#include "os_event.h"
#include "freertos/FreeRTOS.h"
#include "freertos/queue.h"
#include "freertos/task.h"
#include "esp_log.h"

static const char *TAG = "SYS_EVENT";

#define MAX_SUBSCRIBERS 16
#define EVENT_QUEUE_LEN 32

typedef struct {
    sys_event_cb_t callback;
    void *user_arg;
} subscriber_entry_t;

static subscriber_entry_t s_subscribers[MAX_SUBSCRIBERS];
static size_t s_subscriber_count = 0;
static QueueHandle_t s_event_queue = NULL;

static void sys_event_dispatch_task(void *pvParameters)
{
    sys_event_t event;
    while (1) {
        if (xQueueReceive(s_event_queue, &event, portMAX_DELAY) == pdTRUE) {
            for (size_t i = 0; i < s_subscriber_count; i++) {
                if (s_subscribers[i].callback) {
                    s_subscribers[i].callback(&event, s_subscribers[i].user_arg);
                }
            }
        }
    }
}

esp_err_t sys_event_init(void)
{
    if (s_event_queue != NULL) {
        return ESP_OK;
    }
    s_event_queue = xQueueCreate(EVENT_QUEUE_LEN, sizeof(sys_event_t));
    if (!s_event_queue) {
        ESP_LOGE(TAG, "Failed to create event queue");
        return ESP_ERR_NO_MEM;
    }

    BaseType_t ret = xTaskCreate(sys_event_dispatch_task, "sys_event_task", 3072, NULL, 10, NULL);
    if (ret != pdPASS) {
        ESP_LOGE(TAG, "Failed to create event dispatcher task");
        return ESP_FAIL;
    }

    ESP_LOGI(TAG, "System Event Bus initialized");
    return ESP_OK;
}

esp_err_t sys_event_post(sys_event_id_t id, int32_t data, void *ptr_data)
{
    if (!s_event_queue) {
        return ESP_ERR_INVALID_STATE;
    }
    sys_event_t event = {
        .id = id,
        .data = data,
        .ptr_data = ptr_data
    };
    if (xQueueSend(s_event_queue, &event, 0) != pdTRUE) {
        ESP_LOGW(TAG, "Event queue full, dropped event %d", (int)id);
        return ESP_ERR_NO_MEM;
    }
    return ESP_OK;
}

esp_err_t sys_event_subscribe(sys_event_cb_t callback, void *user_arg)
{
    if (!callback) return ESP_ERR_INVALID_ARG;
    if (s_subscriber_count >= MAX_SUBSCRIBERS) {
        ESP_LOGE(TAG, "Max subscribers reached");
        return ESP_ERR_NO_MEM;
    }
    s_subscribers[s_subscriber_count].callback = callback;
    s_subscribers[s_subscriber_count].user_arg = user_arg;
    s_subscriber_count++;
    return ESP_OK;
}