

void motion_gesture_set_sensitivity(shake_sensitivity_t sens)
{
    switch (sens) {
    case SHAKE_SENS_LOW:
        s_threshold = THRESHOLD_LOW_G;
        break;
    case SHAKE_SENS_MED:
        s_threshold = THRESHOLD_MED_G;
        break;
    case SHAKE_SENS_HIGH:
        s_threshold = THRESHOLD_HIGH_G;
        break;
    default:
        LV_ASSERT_MSG(false, "unexpected shake_sensitivity_t");
        break;
    }
    ESP_LOGI(TAG, "Sensitivity set (threshold=%.2f g)", s_threshold);
}

void motion_gesture_on_sample(float ax_g, float ay_g, float az_g)
{
    process_sample(ax_g, ay_g, az_g);
}