#include "os_input.h"
#include "os_event.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_log.h"
#include "esp_timer.h"

static const char *TAG = "SYS_INPUT";

#define DEBOUNCE_TIME_MS      12
#define DOUBLE_CLICK_GAP_MS   260
#define LONG_PRESS_TIME_MS    380
#define HOME_PRESS_TIME_MS    1400

typedef struct {
    sys_input_handler_t handler;
    void *user_arg;
} input_listener_t;

#define MAX_INPUT_LISTENERS 8
static input_listener_t s_listeners[MAX_INPUT_LISTENERS];
static size_t s_listener_count = 0;
static gpio_num_t s_button_pin = GPIO_NUM_9;

static void dispatch_action(input_action_t action)
{
    sys_event_id_t evt_id = SYS_EVENT_CUSTOM;
    switch (action) {
        case INPUT_ACTION_CLICK:
            evt_id = SYS_EVENT_INPUT_SHORT_PRESS;
            break;
        case INPUT_ACTION_DOUBLE_CLICK:
            evt_id = SYS_EVENT_INPUT_DOUBLE_CLICK;
            break;
        case INPUT_ACTION_LONG_PRESS:
            evt_id = SYS_EVENT_INPUT_LONG_PRESS;
            break;
        case INPUT_ACTION_HOLD_HOME:
            evt_id = SYS_EVENT_INPUT_EXTRA_LONG_PRESS;
            break;
        default:
            return;
    }

    sys_event_post(evt_id, (int32_t)action, NULL);

    for (size_t i = 0; i < s_listener_count; i++) {
        if (s_listeners[i].handler) {
            s_listeners[i].handler(action, s_listeners[i].user_arg);
        }
    }
}

void sys_input_inject(input_action_t action)
{
    dispatch_action(action);
}

esp_err_t sys_input_register_handler(sys_input_handler_t handler, void *user_arg)
{
    if (!handler) return ESP_ERR_INVALID_ARG;
    if (s_listener_count >= MAX_INPUT_LISTENERS) return ESP_ERR_NO_MEM;
    s_listeners[s_listener_count].handler = handler;
    s_listeners[s_listener_count].user_arg = user_arg;
    s_listener_count++;
    return ESP_OK;
}

static void button_scanner_task(void *pvParameters)
{
    bool last_state = false;
    uint32_t press_start_ms = 0;
    uint32_t last_click_time_ms = 0;
    bool long_press_fired = false;
    bool home_press_fired = false;

    while (1) {
        vTaskDelay(pdMS_TO_TICKS(5)); // High-rate 200 Hz scan loop for zero input lag
        uint32_t now_ms = (uint32_t)(esp_timer_get_time() / 1000ULL);
        bool current_state = (gpio_get_level(s_button_pin) == 0);

        if (current_state && !last_state) {
            // Button pressed down
            press_start_ms = now_ms;
            long_press_fired = false;
            home_press_fired = false;
        } else if (current_state && last_state) {
            // Button held down
            uint32_t held_duration = now_ms - press_start_ms;
            if (!home_press_fired && held_duration >= HOME_PRESS_TIME_MS) {
                home_press_fired = true;
                dispatch_action(INPUT_ACTION_HOLD_HOME);
            } else if (!long_press_fired && !home_press_fired && held_duration >= LONG_PRESS_TIME_MS) {
                long_press_fired = true;
                dispatch_action(INPUT_ACTION_LONG_PRESS);
            }
        } else if (!current_state && last_state) {
            // Button released
            uint32_t press_duration = now_ms - press_start_ms;
            if (press_duration >= DEBOUNCE_TIME_MS && !long_press_fired && !home_press_fired) {
                if ((now_ms - last_click_time_ms) <= DOUBLE_CLICK_GAP_MS) {
                    dispatch_action(INPUT_ACTION_DOUBLE_CLICK);
                    last_click_time_ms = 0;
                } else {
                    // Instant click dispatch upon tap release (no 280ms lag penalty!)
                    dispatch_action(INPUT_ACTION_CLICK);
                    last_click_time_ms = now_ms;
                }
            }
        }

        last_state = current_state;
    }
}

esp_err_t sys_input_init(gpio_num_t button_gpio)
{
    s_button_pin = button_gpio;

    gpio_config_t io_conf = {
        .pin_bit_mask = (1ULL << s_button_pin),
        .mode = GPIO_MODE_INPUT,
        .pull_up_en = GPIO_PULLUP_ENABLE,
        .pull_down_en = GPIO_PULLDOWN_DISABLE,
        .intr_type = GPIO_INTR_DISABLE,
    };
    esp_err_t err = gpio_config(&io_conf);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "Failed to configure button GPIO %d: %s", (int)s_button_pin, esp_err_to_name(err));
        return err;
    }

    BaseType_t ret = xTaskCreate(button_scanner_task, "btn_scan_task", 3072, NULL, 12, NULL);
    if (ret != pdPASS) {
        ESP_LOGE(TAG, "Failed to create button scanner task");
        return ESP_FAIL;
    }

    ESP_LOGI(TAG, "Input gesture engine started on GPIO %d (Instant-Response Mode)", (int)s_button_pin);
    return ESP_OK;
}